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Advances in single-atom (-site) catalysts (SACs) provide a new solution of atomic economy and accuracy for designing efficient electrocatalysts. In addition to a precise local coordination environment, controllable spatial active structure and tolerance under harsh operating conditions remain great challenges in the development of SACs. Here, we show a series of molecule-spaced SACs (msSACs) using different acid anhydrides to regulate the spatial density of discrete metal phthalocyanines with single Co sites, which significantly improve the effective active-site numbers and mass transfer, enabling one of the msSACs connected by pyromellitic dianhydride to exhibit an outstanding mass activity of (1.63 ± 0.01) × 105A·g–1and TOFbulkof 27.66 ± 1.59 s–1at 1.58 V (vsRHE) and long-term durability at an ultrahigh current density of 2.0 A·cm–2under industrial conditions for oxygen evolution reaction. This study demonstrates that the accessible spatial density of single atom sites can be another important parameter to enhance the overall performance of catalysts.

Cu is a promising electrocatalyst in CO2reduction reaction (CO2RR) to high-value C2+products. However, as important C–C coupling active sites, the Cu+species is usually unstable under reduction conditions. How atomic dopants affect the performance of Cu-based catalysts is interesting to be studied. Herein, we first calculated the difference between the thermodynamic limiting potentials of CO2RR and the hydrogen evolution reaction, as well as the *CO binding energy over Cu2O doped with different metals, and the results indicated that doping atomic Gd into Cu2O could improve the performance of the catalyst effectively. On the basis of the theoretical study, we designed Gd1/CuOxcatalysts. The distinctive electronic structure and large ion radii of Gd not only keep the Cu+species stable during the reaction but also induce tensile strain in Gd1/CuOx, resulting in excellent performance of the catalysts for electroreduction of CO2to C2+products. The Faradic efficiency of C2+products could reach 81.4% with a C2+product partial current density of 444.3 mA cm–2at −0.8 V vs a reversible hydrogen electrode. Detailed experimental and theoretical studies revealed that Gd doping enhanced CO2activation on the catalyst, stabilized the key intermediate O*CCO, and reduced the energy barrier of the C–C coupling reaction.

Cu single-atom catalysts (Cu SACs) have been considered as promising catalysts for efficient electrocatalytic CO2reduction reactions (ECRRs). However, the reports on Cu SACs with an asymmetric atomic interface to obtain CO are few. Herein, we rationally designed two Cu SACs with different asymmetric atomic interfaces to explore their catalytic performance. The catalyst of CuN3O/C delivers high ECRR selectivity with an FECOvalue of above 90% in a wide potential window from −0.5 to −0.9 V vs RHE (in particular, 96% at −0.8 V), while CuCO3/C delivers poor selectivity for CO production with a maximum FECOvalue of only 20.0% at −0.5 V vs RHE. Besides, CuN3O/C exhibited a large turnover frequency (TOF) up to 2782.6 h–1at −0.9 V vs RHE, which is much better than the maximum 4.8 h–1of CuCO3/C. Density functional theory (DFT) results demonstrate that the CuN3O site needs a lower Gibbs free energy than CuCO3in the rate-determining step of CO desorption, leading to the outstanding performance of CuN3O/C on the process of ECRR-to-CO. This work provides an efficient strategy to improve the selectivity and activity of the ECRR via regulating asymmetric atomic interfaces of SACs by adjusting the coordination atoms.

For metal–carbon shell catalysts of the hydrogen evolution reaction (HER), owing to the diversity of the inner metal phases and the adjustability of the outer carbon structure, the structure of the active sites is still puzzling. Here, with the guidance of density functional theory (DFT) calculations, verification of experimental results and operandoX-ray absorption spectroscopy, we found that the multi-interfacial charge polarization around Mo atoms in MoP induced by S on MoS2and N on adjacent NC layers in carbon defect locations of three phase interfaces could improve the adsorption/desorption behavior of H intermediates and accelerate the dissociative adsorption process of H2O molecules, which then exhibited distinct catalytic activities for the HER in both acidic (10.0 mA cm−2at η= 120 mV) and alkaline media (10.0 mA cm−2at η= 80 mV) and outstanding durability. This work offers atom-level insights into the active sites of metal–carbon shell catalysts, contributing to the rational design of efficient HER catalysts. Under the guidance of theoretical calculations, the present paper provides a new catalyst with novel inner metal cores of MoP nanoparticles (NPs) coupled with ultrafine MoS2nanosheets encapsulated with NC shells. A combination of theoretical calculations and electrochemical analysis uncovers that the multi-interfacial charge polarization of MoP, MoS2and NC in carbon defect locations could improve the HER performance in both acidic and alkaline media.

The properties of supports have a significant effect on the activity of noble metal single atoms. In this work, Co-doped CeO2-supported single-atom Pt catalysts (Pt1/Co-CeO2) have been acquired by a synchronous pyrolysis/deposition route and demonstrated to promote low-temperature oxidation of CO. Revealed by a model reaction of 1% CO + 1% O2+ 98% He at a space velocity of 12,000 mL/gcat/h, CO conversion (100 °C) acquired on a (0.5% Pt)/(10% Co-CeO2) catalyst (36.6%) was 3.6 and 4.9 times those of 0.5% Pt/CeO2(10.0%) and 10% Co-CeO2(7.4%) catalysts and 2.1 times that of their conversion sum (17.4%), confirming the positive role of the Co dopant in boosting the low-temperature oxidation of CO. The consistent results are also verified in the comparison of Pt1/Co-ZnO with Pt1/ZnO and Pt1/Co-Al2O3with Pt1/Al2O3. In addition, the activity of single-atom Pt1/Co-CeO2catalysts can be facilely modified by changing the loading of Pt and/or doping amount of Co. These reasonable data will provide a methodology to access more applicable catalysts for CO oxidation at low temperature.

The use of carbon-based materials is an appealing strategy to solve the issue of excessive CO2emissions. In particular, metal-free nitrogen-doped carbon materials (mf-NCs) have the advantages of convenient synthesis, cost-effectiveness, and high conductivity and are ideal electrocatalysts for the CO2reduction reaction (CO2RR). However, the unclear identification of the active N sites and the low intrinsic activity of mf-NCs hinder the further development of high-performance CO2RR electrocatalysts. Achieving precise control over the synthesis of mf-NC catalysts with well-defined active N-species sites is still challenging. To this end, we adopted a facile synthesis method to construct a set of mf-NCs as robust catalysts for CO2RR. The resulting best-performing catalyst obtained a Faradaic efficiency of CO of approximately 90% at −0.55 V (vs.reversible hydrogen electrode) and good stability. The electrocatalytic performance and in situattenuated total reflectance surface-enhanced infrared absorption spectroscopy measurements collectively revealed that graphitic and pyridinic N can synergistically adsorb CO2and H2O and thus promote CO2activation and protonation.

The Co SAs and Co NPs coupling catalyst has been synthesized by doping- adsorption-pyrolysis strategy. The Co SAs-Co NPs/NCFs shows excellent electrocatalytic HER activity and stability in the entire pH range.

Activation of O2is a crucial step in oxidation processes. Here, the concept of sp-hybridized C≡C triple bonds as an electron donor is adopted to develop highly active and stable catalysts for molecular oxygen activation. We demonstrate that the neighboring sp-hybridized C and Cu sites on the interface of the sub-nanocluster CuO/graphdiyne are the key structures to effectively modulate the O2activation process in the bridging adsorption mode. The as-prepared sub-nanocluster CuO/graphdiyne catalyst exhibited the highest CO oxidation activity and readily converted 50% CO at around 133 °C, which is 34 and 94 °C lower than that for CuO/graphene and CuO/active carbon catalysts, respectively. In situ diffused reflectance infrared Fourier transform spectroscopy and density functional theory calculation results proved that the neighboring sp-hybridized C is more favorable to promote the rapid dissociation of carbonate than sp2-hybridized C without overcoming any energy barrier. The gaseous CO directly reacts with the active molecular oxygen and tends to proceed through the E–R mechanism with a relatively low energy barrier (0.20 eV). This work revealed that sp-hybridized C of graphdiyne-based materials could effectively improve the O2activation efficiency, which could facilitate the low-temperature oxidation processes.

The Chang’e-5 mission returned new lunar samples after the last sample mission of the Moon 44 years ago, and is also the first mission that China has completed the sampling of extraterrestrial bodies. Recently, independent teams from the Institute of Geology, Chinese Academy of Geological Sciences, and the National Astronomical Observatories and the Institute of Geology and Geophysics, Chinese Academy of Sciences reported the first batch of results of Chang’e-5 lunar samples. The basic physical properties of the Chang’e-5 soil are within the range of the Apollo and Luna samples though the Chang’e-5 soil is finer-grained, better sorted, and has a slightly lower true density than the mare basalt previosuly reported. The Pb-Pb dating of U-rich minerals in the Chang’e-5 basalt clasts indicated that they formed at about 2.0 Ga, 800 million years younger than the youngest lunar sample recovered previously (2.8 Ga), confirming that lunar volcanic activity can last at least until 2 Ga. In-situSr-Nd isotope analyses suggested that the Chang’e-5 basalt originated from a depleted mantle source. The contribution of the KREEP component is less than 5%, which excluded the hypothesis that KREEP-rich sources provide an additional heat source for mantle melting. In addition, water contents and H isotopes of apatite and melt inclusions of the Chang’e-5 basalt suggested that the source region is not rich in water which can lower the melting point. Therefore, the reason why lunar volcanic activity can last so long is still unclear, which is a new direction for future lunar exploration and research.

The development of highly efficient and cost-effective oxygen evolution reaction (OER) electrocatalysts for renewable energy systems is vitally essential. Modulation of the electronic structure through heteroatom doping is considered as one of the most potential strategies to boost OER performances. Herein, a rational design of Mn-doped NiFe layered double hydroxide/reduced graphene oxide (Mn-NiFe LDH/rGO) is demonstrated by a facile hydrothermal approach, which exhibits outstanding OER activity and durability. Experimental results and density functional theory (DFT) calculations manifest that the introduction of Mn can reprogram the electronic structure of surface active sites and alter the intermediate adsorption energy, consequently reducing the potential limiting activation energy for OER. Specifically, the optimal Mn-NiFe LDH/rGO composite shows an enhanced OER performance with an ultralow overpotential of 240 mV@10 mA cm−2, Tafel slope of 40.0 mV dec−1and excellent stability. Such superior OER activity is comparable to those of the recently reported state-of-the-art OER catalysts. This work presents an advanced strategy for designing electrocatalysts with high activity and low cost for energy conversion applications.

Reducing CO2into fuels via photochemical reactions relies on highly efficient photocatalytic systems. Herein, we report a new and efficient photocatalytic system for CO2reduction. Driven by electrostatic attraction, an anionic metal–organic framework Cu-HHTP(HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene) as host and a cationic photosensitizer [Ru(phen)3]2+(phen = 1,10-phenanthroline) as guest were self-assembled into a photocatalytic system Ru@Cu-HHTP, which showed high activity for photocatalytic CO2reduction under laboratory light source (CO production rate of 130(5) mmol g–1h–1, selectivity of 92.9%) or natural sunlight (CO production rate of 69.5 mmol g–1h–1, selectivity of 91.3%), representing the remarkable photocatalytic CO2reduction performance. More importantly, the photosensitizer [Ru(phen)3]2+in Ru@Cu-HHTPis only about 1/500 in quantity reported in the literature. Theoretical calculations and control experiments suggested that the assembly of the catalysts and photosensitizers via electrostatic attraction interactions can provide a better charge transfer efficiency, resulting in high performance for photocatalytic CO2reduction.

Regulating the selectivity of catalysts in selective hydrogenation reactions at the atomic level is highly desirable but remains a grand challenge. Here we report a simple and practical strategy to synthesize a monolithic single-atom catalyst (SAC) with isolated Pd atoms supported on bulk nitrogen-doped carbon foams (Pd-SAs/CNF). Moreover, we demonstrate that the single-atom Pd sites with unique electronic structure endow Pd-SAs/CNF with an isolated site effect, leading to excellent activity and selectivity in 4-nitrophenylacetylene semi-hydrogenation reaction. In addition, benefiting from the great integrity and excellent mechanical strength, monolithic Pd-SAs/CNF catalyst is easy to separate from the reaction system for conducting the subsequent recycling. The cyclic test demonstrates the excellent reusability and stability of monolithic Pd-SAs/CNF catalyst. The discovery of isolated site effect provides a new approach to design highly selective catalysts. And the development of monolithic SACs provides new opportunities to advance the practical applications of single-atom catalysts.

Electrochemical reduction of CO2to chemicals and fuels is an interesting and attractive way to mitigate greenhouse gas emissions and energy shortages. In this work, we report the use of atomic In catalysts for CO2electroreduction to CO. The atomic In catalysts were anchored on N-doped carbon (InA/NC) through pyrolysis of In-based metal–organic frameworks (MOFs) and dicyandiamide. It was discovered that InA/NC had outstanding performance for selective CO production in the mixed electrolyte of ionic liquid/MeCN. It is different from those common In-based materials, in which formate/formic acid is formed as the main product. The faradaic efficiency (FE) of CO and total current density were 97.2% and 39.4 mA cm-2, respectively, with a turnover frequency (TOF) of ∼40 000 h–1. It is one of the highest TOF for CO production to date for all of the catalysts reported. In addition, the catalyst had remarkable stability. Detailed study indicated that InA/NC had higher double-layer capacitance, larger CO2adsorption capacity, and lower interfacial charge transfer resistance, leading to high activity for CO2reduction. Control experiments and theoretical calculations showed that the In–N site of InA/NC is not only beneficial for dissociation of COOH* to form CO but also hinders formate formation, leading to high selectivity toward CO instead of formate.

Unique active sites make single-atom (SA) catalysts promising to overcome obstacles in homogeneous catalysis but challenging due to their fixed coordination environment. Click chemistry is restricted by the low activity of more available Cu(II) catalysts without reducing agents. Herein, we develop efficient, O-coordinated SA Cu(II) directly catalyzed click chemistry. As revealed by theoretical calculations of the superior coordination structure to promote the click reaction, an organic molecule-assisted strategy is applied to prepare the corresponding SA Cu catalysts with respective O and N coordination. Although they both belong to Cu(II) centers, the O-coordinated one exhibits a 5-fold higher activity than the other and even much better activity than traditional homogeneous and heterogeneous Cu(II) catalysts. Control experiments further proved that the O-coordinated SA Cu(II) catalyst tends to be reduced by alkyne into Cu acetylide rather than the N-coordinated catalyst and thus facilitates click chemistry.

The construction of highly active and stable non-noble-metal electrocatalysts for hydrogen and oxygen evolution reactions is a major challenge for overall water splitting. Herein, we report a novel hybrid nanostructure with CoP nanoparticles (NPs) embedded in a N-doped carbon nanotube hollow polyhedron (NCNHP) through a pyrolysis–oxidation–phosphidation strategy derived from core–shell ZIF-8@ZIF-67. Benefiting from the synergistic effects between highly active CoP NPs and NCNHP, the CoP/NCNHP hybrid exhibited outstanding bifunctional electrocatalytic performances. When the CoP/NCNHP was employed as both the anode and cathode for overall water splitting, a potential as low as 1.64 V was needed to achieve the current density of 10 mA·cm–2, and it still exhibited superior activity after continuously working for 36 h with nearly negligible decay in potential. Density functional theory calculations indicated that the electron transfer from NCNHP to CoP could increase the electronic states of the Co d-orbital around the Fermi level, which could increase the binding strength with H and therefore improve the electrocatalytic performance. The strong stability is attributed to high oxidation resistance of the CoP surface protected by the NCNHP.

Lower olefins are widely used in the chemical industry as basic carbon-based feedstocks. Here, we report the catalytic system featuring isolated single-atom sites of iridium (Ir1) that can function within the entire temperature range of 300–600 °C and transform alkanes with conversions close to thermodynamics-dictated levels. The high turnover frequency values of the Ir1system are comparable to those of homogeneous catalytic reactions. Experimental data and theoretical calculations both indicate that Ir1is the primary catalytic site, while the coordinating C and N atoms help to enhance the activity and stability, respectively; all three kinds of elements cooperatively contribute to the high performance of this novel active site. We have further immobilized this catalyst on particulate Al2O3, and we found that the resulting composite system under mimicked industrial conditions could still give high catalytic performances; in addition, we have also developed and established a new scheme of periodical in situ regeneration specifically for this composite particulate catalyst.

The retention of self-released chalcogenates at reconstructed Co oxyhydroxides derived from selenides can be finely promoted by self-transformed carbonates derived from carbon dopants for boosted oxygen evolution performance.

Here, the unsupported Ni5Ga3catalyst was prepared at different reduction temperatures in H2for methanol synthesis via CO2hydrogenation. The structural variation incurred by changing the reduction temperature was characterized carefully (including extended X-ray absorption fine structure (EXAFS)) and related to the activity and reaction mechanism (by in situdiffuse reflectance Fourier transform spectroscopy (DRIFTS)). The findings show the significant influence of H2activation on the structural properties, activity, and selectivity of the catalysts. Specifically, Ni5Ga3-500 (i.e., reduced at 500 °C) encourages the copresence of Ga2O3and NiGa alloys, which is key to achieve the appropriate interaction strength with the CO2-related intermediates, thus giving comparatively highest CO2conversion and methanol yield. Longevity tests (100 h) of Ni5Ga3-500 showed slightly declined performance at the lower reaction temperature (viz., 220 and 260 °C), which was due to the further reduction of Ga2O3and NiGa alloying during the catalysis.

Melamine-assisted pyrolytic synthesis of core–shell cobalt@carbon nanotubes as efficient bifunctional electrocatalyst for rechargeable zinc–air batteries.

Heterogeneous Pd-based catalysts are receiving great attention in cross-coupling reactions due to their distinct advantages of relatively low cost, high stability, easy separation, and recycling. Nonetheless, great challenges still remain in developing heterogeneous catalysts with excellent performance and revealing the origin for efficient catalysis. Herein, we have synthesized a PdOx/NiO NFs catalyst consisting of porous NiO nanofibers and in situ anchored PdOxspecies by a facile electrospinning–pyrolysis strategy. The electron transfer from NiO to PdO created during the calcination step results in the formation of Pdδ+(δ < 2) in the PdOx/NiO NFs, validated by both spectroscopic analyses and computational modeling. The PdOx/NiO NFs catalyst exhibits much higher activity than the commercial 5.0 wt % Pd/C and other as-prepared Pd-based catalysts in Suzuki coupling reactions. The turnover frequency (TOF) values for the conversions of iodo-, bromo-, and chlorobenzenes over the PdOx/NiO NFs catalyst are 6.6–7.3 times those over the commercial 5 wt % Pd/C catalyst. Theoretical calculations demonstrate that the configuration of PdO(101)/NiO(111) surface is more propitious to the adsorption and activation of arylhalide and phenylboronic acid than that of Pd(111)/NiO(111) surface. The compelling performance of PdOx/NiO NFs is mainly attributed to the special surface configuration of PdOxand unique electronic state of Pdδ+species. These traits can be well retained in a long-term reaction owing to the strong metal–support interaction, ensuring the good durability of the catalyst. This study not only develops a promising heterogeneous catalyst with high performance for green synthesis of fine chemicals but also provides insights into the enhancement of catalytic activity achieved by modulating the active centers.

In the area of catalysis, selective reduction of nitro compounds to amino compounds is a colossal challenge due to the existence of competitive reducible functional groups. Herein, an Fe-based catalyst FeSAs/Fe2O3ACs/N-doped polyhedral carbon (NPC) has been designed and synthesized. As we expected, compared with FeSAsand FeNPs, FeSAs/Fe2O3ACs/NPC shows excellent catalytic performance (turnover frequency up to 1923 h–1, calculated with nitrobenzene), chemoselectivity, and tolerance during the hydrogenation reaction of nitro compounds under room temperature because of the synergistic effects between FeSAsand Fe2O3ACs. The theoretical calculations show that FeSAsprefers to undergo hydrazine decomposition to generate hydrogen and the Fe2O3ACssurface is more active toward the nitrobenzene reduction to aniline.

Stabilized Cu+species have been widely considered as catalytic active sites in composite copper catalysts for catalytic reactions with industrial importance. However, few examples comprehensively explicated the origin of stabilized Cu+in a low-cost and widely investigated CuO/TiO2system. In this study, mass producible CuO/TiO2catalysts with interface-stabilized Cu+were prepared, which showed excellent low-temperature CO oxidation activity. A thorough characterization and theoretical calculations proved that the strong charge-transfer effect and Ti–O–Cu hybridization in Ti-doped CuO(111) at the CuO/TiO2interface contributed to the formation and stabilization of Cu+species. The CO molecule adsorbed on Cu+and reacted directly with Ti doping-promoted active lattice oxygen via a Mars–van Krevelen mechanism, leading to the enhanced low-temperature activity.

Selective hydrogenation of nitroarenes to arylamines is a great challenge because of the complicated mechanism and competitive hydrogenation of reducible functional groups. Isolated single-atomic site catalysts, benefitting from their uniform and well-defined catalytic sites, are promising to achieve high activity and selectivity. Herein, we prepared an isolated iron single-atomic catalyst supported on ordered mesoporous nitrogen-doped carbon (Fe1/N–C). The as-prepared Fe1/N–C showed excellent activity and tolerance for functional groups in the transfer hydrogenation of nitroarenes over hydrazine hydrate. Density functional theory calculations revealed that the single atomically dispersed, partially positively charged Fe atoms and the lowered energy barrier collectively contribute to the superior hydrogenation performances for nitroarenes.

Herein, a series of Fe-based catalysts have been designed and prepared by grinding a mixture of MIL-88d and melamine, and then the mixture was followed by pyrolysis. An unusual Fe/Fe3C-activated site is uniformly encapsulated in the N-doped carbon tubes obtained by pyrolysis of the film-like nanocrystals of MIL-88d. Experimental characterizations and theoretical calculations demonstrate that the surface N sites can effectively trap the nitrobenzene and aniline by their phenyl groups with the formation of three C–N bonds that made the catalyst exhibit excellent catalytic activity (turnover frequencies of ≤11268 h–1calculated on the basis of nitrobenzene) and chemoselectivity for the reduction of nitro derivatives under facile conditions.

Exploring high-performance zeolite-supported metal catalysts is of great significance. Herein, we develop a strategy for fabricating isolated single metal atomic site catalysts in Y zeolite (M-ISAS@Y, M = Pt, Pd, Ru, Rh, Co, Ni, Cu) by in situ separating and confining a metal–ethanediamine complex into β-cages during the crystallization process followed by thermal treatment. The M-ISAS are stabilized by skeletal oxygens of Y zeolite, and the crystallinity, porosity, and large surface area are well inherited in M-ISAS@Y. As a demonstration, acidic Pt-ISAS@Y is used for n-hexane isomerization involving consecutive catalytic dehydrogenation/hydrogenation on Pt-ISAS and isomerization on Brønsted acid sites. The turnover frequency value of Pt-ISAS reaches 727 h–1, 5 times more than Pt nanoparticles (∼3.5 nm), with a total isomer selectivity of more than 98%. This strategy provides a convenient route to fabricate promising zeolite-based M-ISAS catalysts for industrial applications.

A central topic in single-atom catalysis is building strong interactions between single atoms and the support for stabilization. Herein we report the preparation of stabilized single-atom catalysts via a simultaneous self-reduction stabilization process at room temperature using ultrathin two-dimensional Ti3–xC2TyMXene nanosheets characterized by abundant Ti-deficit vacancy defects and a high reducing capability. The single atoms therein form strong metal–carbon bonds with the Ti3–xC2Tysupport and are therefore stabilized onto the sites previously occupied by Ti. Pt-based single-atom catalyst (SAC) Pt1/Ti3–xC2Tyoffers a green route to utilizing greenhouse gas CO2, via the formylation of amines, as a C1source in organic synthesis. DFT calculations reveal that, compared to Pt nanoparticles, the single Pt atoms on Ti3–xC2Tysupport feature partial positive charges and atomic dispersion, which helps to significantly decrease the adsorption energy and activation energy of silane, CO2, and aniline, thereby boosting catalytic performance. We believe that these results would open up new opportunities for the fabrication of SACs and the applications of MXenes in organic synthesis.

The electrochemical reduction of CO2could play an important role in addressing climate-change issues and global energy demands as part of a carbon-neutral energy cycle. Single-atom catalysts can display outstanding electrocatalytic performance; however, given their single-site nature they are usually only amenable to reactions that involve single molecules. For processes that involve multiple molecules, improved catalytic properties could be achieved through the development of atomically dispersed catalysts with higher complexities. Here we report a catalyst that features two adjacent copper atoms, which we call an ‘atom-pair catalyst’, that work together to carry out the critical bimolecular step in CO2reduction. The atom-pair catalyst features stable Cu10–Cu1x+pair structures, with Cu1x+adsorbing H2O and the neighbouring Cu10adsorbing CO2, which thereby promotes CO2activation. This results in a Faradaic efficiency for CO generation above 92%, with the competing hydrogen evolution reaction almost completely suppressed. Experimental characterization and density functional theory revealed that the adsorption configuration reduces the activation energy, which generates high selectivity, activity and stability under relatively low potentials.

The practical application of hydrogen evolution reaction (HER) through water splitting depends on the development of low cost and efficient non-noble-metal catalysts. As a potential electrocatalyst, the improvement of HER performance catalyzed by nanostructured transition metal phosphides still remains a great challenge. Tuning the novel nanostructure, morphology, and electronic state from nanoscale is of great important to achieve highly efficient HER electrocatalysts. Herein, we first developed an electronic structure and d-band center control engineering for accelerating the HER process in both acid and alkaline media over M-doped CoP (M = Ni, Mn, Fe) hollow polyhedron frames (HPFs), which were synthesized by a self-templating transformation (STT) strategy. Impressively, the HER electrocatalytic activity can be maximumly promoted and maintained at least 21 h for Ni-CoP/HPFs catalyst. Synchrotron-based X-ray absorption near-edge structure, X-ray photoelectron spectroscopy, auger electron spectroscopy, ultraviolet photoemission spectroscopy and density functional theory calculations consistently reveal the improved performance is attributed to the changes of the electronic structure and the downshift of d-band center after metal doping. The Ni-CoP/HPFs catalyst also indicates excellent activity with a cell voltage of 1.43 V to achieve the current density of 10 mA cm−2and superior stability when it was employed as a cathode for HER and an anode for urea oxidation in 1 M KOH with 0.5 M urea. The success modulation of HER performance in current STT strategy will provide a promising pathway for designing various transition metal-doped compounds for energy-related catalysis processes.

Herein, a series of Ni-based catalysts with excellent hydrogenation activity have been synthesized viaa new starch-assistant-confinement (SAC) strategy, which is the first time this has been used to develop an effective catalyst in the field of hydrogenation. As expected, the Ni@PC-900-1-4% catalyst shows a large BET surface area of 566 m2g−1, which favors a substrate being transferred with nanoparticles that are dispersed uniformly, making the active sites more exposed to the substrate. The catalyst enables highly-efficient hydrogenation of nitrogen heterocyclic compounds. Most importantly, as a gram-scale test, the catalyst also exhibits efficient activity to obtain an excellent yield of around 90% under mild conditions.

It is very important to explore novel synthesis strategies for constructing highly active and inexpensive electrocatalysts for water-splitting. In present work, a novel and efficient coordination-polymerization-pyrolysis (CPP) strategy was developed to prepare cobalt phosphide nanoparticles modified N-doped porous carbon spheres (CoP@NPCSs) hybrids as a powerful catalyst for overall water-splitting (OWS). It can be found that both the carbonization temperatures and the metal contents affect the electrocatalytic performances. As a result, a device assembled with CoP@NPCSs demonstrates low potential (1.643 V @ 10 mA·cm–2) and good stabilization for OWS. Besides, other transition metal phosphides (TMPs)-based materials also can be synthesized by the CPP approach, evidencing the generality of the CPP strategy. Here, we not only constructs a high-efficiency OWS catalyst, but also broadens the synthetic methodology of TMPs from nanoscale.

Metal–organic frameworks (MOF) have recently emerged as versatile precursors to fabricate functional MOF derivatives for oxygen evolution reactions (OER). Herein, we developed a controlled partial pyrolysis strategy to construct robust NiCo/Fe3O4heteroparticles within MOF-74 for efficient OER using trimetallic NiCoFe-MOF-74 as precursor. The partial pyrolysis method preserves the framework structure of MOF for effective substrates diffusion while producing highly active nanoparticles. The as-prepared NiCo/Fe3O4/MOF-74 delivered remarkably stable OER current with an overpotential as low as 238 mV at 10.0 mA cm–2and an Tafel slop of 29 mV/dec, outperforming those of pristine NiCoFe-MOF-74, totally decomposed MOF derivatives, and most reported non-noble metal based electrocatalysts. The key for the formation of NiCo/Fe3O4/MOF-74 nanostructures is that the metals can be decomposed from NiCoFe-MOF-74 in the order of Ni, Co, and Fe under controlled heat treatment. Density functional theory calculations reveals that the underlying NiCo promotes the OER activity of Fe3O4through exchange stabilization of active oxygen species.

Quantum dots (QDs) derived from two-dimensional (2D) nanosheets (NSs), especially ultrathin transition metal dichalcogenide (TMD, e.g.WS2, WSe2, MoS2, MoSe2) NSs, have attracted great attention due to their broad band absorption and high charge mobility. Herein, WS2QDs, one of the emerging extraordinary zero-dimensional (0D) TMD materials, were applied to the preparation of novel 0D/2D heterojunctions of WS2QDs/BiOCl nanosheets. The obtained WS2/BiOCl composites exhibited significantly enhanced visible-light-driven photocatalytic activity as compared with pure BiOCl. The results indicated that the holes (h+) and O2−are the main active species generated by the catalysts under visible light irradiation. The enhanced photocatalytic performance could be due to the broad band absorption and up-conversion properties of the WS2QDs as well as the band alignment and the strong coupling between the WS2QDs and BiOCl NSs, leading to a broadened light absorption range and enhanced efficiency for electron–hole pair production and separation. These findings offer exciting opportunities using the extraordinary 2D TMD material-derived quantum dots for the fabrication of novel 0D/2D composites and may provide new insights into the application of the novel 0D/2D composites in catalysis.

We report an electron induction regulation mechanism of single-atomic Fe sites by adjacent Te atoms to construct Fe–Te diatomic sites (DASs) for synergistic electrocatalytic CO2reduction reaction (CO2RR). The Fe–Te DASs feature stable and unique N3Fe–TeC3structures, with low-valence Feδ+binding with one C atom and one O atom of CO2, and the adjacent Teδ+acts as an electron donor, adjusting the electronic structure of Feδ+sites, and stabilizes another negative O atom of CO2by favorable electrostatics, strengthening CO2adsorption and activation. Notably, the catalyst delivers a high CO selectivity above 90% over a wide potential range and good stability. The formation of Fe–Te DASs elevates the Fermi level and strengthens the interaction of the 2 πuorbital of CO2, which is easier to bend and forms activated CO2intermediate, thereby decreasing the activation barrier and promoting the CO2RR process.

In the field of a heterogeneous industrial catalysis process, the encapsulated structure plays a crucial role in preventing active sites from leaching during the reaction; however, related studies on the strategy to fabricate encapsulated catalysts under control remain rare. Herein, we develop an amino-assisted strategy to construct a highly stable catalyst with core–shell copper nanoparticles (NPs), namely, Cu@NC (NC represents the nitrogen-doped carbon), presenting not only excellent activity but also high durability on the hydrogenation of quinolines even in the large-scale tests, which is very vital in practical application. In contrast, in the absence of the amino group, the Cu NPs were dispersed out of the carbon surface to form Cu/NC, leading to readily lose activity in the recycling tests due to the leaching occurred during the catalytic process. This work offers a promising method to fabricate a stable catalyst to enhance durability in heterogeneous catalysis.

Mesoporous support-encapsulated fine-size metal nanoclusters hold great potential for catalytic applications by virtue of their high reactivity and fast mass transport kinetics but suffer greatly from particle aggregation and/or sintering, especially under high reaction temperatures. Here, we report an inner surface-confinement strategy to stabilize a variety of ultrafine metal nanoclusters (M = Pt, Pd, Ni, and Ag) inside mesoporous silica supports. The strategy is based on the selective N functionalization of the inner surface of mesopores, which not only assures the direct growth of ultrafine metal nanoclusters therein but also endows the active metal nanoclusters with excellent thermal stability via N-metal coordination. Remarkably, the mesopore-encapsulated N-coordinated Pt nanoclusters are particularly selective for making α,β-unsaturated alcohol, benefiting from their energetically favored reaction pathway for end-on binding α,β-unsaturated aldehyde reactants and heterolytic dissociation of hydrogen. The synthetic methodology is expected to provide new guidelines to improve the thermal stability of mesopore-encapsulated metal nanoclusters for superb catalysis.

Description

Understanding the atomic diffusions at the nanoscale is important for controlling the synthesis and utilization of nanomaterials. Here, using in situX-ray absorption spectroscopy coupled with theoretical calculations, we demonstrate a so far unexplored unidirectional diffusion from the Au shell to the Cu core in thermally alloying Cu@Au core@shell architecture of ca.7.1 nm. The initial diffusion step at 423 K is found to be characterized by the formation of a diffusion layer composed of a Au-dilute substitutional CuAu-like intermetallic compound with short Cu–Au bond length (2.61 Å). The diffusion further happens by the migration of the Au atoms with large disorder into the interior Cu matrix at higher temperatures (453 and 553 K). These results suggest that the structural preference of a CuAu-like compound, along with the nanosized effect, plays a critical role in determining the atomic diffusion dynamics.

Photocatalytic CO2conversion into a high-value-added C2product is a highly challenging task because of insufficient electron deliverability and sluggish C–C coupling kinetics. Engineering catalytic interfaces in photocatalysts provides a promising approach to manipulate photoinduced charge carriers and create multiple catalytic sites for boosting the generation of C2product from CO2reduction. Herein, a Cuδ+/CeO2-TiO2photocatalyst that contains atomically dispersed Cuδ+sites anchored on the CeO2-TiO2heterostructures consisting of highly dispersed CeO2nanoparticles on porous TiO2is designedly constructed by the pyrolytic transformation of a Cu2+-Ce3+/MIL-125-NH2precursor. In the designed photocatalyst, TiO2acts as a light-harvesting material for generating electron–hole pairs that are efficiently separated by CeO2-TiO2interfaces, and the Cu–Ce dual active sites synergistically facilitate the generation and dimerization of *CO intermediates, thus lowering the energy barrier of C–C coupling. As a consequence, the Cuδ+/CeO2-TiO2photocatalyst exhibits a production rate of 4.51 μmol–1·gcat–1·h–1and 73.9% selectivity in terms of electron utilization for CO2to C2H4conversion under simulated sunlight, with H2O as hydrogen source and hole scavenger. The photocatalytic mechanism is revealed by operando spectroscopic methods as well as theoretical calculations. This study displays the rational construction of heterogeneous photocatalysts for boosting CO2conversion and emphasizes the synergistic effect of multiple active sites in enhancing the selectivity of C2product.

Hydrogen production by water splitting and seawater electrolysis is a promising alternative to develop clean hydrogen energy. The construction of high-efficiency and durable electrocatalysts for the hydrogen evolution reaction (HER) in a wide pH range and seawater is critical to overcoming the sluggish kinetic process. Herein, we develop an efficient catalytic material composed of a single-atom Ru–N4site and Ru nanoparticles anchored on nitrogen-doped carbon (Ru1+NPs/N–C) through the coordination-pyrolysis strategy of the melamine formaldehyde resin. The Ru1+NPs/N–C catalyst shows outstanding HER activity with the smallest overpotentials, the lowest Tafel slopes, the highest mass activity and turnover frequency, as well as excellent stability in both acidic and alkaline media. Moreover, Ru1+NPs/N–C shows comparable hydrogen production performance and a higher faradic efficiency to 20% Pt/C in natural seawater and artificial simulated seawater. Theoretical calculations demonstrate that the strong synergistic effects between the Ru–N4site and Ru nanoparticles modify the electronic structure to accelerate the HER kinetics. Ru nanoparticles can effectively realize dissociation of H2O to generate adsorbed hydrogen and also promote the single-atom Ru–N4site to combine adsorbed hydrogen to H2and desorption. This work provides a new perspective for designing high-efficiency hydrogen production electrocatalysts for large-scale seawater electrolysis.

Designing catalysts with specific active sites is a crucial yet challenging task for high-efficiency electrocatalysis of hydrogen evolution reaction (HER). In this paper, we report the construction of atomically dispersed Ni–Ru–P interface sites (ISs) on Ru single-atomic sites doped nickel phosphide nanoparticles (Ru SAs–Ni2P NPs) with high-efficiency HER performances in a wide pH range. Especially, the as-constructed atomically dispersed Ni–Ru–P ISs on 2.20 wt% Ru SAs–Ni2P showed a highly active for catalyzing HER with high turnover frequencies at low overpotential, featuring a high mass activity as well as a superior stability under alkaline conditions. Based on the operando X-ray absorption spectroscopy experiments indicated that the Ni–Ru–P ISs plays an active role in the process of HER and participates in the catalytic process. Density functional theory calculations exhibited that the strong interaction in the atomically dispersed Ni–Ru–P ISs results in an optimized the hydrogen adsorption energy and an elevated hydroxyl adsorption energy, both of which help improve the HER performances. Notably, this work provides a new perspective for the design of high-efficiency HER electrocatalysts by constructing atomically dispersed ISs.

Modifying the electronic structure of electrocatalysts by metal doping is favorable to their electrocatalytic activity. Herein, by a facile one-pot redox process of Fe(III) and Cu(I), Fe(II) was successfully doped into the subsurface of CuS nanosheets (NSs) for the first time to obtain a novel electrocatalyst (Fesub-CuS NSs) that possesses not only subtle lattice defects but also an atomic-level coupled nanointerface, greatly enhancing the oxygen evolution reaction (OER) performances. Meanwhile, Fe(II) and Fe(III) coexisting in Fesub-CuS nanosheets are favorable to OER through valence regulation. As expected, by simultaneously controlling the abovementioned three factors to optimize Fesub-CuS nanosheets, they display a lower overpotential of 252 mV at a current density of 20 mA cm–2for OER, better than 389 mV for pristine CuS nanosheets. This discovery furnishes low-cost and efficient Cu-based electrocatalysts by metal doping. Density functional theory (DFT) calculations further verify that Fesub-CuS(100) is thermodynamically stable and is more active for OER. This research provides a strategy for the atomic-scale engineering of nanocatalysts and also sheds light on the design of novel and efficient electrocatalysts.