Promoting electrocatalytic CO2 reduction to formate via sulfur-boosting water activation on indium surfaces

一般认为，H2O还原析氢反应是CO2还原反应的竞争反应，若促进H2O活化将降低CO2还原反应的法拉第效率。因此，基于该认识设计出的高CO2还原法拉第效率的催化剂常常活性低。王野课题组打破这种认识，提出H2O分子活化在CO2还原中起着重要的作用，成功合成出硫修饰In催化剂来活化H2O分子而促进CO2还原制甲酸的新方法，该催化剂在非常宽的电流密度范围内（25~100 mA cm-2），均可以维持85%以上的甲酸法拉第效率。将硫拓展至硒和碲等其它硫族元素以及将金属铟拓展至铋和锡等其它p区金属，均实现很好的促进效果，表明通过促进水的活化来提高CO2电催化还原性能具有普适性。该工作为理性设计高效的CO2还原电催化剂提供了新策略。 该研究工作实验部分主要由王野、张庆红教授指导，能源材料化学协同创新中心iChEM2016级博士生马文超、固体表面物理化学国家重点实验室高级工程师谢顺吉（共同第一作者）完成；理论计算部分由吴德印教授指导，2015级博士生张霞光（共同第一作者）完成。醇醚酯国家工程实验室高级工程师康金灿参与了部分实验表征。上海光源姜政教授和孙凡飞博士为同步辐射表征提供了支持。【Abstract】Electrocatalytic reduction of CO2 to fuels and chemicals is one of the most attractive routes for CO2 utilization. Current catalysts suffer from low faradaic efficiency of a CO2-reduction product at high current density (or reaction rate). Here, we report that a sulfur-doped indium catalyst exhibits high faradaic efficiency of formate (>85%) in a broad range of current density (25–100 mA cm−2) for electrocatalytic CO2 reduction in aqueous media. The formation rate of formate reaches 1449 μmol h−1 cm−2 with 93% faradaic efficiency, the highest value reported to date. Our studies suggest that sulfur accelerates CO2 reduction by a unique mechanism. Sulfur enhances the activation of water, forming hydrogen species that can readily react with CO2 to produce formate. The promoting effect of chalcogen modifiers can be extended to other metal catalysts. This work offers a simple and useful strategy for designing both active and selective electrocatalysts for CO2This work was supported by the National Key Research and Development Program of the Ministry of Science and Technology of China (No. 2017YFB0602201), the National Natural Science Foundation of China (Nos. 21690082, 91545203, and 21503176). We thank staff at the BL14W1 beamline of the Shanghai Synchrotron Radiation Facilities (SSRF) for assistance with the EXAFS measurements. 研究工作得到科技部重点研发计划（批准号：2017YFB0602201）和国家自然科学基金（批准号：21690082、91545203、21503176）等项目的资助

Electrocatalytic reduction of CO2 to ethylene and ethanol through hydrogen-assisted C-C coupling over fluorine-modified copper

精准控制C1分子C-C偶联合成特定C2+化合物是C1化学中极具挑战性的难题。由于C2+化合物(如乙烯和乙醇)在化工和能源领域具有重要用途，将CO2直接转化为C2+产物极具吸引力。发展高效催化剂，实现高电流密度、高C2+选择性、高稳定性的“三高”性能，是推进电催化还原CO2走向实际应用的关键。研究团队针对电催化还原CO2中高CO2还原法拉第效率的催化剂常常活性低的问题，提出了适当提高催化剂活化水的能力对增加CO2还原活性的重要性，发展出氢助碳碳偶联(hydrogen-assisted C-C coupling)的新策略，在氟修饰的铜(F-Cu)催化剂上实现了CO2电催化还原制乙烯和乙醇的新突破。该研究工作实验部分主要由王野、张庆红教授指导，能源材料协同创新中心iChEM2016级博士生马文超、固体表面物理化学国家重点实验室高级工程师谢顺吉(共同第一作者)完成；理论计算部分由程俊教授指导，2017级硕士生刘彤彤(共同第一作者)、2016级博士生樊祺源完成。叶进裕博士为原位红外测试提供了支持。上海光源姜政研究员、孙凡飞博士、杨若欧为同步辐射表征提供了支持。 这是投稿的最终版本，正式出版的论文版本请访问官方链接（https://doi.org/10.1038/s41929-020-0450-0）。Electrocatalytic reduction of CO2 into multi-carbon (C2+) products is a highly attractive route for CO2 utilization. However, the yield of C2+ products remains low because of the limited C2+ selectivity at high CO2 conversion rate. Here, we report a fluorine-modified copper catalyst that exhibits an ultrahigh current density of 1.6 A cm−2 at C2+ (mainly ethylene and ethanol) Faradaic efficiency of 80% for electrocatalytic CO2 reduction in a flow cell. The C2-4 selectivity reaches 85.8% at a single-pass yield of 16.5%. We show a hydrogen-assisted C−C coupling mechanism between adsorbed formyl (CHO) intermediates for C2+ formation. Fluorine enhances water activation, CO adsorption and hydrogenation of adsorbed CO to CHO intermediate that can readily undergo coupling. Our findings offer an opportunity to design highly active and selective CO2 electroreduction catalysts with potential for practical applicationThis work was supported by the National Key Research and Development Program of the Ministry of Science and Technology of China (No. 2017YFB0602201), the National Natural Science Foundation of China (Nos. 21690082, 91545203, 21503176 and 21802110), We thank staffs at the BL14W1 beamline of the Shanghai Synchrotron Radiation Facilities (SSRF) for assistance with the EXAFS measurements.研究工作得到科技部重点研发计划（批准号：2017YFB0602201）和国家自然科学基金（批准号：21690082、91545203、21503176、21802110）项目的资助

Theory-guided design of atomically dispersed dual-metal catalysts for superior oxygen reduction reaction activity

The widespread application of electrochemical energy conversion devices, such as proton exchange membrane fuel cells, is hindered by the kinetically sluggish oxygen reduction reaction (ORR) at the cathode. Transition-metal and nitrogen codoped carbon materials (TM−N−C) are among the most promising catalysts to solve this problem. Particularly, dual-metal TM−N−C have already displayed excellent performance. However, further knowledge on the reaction mechanism and the structure−activity relationship is still required. In this study, we established three dual-metal TM−N−C models (FeMn−N−C, FeCo−N−C, and FeNi−N−C) to investigate the electronic interaction between the metallic sites and their corresponding adsorption strength for oxygenated intermediates in ORR electrocatalysis. Then, using density functional theory calculations, we determined that the ORR activity of the dual-metal TM−N−C models followed the order of FeCo−N−C > FeNi−N−C > FeMn−N−C. We confirmed the theoretically predicted activity by synthesizing atomically dispersed FeMn−N−C, FeCo−N−C, and FeNi−N−C catalysts using metal-organic framework precursors, among which FeCo−N−C showed the best results in terms of ORR onset potential and half-wave potential (0.92 and 0.81 V vs. the reference hydrogen electrode in 0.1 M HClO4, respectively.). The results demonstrate the feasibility of the theory-guided rational design of efficient dual-metal catalysts for ORR electrocatalysis.This work has been financially supported by the National Key Research and Development Program of China (2022YFA1503801), the National Natural Science Foundation of China (12205359) and Natural Science Foundation of Shanghai (23ZR1471400)

Immobilization of Platinum Nanoparticles on Covalent Organic Framework‐Derived Carbon for Oxygen Reduction Catalysis

Platinum (Pt)‐based catalysts are considered as the most active catalysts for the oxygen reduction reaction (ORR). However, their applications have remained limited because of the high cost of Pt, and developing catalysts with low Pt contents is a challenge. Herein, a highly active catalyst (Pt–COF800) is constructed for the ORR by immobilizing hierarchical Pt subnano‐ and nanoparticles on covalent organic framework (COF)‐derived carbon. The catalyst shows excellent activity in alkaline conditions. The physical characterization demonstrates low nuclear Pt atoms and nanoparticles and confirms the role of heterogeneous active sites. This work paves the way for the construction of functional porous carbon materials with dual‐scale Pt clusters and may be applied to industrial catalytic reactions

Maximizing the Interface of Dual Active Sites to Enhance Higher Oxygenate Synthesis from Syngas with High Activity

Selective synthesis of higher oxygenates from syngas provides a promising route for the conversion of nonpetroleum carbon resources into valuable chemicals. However, it remains a grand challenge to design highly efficient and stable dual-sites structures to promote the production of higher oxygenates. Herein, we reported an effective method to maximize the interface of dual active sites via designing the structure of alloy carbide derived from the FeCo layered double hydroxide precursor. Cobalt atoms were well-distributed and doped into Fe2C to form (FexCoy)2C alloy carbide. The atomic-scale contact Fe–Co interfacial sites could achieve a >35% oxygenate selectivity at a CO conversion of >80% during 200 h of running, and a high space–time yield of 183.9 mg/gcat./h for oxygenates with 95.6% being the C2+OH fraction was obtained. The kinetic study confirmed that the apparent activation energy of (FexCoy)2C alloy carbide was lower than that of separated Fe2C-Co2C dual sites. This work provides a strategy for the design of an effective catalyst for selective synthesis of higher oxygenates from syngas by tuning the interface of dual active sites at an atomic level

Insight into the Formation of Co@Co2C Catalysts for Direct Synthesis of Higher Alcohols and Olefins from Syngas

Cobalt carbide (Co2C) has recently been reported to be efficient for the conversion of syngas (CO+H-2) to lower olefins (C-2-C-4) and higher alcohols (C2+, alcohols); however, its properties and formation conditions remain ambiguous. On the basis of our previous investigations concerning the formation of Co2C, the work herein was aimed at defining the mechanism by which the manganese promoter functions in the Co-based catalysts supported on activated carbon (CoxMn/AC). Experimental studies validated that Mn facilitates the dissociation and disproportionation of CO on the surface of catalyst and prohibits H-2 adsorption to some extent, creating a relative C-rich and H-lean surface chemical environment. We advocate that the surface conditions result in the transformation from metallic Co to Co2C phase under realistic reaction conditions to form Co@Co2C nanoparticles, in which residual small Co-0 ensembles (<6 nm) distribute on the surface of Co2C nanoparticles (similar to 20 nm). Compared with the Co/AC catalyst, where the active site is composed of Co2C phase on the surface of Co-0 nanoparticles (Co2C@Co), the Mn-promoted catalysts (Co@Co2C) displayed much higher olefin selectivity (10% versus 40%), while the selectivity to alcohols over the two catalysts are similar (similar to 20%). The rationale behind the strong structure performance relationship is twofold. On the one hand, Co Co2C interfaces exist universally in the catalysts, where synergistic effects between metallic Co and Co2C phase occur and are responsible for the formation of alcohols. On the other hand, the relative C-rich environment created by Mn on the Co@Co2C catalysts facilitates the formation of olefins

Boosting hydrogen peroxide production via establishment and reconstruction of single‐metal sites in covalent organic frameworks

Abstract Covalent organic frameworks (COFs) have been well developed in electrocatalytic systems owing to their controllable skeletons, porosities, and functions. However, the catalytic process in COFs remains underexplored, hindering an in‐depth understanding of the catalytic mechanism. In this work, uniform Pt–N1O1Cl4 sites chelated via C–N and C=O bonds along the one‐dimensional and open channels of TP–TTA–COF were established. Different from conventional single‐metal sites constructed for the near‐free platinum for hydrogen evolution, the as‐constructed PtCl–COF showed 2e− oxygen reduction for H2O2 production. We tracked the dynamic evolution process of atomic Pt sites in which Pt–N1O1Cl4 was transformed into Pt–N1O1(OH)2 using in situ X‐ray adsorption. The theoretical calculations revealed that the strong Pt–support interaction in Pt–N1O1(OH)2 facilitated *OOH formation and thus led to higher selectivity and activity for the oxygen reduction reaction in the 2e− pathway. This work can expand the applications of COFs through the regulation of their local electronic states for the manipulation of the metal center

Interfacial Proton Transfer for Hydrogen Evolution at the Sub-Nanometric Platinum/Electrolyte Interface

Understanding the dynamic process of interfacial charge transfer prior to chemisorption is crucial to the development of electrocatalysis. Recently, interfacial water has been highlighted in transferring protons through the electrode/electrolyte interface; however, the identification of the related structural configurations and their influences on the catalytic mechanism is largely complicated by the amorphous and mutable structure of the electrical double layer (EDL). To this end, sub-nanometric Pt electrocatalysts, potentially offering intriguing activity and featuring fully exposed atoms, are studied to uncover the elusive electrode/electrolyte interface via operando X-ray absorption spectroscopy during the hydrogen evolution reaction (HER). Our results show that the metallic Pt clusters derived from the reduction of sub-nanometric Pt clusters (SNM-Pt) exhibit excellent HER activity, with an only 18 mV overpotential at 10 mA/cm(2) and one-magnitude-higher mass activity than commercial Pt/C. More importantly, a unique Pt-interfacial water configuration with a Pt (from Pt clusters)-O (from water) radial distance of approximately 2.5 angstrom is experimentally identified as the structural foundation for the interfacial proton transfer. Toward high overpotentials, the interfacial water that structurally evolves from "O-close" to "O-far" accelerates the proton transfer and is responsible for the improved reaction rate by increasing the hydrogen coverage