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[Display omitted] Interactions between manganese (Mn) and iron (Fe) are widespread processes in soils and sediments, however, the abiotic transformation mechanisms are not fully understood. Herein, Mn(II) oxidation on hematite were investigated at various pH under oxic condition. Mn(II) oxidation rates increased from 3 × 10−4 to 8 × 10−2 h−1 as pH increased from 7.0 to 9.0, whereas hematite enhanced Mn(II) oxidation rates to 1 h−1. During oxidation process, high pH could promote the oxidation of Mn(II) into Mn minerals, resulting in the rapid consumption of the newly-formed H+, and high pH facilitated Mn(II) adsorption and oxidation by altering Mn(II) reactivity and speciation. Only granule-like hausmannite was found on the hematite surface at pH 7.0, whereas hausmannite particles and feitknechtite and manganite nanowires were formed at pH from 7.5 to 9.0. Moreover, a co-shell structured nanowire composed of manganite and feitknechtite was observed owing to autocatalytic reactions. Specifically, electron transfers between Mn(II) and O 2 occurred on the surface or through bulk phase of hematite, and direct electron transfers in the O 2 -Mn(II) complex and indirect electron transfers in the O 2 -Fe(II/III)-Mn(II) complex may both have contribution to the overall reactions. The findings provide a comprehensive interpretation of Fe-Mn interaction and have implications for the formation of soil Fe-Mn oxyhydroxides with unique properties in controlling element cycling. [ABSTRACT FROM AUTHOR]

Objective. To study the feasibility of intensity modulated radiation therapy (IMRT) for stage N0 nasopharyngeal carcinoma (NPC) and its parotid gland (PG) function preservation from physical and dosimetric aspects. Methods. All the clinical data of 77 patients with pathologically confirmed T1-4N0M0 NPC who received radiotherapy between July 2017 and October 2019 in the Radiotherapy Center of Taizhou Hospital of Zhejiang Province affiliated to Wenzhou Medical University were analyzed retrospectively. Three-dimensional conformal radiotherapy (3D-CRT) and IMRT were used in 35 and 42 cases, respectively. The treatment efficiency and the dosimetry differences of the PG in the intensity modulation plan were compared between groups. Quantitative monitoring of 99mTc radionuclide imaging of PG was performed before, at the end of, and 3, 6, and 12 months after radiotherapy. The degree of PG function injury and xerostomia was compared between groups at the end of radiotherapy and 12 months later. Results. Higher minimal, maximal, and average irradiation doses of PG were determined in 3D-CRT-treated patients compared with IMRT-treated cases (P < 0.05). Compared with before radiotherapy, the PG uptake index (UI) and excretion index (EI) of both cohorts of patients decreased to varying degrees at the end of radiotherapy, with PG function injury and xerostomia symptoms observed in all cases but with no obvious difference between groups (P > 0.05). To a certain extent, the PG function recovered and the xerostomia symptoms relieved in both groups 12 months after radiotherapy, with better improvements in IMRT group versus 3D-CRT group. Conclusion. IMRT has similar short-term efficacy to 3D-CRT in treating patients with stage N0 NPC, but it can effectively reduce the dose of PG radiotherapy and protect the PG function on the premise of ensuring sufficient tumor coverage and dose, showing certain dosimetry advantages. [ABSTRACT FROM AUTHOR]

Objective. Parotid gland (PG) is a radiosensitive organ, and xerostomia (XS) is a key factor affecting patients' life quality after conventional radiotherapy for head and neck tumors. In this study, dosimetry analysis was performed on PG stem cell preservation in intensity-modulated radiotherapy (IMRT) for nasopharyngeal carcinoma (NPC). Methods. All clinical data of 80 NPC patients diagnosed pathologically in the Radiotherapy Department of Taizhou Hospital of Zhejiang Province Affiliated with Wenzhou Medical University from August 2017 to September 2019 were retrospectively analyzed. Patients were assigned to a regular group and a restricted group according to different IMRT plans, in which a dose limitation for the parotid duct was added in the restricted group in addition to the conventional plan used in the regular group to minimize the parotid duct radiation dose. The differences in planning target volume (PTV) dose distribution, organ at risk (OAR) dose, and dose to the PG and its ducts were compared between the two groups. Results. Significantly higher mean irradiation doses of the brainstem, mandible, and oral cavity were determined in the restricted group compared with the regular group (P > 0.05), but there was no significant difference in the mean dose of other OARs irradiated (P > 0.05). As compared to the irradiation of bilateral PGs, no statistical differences were found in the mean irradiation dose and V30 between regular and restricted groups (P > 0.05), but lower V20 and higher V45 were determined in the restricted group (P < 0.05). The mean irradiation dose, V15, V20, and V26 of bilateral parotid ducts were lower in the restricted group as compared to the regular group (P < 0.05). Conclusion. IMRT for NPC can effectively reduce the mean irradiation dose and play a PG stem cell preservation role by giving specific dose limitation conditions to the parotid duct area without affecting PTV dose distribution and OAR irradiation dose, which has certain feasibility. [ABSTRACT FROM AUTHOR]

Investigating whether landmarks and routes affect navigational efficiency and learning transfer in traffic is essential. In this study, a virtual reality-based driving system was employed to determine the effects of landmarks and routes on human neurocognitive behavior. The participants made four (4) journeys to predetermined destinations. They were provided with different landmarks and routes to aid in reaching their respective destinations. We considered two (2) groups and conducted two (2) sessions per group in this study. Each group had sufficient and insufficient landmarks. We hypothesized that using insufficient landmarks would elicit an increase in psychophysiological activation, such as increased heart rate, eye gaze, and pupil size, which would cause participants to make more errors. Moreover, easy and difficult routes elicited different cognitive workloads. Thus, a high cognitive load would negatively affect the participants when trying to apply the knowledge acquired at the beginning of the exercise. In addition, the navigational efficiency of routes with sufficient landmarks was remarkably higher than that of routes with insufficient landmarks. We evaluated the effects of landmarks and routes by assessing the recorded information of the drivers' pupil size, heart rate, and driving performance data. An analytical strategy, several machine learning algorithms, and data fusion methods have been employed to measure the neurocognitive load of each participant for user classification. The results showed that insufficient landmarks and difficult routes increased pupil size and heart rate, which caused the participants to make more errors. The results also indicated that easy routes with sufficient landmarks were deemed more efficient for navigation, where users' cognitive loads were much lower than those with insufficient landmarks and difficult routes. The high cognitive workload hindered the participants when trying to apply the knowledge acquired at the beginning of the exercise. Meanwhile, the data fusion method achieved higher accuracy than the other classification methods. The results of this study will help improve the use of landmarks and design of driving routes, as well as paving the way to analyze traffic safety using the drivers' cognition and performance data. [ABSTRACT FROM AUTHOR]

A new quick-scanning X-ray absorption fine-structure (QXAFS) system has been established on beamline 1W1B at the Beijing Synchrotron Radiation Facility. As an independent device, the QXAFS system can be employed by other beamlines equipped with a double-crystal monochromator to carry out quick energy scans and data acquisition. Both continuous-scan and trapezoidal-scan modes are available in this system to satisfy the time scale from subsecond (in the X-ray absorption near-edge structure region) to 1 min. Here, the trapezoidal-scan method is presented as being complementary to the continuous-scan method, in order to maintain high energy resolution and good signal-to-noise ratio. The system is demonstrated to be very reliable and has been combined with in situ cells to carry out time-resolved XAFS studies. [ABSTRACT FROM AUTHOR]

Searching low sintering temperature material with ultra-high Curie temperature (>800 °C) is urgent to seafloor hydrothermal vents detection. Bi 2 WO 6 was first improved to possess ultra-high Curie temperature and ultra-high depolarization temperature by experiment. The MnCO 3 was selected as dopant materials due to its excellent effect on improvement of sintering abilities and piezoelectric properties. The density test shows that Mn addition can obviously improve the density of Bi 2 WO 6 ceramics from 93.6% to 97.76%, and the grains also changed from round to layered. The crystal structure change with Mn addition was tested by synchrotron radiation and calculated by ab initio and Rietveld refinement. The symmetry group of ultra-high Curie temperature Bi 2 WO 6 is Aba2 (41). The XAFS results show that Mn atom more likely at the Bi-site in the crystal structure of Bi 2 W 1-x Mn x O 6 and the Mn ion has the valence alternation. The Curie temperature of Bi 2 W 1-x Mn x O 6 with increasing x are 997 °C, 915 °C, 890 °C, 729 °C, respectively, and the depolarization temperatures are around 940 °C, 895 °C, 825 °C, and 700 °C, respectively. The results show that Bi 2 W 1-x Mn x O 6 (x ≤ 0.01) ceramics are suitable for the ultra-high temperature applications of sensors or transducers on seafloor hydrothermal vents detection. [ABSTRACT FROM AUTHOR]

Simulations of the periods, split regularities and mirror symmetries of the glitch pattern of a Si(111) crystal along with the azimuthal angles are presented. The glitch patterns of Si(111) double-crystal monochromators (DCMs) are found to be the superposition of the two sets of glitch patterns from the two crystals. The optimal azimuthal orientation ϕ1,2 = [(2 n+1)π]/6 ( n = 0, ±1, ±2...) for Si(111) DCMs to achieve the least amount of glitches in the hard X-ray region has been suggested. [ABSTRACT FROM AUTHOR]

Different B 2 O 3 content was added to Ce3+–doped Gd 2 O 3 –Al 2 O 3 –SiO 2 (xBGAS:1.1Ce3+, x = 0, 5, 10, 15) glasses to improve the photoluminescence (PL) and scintillation properties. The transmittance of 15BGAS:1.1Ce3+ glass is over 80%. The X–ray absorption near edge spectroscopy (XANES) spectra imply that Ce4+ can be effectively reduced to Ce3+ in the glasses by adding Si 3 N 4. The excitation and emission spectra show a blue shift with increase of B 2 O 3 content. The photoluminescence quantum yield (PL QY) increases with the increase of B 2 O 3 content, reached the maximum of 59.55% when x = 15. The PL decay time of the glasses exhibits typical values (44–50 ns) due to 5d→4f transition of Ce3+ ions. The PL thermal activation energy become larger, indicating that xBGAS:1.1Ce3+ glasses have better luminescent thermal stability. The integral X–ray excited luminescence (XEL) intensity of the 15BGAS:1.1Ce3+ glass is 37.38% of Bi 4 Ge 3 O 12 (BGO) crystal, and the light yield is 1267 ph/MeV with an energy resolution of 23.22% at 662 keV when exposed to γ–rays. With the increase of B 2 O 3 content, the fast component of scintillation decay time gradually becomes shorter and the slow component becomes longer. The thermally stimulated luminescence (TSL) curves were measured to investigate the trap depth and density of defects in xBGAS:1.1Ce3+ glasses. [ABSTRACT FROM AUTHOR]

Mn substitution provides perfect perturbation on the local structure and electronic behavior of BiFeO 3. The crystal structure of BiFe 1− x Mn x O 3 (0 ⩽ x ⩽ 0.3) changes from rhombohedral R 3 c to orthorhombic Pbnm via a biphasic region with increasing x . It is found that Mn doping leads to the depolarization of the Bi–O configuration, and the Jahn–Teller distortion of Fe/MnO 6 octahedra. An enhancement of remanent magnetization of BiFe 1− x Mn x O 3 is observed. [ABSTRACT FROM AUTHOR]

Highlights: [•] Porous ZnO/Sn1−x Zn x O2−x nanocatalysts with high photocatalytic activity were synthesized by a two-step solvothermal method. [•] Zn doping in SnO2 shows an influence on particle size, specific surface area and band gap. [•] The formation of ZnO/Sn1−x Zn x O2−x heterostructure improves the separation of photogenerated electron–hole pairs. [•] The synergistic effects of metal ion doping and semiconductor/semiconductor heterostructure are reported. [ABSTRACT FROM AUTHOR]

Machine learning models often converge slowly and are unstable due to the significant variance of random data when using a sample estimate gradient in SGD. To increase the speed of convergence and improve stability, a distributed SGD algorithm based on variance reduction, named DisSAGD, is proposed in this study. DisSAGD corrects the gradient estimate for each iteration by using the gradient variance of historical iterations without full gradient computation or additional storage, i.e., it reduces the mean variance of historical gradients in order to reduce the error in updating parameters. We implemented DisSAGD in distributed clusters in order to train a machine learning model by sharing parameters among nodes using an asynchronous communication protocol. We also propose an adaptive learning rate strategy, as well as a sampling strategy, to address the update lag of the overall parameter distribution, which helps to improve the convergence speed when the parameters deviate from the optimal value—when one working node is faster than another, this node will have more time to compute the local gradient and sample more samples for the next iteration. Our experiments demonstrate that DisSAGD significantly reduces waiting times during loop iterations and improves convergence speed when compared to traditional methods, and that our method can achieve speed increases for distributed clusters. [ABSTRACT FROM AUTHOR]

Pt cocatalyst play bifunctions in the photoreforming of polyethylene terephthalate plastic waste by improving the charge transfer kinetics and regulating the adsorption-desorption of oxidation intermediates, thereby achieving efficient photocatalytic H 2 evolution rate and producing valuable commodities in the photoreforming reactions. [Display omitted] Upcycle polyethylene terephthalate (PET) waste by photoreforming (PR) is a sustainable and green approach to tackle environmental problems but with challenges to obtain valuable oxidation products and high purity hydrogen simultaneously. Noble metal cocatalysts are essential to enhance the overall PR reaction efficacy. In this work, TiO 2 nanotubes (TiO 2 NTs) decorated with single Pt atoms (Pt 1 /TiO 2) or Pt nanoparticles (Pt NPs /TiO 2) are used in the photoreforming reaction (in one batch), and the oxidation products from ethylene glycol (EG, hydrolysed product of PET) in liquid phase and hydrogen are detected. With Pt 1 /TiO 2 , EG is oxidized to glyoxal, glyoxylate or lactate, and hydrogen evolution rate (r H 2) reaches 51.8 μmol⋅h−1⋅g cat −1, that is 30 times higher than that of TiO 2. For Pt NPs /TiO 2 (size of Pt NPs: 1.97 nm), hydrogen evolution reaches 219.1 μmol⋅h−1⋅g cat −1, but with the oxidation product of acetate only. DFT calculation demonstrates that for Pt NPs, the reaction path for hydrogen evolution is preferred thermodynamically, due to the formation of Schottky junction. On the oxidation of EG, theoretical and spectroscopic analysis suggest that bidentate adsorption of EG at the interface is facile on Pt 1 /TiO 2 , compared to that on Pt NPs /TiO 2 (two Pt sites), but oxidation products, adsorb less strongly, compared to Pt NPs /TiO 2 , that eventually regulates the distribution of oxidation products. The results thus demonstrate the bifunctions of Pt in the PR reaction, i.e., electron transfer mediator for hydrogen evolution and reactive sites for molecules adsorption. The oxidation reaction is dominated by the adsorption-desorption behavior of molecules but the reduction reaction is controlled by the electron transfer. In addition, acidification of pretreated PET alkaline solution achieves separation of pure terephthalic acid (PTA), which further improves the reaction efficiency possibly by offering high density of active sites and acidic environment. Our work thus demonstrates that to upcycle PET plastics, an optimized process can be reached by atomic design of photocatalysts and proper treatment on the plastic wastes. [ABSTRACT FROM AUTHOR]

Highlights: Oxygen-coordinated single-atom Mn catalyst was fabricated via introducing oxygen functional groups rich bacterial cellulose as the adsorption regulator through a combined impregnation–pyrolysis–etching synthetic route. Mn–O–C as the electrocatalyst exhibits superior electrocatalytic activity toward ammonia synthesis with a maximum NH3 yield rate of 1476.9 ± 62.6 μg h−1 cm−2 at − 0.7 V (vs. RHE) and a faradaic efficiency of 89.0 ± 3.8% at − 0.5 V (vs. RHE) under ambient conditions. Electrocatalytic mechanism of Mn–(O–C2)4 site for nitrate reduction reaction is unveiled by a combination of in situ spectroscopy characterization and computational study. Electrocatalytic nitrate reduction reaction has attracted increasing attention due to its goal of low carbon emission and environmental protection. Here, we report an efficient NitRR catalyst composed of single Mn sites with atomically dispersed oxygen (O) coordination on bacterial cellulose-converted graphitic carbon (Mn–O–C). Evidence of the atomically dispersed Mn–(O–C2)4 moieties embedding in the exposed basal plane of carbon surface is confirmed by X-ray absorption spectroscopy. As a result, the as-synthesized Mn–O–C catalyst exhibits superior NitRR activity with an NH3 yield rate (RNH3) of 1476.9 ± 62.6 μg h−1 cm−2 at − 0.7 V (vs. reversible hydrogen electrode, RHE) and a faradaic efficiency (FE) of 89.0 ± 3.8% at − 0.5 V (vs. RHE) under ambient conditions. Further, when evaluated with a practical flow cell, Mn–O–C shows a high RNH3 of 3706.7 ± 552.0 μg h−1 cm−2 at a current density of 100 mA cm−2, 2.5 times of that in the H cell. The in situ FT-IR and Raman spectroscopic studies combined with theoretical calculations indicate that the Mn–(O–C2)4 sites not only effectively inhibit the competitive hydrogen evolution reaction, but also greatly promote the adsorption and activation of nitrate (NO3−), thus boosting both the FE and selectivity of NH3 over Mn–(O–C2)4 sites. [ABSTRACT FROM AUTHOR]

Recently, nanozyme-based sensing platforms have attracted widespread attention due to their excellent performance in practical applications. In this paper, phosphorus-doped porous materials were synthesized by a one-step method and metal-doped with different metal salts. The results show that the iron-containing porous nitrogen-phosphorus material (FeNPC) has the best peroxidase activity. FeNPC catalyzes hydrogen peroxide to generate hydroxyl radical (•OH) which oxidizes colorless 3,3',5,5'-tetramethylbenzidine (TMB) to blue oxTMB. When the above system encounters ferulic acid, the blue product will be inhibited, and the color of the reaction solution will change, so ferulic acid can be detected by the colorimetric method. Ferulic acid is an antioxidant used in humans as an antibacterial and antiviral drug. The detection limit of this colorimetric sensor is as low as 1.3 nM. Compared with other detection methods, the colorimetric method is simple, fast, and cheap and has a good development prospect. [ABSTRACT FROM AUTHOR]

H9N2 avian influenza virus has spread worldwide, and vaccination with an inactivated virus is currently the major prevention method in China. To further understand the effect of the selection pressure from antibodies on the evolution of H9N2 avian influenza virus, F/98 (A/Chicken/Shanghai/F/98), which is the vaccine representative of H9N2 avian influenza virus in East China, was used for serial passaging for 20 generations in chickens with and without vaccination. After plaque purification from trachea and lung tissues, 390 quasispecies were obtained. The second-generation quasispecies under the selection pressure of vaccine antibodies had undergone 100% antigen variation, while after passaging to the fifth generation, only 30–40% of the quasispecies displayed antigen variation when there was no selection pressure of vaccine antibodies, implying that the selection pressure of vaccine antibodies promotes the antigen variation of F/98. We found for the first time that there were three mutation hotspots in the HA genes of the quasispecies under the selection pressure of vaccine antibodies, which were K131R, A168T, and N201D. Moreover, under the selection pressure of vaccine antibodies, 10 amino acids (67–76) of the NA protein of all quasispecies were deleted, and PB2 of the quasispecies had undergone a high-frequency R355K mutation. However, without selection pressure of vaccine antibodies, NP had undergone two high-frequency mutations, namely, V186I and L466I, and a high-frequency mutation of L77I appeared in the NS gene. This result shows that the vaccine antibody selection pressure could control and regulate gene variation of the F/98 virus. Compared to that of the parental virus F/98, the EID50 of the twentieth passaged virus under the selection pressure of vaccine antibodies did not change, while the EID50 of the twentieth passaged virus without selection pressure of vaccine antibodies was significantly enhanced by 794 times. Furthermore, the twentieth passaged virus with selection pressure from vaccine antibodies lost its lethal ability in embryonated chicken eggs, whereas the EID50 of the twentieth passaged virus without selection pressure of vaccine antibodies increased to 6.3 times that of the F/98 strain. All the above results show that the selection pressure of vaccine antibodies promotes the antigen variation of H9N2 avian influenza virus and plays a role in regulating and controlling gene mutation of H9N2 avian influenza virus. [ABSTRACT FROM AUTHOR]

Great efforts are exploring single-atom (SA) sites for tailoring catalytic effects on the sulfur-related redox reaction in Li-S battery, while edge-distributed SA sites lack attention. Herein, we implanted SA iron sites in N-doped porous carbon on CNTs (Fe-NPC@CNTs) to obtain edge-distributed FeN 4 moieties via a polymer inductive strategy. The Fe-NPC@CNTs own enhanced "trapping-conversion" ability for polysulfides. The Li-S battery based on Fe-NPC@CNTs achieves a wonderful capacity of 1004 mAh g−1 at 1 C with long-term cycling stability, where the capacity fading rate is 0.032% per cycle over 1200 cycles. Noteworthy, the cell delivers very large capacities of 3.94/6.12 mAh cm−2 under high sulfur loadings of 4.50/5.04 mg cm−2 at 0.5/0.2 C, corresponding to 82.5/82.4% capacity retentions over 100 cycles. Under ultrahigh sulfur loadings (7.8/10.9 mg cm−2), the cell exhibits amazing large areal capacities of 7.63/10.76 mAh cm−2. The edge-distributed SA sites engineering provides a bright blueprint for advanced Li-S battery. [Display omitted] • Fe-NPC@CNTs has highly exposed edge-distributed Fe-N 4 moieties. • Charge redistribution of Fe atoms is found for Fe-NPC@CNTs. • Enhanced "trapping-conversion" property for polysulfides is obtained for Fe-NPC@CNTs. • The Li-S battery employing Fe-NPC@CNTs demonstrates outstanding performance. [ABSTRACT FROM AUTHOR]

Simultaneously optimizing elementary steps, such as water dissociation, hydroxyl transferring, and hydrogen combination, is crucial yet challenging for achieving efficient hydrogen evolution reaction (HER) in alkaline media. Herein, Ru single atom‐doped WO2 nanoparticles with atomically dispersed Ru–W pair sites (Ru–W/WO2‐800) are developed using a crystalline lattice‐confined strategy, aiming to gain efficient alkaline HER. It is found that Ru–W/WO2‐800 exhibits remarkable HER activity, characterized by a low overpotential (11 mV at 10 mA cm−2), notable mass activity (5863 mA mg−1 Ru at 50 mV), and robust stability (500 h at 250 mA cm−2). The highly efficient activity of Ru–W/WO2‐800 is attributed to the synergistic effect of Ru–W sites through ensemble catalysis. Specifically, the W sites expedite rapid hydroxyl transferring and water dissociation, while the Ru sites accelerate the hydrogen combination process, synergistically facilitating the HER activity. This study opens a promising pathway for tailoring the coordination environment of atomic‐scale catalysts to achieve efficient electro‐catalysis. [ABSTRACT FROM AUTHOR]

Li-rich layered oxide cathodes suffer from poor rate capability, voltage decay and inferior cycling stability. Herein, we propose a novel synergistic strategy to improve the electrochemical performances of Li-rich Li 1.20 Ni 0.13 Co 0.13 Mn 0.54 O 2 by the co-doping of Na + and PO 4 3− . The co-doping of Na + for Li and PO 4 3− for Mn is simultaneously achieved using Na 3 PO 4 as a dopant. The co-doping of Na + and PO 4 3− not only enhances the high-rate performance (106.4 mAhg −1 @10C) and capacity retention (93.8%@1C@100 cycles) but also mitigates the voltage decay owing to the synergistic effect of Na + and PO 4 3− co-doping. The synergistic mechanism is unraveled based on neutron diffraction, aberration-corrected scanning transmission electron microscope, X-ray photoelectron spectroscopy, ex-situ X-ray absorption spectra, ex-situ X-ray diffraction, electrochemical impedance spectroscopy and electrochemical measurements. The co-doping of Na + and PO 4 3− enlarges the interlayer spacing and suppresses Li/Ni mixing which increases Li + diffusivity and enhances the rate capability. Meanwhile, the co-doping of Na + and PO 4 3− shrinks the thickness of the slabs, weakens the TM-O covalency and alleviates the volume change in the charge/discharge process which improves the layered structure stability and the cycling performances. This study presents some new insights into designing high performance cathode materials through a cooperative modulation of different crystal sites doping. [ABSTRACT FROM AUTHOR]

Aiming at the efficient and convenient treatment of radioactive wastewater, a graphene oxide-chitosan aerogel (GO-CS) was fabricated and utilized for uranium(VI) elimination. The adsorption of U(VI) on the aerogel was evaluated as a function of contact time, solution pH, ionic strength, initial uranium concentration, and competing metal ions. High adsorption capacity for the uranium could be achieved over a wide pH range, e.g., 200, 319.9, and 384.6 mg/g at pH 3.5, 5.0, and 8.3, respectively. The interaction mechanism of U(VI) with GO-CS was systematically clarified by using Fourier transformation infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), and extended X-ray absorption fine structure spectroscopy (EXAFS). It was found that the U(VI) adsorption was mainly ascribed to the inner-sphere surface complexation by –COO − , –OH, and –NH 2 groups anchored on the GO-CS and the involvement of these functional groups toward the coordination sphere was largely relevant to solution pH. At mild alkaline pH, –NH 2 groups play a more important role, therefore leading to an extraordinarily high extraction of uranium from simulated seawater. [ABSTRACT FROM AUTHOR]

Understanding the dynamical evolution from metal ions to single atoms is of great importance to the rational development of synthesis strategies for single atom catalysts (SACs) against metal sintering during pyrolysis. Herein, an in situ observation is disclosed that the formation of SACs is ascertained as a two‐step process. There is initially metal sintering into nanoparticles (NPs) (500–600 °C), followed by the conversion of NPs into metal single atoms (Fe, Co, Ni, Cu SAs) at higher temperature (700–800 °C). Theoretical calculations together with control experiments based on Cu unveil that the ion‐to‐NP conversion can arise from the carbon reduction, and NP‐to‐SA conversion being steered by generating more thermodynamically stable Cu‐N4 configuration instead of Cu NPs. Based on the evidenced mechanism, a two‐step pyrolysis strategy to access Cu SACs is developed, which exhibits excellent ORR performance. [ABSTRACT FROM AUTHOR]

Efficient electrocatalytic reactions require a coordinated active center that may provide a properly reaction intermediates adsorption in water splitting. Herein, a Ni active center coordination reconstruction method achieved by multidimensional modulation of phase transition, iodine coordination, and vacancy defects is designed and implemented. This coordination reconstruction results in the successful synthesis of Ni5P4−xIx/Ni2P nanocorals that show outstanding bifunctional catalytic activity due to deep optimization of the adsorption energy. The overpotentials of hydrogen evolution reaction and oxygen evolution reaction at 10 mA cm−2 are 46 and 163 mV, respectively. Only 1.46 V is required to drive alkaline overall water splitting. Novel coordination environment is investigated by electron paramagnetic resonance spectroscopy and extended X‐ray absorption fine structure spectroscopy. A 4D integrated material design strategy of "thermodynamic stability‐electronic properties‐charge transfer‐adsorption energy" for water‐splitting catalysts is proposed. This coordination reconstruction concept and material design method provide new perspectives for the research of novel catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • The unique Pt-O-Cu structure is constructed on the 2.5Pt-2Cu/Fe 2 O 3 catalyst. • The Pt-O-Cu site shows the best reactivity for EWGS reaction. • The Pt-O-Cu site balances the binding ability of CO and the activation of OH–. • The Pt-O-Cu structure greatly boots the capability in antioxidation of Pt. Electrochemical water–gas shift (EWGS) reaction is an emerging technology with energy-saving and environmental-friendly advantages to produce high-purity hydrogen form the waste gas containing CO. However, it remains a significant challenge to design superior activity and highly durable EWGS electrocatalysts, particularly with low content of noble metals. Herein, a series of Pt-xCu/Fe 2 O 3 (x = 0, 2, 5) catalysts are synthesized by the complexation precipitation method to construct coupling sites between Pt and CuOx, aiming to optimize the adsorption of CO and the activation of OH–. The obtained 2.5Pt-2Cu/Fe 2 O 3 catalyst presents a unique Pt-O-Cu structure, delivering a much lowest onset potential, high specific activity, and excellent mass activity (1.5 A·mg Pt -1) at 0.73 V (vs. RHE), which is over 15 and 3 times that of commercial Pt/C (20%) and unmodified Pt/Fe 2 O 3 catalyst, respectively. Meanwhile, the in-situ X-ray absorption results demonstrate that the facilitated interaction among the Pt-O-Cu structure promotes the high durability of the 2.5Pt-2Cu/Fe 2 O 3 catalyst and the operability at high potential. More importantly, the moderate binding of CO and moderate activation of OH* are suggested for boosting the reactivity in the CO electro-oxidation reaction. In particular, the fabricated Pt||2.5Pt-2Cu/Fe 2 O 3 , employed in coupling the HER and CO electro-oxide reaction, shows a remarkable hydrogen production of about 98 mmol H2 ·h−1·mg Pt −1 at 0.8 V (vs. RHE). This work also definitely confirms the possibility of the catalyst being applied to produce hydrogen under practical conditions with different concentrations of CO, even being applied in the purification of trace CO in a hydrogen-rich atmosphere. [ABSTRACT FROM AUTHOR]

Direct electrocatalytic oxidation of benzene has been regarded as a promising approach for achieving high‐value phenol product, but remaining a huge challenge. Here an oxygen‐coordinated nickel single‐atom catalyst (Ni–O–C) is reported with bifunctional electrocatalytic activities toward the two‐electron oxygen reduction reaction (2e− ORR) to H2O2 and H2O2‐assisted benzene oxidation to phenol. The Ni–(O–C2)4 sites in Ni–O–C ar proven to be the catalytic active centers for bifunctional 2e− ORR and H2O2‐assisted benzene oxidation processes. As a result, Ni–O–C can afford a benzene conversion as high as 96.4 ± 3.6% with a phenol selectivity of 100% and a Faradaic efficiency (FE) of 80.2 ± 3.2% with the help of H2O2 in 0.1 m KOH electrolyte at 1.5 V (vs RHE). A proof of concept experiment with Ni–O–C concurrently as cathode and anode in a single electrochemical cell demonstrates a benzene conversion of 33.4 ± 2.2% with a phenol selectivity of 100% and a FE of 44.8 ± 3.0% at 10 mA cm−2. [ABSTRACT FROM AUTHOR]

A better understanding of different retention mechanisms of potentially toxic elements (PTEs) by biochars during the remediation of contaminated sites is critically needed. In this study, different spectroscopic techniques including synchrotron-based micro-X-ray fluorescence (μ-XRF), X-ray absorption fine structure (XAFS), and near-edge XAFS spectroscopy (NEXAFS), were used to investigate the spatial distributions and retention mechanisms of lead (Pb) and copper (Cu) on phytolith-rich coconut-fiber biochar (CFB), and ammonia, nitric acid and hydrogen peroxide modified CFB (MCFB) (i.e., ACFB, NCFB and HCFB). The μ-XRF analyses indicated that sorption sites on ACFB and NCFB were more efficient compared to those on CFB and HCFB to bind Pb/Cu. XAFS analyses revealed that the percentage of Pb species as Pb(C 2 H 3 O 2) 2 increased from 22.2% (Pb-loaded CFBs) to 47.4% and 41.9% on Pb-loaded NCFBs and HCFBs, while the percentage of Cu(OH) 2 and Cu(C 2 H 3 O 2) 2 increased from 5.8% to 32.8% (Cu-loaded CFBs) to 41.5% and 43.4% (Cu-loaded NCFBs), and 27.1% and 35.1% (Cu-loaded HCFBs), respectively. Due to their similar atomic structures of Pb/Cu, Pb(C 2 H 3 O 2) 2 /Pb-loaded montmorillonite and Cu(C 2 H 3 O 2) 2 /Cu(OH) 2 were identified as the predominant Pb/Cu species observed in Pb- and Cu-loaded MCFBs. The NEXAFS analyses of carbon confirmed that increasing amounts of carboxylic groups were formed on HCFB and NCFB by oxidizing carbon-containing functional groups, which could provide additional active binding sites for Pb/Cu retention. Results from the X-ray photoelectron spectroscopy analyses of nitrogen showed that azido-groups of ACFB played major roles in Pb/Cu retention, while amide-groups and pyridine-groups of NCFB primarily participated in Pb/Cu retention. Overall, density functional theory calculations suggested that silicate and the synergistic effect of hydroxyl and carboxylic-groups on MCFBs were highly efficient in Pb retention, while azido-groups and/or carboxylic-groups played major roles in Cu retention. These results provide novel insights into the PTE retention mechanisms of MCFBs. [Display omitted] • Chemical modifications observably affect the properties of phytolith-rich biochar. • Amount of sorbed Pb/Cu on NH 3 ·H 2 O and HNO 3 modified biochar significantly increased. • Sorbed Pb on modified biochars was mainly as Pb(C 2 H 3 O 2) 2 /Pb-loaded montmorillonite. • Major species of sorbed Cu on modified biochars were Cu(C 2 H 3 O 2) 2 and Cu(OH) 2. • The increased carboxylic-groups in biochars caused enhanced retention of Pb and Cu. [ABSTRACT FROM AUTHOR]

Combining isolated atomic active sites with those in nanoparticles for synergizing complex multistep catalysis is being actively pursued in the design of new electrocatalyst systems. However, these novel systems have been rarely studied due to the challenges with synthesis and analysis. Herein, a synergistically catalytic performance is demonstrated with a 0.89 V (vs reversible hydrogen electrode) onset potential in the four‐step oxygen reduction reaction (ORR) by localizing tungsten single atoms around tungsten nitride nanoparticles confined into nitrogen‐doped carbon (W SAs/WNNC). Through density functional theory calculations, it is shown that each of the active centers in the synergistic entity feature a specific potential‐determining step in their respective reaction pathway that can be merged to optimize the intermediate steps involving scaling relations on individual active centers. Impressively, the W SAs/WNNC as the air cathode in all‐solid‐state Zn‐air and Al‐air batteries demonstrate competitive durability and reversibility, despite the acknowledged low activity of W‐based catalyst toward the ORR. [ABSTRACT FROM AUTHOR]

A strategy for one-pot asymmetric β-C-H functionalization of aldehydes under O 2 has been proposed, catalysed by the hydroxide-layered Fe(III) sites synergistic with confined interlayer amines through a cascade oxidation-addition process. [Display omitted] • First proposal of a heterogeneous strategy to boost the one-pot asymmetric β-C-H functionalization of aldehyde under O 2 using hydroxide-layered Fe(III) sites synergistic with confined interlayer amine. • Achievements of an excellent regioselectivity (>99%), a good stereoselectivity (90%), and a moderate yield (65%) for the major β-functionalized diastereomer. • Good reusability of the L-proline intercalated Fe(III)-containing LDHs in the heterogeneous catalysis. Asymmetric functionalization of inert β-C-H is one of the most powerful strategies in organic synthesis, but of great challenge in the efficient β-C-H activation and the enantioselective C-heteroatom formation. Here, this work proposes an elegant strategy for one-pot asymmetric β-C-H functionalization of aldehyde under O 2 catalyzed by hydroxide-layered Fe(III) sites synergistic with confined interlayer amine through a cascade oxidation-addition process on L-proline intercalated Fe-containing layered double hydroxides (LDHs), in which the direct β-H elimination of aldehyde on hydroxide-layered Fe(III) sites with the two-electron abstraction promoted by the Fe(III):N coordination as the key step to efficiently oxidize the enamine. The major β-functionalized diastereomer in the asymmetric nitromethylation of 3-phenylpropanal has been afforded in a regioselectivity of up to >99%, a stereoselectivity of 90%, and a yield of 65% on L-proline intercalated Mg 3.00 Al 0.47 Fe 0.45 -LDHs. [ABSTRACT FROM AUTHOR]

For single-atom catalysts (SACs), the catalyst supports are not only anchors for single atoms, but also modulators for geometric and electronic structures, which determine their catalytic performance. Selecting an appropriate support to prepare SACs with uniform coordination environments is critical for achieving optimal performance and clarifying the relationship between the structure and the property of SACs. Approaching such a goal is still a significant challenge. Taking advantage of the strong d-π interaction between Cu atoms and diacetylenic in a graphdiyne (GDY) support, we present an efficient and simple strategy for fabricating Cu single atoms anchored on GDY (Cu1/GDY) with uniform Cu1-C4 single sites under mild conditions. The Cu atomic structure was confirmed by combining synchrotron radiation X-ray absorption spectroscopy, X-ray photoelectron spectroscopy and density functional theory (DFT) calculations. The as-prepared Cu1/GDY exhibits much higher activity than state-of-the-art SACs in direct benzene oxidation to phenol with H2O2 reaction, with turnover frequency values of 251 h−1 at room temperature and 1889 h−1 at 60°C, respectively. Furthermore, even with a high benzene conversion of 86%, high phenol selectivity (96%) is maintained, which can be ascribed to the hydrophobic and oleophyllic surface nature of Cu1/GDY for benzene adsorption and phenol desorption. Both experiments and DFT calculations indicate that Cu1-C4 single sites are more effective at activating H2O2 to form Cu=O bonds, which are important active intermediates for benzene oxidation to phenol. [ABSTRACT FROM AUTHOR]

A template-engaged multistep synthesis process is developed to fabricate ultrathin carbon nanosheets assembled hierarchical nanoboxes embedded with dense Mo-N 4 active sites, which exhibited excellent activity and superb stability for oxygen reduction reaction. [Display omitted] • Unique hierarchical SA-Mo-C nanoboxes were fabricated via a template-engaged multistep synthesis process. • Comprehensive characterizations including EXAFS reveal Mo-N 4 atomic sites were formed and densely dispersed in the SA-Mo-C nanoboxes. • SA-Mo-C nanoboxes exhibited better ORR performance compared to commercial Pt/C catalysts. Construction of single-atom catalysts (SACs) with maximally exposed active sites remains a challenging task mainly because of the lack of suitable host matrices. In this study, hierarchical N -doped carbon nanoboxes composed of ultrathin nanosheets with dispersed atomic Mo (denoted as hierarchical SA-Mo-C nanoboxes) were fabricated via a template-engaged multistep synthesis process. Comprehensive characterizations, including X-ray absorption fine structure analysis, reveal the formation of Mo-N 4 atomic sites uniformly anchored on the hierarchical carbon nanoboxes. The prepared catalysts offer structural and morphological advantages, including ultrathin nanosheet units, unique hollow structures and abundant active Mo-N 4 species, that result in excellent activity with a half-wave potential of 0.86 V vs. RHE and superb stability for the oxygen reduction reaction in 0.1 M KOH; thus, the catalysts are promising air–cathode catalysts for Zn-air batteries with a high peak power density of 157.6 mW cm−2. [ABSTRACT FROM AUTHOR]

Atomically distributed iron electrocatalyst is valid for oxygen reduction reaction (ORR). However, accurate regulation of the structure improving its intrinsic activity is a challenge. Herein, a dual-atom catalyst FeCu-NC with atomically distributed Fe and Cu co-anchored on porous N-doped carbon is obtained. The FeN 4 and CuN 3 couple sites bridged by two nitrogen atoms, exist as Fe(II,III)N 2 (µ 2 -N) 2 Cu(I,II)N moieties with the metal distance of ∼2.5 Å in the structure of FeCu-NC. The synergistic effect of Fe and Cu dual-atom reducing the dissociation energy of *OOH intermediate, allows an optimized 4e- ORR reaction pathway. The FeCu-NC exhibits high-efficiency ORR activity with the half-wave potential (E 1/2) of 0.889 V (vs RHE) and outstanding stability without obvious decay for the E 1/2 after 10,000 cycles. The FeCu-NC based Zn-air battery presents large specific capacity of 795 mAh g−1 and energy density of 998 Wh kg−1 as well as high charge-discharge cycling stability superior to the Pt/C. [Display omitted] • A dual-atom catalyst FeCu-NC with Fe(II,III)N 2 (µ 2 -N) 2 Cu(I,II)N moieties is prepared. • The synergistic effect of Fe and Cu clearly reduces the dissociation energy of *OOH. • The FeCu-NC has a high ORR activity in an optimized 4e- reaction pathway. • The FeCu-NC based Zn-air battery exhibits a large stable energy density. [ABSTRACT FROM AUTHOR]

• A potential-induced self-reconstruction process was proposed for the synthesis of single-atomic Ru sites anchored on Co(OH) 2 ; • The single-atomic Ru sites reduced the overpotential for nitrate reduction and improved the NH 3 yield; • The single-atomic Ru sites facilitate the thermodynamic-determining step of *NH 2 -to-*NH 3 thus promoting the overall NO 3 −-to-NH 3 conversion. Conversion of NO 3 −-to-NH 3 via the electrocatalytic nitrate reduction reaction (NO 3 -RR) is an emerging strategy for ammonia production and storage of "green hydrogen", but is limited by the dissatisfactory activity and selectivity. In this study, we discovered that cobalt carbonate hydroxide (Co 2 (OH) 2 CO 3) underwent a potential-induced self-reconstruction to cobalt hydroxide (Co(OH) 2) during NO 3 -RR. The incorporation of Ru into Co 2 (OH) 2 CO 3 expedited the aforementioned self-reconstruction process and resulted in the formation of Ru single-atomic sites (Ru SASs) anchored on Co(OH) 2 nanosheets. This structure is reported as a highly efficient electrocatalyst for NO 3 −-to-NH 3 conversion and exhibits exceptional electrochemical performance in zinc-NO 3 − batteries. Theoretical analysis revealed that the conversion of NO 3 −-to-NH 3 occurred on Ru SASs through an N-end pathway with *NO as a characteristic intermediate. Furthermore, Ru SASs facilitated the thermodynamic-determining step of *NH 2 -to-*NH 3 , thus promoting the overall NO 3 −-to-NH 3 conversion process. [ABSTRACT FROM AUTHOR]

[Display omitted] • The K-mediated ultrasmall Ru nanoclusters show excellent NH3 synthesis activity. • Avoiding hydrogen poisoning on ultrasmall Ru nanoclusters through K mediation. • The addition of K could mediate the H-spillover and d-band center. • K addition significantly affects the electronic structure of Ru and oxygen vacancies. The effects of promoters on Ru nanoparticles (≥2 nm) catalysts for NH 3 synthesis have been extensively elaborated, but their roles on ultrasmall Ru nanoclusters (NCs, 1–2 nm) remain largely unknown and need to be further uncovered. Herein, a series of K-promoted MgO supported Ru NCs were synthesized and investigated for NH 3 synthesis. The addition of 5wt.%K onto Ru/MgO NCs leads to a significantly high NH 3 synthesis rate of 21.7 mmol NH3 g cat −1h−1 at 400 °C and 0.2 MPa, close to the thermodynamic equilibrium. Out studies reveal that anchoring K onto Ru NCs can increase the electron density and cause an upshift of the d -band center of Ru entities. Moreover, the addition of K regulates the hydrogen affinity and accelerates the migration of hydrogen from the Ru NCs surface to MgO support, which is crucial in avoiding the hydrogen poisoning effect on Ru NCs. With the synergistic effect of the Ru NCs sites bridged by H-spillover, makes the K-mediated Ru/MgO NCs catalysts efficient for NH 3 synthesis at mild conditions. [ABSTRACT FROM AUTHOR]

Selective catalytic conversion of biomass-derived compounds to fuels and fine chemicals serves as a renewable energy pathway for the partial substitution of fossil resources, in which reaction pathway and selectivity control are key issues. Herein, we report a fully exposed Pt clusters immobilized on CoAl mixed metal oxides catalyst (denoted as Pt n /CoAl-MMOs), which exhibits prominent catalytic performance towards liquid phase hydrogenation reaction of furfural (FAL). Noteworthily, the hydrogenation chemoselectivity can be switched among four products via using four different solvents: tetrahydrofurfuryl alcohol (THFA; yield: 91.4%), furfuryl alcohol (FA; yield: 97.7%), 2-methylfuran (2-MF; yield: 92.1%) and furan (FU; yield: 90.8%) are obtained in ethanol, dioxane, isopropanol and n -hexane solvent, respectively. Experimental studies (in situ FT-IR and TPSR-Mass) combined with theoretical calculations (DFT) reveal that solvent molecules exert an essential influence on the adsorption configuration of FAL via changing the solvent-catalyst and/or substrate-catalyst interaction, which ultimately determines the hydrogenation pathway, key intermediate and final product. This work demonstrates a facile solvent-dependent product-switching strategy within one catalytic system, which opens up potential opportunities for tailoring hydrogenation selectivity in liquid-solid catalytic reactions towards biomass upgrading. [Display omitted] • A fully exposed cluster catalyst was prepared based on layered double hydroxides. • The hydrogenation chemoselectivity can be switched via using different solvents. • The solvent and substrate compete for the adsorption sites onto the Pt n surface. • The solvent/substrate-catalyst interaction govern the adsorption configuration. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel strategy on targeted activation of alcoholic sp 3 C α -H bonds by synergistic H-bonding protection of O–H bonds is put forward. • Atomic Fe-N sites with the uncoordinated N species presents a synergistic adsorption of ethanol O–H bonds, providing the O–H protection by H bonding. • Targeted generation and excellent stabilization of •CH(OH)R radicals under ambient temperature are achieved. • Direct C–C construction of generated •CH(OH)R radicals with a variety of N -heterocycles contributes to an efficient Minisci hydroxyalkylation in a yield of 64 ∼ 98 %. The direct sp 3 C–H functionalization of alcohol with N -heterocycles is the most atom-economical pathway to produce hydroxyalkylated N -heterocycles. However, the targeted C–H activation to enable the direct C–C coupling still remains of great challenge due to the concomitant activation of alcoholic O–H. This work puts forward a H-bonding protection for alcoholic O–H for the targeted activation of alcoholic C α -H bonds. Atomic Fe-N sites anchored in graphitic carbon nitride with uncoordinated nitrogen sites has thus been proposed for this strategy, in which atomic Fe(II)-N sites are supposed to be responsible for the targeted activation of alcoholic C α -H and the surface uncoordinated nitrogen to for the H-bonding with alcoholic O–H. To demonstrate the strategy, the precise modulation on the atomic Fe-N coordination in the 6-fold cavity from three heptazines have been elaborated. Atomic Fe with four N atoms from two heptazines assisted with the uncoordinated N from the free one heptazine has presented a synergistic H-bonding protection of alcoholic O–H bonds. As a result, the targeted generation and excellent stabilization of hydroxyethyl radicals have been achieved under ambient temperature. The strategy has been successfully applied for 1-propanol, 2-propanol, 1-butanol, and 1-pentanol, thus achieving efficient C–C formation in the hydroxyalkylation of varied N -heterocycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • A class of Ru-Co single-atom alloy catalysts (marked as Ru x Co 1 SAA, x stands for Ru/Co molar ratio) were prepared. • The electronic structure of Ru x Co 1 SAA could be effectively tuned by regulating the Ru/Co molar ratio. • A moderate ratio of Ru/Co (1.7:1) favors superior NH 3 synthesis rate. • The excess Ru destroys the SAA structure, resulting in the diminution of SAA advantages. Rational design of efficient catalysts for ammonia (NH 3) synthesis at mild conditions is of paramount importance for the development of electrolysis driven Haber-Bosch (e HB) process. Ammonia synthesis is a structure sensitive reaction, and any small change of electronic structure could result in dramatic change of catalytic activity, especially for the Ru-based NH 3 synthesis catalysts. Electronic structure modulation of the Ru-based catalysts could provide desirable catalytic activity. Herein, we explore a class of Ru-Co single-atom alloy catalysts (marked as Ru x Co 1 SAA, x stands for Ru/Co molar ratio), in which Co single atoms are located on Ru nanoclusters to form Co-Ru coordination, and then electronic structure of Ru x Co 1 SAA could be effectively tuned by regulating the Ru/Co molar ratio. Our studies show that a moderate ratio of Ru/Co (1.7:1) favors superior NH 3 synthesis rate and low activation energy. Using a suite of elaborate characterizations, we have observed that the outstanding performance over Ru 1.7 Co 1 SAA can be attributed to the electron redistribution between Ru and Co atom, resulting in an upshift of d band center and lowering of work function. However, there is decrease of NH 3 synthesis rate when Ru/Co molar ratio is 2, due to the partial detachment of Ru entities from SAA structure, and the formed individual Ru nanoparticles (NPs) overlay the surface of catalyst. In such a case, N 2 activation behavior over Ru 2 Co 1 is alike that of Ru NPs catalysts. The present study demonstrates that the Ru/Co ratio in SAA structure can effectively regulate the electronic structure of catalyst for NH 3 synthesis rate enhancement. [ABSTRACT FROM AUTHOR]

The decrease of Ru particle size from nanoparticles (NPs) to nanoclusters (NCs) can not only increase the NH 3 synthesis performance, but also increase the proportion of corner sites. [Display omitted] • A series of diverse Ru particle sizes (1.4–5.0 nm) over N-doped carbon support were successfully prepared by colloidal Ru deposition method. • The decrease of Ru particle size from nanoparticles (NPs) to nanoclusters (NCs) can not only increase the NH 3 synthesis performance, but also promote the activation of N 2 via an association pathway. • The ample corner sites over Ru NCs can decrease the work function and thus promote N 2 activation. Ammonia (NH 3) synthesis is a structure-sensitive reaction, where a minute variation of catalyst structure would lead to a dramatic change of activity. To date, the roles of Ru size on NH 3 synthesis still remain elusive, and it remains a major challenge. Herein, a series of Ru catalysts with sizes ranging from 1.4 to 5.0 nm were prepared by colloidal Ru deposition, which allows the investigation of size influence on NH 3 synthesis. Through analyses of the geometric and electronic properties of variable-sized Ru particles, it shows that the reduction of Ru particle size could increase the proportion of corner sites while decrease that of terrace sites, which can decrease the work function and thus promote N 2 for its activation. Isotopic investigations show that the decrease of dissociative contribution but the increase of associative contribution as Ru particle size was decreased from 5.0 to 1.4 nm. Meanwhile, the NH 3 synthesis rate increases when the size of Ru catalysts decreases from 5.0 to 1.4 nm. Using a suite of elaborate characterizations, we have observed that 1.4 nm Ru nanoclusters (NCs) with ample corner sites are conducive to activate N 2 via an associative route. As a result, the 1.4 nm Ru NCs catalyst shows the highest NH 3 synthesis rate (up to 17.13 mmol NH3 g cat −1h−1) at 400 ℃ and 1 MPa. [ABSTRACT FROM AUTHOR]

High-efficient and long-cycle air cathodes are crucial for the development of rechargeable zinc-air batteries (ZABs). Herein, we develop a strategy of micro-spherical cobalt-doped Fe 5 (PO 4) 4 (OH) 3 ·H 2 O (Co-FPOH), synthesized by a novel water-oil two-phase hydrothermal method, which was used as ORR/OER bifunctional electrocatalyst for ZABs. The change of local electronic distribution is identified by doping of Co into Fe 5 (PO 4) 4 (OH) 3 ·H 2 O (FPOH), effectively improving the electrocatalytic performance of the resulted Co-FPOH. The OER overpotential of Co-FPOH (290 mV) far outperforms state-of-the-art RuO 2 (350 mV); the ORR catalytic reaction of Co-FPOH is near 4e-, almost reaching the theoretical value of Pt/C (n = 4.00). The ZAB assembled with Co-FPOH as an air electrode exhibits an ultralong cycling lifetime of 450 h at 5 mA cm−2, a super high peak power density of 167.8 Wh cm−2, a high open circuit voltage of about 1.42 V and a large discharge specific capacity of 817 mAh g Zn −1 at 10 mA cm−2. The proposed Co-FPOH is expected to outperform precious metal electrocatalysts as a potential bifunctional electrocatalyst for advanced ZABs. Also, this work offers a novel strategy to synthesize excellent bifunctional electrocatalysts for this kind of energy-related electrocatalytic reactions. [Display omitted] Bifunctional electrocatalyst of Co-FPOH was synthesized by a novel water-oil two-phase hydrothermal method, which exhibited a long-cycle stability of up to 450 h at a current density of 5 mA cm−2 and a super high power density of 167.8 mW cm−2. ● A strategy of Co-FPOH is designed for ORR/OER bifunctional electrocatalyst. ● The local electronic distribution contributes to high-efficient electrocatalysis. ● ZABs assembled with Co-FPOH demonstrate excellent electrochemical performances. [ABSTRACT FROM AUTHOR]

[Display omitted] • Designing three congeneric Co-N 4 model molecules with recognizable configurations. • Unravelling the structure-induced interfacial activation in CO 2 electroconversion. • Exotic paired tandem electrosynthesis steers value-added conversion of CO 2 to DMC. The recognition of structure-induced interfacial activation in heterogenized molecule catalysts is essential to steer CO 2 value-added electroconversion but remains inadequate. Herein, through designing three congeneric Co-N 4 model molecules (Co-CPY, Co-TAA and Co-PHE) with recognizable steric configurations, we systematically investigated the impact of structure-induced interfacial activation on promoting CO 2 electroconversion. Concretely, the Co-CPY/CNTs, featuring highly planar and conjugated molecules immobilized onto CNTs, delivers an ultra-high current density and enables near-unity Faradaic efficiency for CO 2 electroconversion, exceeding the counterparts. The theoretical and spectrographic findings demonstrate that the Co-CPY/CNTs not only creates the adaptive interfaces with strong communication to greatly expedite electron transfer but also reconstructs the electronic structures of active Co-N 4 units to effectively promote the formation of intermediates. Furthermore, the electroconversion of CO 2 to dimethyl carbonate was reliably performed with a high yield of 96 μmol cm–2 h−1 through paired tandem electrosynthesis, highlighting the superior expansibility of Co-CPY/CNTs. [ABSTRACT FROM AUTHOR]

[Display omitted] • A S-modified Cu/Cu 2 O by a simple in-situ wet chemical reduction method is obtained for hybrid capacitors. • The S can affect the electronic structure, then promote the electron transfer during the charge/discharge process. • The S can occupy the O sites in Cu 2 O evidenced by DFT calculation, XRD, XPS and XAS measurements. • A high capacity of 669 mAh g−1 at 1 A g−1 was obtained. Due to the modification of anions, an electron redistribution occurs at the metal ions can affect the electronic structure, and induce excellent specific capacity. Herein, we report an effective and low time-consuming method by in-situ wet chemical reduction at room temperature to construct S-modified Cu/Cu 2 O negative electrode material. Moreover, the sulfur can occupy partial O sites in Cu 2 O to play a crucial role in the electronic structure of the material, demonstrated by DFT calculation, XRD, XPS and XAS measurements. The prepared S-Cu/Cu 2 O samples exhibit excellent electrochemical performance with high specific capacity of 669 mAh·g−1 at 1 A·g−1, even 450 mAh·g−1 at 10 A·g−1. When the materials are composed as pseudo capacity-type cathode//battery-like anode (MnO 2 //S-Cu/Cu 2 O), and (+) battery-type//battery-type (-) (Ni-Cu hydroxide/Cu(OH) 2 /CF//S-Cu/Cu 2 O) hybrid capacitors, they show the energy density of 47.7 and 147.3 Wh·kg−1 at the power density of 636.2 and 800 kW·kg−1, respectively. Otherwise, the flexible MnO 2 //S-Cu/Cu 2 O hybrid capacitor is assembled, which also exhibits good performance at different bending conditions. This work can provide a simple method to prepare the electrode materials via in situ anion modification for high-energy density battery-like energy storage systems. [ABSTRACT FROM AUTHOR]

Nitrate (NO 3 –) is an important raw ingredient for fertilizer, but its conventional synthesis is restricted by high energy consumption and CO 2 emissions. Though there have been some studies on photocatalytic nitrogen oxidation, the production rate of nitrate is undesirable and the excited-state charge-transfer pathway still remains unclear. Herein, we fabricated the V-doped W 18 O 49 nanowires (V- W 18 O 49) for direct nitrate synthesis from N 2 photooxidation. The NO 3 - production rate is as high as 39.85 μmol g−1 h−1 with exceptional catalytic stability and the photosynthetic nitrate fertilizer was employed to promote the growth of crops. Time-resolved spectroscopic results confirmed that the introduction of V doping in V- W 18 O 49 has created new high-efficiency electron-transfer (ET) pathways from the W-O site to the V-dopant under photoirradiation, which leads to an improved π-backdonation process that facilitates nitrogen activation. This newly formed ET channel facilitated efficient charge separation and ultrafast photogenerated carriers transfer, thus overcame the sluggish ET kinetics. [Display omitted] The V-doped W 18 O 49 nanowires were rationally designed and successfully fabricated through a facile solvothermal method. The NO 3 - production rate is as high as 39.85 μmol g−1 h−1 and the photosynthetic nitrate was employed as N-fertilizer. The introduction of V dopants created new high-efficiency electron-transfer (ET) pathways that facilitated the photogenerated carriers transfer. [ABSTRACT FROM AUTHOR]

Five ZSM-5-based catalysts with diverse zeolitic morphologies were prepared to experimentally investigate and computationally analyze the correlation between crystal plane and copper species. The types and numbers of copper species dispersed over Cu-ZSM-5 catalysts were emphatically determined to elucidate the structure-performance relationship of the Cu-ZSM-5 catalyst with broad sheet in the selective catalytic reduction (SCR) of NO by NH 3. This study indicates that the broad Cu-ZSM-5 sheet exhibits outstanding low-temperature performance, achieving complete NO x removal at 250–550 °C. Operando X-ray absorption spectroscopy (XAS) experiments demonstrated this nanosheet catalyst has highly dispersed Cu2+ ions as key active sites, which are facilely solubilized by NH 3 at low temperatures, further promoting rapid dynamic switching between Cu2+ and Cu+ species. And the density functional theory (DFT) calculations showed the Cu2+ forms a unique interaction with the [010] crystal plane, leading to a lower energy barrier of the rate-determining step, resulting in extraordinary NO x conversion. [Display omitted] • The broad Cu-ZSM-5 sheet exhibits extraordinary SCR activity. • Highest aspect ratio [(c+a)/b] of Cu-ZSM-5 facilitates copper dispersion. • Rapid dynamic switch of Cu2+ ↔ Cu+ is crucial for activity promotion. • The [010] facet induces the lowest energy barrier for rate-controlling step. [ABSTRACT FROM AUTHOR]

• The Mn-N 4 SACs were successfully synthesized by pyrolysis process. • Mechanism studies disclosed that Mn-N 4 SACs could catalyze the conversion from Li 2 S 2 to Li 2 S. • Li-S battery with Mn-N 4 SACs released 1400 mA h g–1 capacity and a decay rate of 0.052 % • Mn-N 4 SACs enabled high-loading Li-S battery with high performance. The shuttle effects of lithium polysulfides (LiPSs) and the sluggish conversion reaction between LiPSs and Li 2 S significantly limit the electrochemical performance of Li-S batteries. In this study, a unique structured single atomic Mn anchored on nitrogen-doped carbon black (SAMnN@C) is developed to address above challenges. Physical characterizations confirmed atomically dispersed Mn atoms were anchored on carbon by 4 N atoms forming a typical structure of planar Mn-N 4. Li-S battery assembled by as-prepared SAMnN@C displayed a discharge capacity of 1400 mA h g-1 at 0.1C, and outstanding stability with a capacity decay rate of 0.052 % per cycle during 1000 cycles at 1C. Moreover, excellent electrochemical performances could be preserved even if the S mass loading increased to 5.7 mg cm−2 with ∼ 5 μL (mg S)-1 electrolyte. The mechanism studies revealed that SAMnN@C exhibited a unique Lewis acid-base interaction between Mn-N 4 site and S atom, which significantly lowered the decomposition energy barrier of Li 2 S 2 , and eventually accelerated the sluggish solid-state conversion reaction of Li 2 S 2 to Li 2 S. This study is believed to shed light on the mechanism of SACs for high performance Li-S batteries. [ABSTRACT FROM AUTHOR]

The unique Fe-O-V structure in the dual-functional Fe-V mixed oxides catalyst promotes the formation of oxygen vacancies in the catalyst and accelerates the dissociation of CO 2 , which boost the cyclic replenishment of the lattice oxygen during the oxidative dehydrogenation of propane, and thereby achieving an enhanced catalytic performance. [Display omitted] • A dual-functional Fe-V mixed oxides was controllably synthesized over Al 2 O 3. • 5Fe-5V-Al 2 O 3 achieved a record-high C 3 H 6 yield in V-based CO 2 -ODP catalysts. • Fe sites in the unique Fe-O-V structure can accelerate the dissociation of CO 2. • CO 2 was dissociated into active oxygen species and supplemented lattice oxygen. Selective oxidative dehydrogenation of propane with CO 2 (CO 2 -ODP) represents a promising pathway of propylene production and CO 2 utilization. Presently, vanadium (V) based catalysts are commonly used due to the excellent redox ability originated from the multivalent V. However, the CO 2 -ODP reaction mechanism remains elusive, limiting the rational design of highly efficient catalytic systems. Herein, we introduced Fe into impregnated V-Al 2 O 3 to build a dual-sites catalyst including Fe and V, achieving a C 3 H 8 conversion at ∼43 % and C 3 H 6 selectivity exceed 80 %. Via regulating the Fe/V molar ratio, we clearly describe that the formation of unique Fe-O-V facilitated the CO 2 dissociation. Intrinsically, V is the main active site contributing for C 3 H 8 dehydrogenation while Fe site is responsible for the CO 2 dissociation, replenishing lattice oxygen to enhance oxidative dehydrogenation of C 3 H 8. The design of dual-sites catalyst and extraction of molecular understanding provide guidance for the rational development of highly active CO 2 -ODP catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Rux/BaCeO 3 catalysts with different Ru particle sizes were accurately synthesized. • NH 3 synthesis rate increases obviously with the decrease of Ru particle size. • The reduction of Ru size promotes the generation of more Ce3+ and O v species. • The electron donation from Ce3+ and O v to Ru centers promotes N 2 dissociation. • The enhanced hydrogen spillover on small Ru size decreases hydrogen poisoning. Identifying optimal Ru size in NH 3 synthesis can improve reaction activity and maximize the utilization of Ru to reduce catalyst cost. However, previous researches are focused on large Ru particle size (≥2 nm) while that below 2 nm in NH 3 synthesis is unclear. Here we synthesized a series of Ru x /BaCeO 3 with different Ru sizes (x = 1.1–3.0 nm) through size-controlled Ru colloid. With the decrease of Ru size, NH 3 synthesis rate over Ru1.1/BaCeO 3 increases to 19.4 mmol g cat −1h−1 at 400 °C and 1 MPa, which is 5.7 times that of Ru3.0/BaCeO 3 and superior to most of Ru-based catalysts previously reported. It reveals that the reduction of Ru size enhances the generation of Ce3+ and oxygen vacancies in BaCeO 3 , which can donate electron to Ru centers and promote N 2 dissociation. Moreover, the small Ru size enhances hydrogen spillover from Ru to BaCeO 3 to alleviate hydrogen poisoning, resulting in efficient NH 3 synthesis. [ABSTRACT FROM AUTHOR]

[Display omitted] • M single atom (M = Fe, Co, Ni) anchored on Ru nanoclusters were prepared to form M 1 Ru SAA. • Co 1 Ru SAA shows the highest NH 3 synthesis rate and TOF Ru value. • Compared with Co-Ru nanoparticle alloy, Co 1 Ru SAA exhibits lower work function and up-shift d band center. • SAA structure effectively tune N 2 activation pathway. The desire of green ammonia (NH 3) production requires efficient catalysts that could operate at mild conditions. However, the activity of catalysts is restricted by scaling relation that low activation energy of N 2 is in conjunction with the over-strong affinity of intermediates, which blocks adsorption sites of catalyst and hinders NH 3 production. Single atom alloy (SAA) is an efficient approach to circumvent this relation. In the present work, we offer a feasible strategy of preparing M 1 Ru (M = Fe, Co, Ni) SAA. Our studies show that Co 1 Ru SAA has the highest NH 3 synthesis rate and the largest TOF Ru value among M 1 Ru SAA. Compared with CoRu nanoparticle alloy (NPA), Co 1 Ru SAA has stronger electronic interaction between Co and Ru, which induces lower work function and up-shift d band center toward Fermi level for Co 1 Ru SAA, thus promoting N 2 activation. Meanwhile, the unique SAA structure could effectively tune N 2 activation pathway. Those findings make a contribution to the development of advanced catalysts for efficient NH 3 synthesis at mild conditions. [ABSTRACT FROM AUTHOR]

Li4Ti5O12 (LTO) attracts great interest due to the "zero strain" during cycles but the poor electronic and ionic conductivity critically impede the practical application. Herein, we report a synergy strategy of tuning localized electrons to shift Fermi level and band gap by Mg/Zr co‐doping and oxygen vacancy incorporation, which significantly improves Li+ and electronic transport. More importantly, the intrinsic synergistic mechanism has been revealed by neutron diffraction, X‐ray absorption spectra, and first‐principles calculations. The "elastic effect" of lattice induced by Mg/Zr co‐doping allows LTO to accommodate more oxygen vacancies to a certain degree without a severe lattice distortion, which largely improves the electronic conductivity. Mg/Zr co‐doping and oxygen vacancy incorporation effectively enhanced the dynamic characteristics of LTO electrode, achieving the excellent rate performance (90 mAh/g at 20C) and cycle stability (96.9% after 500 cycles at 10C). First‐principles calculations confirm Fermi level shifts to the conduction band, and the band gap becomes narrowed due to the synergistic modulation, and the intrinsic mechanism of the enhanced electronic and Li‐ion conductivity is clarified. This study offers some insights into achieving the fast Li+ insertion/extraction by tuning the crystal and electronic structure with lattice doping and oxygen vacancy engineering. [ABSTRACT FROM AUTHOR]

Atomically dispersed Pt species are advocated as a promising electrocatalyst for the oxygen reduction reaction (ORR) to boost noble metal utilization efficiency. However, when assembled on various substrates, isolated Pt single atoms are often demonstrated to proceed through the two‐electron ORR pathway due to the unfavorable O─O bond cleavage thermodynamics in the absence of catalytic ensemble sites. In addition, although their distinct local coordination environments at the exact single active sites are intensively explored, the interactions and synergy between closely neighboring single atom sites remain elusive. Herein, atomically dispersed Pt monomers strongly interacting on a Mo2C support is demonstrated as a model catalyst in the four‐electron ORR, and the beneficial interactions between two closely neighboring and yet non‐contiguous Pt single atom sites (named as quasi‐paired Pt single atoms) are shown. Compared to isolated Pt single atom sites, the quasi‐paired Pt single atoms deliver a superior mass activity of 0.224 A mg−1Pt and near‐100% selectivity toward four‐electron ORR due to the synergistic interaction from the two quasi‐paired Pt atom sites in modulating the binding mode of reaction intermediates. Our first‐principles calculations reveal a unique mechanism of such quasi‐paired configuration for promoting four‐electron ORR. [ABSTRACT FROM AUTHOR]

Identifying the structure of iodoplumbate complexes in various solutions is essential for linking the coordination environment of the perovskite precursor to its final properties. In this study, we investigate the structure of methylammonium lead iodide (MAPbI3) perovskite precursor solutions as a function of the volume ratio of N,N-dimethylformamide and dimethyl sulfoxide (DMSO) using X-ray absorption fine structure spectroscopy. It was demonstrated that DMSO modifies the precursor structure at the atomic level. X-ray diffraction, scanning electron microscopy, and UV–Vis spectroscopy analyses showed that the coordination environment of iodoplumbate complexes in precursor solutions is strongly correlated with the morphology of perovskite films. The appropriate amount of DMSO in the precursor solution modifies the Pb-O and Pb-I coordination of iodoplumbate complexes, which could change the growth process of high-crystallization perovskite films. This study sheds light on the formation mechanism of perovskite films from precursor solutions, which will lead to the development of high-quality films and ultimately high-efficiency devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Unique pompon-like RuCo catalysts were fabricated. • Atomically dispersed Ru-Co sites facilitated the adsorption/activation of reactants. • Excellent catalytic performance was achieved in the guaiacol hydrodeoxygenation. • Ru-Co synergy, as well as favorable hcp structure, contributed to high catalytic efficiency. Currently, the highly efficient conversion of biomass resources into highly valuable chemicals and biofuels is one of the most prospective approaches to reduce greenhouse gases emission and environmental pollution caused by excess consumption of fossil fuels. Herein, three-dimensional pompon-like well-defined RuCo particles with tunable crystallographic structures and surface atomically dispersed Ru atoms were constructed and intensively investigated as support-free metal catalysts in the hydrodeoxygenation (HDO) of lignin-derived guaiacol. It was demonstrated that the 300 °C-reduced RuCo sample possessed the hexagonal close-packed (hcp) crystallographic structure with surface abundant atomically dispersed Ru atoms, whereas 600 °C-reduced RuCo sample presented the face-centered cubic phase with lower surface Ru concentration. The as-fabricated RuCo-300 sample showed excellent catalytic HDO activity with a high cyclohexane yield of 85.3%. Comprehensive structural characterizations unveiled that the introduction of atomically dispersed Ru atoms into the RuCo-300 favored the formation of abundant surface Ru-Co sites, as well as electron-rich Ru0, and such-constructed Ru-Co sites were highly beneficial to the hydrogen dissociation on single Ru0 atoms and the further hydrogen spillover to adjacent Co0 atoms to promote the HDO process. Moreover, density functional theory (DFT) calculations revealed that the hcp structure of RuCo catalysts benefited the adsorption of guaiacol. The unique pompon-like microstructure of RuCo catalysts was conducive to the exposure of active sites and provided more open channels for the easy diffusion of reactants and products. Over the RuCo-300 catalyst, the guaiacol HDO could proceed rapidly via an initial demethoxylation reaction. The present Ru-Co synergetic catalysis in the structure of RuCo catalysts would provide a new strategy for constructing robust heterogeneous bimetal catalysts applied in practical HDO processes of a variety of lignin-derived phenolic compounds. [ABSTRACT FROM AUTHOR]