Oxygen Vacancies in ZnO Nanosheets Enhance CO2 Electrochemical Reduction to CO

Oxygen Vacancy-Electron Polarons Featured InSnRuO2 Oxides: Orderly and Concerted In-Ov-Ru-O-Sn Substructures for Acidic Water Oxidation

Polymetallic oxides with extraordinary electrons/geometry structure ensembles, trimmed electron bands, and way-out coordination environments, built by an isomorphic substitution strategy, may create unique contributing to concertedly catalyze water oxidation, which is of great significance for proton exchange membrane water electrolysis (PEMWE). Herein, well-defined rutile InSnRuO2 oxides with density-controllable oxygen vacancy (Ov)-free electron polarons are firstly fabricated by in situ isomorphic substitution, using trivalent In species as Ov generators and the adjacent metal ions as electron donors to form orderly and concerted In-Ov-Ru-O-Sn substructures in the tetravalent oxides. For acidic water oxidation, the obtained InSnRuO2 displays an ultralow overpotential of 183 mV (versus RHE) and a mass activity (MA) of 103.02 A mgRu -1, respectively. For a long-term stability test of PEMWE, it can run at a low and unchangeable cell potential (1.56 V) for 200 h at 50 mA cm-2, far exceeding current IrO2||Pt/C assembly in 0.5 m H2SO4. Accelerated degradation testing results of PEMWE with pure water as the electrolyte show no significant increase in voltage even when the voltage is gradually increased from 1 to 5 A cm-2. The remarkably improved performance is associated with the concerted In-Ov-Ru-O-Sn substructures stabilized by the dense Ov-electron polarons, which synergistically activates band structure of oxygen species and adjacent Ru sites and then boosting the oxygen evolution kinetics. More importantly, the self-trapped Ov-electron polaron induces a decrease in the entropy and enthalpy, and efficiently hinder Ru atoms leaching by increasing the lattice atom diffusion energy barrier, achieves long-term stability of the oxide. This work may open a door to design next-generation Ru-based catalysts with polarons to create orderly and asymmetric substructures as active sites for efficient electrocatalysis in PEMWE application.

Synthesis of Self-Assembled Mesoporous ZnO Microspheres Designed for Microwave-Assisted Photocatalytic Degradation of Tetracycline

Microwave-assisted photocatalysis offers a novel approach for degrading antibiotics, while the mechanism of enhancement of microwave-induced photocatalysis remains poorly understood. In this study, tetracycline (TC) was degraded using the method of microwave-assisted photocatalysis with a ZnO catalyst, which was synthesized by the combination of hydrothermal and calcination methods. The self-assembled mesoporous ZnO catalyst exhibited superior catalytic activity in degrading TC. It is found that the degradation efficiency of TC by the ZnO catalysts with microwave-assisted photocatalysis is 4.27 times higher than that of photocatalysis alone. Of particular significance, we found that the optical absorption range of ZnO increased and the band gap decreased when microwave was introduced into the photocatalytic system. Semi-in situ photochemical tests demonstrated that more photogenerated electron-hole pairs were detected under microwave, thus further improving the photocatalytic activity of ZnO. The separation efficiency and charge transfer efficiency of photogenerated electron-hole pairs also improved due to the increase of oxygen vacancies in the synergistic effect. Meanwhile, h+ and ·OH were the main active species in the degradation system. The mechanism of microwave-induced photocatalysis is illustrated, and an efficient way for degrading antibiotic is provided in this work.

Direct cleavage of C=O double bond in CO2 by the subnano MoOx surface on Mo2N

Compared to H2-assisted activation mode, the direct dissociation of CO2 into carbonyl (*CO) with a simplified reaction route is advantageous for CO2-related synthetic processes and catalyst upgrading, while the stable C = O double bond makes it very challenging. Herein, we construct a subnano MoO3 layer on the surface of Mo2N, which provides a dynamically changing surface of MoO3↔MoOx (x < 3) for catalyzing CO2 hydrogenation. Rich oxygen vacancies on the subnano MoOx surface with a high electron donating capacity served as a scissor to directly shear the C = O double bond of CO2 to form CO at a high rate. The O atoms leached in CO2 dissociation are removed timely by H2 to regenerate active oxygen vacancies. Owing to the greatly enhanced dissociative activation of CO2, this MoOx/Mo2N catalyst without any supported active metals shows excellent performance for catalyzing CO2 hydrogenation to CO. The construction of highly disordered defective surface on heterostructures paves a new pathway for molecule activation.

Atmosphere Induces Tunable Oxygen Vacancies to Stabilize Single-Atom Copper in Ceria for Robust Electrocatalytic CO2 Reduction to CH4

Electrochemical carbon dioxide reduction (ECO2RR) shows great potential to create high-value carbon-based chemicals, while designing advanced catalysts at the atomic level remains challenging. The ECO2RR performance is largely dependent on the catalyst microelectronic structure that can be effectively modulated through surface defect engineering. Here, we provide an atmosphere-assisted low-temperature calcination strategy to prepare a series of single-atomic Cu/ceria catalysts with varied oxygen vacancy concentrations for robust electrolytic reduction of CO2 to methane. The obtained Cu/ceria catalyst under H2 environment (Cu/ceria-H2) exhibits a methane Faraday efficiency (FECH4) of 70.03 % with a turnover frequency (TOFCH4) of 9946.7 h-1 at an industrial-scale current density of 150 mA cm-2 in a flow cell. Detailed studies indicate the copious oxygen vacancies in the Cu/ceria-H2 are conducive to regulating the surface microelectronic structure with stabilized Cu+ active center. Furthermore, density functional theory calculations and operando ATR-SEIRAS demonstrate that the Cu/ceria-H2 can markedly enhance the activation of CO2, facilitate the adsorption of pivotal intermediates *COOH and *CO, thus ultimately enabling the high selectivity for CH4 production. This study presents deep insights into designing effective electrocatalysts for CO2 to CH4 conversion by controlling the surface microstructure via the reaction atmosphere.

Atomic Defects Engineering Boosts Urea Synthesis toward Carbon Dioxide and Nitrate Coelectroreduction

The atomic defect engineering could feasibly decorate the chemical behaviors of reaction intermediates to regulate catalytic performance. Herein, we created oxygen vacancies on the surface of In(OH)3 nanobelts for efficient urea electrosynthesis. When the oxygen vacancies were constructed on the surface of the In(OH)3 nanobelts, the faradaic efficiency for urea reached 80.1%, which is 2.9 times higher than that (20.7%) of the pristine In(OH)3 nanobelts. At -0.8 V versus reversible hydrogen electrode, In(OH)3 nanobelts with abundant oxygen vacancies exhibited partial current density for urea of -18.8 mA cm-2. Such a value represents the highest activity for urea electrosynthesis among recent reports. Density functional theory calculations suggested that the unsaturated In sites adjacent to oxygen defects helped to optimize the adsorbed configurations of key intermediates, promoting both the C-N coupling and the activation of the adsorbed CO2NH2 intermediate. In-situ spectroscopy measurements further validated the promotional effect of the oxygen vacancies on urea electrosynthesis.

Amorphous ZnSnOx Hollow Spheres Enable Highly Efficient CO2 Reduction

Carbon dioxide (CO2) adsorption and electron transport play an important role in CO2 reduction reaction (CO2RR). Herein, we have demonstrated a new class of diverse hollow ZnSnOx (ZSO) through the amorphization of hydroxides to enhance CO2 adsorption and accelerate electron transport. The amorphization is occurred by calcination process, as indicated by Fourier transform infrared spectroscopy and Raman spectra. In particular, the ZnSnOx hollow spheres (ZSO HSs) achieve a high Faradaic efficiency (FE) of HCOOH up to 92.7 % at best, outperforming the commercial ZSO (Comm. ZSO, 85.7 %). ZSO HSs also exhibit durable stability with negligible activity decay after 10 h of successive electrolysis. In-situ attenuated total reflectance infrared absorption spectroscopy further reveals strong adsorption of CO2 and rapid intermediate configuration transformation in amorphous ZSO HSs. This work demonstrates the practical application of ZSO for CO2RR and provides a new insight to create efficient CO2RR electrocatalysts.

Electrocatalysts for Urea Synthesis from CO2 and Nitrogenous Species: From CO2 and N2/NOx Reduction to urea synthesis

The traditional industrial synthesis of urea relies on the energy-intensive and polluting process, namely the Haber-Bosch method for ammonia production, followed by the Bosch-Meiser process for urea synthesis. In contrast, electrocatalytic C-N coupling from carbon dioxide (CO2) and nitrogenous species presents a promising alternative for direct urea synthesis under ambient conditions, bypassing the need for ammonia production. This review provides an overview of recent progress in the electrocatalytic coupling of CO2 and nitrogen sources for urea synthesis. It focuses on the role of intermediate species and active site structures in promoting urea synthesis, drawing from insights into reactants' adsorption behavior and interactions with catalysts tailored for CO2 reduction, nitrogen reduction, and nitrate reduction. Advanced electrocatalyst design strategies for urea synthesis from CO2 and nitrogenous species under ambient conditions are explored, providing insights for efficient catalyst design. Key challenges and prospective directions are presented in the conclusion. Mechanistic studies elucidating the C-N coupling reaction and future development directions are discussed. The review aims to inspire further research and development in electrocatalysts for electrochemical urea synthesis.

Grain-Boundary-Rich Ceria Metallene Nanozyme with Abundant Metal Site Pairs Boosts Phosphatase-like Activity

Natural phosphatases featuring paired metal sites inspire various advanced nanozymes with phosphatase-like activity as alternatives in practical applications. Numerous efforts to create point defects show limited metal site pairs, further resulting in insufficient activity. However, it remains a grand challenge to accurately engineer abundant metal site pairs in nanozymes. Herein, we report a grain-boundary-rich ceria metallene nanozyme (GB-CeO2) with phosphatase-like activity. Grain boundaries acting as the line or interfacial defects can effectively increase the content of Ce4+/Ce3+ site pairs to 72.28%, achieving a 49.28-fold enhancement in activity. Furthermore, abundant grain boundaries optimize the band structure to assist the photoelectron transfer under irradiation, which further increases the content of metal site pairs to 88.96% and finally realizes a 114.39-fold enhanced activity over that of CeO2 without irradiation. Given the different inhibition effects of pesticides on catalysts with and without irradiation, GB-CeO2 was successfully applied to recognize mixed toxic pesticides.

Construction of Cobalt Porphyrin-Modified Cu2O Nanowire Array as a Tandem Electrocatalyst for Enhanced CO2 Reduction to C2 Products

Here, the molecule-modified Cu-based array is first constructed as the self-supporting tandem catalyst for electrocatalytic CO2 reduction reaction (CO2RR) to C2 products. The modification of cuprous oxide nanowire array on copper mesh (Cu2O@CM) with cobalt(II) tetraphenylporphyrin (CoTPP) molecules is achieved via a simple liquid phase method. The systematical characterizations confirm that the formation of axial coordinated Co-O-Cu bond between Cu2O and CoTPP can significantly promote the dispersion of CoTPP molecules on Cu2O and the electrical properties of CoTPP-Cu2O@CM heterojunction array. Consequently, as compared to Cu2O@CM array, the optimized CoTPP-Cu2O@CM sample as electrocatalyst can realize the 2.08-fold C2 Faraday efficiency (73.2% vs 35.2%) and the 2.54-fold current density (‒52.9 vs ‒20.8 mA cm-2) at ‒1.1 V versus RHE in an H-cell. The comprehensive performance is superior to most of the reported Cu-based materials in the H-cell. Further study reveals that the CoTPP adsorption on Cu2O can restrain the hydrogen evolution reaction, improve the coverage of *CO intermediate, and maintain the existence of Cu(I) at low potential.

Promoting CO2 Electroreduction Over Nano-Socketed Cu/Perovskite Heterostructures via A-Site-Valence-Controlled Oxygen Vacancies

Despite the intriguing potential, nano-socketed Cu/perovskite heterostructures for CO2 electroreduction (CO2RR) are still in their infancy and rational optimization of their CO2RR properties is lacking. Here, an effective strategy is reported to promote CO2-to-C2+ conversion over nano-socketed Cu/perovskite heterostructures by A-site-valence-controlled oxygen vacancies. For the proof-of-concept catalysts of Cu/La0.3-xSr0.6+xTiO3-δ (x from 0 to 0.3), their oxygen vacancy concentrations increase controllably with the decreased A-site valences (or the increased x values). In flow cells, their activity and selectivity for C2+ present positive correlations with the oxygen vacancy concentrations. Among them, the Cu/Sr0.9TiO3-δ with most oxygen vacancies shows the optimal activity and selectivity for C2+. And relative to the Cu/La0.3Sr0.6TiO3-δ with minimum oxygen vacancies, the Cu/Sr0.9TiO3-δ exhibits marked improvements (up to 2.4 folds) in activity and selectivity for C2+. The experiments and theoretical calculations suggest that the optimized performance can be attributed to the merits provided by oxygen vacancies, including the accelerated charge transfer, enhanced adsorption/activation of reaction species, and reduced energy barrier for C─C coupling. Moreover, when explored in a membrane-electrode assembly electrolyzer, the Cu/Sr0.9TiO3-δ catalyst shows excellent activity, selectivity (43.9%), and stability for C2H4 at industrial current densities, being the most effective perovskite-based catalyst for CO2-to-C2H4 conversion.

Oxygen Vacancy and Bandgap Simultaneous Modulation to Achieve High Lithiophilicity and Mechanical Strength of Lithium Metal Anodes

Metal oxides with conversion and alloying mechanisms are more competitive in suppressing lithium dendrites. However, it is difficult to simultaneously regulate the conversion and alloying reactions. Herein, conversion and alloying reactions are regulated by modulation of the zinc oxide bandgap and oxygen vacancies. State-of-the-art advanced characterization techniques from a microcosmic to a macrocosmic viewpoint, including neutron diffraction, synchrotron X-ray absorption spectroscopy, synchrotron X-ray microtomography, nanoindentation, and ultrasonic C-scan demonstrated the electrochemical gain benefit from plentiful oxygen vacancies and low bandgaps due to doping strategies. In addition, high mechanical strength 3D morphology and abundant mesopores assist in the uniform distribution of lithium ions. Consequently, the best-performed ZnO-2 offers impressive electrochemical properties, including symmetric Li cells with 2000 h and full cells with 81% capacity retention after 600 cycles. In addition to providing a promising strategy for improving the lithiophilicity and mechanical strength of metal oxide anodes, this work also sheds light on lithium metal batteries for practical applications.

Crystalline-Amorphous Interfaces Engineering of CoO-InOx for Highly Efficient CO2 Electroreduction to CO

As a fundamental product of CO2 conversion through two-electron transfer, CO is used to produce numerous chemicals and fuels with high efficiency, which has broad application prospects. In this work, it has successfully optimized catalytic activity by fabricating an electrocatalyst featuring crystalline-amorphous CoO-InOx interfaces, thereby significantly expediting CO production. The 1.21%CoO-InOx consists of randomly dispersed CoO crystalline particles among amorphous InOx nanoribbons. In contrast to the same-phase structure, the unique CoO-InOx heterostructure provides plentiful reactive crystalline-amorphous interfacial sites. The Faradaic efficiency of CO (FECO) can reach up to 95.67% with a current density of 61.72 mA cm-2 in a typical H-cell using MeCN containing 0.5 M 1-Butyl-3-methylimidazolium hexafluorophosphate ([Bmim]PF6) as the electrolyte. Comprehensive experiments indicate that CoO-InOx interfaces with optimization of charge transfer enhance the double-layer capacitance and CO2 adsorption capacity. Theoretical calculations further reveal that the regulating of the electronic structure at interfacial sites not only optimizes the Gibbs free energy of *COOH intermediate formation but also inhibits HER, resulting in high selectivity toward CO.

Facet-switching of rate-determining step on copper in CO2-to-ethylene electroreduction

Reduction of carbon dioxide (CO2) by renewable electricity to produce multicarbon chemicals, such as ethylene (C2H4), continues to be a challenge because of insufficient Faradaic efficiency, low production rates, and complex mechanistic pathways. Here, we report that the rate-determining steps (RDS) on common copper (Cu) surfaces diverge in CO2 electroreduction, leading to distinct catalytic performances. Through a combination of experimental and computational studies, we reveal that C─C bond-making is the RDS on Cu(100), whereas the protonation of *CO with adsorbed water becomes rate-limiting on Cu(111) with a higher energy barrier. On an oxide-derived Cu(100)-dominant Cu catalyst, we reach a high C2H4 Faradaic efficiency of 72%, partial current density of 359 mA cm-2, and long-term stability exceeding 100 h at 500 mA cm-2, greatly outperforming its Cu(111)-rich counterpart. We further demonstrate constant C2H4 selectivity of >60% over 70 h in a membrane electrode assembly electrolyzer with a full-cell energy efficiency of 23.4%.

Advances and challenges in the electrochemical reduction of carbon dioxide

The electrocatalytic carbon dioxide reduction reaction (ECO2RR) is a promising way to realize the transformation of waste into valuable material, which can not only meet the environmental goal of reducing carbon emissions, but also obtain clean energy and valuable industrial products simultaneously. Herein, we first introduce the complex CO2RR mechanisms based on the number of carbons in the product. Since the coupling of C-C bonds is unanimously recognized as the key mechanism step in the ECO2RR for the generation of high-value products, the structural-activity relationship of electrocatalysts is systematically reviewed. Next, we comprehensively classify the latest developments, both experimental and theoretical, in different categories of cutting-edge electrocatalysts and provide theoretical insights on various aspects. Finally, challenges are discussed from the perspectives of both materials and devices to inspire researchers to promote the industrial application of the ECO2RR at the earliest.

Oxygen vacancies synergistic cobalt phosphide electron bridge modulated bismuth oxychloride/carbon nitride Z-scheme junction for efficient carbon dioxide reduction coupled with tetracycline oxidation

Although great progress has been made with respect to electron bridges, the electron mobility of the state-of-the-art electron bridges is far from satisfactory because of weak electrical conductivity. To overcome the above issue, cobalt phosphide (CoP), as a model electron bridge, was modified by superficial oxygen vacancies (OVs) and embedded into a defective bismuth oxychloride/carbon nitride (BiO1-xCl/g-C3N4) Z-scheme heterojunction to obtain atomic-level insights into the effect of surface OVs on CoP electron bridges. Compared to BiO1-xCl/g-C3N4 and bismuth oxychloride/cobalt phosphide/carbon nitride (BiOCl/CoP/g-C3N4) composites, the defective bismuth oxychloride/cobalt phosphide/carbon nitride (BiO1-xCl/CoP/g-C3N4) heterojunction exhibited remarkable photocatalytic redox performance, indicating that the surface OVs-assisted CoP electron bridge effectively boosted electrical conductivity and yielded ultrafast electron transfer rates. The theoretical and experimental results demonstrate that the surface OVs play a critical role in improving the electrical conductivity of the CoP electron bridge, thereby accelerating electron mobility. This research provides insights into interfacial OVs-modified transition metal phosphide (TMP) electron bridges and their potential application in heterojunctions for energy crisis mitigation and environmental remediation.

Advances in Defect Engineering of Metal Oxides for Photocatalytic CO2 Reduction

Photocatalytic CO2 reduction technology, capable of converting low-density solar energy into high-density chemical energy, stands as a promising approach to alleviate the energy crisis and achieve carbon neutrality. Semiconductor metal oxides, characterized by their abundant reserves, good stability, and easily tunable structures, have found extensive applications in the field of photocatalysis. However, the wide bandgap inherent in metal oxides contributes to their poor efficiency in photocatalytic CO2 reduction. Defect engineering presents an effective strategy to address these challenges. This paper reviews the research progress in defect engineering to enhance the photocatalytic CO2 reduction performance of metal oxides, summarizing defect classifications, preparation methods, and characterization techniques. The focus is on defect engineering, represented by vacancies and doping, for improving the performance of metal oxide photocatalysts. This includes advancements in expanding the photoresponse range, enhancing photogenerated charge separation, and promoting CO2 molecule activation. Finally, the paper provides a summary of the current issues and challenges faced by defect engineering, along with a prospective outlook on the future development of photocatalytic CO2 reduction technology.

Highly selective electroreduction of CO2 to CO with ZnO QDs/N-doped porous carbon catalysts

ZnO quantum dots (QDs) supported on porous nitrogen-doped carbon (ZnOQDs/P-NC) exhibited excellent electrochemical performance for the electroreduction of CO2 to CO with a faradaic efficiency of 95.3% and a current density of 21.6 mA cm-2 at -2.2 V vs. Ag/Ag+.

Constructing Highly Efficient ZnO Nanocatalysts with Exposed Extraordinary (110) Facet for CO2 Electroreduction

Electrochemical reduction of CO2 to highly valuable products is a promising way to reduce CO2 emissions. The shape and facets of metal nanocatalysts are the key parameters in determining the catalytic performance. However, the exposed crystal facets of ZnO with different morphologies and which facets achieve a high performance for CO2 reduction are still controversial. Here, we systematically investigate the effect of the facet-dependent reactivity of reduction of CO2 to CO on ZnO (nanowire, nanosheet, and flower-like). The ZnO nanosheet with exposed (110) facet exhibited prominent catalytic performance with a Faradaic efficiency of CO up to 84% and a current density of -10 mA cm-2 at -1.2 V versus RHE, far outperforming the ZnO nanowire (101) and ZnO nanoflower (103). Based on detailed characterizations and kinetic analysis, the ZnO nanosheet (110) with porous architecture increased the exposure of active sites. Further studies revealed that the high CO selectivity originated from the enhancement of CO2 adsorption and activation on the ZnO (110) facet, which promoted the conversion of CO2 toward CO. This study provides a new way to tailor the activity and selectivity of metal catalysts by engineering exposed specific facets.

Regulation Strategy of Nanostructured Engineering on Indium-Based Materials for Electrocatalytic Conversion of CO2

Electrochemical carbon dioxide reduction (CO2 RR), as an emerging technology, can combine with sustainable energies to convert CO2 into high value-added products, providing an effective pathway to realize carbon neutrality. However, the high activation energy of CO2 , low mass transfer, and competitive hydrogen evolution reaction (HER) leads to the unsatisfied catalytic activity. Recently, Indium (In)-based materials have attracted significant attention in CO2 RR and a series of regulation strategies of nanostructured engineering are exploited to rationally design various advanced In-based electrocatalysts, which forces the necessary of a comprehensive and fundamental summary, but there is still a scarcity. Herein, this review provides a systematic discussion of the nanostructure engineering of In-based materials for the efficient electrocatalytic conversion of CO2 to fuels. These efficient regulation strategies including morphology, size, composition, defects, surface modification, interfacial structure, alloying, and single-atom structure, are summarized for exploring the internal relationship between the CO2 RR performance and the physicochemical properties of In-based catalysts. The correlation of electronic structure and adsorption behavior of reaction intermediates are highlighted to gain in-depth understanding of catalytic reaction kinetics for CO2 RR. Moreover, the challenges and opportunities of In-based materials are proposed, which is expected to inspire the development of other effective catalysts for CO2 RR.

Improving Stability of CO2 Electroreduction by Incorporating Ag NPs in N-Doped Ordered Mesoporous Carbon Structures

The electroreduction of carbon dioxide (eCO2RR) to CO using Ag nanoparticles as an electrocatalyst is promising as an industrial carbon capture and utilization (CCU) technique to mitigate CO2 emissions. Nevertheless, the long-term stability of these Ag nanoparticles has been insufficient despite initial high Faradaic efficiencies and/or partial current densities. To improve the stability, we evaluated an up-scalable and easily tunable synthesis route to deposit low-weight percentages of Ag nanoparticles (NPs) on and into the framework of a nitrogen-doped ordered mesoporous carbon (NOMC) structure. By exploiting this so-called nanoparticle confinement strategy, the nanoparticle mobility under operation is strongly reduced. As a result, particle detachment and agglomeration, two of the most pronounced electrocatalytic degradation mechanisms, are (partially) blocked and catalyst durability is improved. Several synthesis parameters, such as the anchoring agent, the weight percentage of Ag NPs, and the type of carbonaceous support material, were modified in a controlled manner to evaluate their respective impact on the overall electrochemical performance, with a strong emphasis on operational stability. The resulting powders were evaluated through electrochemical and physicochemical characterization methods, including X-ray diffraction (XRD), N2-physisorption, Inductively coupled plasma mass spectrometry (ICP-MS), scanning electron microscopy (SEM), SEM-energy-dispersive X-ray spectroscopy (SEM-EDS), high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), STEM-EDS, electron tomography, and X-ray photoelectron spectroscopy (XPS). The optimized Ag/soft-NOMC catalysts showed both a promising selectivity (∼80%) and stability compared with commercial Ag NPs while decreasing the loading of the transition metal by more than 50%. The stability of both the 5 and 10 wt % Ag/soft-NOMC catalysts showed considerable improvements by anchoring the Ag NPs on and into a NOMC framework, resulting in a 267% improvement in CO selectivity after 72 h (despite initial losses) compared to commercial Ag NPs. These results demonstrate the promising strategy of anchoring Ag NPs to improve the CO selectivity during prolonged experiments due to the reduced mobility of the Ag NPs and thus enhanced stability.

Recent insights on the use of modified Zn-based catalysts in eCO2RR

Converting CO2 into valuable chemicals can provide a new path to mitigate the greenhouse effect, achieving the aim of "carbon neutrality" and "carbon peaking". Among numerous electrocatalysts, Zn-based materials are widely distributed and cheap, making them one of the most promising electrocatalyst materials to replace noble metal catalysts. Moreover, the Zn metal itself has a certain selectivity for CO. After appropriate modification, such as oxide derivatization, structural reorganization, reconstruction of the surfaces, heteroatom doping, and so on, the Zn-based electrocatalysts can expose more active sites and adjust the d-band center or electronic structure, and the FE and stability of them can be effectively improved, and they can even convert CO2 to multi-carbon products. This review aims to systematically describe the latest progresses of modified Zn-based electrocatalyst materials (including organic and inorganic materials) in the electrocatalytic carbon dioxide reduction reaction (eCO2RR). The applications of modified Zn-based catalysts in improving product selectivity, increasing current density and reducing the overpotential of the eCO2RR are reviewed. Moreover, this review describes the reasonable selection and good structural design of Zn-based catalysts, presents the characteristics of various modified zinc-based catalysts, and reveals the related catalytic mechanisms for the first time. Finally, the current status and development prospects of modified Zn-based catalysts in eCO2RR are summarized and discussed.

Electrocatalytic activity of CO2 reduction to CO on cadmium sulfide enhanced by chloride anion doping

The electrocatalytic CO2 reduction (ECR) to produce valuable fuel is a promising process for addressing atmospheric CO2 emissions and energy shortages. In this study, Cl-anion doped cadmium sulfide structures were directly fabricated on a nickel foam surface (Cl/CdS-NF) using an in situ hydrothermal method. The Cl-anion doping could significantly improve ECR activity for CO production in ionic liquid and acetonitrile mixed solution, compared to pristine CdS. The highest Faradaic efficiency of CO is 98.1 % on a Cl/CdS-NF-2 cathode with an excellent current density of 137.0 mA cm-2 at -2.25 V versus ferrocene/ferrocenium (Fc/Fc+ , all potentials are versus Fc/Fc+ in this study). In particular, CO Faradaic efficiencies remained above 80 % in a wide potential range of -2.05 V to -2.45 V and a maximum partial current density (192.6 mA cm-2 ) was achieved at -2.35 V. The Cl/CdS-NF-2, with appropriate Cl anions, displayed abundant active sites and a suitable electronic structure, resulting in outstanding ECR activity. Density functional theory calculations further demonstrated that Cl/CdS is beneficial for increasing the adsorption capacities of *COOH and *H, which can enhance the activity of the ECR toward CO and suppress the hydrogen evolution reaction.

Stabilizing Undercoordinated Zn Active Sites through Confinement in CeO2 Nanotubes for Efficient Electrochemical CO2 Reduction

Zn-based catalysts hold great potential to replace the noble metal-based ones for CO2 reduction reaction (CO2 RR). Undercoordinated Zn (Znδ+ ) sites may serve as the active sites for enhanced CO production by optimizing the binding energy of *COOH intermediates. However, there is relatively less exploration into the dynamic evolution and stability of Znδ+ sites during CO2 reduction process. Herein, we present ZnO, Znδ+ /ZnO and Zn as catalysts by varying the applied reduction potential. Theoretical studies reveal that Znδ+ sites could suppress HER and HCOOH production to induce CO generation. And Znδ+ /ZnO presents the highest CO selectivity (FECO 70.9 % at -1.48 V vs. RHE) compared to Zn and ZnO. Furthermore, we propose a CeO2 nanotube with confinement effect and Ce3+ /Ce4+ redox to stabilize Znδ+ species. The hollow core-shell structure of the Znδ+ /ZnO/CeO2 catalyst enables to extremely expose electrochemically active area while maintaining the Znδ+ sites with long-time stability. Certainly, the target catalyst affords a FECO of 76.9 % at -1.08 V vs. RHE and no significant decay of CO selectivity in excess of 18 h.

Mechanism insights into photo-assisted peroxymonosulfate activation on oxygen vacancy-enriched nolanites via an electron transfer regime

The utilization of photo-assisted persulfate activation for the removal of organic contaminants in water has garnered significant research interest in recent times. However, there remains a lack of clarity regarding specific contributions of light irradiation and catalyst structure in this process. Herein, a photo-assisted peroxymonosulfate (PMS) activation system is designed for the highly efficient degradation of organic contaminants on oxygen vacancy-enriched nolanites (Vo-FVO). Results suggest that the degradation of bisphenol A (BPA) in this system is a nonradical-dominated process via an electron transfer regime, in which VO improves the local electron density and thus facilitates the electron shuttling between BPA and PMS. During BPA degradation, PMS adsorbed at the surface of FVO-180 withdraws electrons near VO and forms FVO-PMS* complexes. Upon light irradiation, photoelectrons effectively restore the electron density around VO, thereby enabling a sustainable electron transfer for the highly efficient degradation of BPA. Overall, this work provides new insights into the mechanism of persulfate activation based on defects engineering in nolanite minerals.

Bioinspired Hydrophobicity for Enhancing Electrochemical CO2 Reduction

Electrochemical carbon dioxide reduction (CO2 R) is a promising pathway for converting greenhouse gasses into valuable fuels and chemicals using intermittent renewable energy. Enormous efforts have been invested in developing and designing CO2 R electrocatalysts suitable for industrial applications at accelerated reaction rates. The microenvironment, specifically the local CO2 concentration (local [CO2 ]) as well as the water and ion transport at the CO2 -electrolyte-catalyst interface, also significantly impacts the current density, Faradaic efficiency (FE), and operation stability. In nature, hydrophobic surfaces of aquatic arachnids trap appreciable amounts of gases due to the "plastron effect", which could inspire the reliable design of CO2 R catalysts and devices to enrich gaseous CO2 . In this review, starting from the wettability modulation, we summarize CO2 enrichment strategies to enhance CO2 R. To begin, superwettability systems in nature and their inspiration for concentrating CO2 in CO2 R are described and discussed. Moreover, other CO2 enrichment strategies, compatible with the hydrophobicity modulation, are explored from the perspectives of catalysts, electrolytes, and electrolyzers, respectively. Finally, a perspective on the future development of CO2 enrichment strategies is provided. We envision that this review could provide new guidance for further developments of CO2 R toward practical applications.

Cd/Cd(OH)2 Nanosheets Enhancing the Electrocatalytic Activity of CO2 Reduction to CO

Electric-driven conversion of carbon dioxide (CO2 ) to carbon monoxide (CO) under mild reaction conditions offers a promising approach to mitigate the greenhouse effect and the energy crisis. Surface engineering is believed to be one of the prospective methods for enhancing the electrocatalytic activity of CO2 reduction. Herein, hydroxyl (OH) groups were successfully introduced to cadmium nanosheets to form cadmium and cadmium hydroxide nanocomposites (i. e. Cd/Cd(OH)2 nanosheets) via a facile two-step method. The as-prepared Cd/Cd(OH)2 /CP (CP indicates carbon paper) electrode displays excellent electrocatalytic activity for CO2 reduction to produce CO. The Faradaic efficiency of CO reaches 98.3 % and the current density achieves 23.8 mA cm-2 at -2.0 V vs. Ag/Ag+ in a CO2 -saturated 30 wt% 1-butyl-3-methylimidazole hexafluorophosphate ([Bmim]PF6 )-65 wt% acetonitrile (CH3 CN)-5 wt% water (H2 O) electrolyte. And the CO partial current density can reach up to 71.6 mA cm-2 with the CO Faradaic efficiency of more than 85 % at -2.3 V vs. Ag/Ag+ , which stands out against Cd/CP, Cd(OH)2 /CP, and Cd/CdO/CP electrodes. The excellent electrocatalytic performance of the Cd/Cd(OH)2 /CP electrode can be attributed to its unique structural properties, suitable OH groups, perfect interaction with electrolyte, abundant active sites and fast electron transfer rate.

Integration of MnO2 Nanosheets with Pd Nanoparticles for Efficient CO2 Electroreduction to Methanol in Membrane Electrode Assembly Electrolyzers

It remains a challenge to design a catalyst with high selectivity at a large current density toward CO2 electrocatalytic reduction (CO2ER) to a single C1 liquid product of methanol. Here, we report the design of a catalyst by integrating MnO2 nanosheets with Pd nanoparticles to address this challenge, which can be implemented in membrane electrode assembly (MEA) electrolyzers for the conversion of CO2ER to methanol. Such a strategy modifies the electronic structure of the catalyst and provides additional active sites, favoring the formation of key reaction intermediates and their successive evolution into methanol. The optimal catalyst delivers a Faradaic efficiency of 77.6 ± 1.3% and a partial current density of 250.8 ± 4.3 mA cm-2 for methanol during CO2ER in an MEA electrolyzer by coupling anodic oxygen evolution reaction with a full-cell energy efficiency achieving 29.1 ± 1.2% at 3.2 V. This work opens a new avenue to the control of C1 intermediates for CO2ER to methanol with high selectivity and activity in an MEA electrolyzer.

Homogeneous Vacancies-Enhanced Orbital Hybridization for Selective and Efficient CO2-to-CO Electrocatalysis

Crafting vacancies offers an efficient route to upgrade the selectivity and productivity of nanomaterials for CO2 electroreduction. However, defective nanoelectrocatalysts bear catalytically active vacancies mostly on their surface, with the rest of the interior atoms adiaphorous for CO2-to-product conversion. Herein, taking nanosilver as a prototype, we arouse the catalytic ability of internal atoms by creating homogeneous vacancies realized via electrochemical reconstruction of silver halides. The homogeneous vacancies-rich nanosilver, compared to the surface vacancies-dominated counterpart, features a more positive d-band center to trigger an intensified hybridization of the Ag_d orbital with the C_P orbital of the *COOH intermediate, leading to an accelerated CO2-to-CO transformation. These structural and electronic merits allow a large-area (9 cm-2) electrode to generate nearly pure CO with a CO/H2 Faradaic efficiency ratio of 6932 at an applied current of 7.5 A. These findings highlight the potential of designing new-type defects in realizing the industrialization of electrocatalytic CO2 reduction.

Sr2+-Doped CuO Nanoribbons with the Hydrophobic Surface Enabling CO2 Electroreduction to Ethane

Electrochemical reduction of carbon dioxide to value-added multicarbon (C2+) products is a promising way to obtain renewable fuels of high energy densities and chemicals and close the carbon cycle. However, the difficulty of C-C coupling and complexity of the proton-coupled electron transfer process greatly hinder CO2 electroreduction into specific C2+ products with high selectivity. Here, we design an electrocatalyst of Sr-doped CuO nanoribbons with a hydrophobic surface for CO2 electroreduction to ethane with high selectivity. Sr doping enhances the chemical adsorption and activation of CO2 by inducing oxygen vacancies and increasing *CO coverage by stabilizing Cu2+ active sites, thus further boosting subsequent C-C coupling. The hydrophobic surface with dodecyl sulfate anions (DS-) adsorption increases the oxophilicity of the catalyst surface, enhancing the conversion of the *OCH2CH3 intermediate to ethane. As a result, the optimized Sr1.97%-CuO exhibits a Faradaic efficiency of 53.4% and a partial current density of 13.5 mA cm-2 for ethane under a potential of -0.8 V. This study provides a strategy to design a Cu-based catalyst by alkaline earth metal ions doping with the hydrophobic surface to engineer the evolution of the intermediates for a desired product during CO2RR.

Tuning Oxygen Vacancies in Oxides by Configurational Entropy

Tuning surface oxygen vacancies is important for oxide catalysts. Doping elements with different chemical valence states or different atomic radii into host oxides is a common method to create oxygen vacancies. However, the concentration of oxygen vacancies in oxide catalysts is still limited to the amount of foreign dopants that can be tolerated (generally less than 10% atoms). Herein, a principle of engineering the configurational entropy to tune oxygen vacancies was proposed. First, the positive relationship between the configuration entropy and the formation energy of oxygen vacancies (Eov) in 16 model oxides was estimated by a DFT calculation. To verify this, single binary oxides and high-entropy quinary oxides (HEOs) were prepared. Indeed, the concentration of oxygen vacancies in HEOs (Oβ/α = 3.66) was higher compared to those of single or binary oxides (Oβ/α = 0.22-0.75) by O1s XPS, O2-TPD, and EPR. Interestingly, the reduction temperatures of transition metal ions in HEOs were generally lower than that in single-metal oxides by H2-TPR. The lower Eov of HEOs may contribute to this feature, which was confirmed by in situ XPS and in situ XRD. Moreover, with catalytic CO/C3H6 oxidation as a model, the high-entropy (MnCuCo3NiFe)xOy catalyst showed higher catalytic activity than single and binary oxides, which experimentally verified the hypothesis of the DFT calculation. This work may inspire more oxide catalysts with preferred oxygen vacancies.

Operando Mössbauer Spectroscopic Tracking the Metastable State of Atomically Dispersed Tin in Copper Oxide for Selective CO2 Electroreduction

Metastable state is the most active catalyst state that dictates the overall catalytic performance and rules of catalytic behaviors; however, identification and stabilization of the metastable state of catalyst are still highly challenging due to the continuous evolution of catalytic sites during the reaction process. In this work, operando 119Sn Mössbauer measurements and theoretical simulations were performed to track and identify the metastable state of single-atom Sn in copper oxide (Sn1-CuO) for highly selective CO2 electroreduction to CO. A maximum CO Faradaic efficiency of around 98% at -0.8 V (vs. RHE) over Sn1-CuO was achieved at an optimized Sn loading of 5.25 wt. %. Operando Mössbauer spectroscopy clearly identified the dynamic evolution of atomically dispersed Sn4+ sites in the CuO matrix that enabled the in situ transformation of Sn4+-O4-Cu2+ to a metastable state Sn4+-O3-Cu+ under CO2RR conditions. In combination with quasi in situ X-ray photoelectron spectroscopy, operando Raman and attenuated total reflectance surface enhanced infrared absorption spectroscopies, the promoted desorption of *CO over the Sn4+-O3 stabilized adjacent Cu+ site was evidenced. In addition, density functional theory calculations further verified that the in situ construction of Sn4+-O3-Cu+ as the true catalytic site altered the reaction path via modifying the adsorption configuration of the *COOH intermediate, which effectively reduced the reaction free energy required for the hydrogenation of CO2 and the desorption of the *CO, thereby greatly facilitating the CO2-to-CO conversion. This work provides a fundamental insight into the role of single Sn atoms on in situ tuning the electronic structure of Cu-based catalysts, which may pave the way for the development of efficient catalysts for high-selectivity CO2 electroreduction.

Molecular oxygen-assisted in defect-rich ZnO for catalytic depolymerization of polyethylene terephthalate

Polyethylene terephthalate (PET) is the most produced polyester plastic; its waste has a disruptive impact on the environment and ecosystem. Here, we report a catalytic depolymerization of PET into bis(2-hydroxyethyl) terephthalate (BHET) using molecule oxygen (O2)-assisted in defect-rich ZnO. At air, the PET conversion rate, the BHET yield, and the space-time yield are 3.5, 10.6, and 10.6 times higher than those in nitrogen, respectively. Combining structural characterization with the results of DFT calculations, we conclude that the (100) facet of defect-rich ZnO nanosheets conducive to the formation of reactive oxygen species (∗O2-) and Zn defect, promotes the PET breakage of the ester bond and thus complete the depolymerization processed. This approach demonstrates a sustainable route for PET depolymerization by molecule-assisted defect engineering.

Synergy of Surface Phosphates and Oxygen Vacancies Enables Efficient Photocatalytic Methane Conversion at Room Temperature

Room-temperature photocatalytic conversion of CH₄ into liquid oxygenates with O₂/H₂O provides an appealing route for sustainable chemical industry, which, however, suffers from poor efficiency due to the undesired carrier kinetics and low yield of reactive oxygen species of the currently available photocatalysts. Here, we report an effective surface engineering strategy where concurrent constructions of oxygen vacancies and phosphate sites on TiO₂ nanosheets address the above challenge. The surface oxygen vacancies and phosphates are respective acceptors of photogenerated electrons and holes for promoted separation and migration of charge carriers. Moreover, in addition to the facilitated activation of O₂ to ^•OH by electrons at oxygen vacancies, the surface phosphates also facilely adsorb H₂O via hydrogen bonds and thus effectively transfer holes to H₂O for enhanced ^•OH production, thereby boosting CH₄ conversion. As a result, compared with TiO₂ sheets with only oxygen vacancies, a 2.8 times improvement in liquid oxygenate production with near-unity selectivity is achieved by virtue of the synergy of surface oxygen vacancies and phosphate sites, together with an unprecedent quantum efficiency of 19.8% under 365 nm irradiation.

Favoring Product Desorption by a Tailored Electronic Environment of Oxygen Vacancies in SrTiO3 via Cr Doping for Enhanced and Selective Electrocatalytic CO2 to CO Conversion

The electrochemical CO₂ reduction reaction (ECO₂RR) into value-added products is crucial to address the herculean task of CO₂ mitigation. Several efforts are being made to develop active ECO₂RR catalysts, targeting enhanced CO₂ adsorption and activation. A rational design of ECO₂RR catalysts with a facile product desorption step is seldom reported. Herein, ensuing the Sabatier principle, we report a strategy for an enhanced ECO₂RR with a faradaic efficiency of 85% for CO production by targeting the product desorption step. The energy barrier for product desorption was lowered via a tailored electronic environment of oxygen vacancies (O_vac) in Cr-doped SrTiO₃. The substitutional doping of Cr³⁺ for Ti⁴⁺ into the SrTiO₃ lattice favors the generation of more O_vac and modifies the local electronic environment. Density functional theory analysis evinces the spontaneous dissociation of COOH^# intermediates over O_vac and lower CO intermediate binding on O_vac reducing the energy demand for CO release due to Cr doping.

Defective TiO2- x for High-Performance Electrocatalytic NO Reduction toward Ambient NH3 Production

Synthesis of green ammonia (NH₃ ) via electrolysis of nitric oxide (NO) is extraordinarily sustainable, but multielectron/proton-involved hydrogenation steps as well as low concentrations of NO can lead to poor activities and selectivities of electrocatalysts. Herein, it is reported that oxygen-defective TiO₂ nanoarray supported on Ti plate (TiO_{2- x} /TP) behaves as an efficient catalyst for NO reduction to NH₃ . In 0.2 m phosphate-buffered electrolyte, such TiO_{2- x} /TP shows competitive electrocatalytic NH₃ synthesis activity with a maximum NH₃ yield of 1233.2 µg h^-1  cm^-2 and Faradaic efficiency of 92.5%. Density functional theory calculations further thermodynamically faster NO deoxygenation and protonation processes on TiO_{2- x} (101) compared to perfect TiO₂ (101). And the low energy barrier of 0.7 eV on TiO_{2- x} (101) for the potential-determining step further highlights the greatly improved intrinsic activity. In addition, a Zn-NO battery is fabricated with TiO_{2- x} /TP and Zn plate to obtain an NH₃ yield of 241.7 µg h^-1  cm^-2 while providing a peak power density of 0.84 mW cm^-2 .

Tuning the Microstructures of ZnO To Enhance Photocatalytic NO Removal Performances

Effective removal of kinetically inert dilute nitrogen oxide (NO, ppb) without NO₂ emission is still a challenging topic in environmental pollution control. One effective approach to reducing the harm of NO is the construction of photocatalysts with diversified microstructures and atomic arrangements that could promote adsorption, activation, and complete removal of NO without yielding secondary pollution. Herein, microstructure regulations of ZnO photocatalysts were attempted by altering the reaction temperature and alkalinity in a unique ionic liquid-based solid-state synthesis and further investigated for the removal of dilute NO upon light irradiation. Microstructure observations indicated that as-tuned photocatalysts displayed unique nucleation, diverse morphologies (spherical nanoparticles, short and long nanorods), defect-related optical characteristics, and enhanced carrier separations. Such defect-related surface-interface aspects, especially V_o″-related defects of ZnO devoted them to the 4.16-fold enhanced NO removal and 2.76 magnitude order decreased NO₂ yields, respectively. Improved NO removal and toxic product inhabitation in as-tuned ZnO was disclosed by mechanistic exploitations. It was revealed that regulated microstructures, defect-related charge carrier separation, and strengthened surface interactions were beneficial to active species production and molecular oxygen activation in ZnO, subsequently contributing to the improved NO removal and simultaneous avoidance of NO₂ formation. This investigation shed light on the facile regulation of microstructures and the roles of surface chemistry in the oxidation of low concentration NO in the ppb level upon light illumination.

The role of oxygen-vacancy in bifunctional indium oxyhydroxide catalysts for electrochemical coupling of biomass valorization with CO2 conversion

Electrochemical coupling of biomass valorization with carbon dioxide (CO₂) conversion provides a promising approach to generate value-added chemicals on both sides of the electrolyzer. Herein, oxygen-vacancy-rich indium oxyhydroxide (InOOH-O_V) is developed as a bifunctional catalyst for CO₂ reduction to formate and 5-hydroxymethylfurfural electrooxidation to 2,5-furandicarboxylic acid with faradaic efficiencies for both over 90.0% at optimized potentials. Atomic-scale electron microscopy images and density functional theory calculations reveal that the introduction of oxygen vacancy sites causes lattice distortion and charge redistribution. Operando Raman spectra indicate oxygen vacancies could protect the InOOH-O_V from being further reduced during CO₂ conversion and increase the adsorption competitiveness for 5-hydroxymethylfurfural over hydroxide ions in alkaline electrolytes, making InOOH-O_V a main-group p-block metal oxide electrocatalyst with bifunctional activities. Based on the catalytic performance of InOOH-O_V, a pH-asymmetric integrated cell is fabricated by combining the CO₂ reduction and 5-hydroxymethylfurfural oxidation together in a single electrochemical cell to produce 2,5-furandicarboxylic acid and formate with high yields (both around 90.0%), providing a promising approach to generate valuable commodity chemicals simultaneously on both electrodes.

The built-in electric field across FeN/Fe3N interface for efficient electrochemical reduction of CO2 to CO

Nanostructured metal-nitrides have attracted tremendous interest as a new generation of catalysts for electroreduction of CO₂, but these structures have limited activity and stability in the reduction condition. Herein, we report a method of fabricating FeN/Fe₃N nanoparticles with FeN/Fe₃N interface exposed on the NP surface for efficient electrochemical CO₂ reduction reaction (CO₂RR). The FeN/Fe₃N interface is populated with Fe-N₄ and Fe-N₂ coordination sites respectively that show the desired catalysis synergy to enhance the reduction of CO₂ to CO. The CO Faraday efficiency reaches 98% at -0.4 V vs. reversible hydrogen electrode, and the FE stays stable from -0.4 to -0.9 V during the 100 h electrolysis time period. This FeN/Fe₃N synergy arises from electron transfer from Fe₃N to FeN and the preferred CO₂ adsorption and reduction to *COOH on FeN. Our study demonstrates a reliable interface control strategy to improve catalytic efficiency of the Fe-N structure for CO₂RR.

A cathodic photoelectrochemical immunoassay with dual signal amplification for the ultrasensitive detection of DNA damage biomarkers

Toxicity screening and risk assessment of an overwhelmingly large and ever-increasing number of chemicals are vitally essential for ecological safety and human health. Genotoxicity is particularly important because of its association with mutagenicity, carcinogenicity and cancer. Phosphorylated histone H2AX (γH2AX) is an early sensitive genotoxic biomarker. It is therefore highly desirable to develop analytical methods for the detection of trace γH2AX to enable screening and assessment of genotoxicity. Here, we developed a novel cathodic photoelectrochemical (PEC) immunoassay with dual signal amplification for the rapid and ultrasensitive detection of γH2AX in cell lysates. A sandwich immuno-reaction targeting γH2AX was first carried out on a 96-well plate, using a secondary antibody/gold nanoparticle/glucose oxidase conjugate as the labeled detection antibody. The conjugate increased the production of H₂O₂ and thus provided the first mechanism of signal amplification. The immuno-reaction product containing H₂O₂ was then detected on a photocathode prepared from Bi_2+xWO₆ rich in oxygen vacancies, with H₂O₂ acting as electron acceptor. The oxygen vacancies acted as both adsorption and activation sites of H₂O₂ and thus enhanced the photocurrent, which provided another mechanism of signal amplification. As a result, an ultrasensitive immunoassay for γH2AX determination was established with a limit of detection of 6.87 pg/mL (S/N = 3) and a wide linear range from 0.01 to 500 ng/mL. The practicability of this assay was verified by detecting γH2AX in cell lysates exposed to known genotoxic chemicals. Our work offers a promising tool for the screening of genotoxic chemicals and opening a new avenue toward environmental risk assessment.

Electron-Rich Bi Nanosheets Promote CO2 ⋅- Formation for High-Performance and pH-Universal Electrocatalytic CO2 Reduction

Electrochemical CO₂ reduction reaction (CO₂ RR) to chemical fuels such as formate offers a promising pathway to carbon-neutral future, but its practical application is largely inhibited by the lack of effective activation of CO₂ molecules and pH-universal feasibility. Here, we report an electronic structure manipulation strategy to electron-rich Bi nanosheets, where electrons transfer from Cu donor to Bi acceptor in bimetallic Cu-Bi, enabling CO₂ RR towards formate with concurrent high activity, selectivity and stability in pH-universal (acidic, neutral and alkaline) electrolytes. Combined in situ Raman spectra and computational calculations unravel that electron-rich Bi promotes CO₂ ⋅^- formation to activate CO₂ molecules, and enhance the adsorption strength of *OCHO intermediate with an up-shifted p-band center, thus leading to its superior activity and selectivity of formate. Further integration of the robust electron-rich Bi nanosheets into III-V-based photovoltaic solar cell results in an unassisted artificial leaf with a high solar-to-formate (STF) efficiency of 13.7 %.

Enhanced Interfacial Electron Transfer by Asymmetric Cu-Ov -In Sites on In2 O3 for Efficient Peroxymonosulfate Activation

Enhancing the peroxymonosulfate (PMS) activation efficiency to generate more radicals is vital to promote the Fenton-like reaction activity, however, how to promote the PMS adsorption and accelerate the interfacial electron transfer to boost its activation kinetics remains a great challenge. Herein, we prepared Cu-doped defect-rich In₂ O₃ (Cu-In₂ O₃ /O_v ) catalysts containing asymmetric Cu-O_v -In sites for PMS activation in water purification. The intrinsic catalytic activity is that the side-on adsorption configuration of the O-O bond (Cu-O-O-In) at the Cu-O_v -In sites significantly stretches the O-O bond length. Meanwhile, the Cu-O_v -In sites increase the electron density near the Fermi energy level, promoting more and faster electron transfer to the O-O bond for generating more SO₄ ⋅^- and ⋅OH. The degradation rate constant of tetracycline achieved by Cu-In₂ O₃ /O_v is 31.8 times faster than In₂ O₃ /O_v , and it shows the possibility of membrane reactor for practical wastewater treatment.

Microwave-assisted synthesis of metal-organic chalcogenolate assemblies as electrocatalysts for syngas production

Today, many essential industrial processes depend on syngas. Due to a high energy demand and overall cost as well as a dependence on natural gas as its precursor, alternative routes to produce this valuable mixture of hydrogen and carbon monoxide are urgently needed. Electrochemical syngas production via two competing processes, namely carbon dioxide (CO₂) reduction and hydrogen (H₂) evolution, is a promising method. Often, noble metal catalysts such as gold or silver are used, but those metals are costly and have limited availability. Here, we show that metal-organic chalcogenolate assemblies (MOCHAs) combine several properties of successful electrocatalysts. We report a scalable microwave-assisted synthesis method for highly crystalline MOCHAs ([AgXPh] _∞: X = Se, S) with high yields. The morphology, crystallinity, chemical and structural stability are thoroughly studied. We investigate tuneable syngas production via electrocatalytic CO₂ reduction and find the MOCHAs show a maximum Faraday efficiency (FE) of 55 and 45% for the production of carbon monoxide and hydrogen, respectively.

Introducing oxygen vacancies in a bi-metal oxide nanosphere for promoting electrocatalytic nitrogen reduction

The sluggish breakage of the N-N triple bond, as well as the existence of a competing hydrogen evolution reaction (HER), restricts the nitrogen reduction reaction process. Modification of the catalyst surface to boost N₂ adsorption and activation is essential for nitrogen fixation. Herein, we introduced surface oxygen vacancies in bimetal oxide NiMnO₃ by pyrolysis at 450 °C (450-NiMnO₃) to achieve remarkable NRR activity. The NiMnO₃ 3D nanosphere with a rough surface could increase catalytically active metal sites and introduce oxygen vacancies that are able to enhance N₂ adsorption and further improve the reaction rate. Benefiting from the introduced oxygen vacancies in NiMnO₃, 450-NiMnO₃ showed excellent performance for nitrogen reduction to ammonia with a high NH₃ yield of 31.44 μg h^-1 mg_cat^-1 (at -0.3 V vs. RHE) and a splendid FE of 14.5% (at -0.1 V vs. RHE) in 0.1 M KOH. 450-NiMnO₃ also shows high long-term electrochemical stability with excellent selectivity for NH₃ formation. ¹⁵N isotope labeling experiments further verify that the source of produced ammonia is derived from 450-NiMnO₃. The present study opens new avenues for the rational construction of efficient electrocatalysts for the synthesis of ammonia from nitrogen.

Defective Metal Oxides: Lessons from CO2 RR and Applications in NOx RR

Sluggish reaction kinetics and the undesired side reactions (hydrogen evolution reaction and self-reduction) are the main bottlenecks of electrochemical conversion reactions, such as the carbon dioxide and nitrate reduction reactions (CO₂ RR and NO₃ RR). To date, conventional strategies to overcome these challenges involve electronic structure modification and modulation of the charge-transfer behavior. Nonetheless, key aspects of surface modification, focused on boosting the intrinsic activity of active sites on the catalyst surface, are yet to be fully understood. Engingeering of oxygen vacancies (OVs) can tune surface/bulk electronic structure and improve surface active sites of electrocatalysts. The continuous breakthroughs and significant progress in the last decade position engineering of OVs as a potential technique for advancing electrocatalysis. Motivated by this, the state-of-the-art findings of the roles of OVs in both the CO₂ RR and the NO₃ RR are presented. The review starts with a description of approaches to constructing and techniques for characterizing OVs. This is followed by an overview of the mechanistic understanding of the CO₂ RR and a detailed discussion on the roles of OVs in the CO₂ RR. Then, insights into the NO₃ RR mechanism and the potential of OVs on NO₃ RR based on early findings are highlighted. Finally, the challenges in designing CO₂ RR/NO₃ RR electrocatalysts and perspectives in studying OV engineering are provided.

Challenges and Opportunities in Electrocatalytic CO2 Reduction to Chemicals and Fuels

The global temperature increase must be limited to below 1.5 °C to alleviate the worst effects of climate change. Electrocatalytic CO2 reduction (ECO2 R) to generate chemicals and feedstocks is considered one of the most promising technologies to cut CO2 emission at an industrial level. However, despite decades of studies, advances at the laboratory scale have not yet led to high industrial deployment rates. This Review discusses practical challenges in the industrial chain that hamper the scaling-up deployment of the ECO2 R technology. Faradaic efficiencies (FEs) of about 100 % and current densities above 200 mA cm-2 have been achieved for the ECO2 R to CO/HCOOH, and the stability of the electrolysis system has been prolonged to 2000 h. For ECO2 R to C2 H4 , the maximum FE is over 80 %, and the highest current density has reached the A cm-2 level. Thus, it is believed that ECO2 R may have reached the stage for scale-up. We aim to provide insights that can accelerate the development of the ECO2 R technology.

Sn Dopants with Synergistic Oxygen Vacancies Boost CO2 Electroreduction on CuO Nanosheets to CO at Low Overpotential

Using the electrochemical CO₂ reduction reaction (CO₂RR) with Cu-based electrocatalysts to achieve carbon-neutral cycles remains a significant challenge because of its low selectivity and poor stability. Modulating the surface electron distribution by defects engineering or doping can effectively improve CO₂RR performance. Herein, we synthesize the electrocatalyst of V_o-CuO(Sn) nanosheets containing oxygen vacancies and Sn dopants for application in CO₂RR-to-CO. Density functional theory calculations confirm that the incorporation of oxygen vacancies and Sn atoms substantially reduces the energy barrier for *COOH and *CO intermediate formation, which results in the high efficiency, low overpotential, and superior stability of the CO₂RR to CO conversion. This electrocatalyst possesses a high Faraday efficiency (FE) of 99.9% for CO at a low overpotential of 420 mV and a partial current density of up to 35.22 mA cm^-2 at -1.03 V versus reversible hydrogen electrode (RHE). The FE_CO of V_o-CuO(Sn) could retain over 95% within a wide potential area from -0.48 to -0.93 V versus RHE. Moreover, we obtain long-term stability for more than 180 h with only a slight decay in its activity. Therefore, this work provides an effective route for designing environmentally friendly electrocatalysts to improve the selectivity and stability of the CO₂RR to CO conversion.