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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]

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]

[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]

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]

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]

[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]

[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]

Nanozymes have been relatively well explored, and bimetal-doped nanozymes have attracted much exploration due to their superior catalytic activity. We developed bimetallic FeCu/NPCs and Cu/NPCs nanozymes, which have good catalytic properties due to the coordination of Fe and Cu with N and P. The nanozymes acted as sensing elements in a cascade reaction system to effectively recognize seven terpenoids, including menthol (Men), paeoniflorin (Pae), camphor (Cam), paclitaxel (Pac), andrographolide (Andro), ginkgolide A (Gin A), and piperone (Pip). Terpenoids act as inhibitors of acetylcholinesterase (AChE) and reduce the hydrolysis of acetylcholine (ATCh), providing insight into establishing a simple and distinct assay for terpenoids. Notably, the sensor array distinguished seven terpenoids with concentrations as low as 10 ng/mL and achieved high-precision detection of mixed samples with different molar ratios and 21 unknown samples. Finally, the sensor array successfully distinguished and identified multiple terpenoids in herbal samples. [Display omitted] • A bimetallic and multi-atom co-doped nanozyme was synthesized. Due to the coordination of metal and N, P, the peroxidase activity is much higher than other reported nanozymes. • A simple P doping strategy for pyrolysis of polymer spheres at high temperature was designed. P doping not only formed uniform pore structure, and achieve high coordination with the metal, significantly enhance the catalytic activity of the material • Based on the good activity of nanozymes, different terpenoids have different inhibitory effects on acetylcholinesterase. A colorimetric array sensor for seven terpenoids was constructed. • 4. The sensor array can distinguish 7 terpenoids with a concentration as low as 10 ng / mL in actual Chinese herbal medicine samples, and the discrimination degree reaches 100 %。 [ABSTRACT FROM AUTHOR]