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We report the unprecedented electrocatalytic activity of a series of molecular nickel thiolate complexes (1–5) in reducing CO2 to C1–3 hydrocarbons on carbon paper in pH‐neutral aqueous solutions. Ni(mpo)2 (3, mpo=2‐mercaptopyridyl‐N‐oxide), Ni(pyS)3− (4, pyS=2‐mercaptopyridine), and Ni(mp)2− (5, mp=2‐mercaptophenolate) were found to generate C3 products from CO2 for the first time in molecular complex. Compound 5 exhibits Faradaic efficiencies (FEs) of 10.6 %, 7.2 %, 8.2 % for C1, C2, C3 hydrocarbons respectively at −1.0 V versus the reversible hydrogen electrode. Addition of CO to the system significantly promotes the FEC1–C3 to 41.1 %, suggesting that a key Ni−CO intermediate is associated with catalysis. A variety of spectroscopies have been performed to show that the structures of nickel complexes remain intact during CO2 reduction. [ABSTRACT FROM AUTHOR]

Green production of NH3, especially the Li‐mediated electrochemical N2 reduction reaction (NRR) in non‐aqueous solutions, is attracting research interest. Controversies regarding the NRR mechanism greatly impede its optimization and wide applications. To understand the electrocatalytic process, we treated Au coated carbon fibrous paper (Au/CP) as the model catalyst. In situ XRD confirmed the transformation of lithium intermediates during NRR. Au greatly improved electron transfer kinetics to catalyze metallic Li formation, and accordingly highly accelerated spontaneous NRR. The Faradaic efficiency of NRR on Au/CP reached 34.0 %, and NH3 yield was as high as 50 μg h−1 cm−2. Our research shows that the key step of Li‐mediated non‐aqueous NRR is electrocatalytic Li reduction and offers a novel electrocatalyst design method for Li reduction. [ABSTRACT FROM AUTHOR]

Modulation of the microenvironment on the electrode surface is one of the effective means to improve the efficiency of electrocatalytic carbon dioxide reduction (eCO2RR). To achieve high conversion rates, the phase boundary at the electrode surface should be finely controlled to overcome the limitation of CO2 solubility in the aqueous electrolyte. Herein, we developed a simple and efficient method to structure electrocatalyst with a superhydrophobic surface microenvironment by one‐step co‐electrodeposition of Cu and polytetrafluoroethylene (PTFE) on carbon paper. The super‐hydrophobic Cu‐based electrode displayed a high ethylene (C2H4) selectivity with a Faraday efficiency (FE) of 67.3 % at −1.25 V vs. reversible hydrogen electrode (RHE) in an H‐type cell, which is 2.5 times higher than a regular Cu electrode without PTFE. By using PTFE as a surface modifier, the activity of eCO2RR is enhanced and water (proton) adsorption is inhibited. This strategy has the potential to be applied to other gas‐conversion electrocatalysts. [ABSTRACT FROM AUTHOR]

Electrochemical reduction of NO not only offers an attractive alternative to the Haber–Bosch process for ambient NH3 production but mitigates the human‐caused unbalance of nitrogen cycle. Herein, we report that MoS2 nanosheet on graphite felt (MoS2/GF) acts as an efficient and robust 3D electrocatalyst for NO‐to‐NH3 conversion. In acidic electrolyte, such MoS2/GF attains a maximal Faradaic efficiency of 76.6 % and a large NH3 yield of up to 99.6 μmol cm−2 h−1. Using MoS2 nanosheet‐loaded carbon paper as the cathode, a proof‐of‐concept device of Zn‐NO battery was assembled to deliver a discharge power density of 1.04 mW cm−2 and an NH3 yield of 411.8 μg h−1 mgcat.−1. Calculations reveal that the positively charged Mo‐edge sites facilitate NO adsorption/activation via an acceptance–donation mechanism and disfavor the binding of protons and the coupling of N−N bond. [ABSTRACT FROM AUTHOR]

Developing easily accessible descriptors is crucial but challenging to rationally design single‐atom catalysts (SACs). This paper describes a simple and interpretable activity descriptor, which is easily obtained from the atomic databases. The defined descriptor proves to accelerate high‐throughput screening of more than 700 graphene‐based SACs without computations, universal for 3–5d transition metals and C/N/P/B/O‐based coordination environments. Meanwhile, the analytical formula of this descriptor reveals the structure–activity relationship at the molecular orbital level. Using electrochemical nitrogen reduction as an example, this descriptor's guidance role has been experimentally validated by 13 previous reports as well as our synthesized 4 SACs. Orderly combining machine learning with physical insights, this work provides a new generalized strategy for low‐cost high‐throughput screening while comprehensive understanding the structure‐mechanism‐activity relationship. [ABSTRACT FROM AUTHOR]

The electrochemical CO2 reduction (CO2ER) to multi‐carbon chemical feedstocks over Cu‐based catalysts is of considerable attraction but suffers with the ambiguous nature of active sites, which hinder the rational design of catalysts and large‐scale industrialization. This paper describes a large‐scale simulation to obtain realistic CuZn nanoparticle models and the atom‐level structure of active sites for C2+ products on CuZn catalysts in CO2ER, combining neural network based global optimization and density functional theory calculations. Upon analyzing over 2000 surface sites through high throughput tests based on NN potential, two kinds of active sites are identified, balanced Cu−Zn sites and Zn‐heavy Cu−Zn sites, both facilitating C−C coupling, which are verified by subsequent calculational and experimental investigations. This work provides a paradigm for the design of high‐performance Cu‐based catalysts and may offer a general strategy to identify accurately the atomic structures of active sites in complex catalytic systems. [ABSTRACT FROM AUTHOR]

It is of great significance to reveal the detailed mechanism of neighboring effects between monomers, as they could not only affect the intermediate bonding but also change the reaction pathway. This paper describes the electronic effect between neighboring Zn/Co monomers effectively promoting CO2 electroreduction to CO. Zn and Co atoms coordinated on N doped carbon (ZnCoNC) show a CO faradaic efficiency of 93.2 % at −0.5 V versus RHE during a 30‐hours test. Extended X‐ray absorption fine structure measurements (EXAFS) indicated no direct metal–metal bonding and X‐ray absorption near‐edge structure (XANES) showed the electronic effect between Zn/Co monomers. In situ attenuated total reflection‐infrared spectroscopy (ATR‐IR) and density functional theory (DFT) calculations further revealed that the electronic effect between Zn/Co enhanced the *COOH intermediate bonding on Zn sites and thus promoted CO production. This work could act as a promising way to reveal the mechanism of neighboring monomers and to influence catalysis. [ABSTRACT FROM AUTHOR]

Cu‐based electrocatalysts facilitate CO2 electrochemical reduction (CO2ER) to produce multi‐carbon products. However, the roles of Cu0 and Cu+ and the mechanistic understanding remain elusive. This paper describes the controllable construction of Cu0‐Cu+ sites derived from the well‐dispersed cupric oxide particles supported on copper phyllosilicate lamella to enhance CO2ER performance. 20 % Cu/CuSiO3 shows the superior CO2ER performance with 51.8 % C2H4 Faraday efficiency at −1.1 V vs reversible hydrogen electrode during the 6 hour test. In situ attenuated total reflection infrared spectra and density functional theory (DFT) calculations were employed to elucidate the reaction mechanism. The enhancement in CO2ER activity is mainly attributed to the synergism of Cu0‐Cu+ pairs: Cu0 activates CO2 and facilitates the following electron transfers; Cu+ strengthens *CO adsorption to further boost C−C coupling. We provide a strategy to rationally design Cu‐based catalysts with viable valence states to boost CO2ER. [ABSTRACT FROM AUTHOR]

The design of catalysts with high activity, selectivity, and stability is key to the electroreduction of CO2. Herein, we report the synthesis of 3D hierarchical metal/polymer–carbon paper (M/polymer‐CP) electrodes by in situ electrosynthesis. The 3D polymer layer on CP (polymer‐CP) was first prepared by in situ electropolymerization, then a 3D metal layer was decorated on the polymer‐CP to produce the M/polymer‐CP electrode. Electrodes with different metals (e.g. Cu, Pd, Zn, Sn) and various polymers could be prepared by this method. The electrodes could efficiently reduce CO2 to desired products, such as C2H4, CO, and HCOOH, depending on the metal used. For example, C2H4 could be formed with a Faradaic efficiency of 59.4 % and a current density of 30.2 mA cm−2 by using a very stable Cu/PANI‐CP electrode in an H‐type cell. Control experiments and theoretical calculations showed that the 3D hierarchical structure of the metals and in situ formation of the electrodes are critical for the excellent performance. [ABSTRACT FROM AUTHOR]

Single‐atom catalysts (SACs) show great promise for electrochemical CO2 reduction reaction (CRR), but the low density of active sites and the poor electrical conduction and mass transport of the single‐atom electrode greatly limit their performance. Herein, we prepared a nickel single‐atom electrode consisting of isolated, high‐density and low‐valent nickel(I) sites anchored on a self‐standing N‐doped carbon nanotube array with nickel–copper alloy encapsulation on a carbon‐fiber paper. The combination of single‐atom nickel(I) sites and self‐standing array structure gives rise to an excellent electrocatalytic CO2 reduction performance. The introduction of copper tunes the d‐band electron configuration and enhances the adsorption of hydrogen, which impedes the hydrogen evolution reaction. The single‐nickel‐atom electrode exhibits a specific current density of −32.87 mA cm−2 and turnover frequency of 1962 h−1 at a mild overpotential of 620 mV for CO formation with 97 % Faradic efficiency. [ABSTRACT FROM AUTHOR]

The controlled electrochemical reduction of carbon dioxide to value added chemicals is an important strategy in terms of renewable energy technologies. Therefore, the development of efficient and stable catalysts in an aqueous environment is of great importance. In this context, we focused on synthesizing and studying a molecular MnIII‐corrole complex, which is modified on the three meso‐positions with polyethylene glycol moieties for direct and selective production of acetic acid from CO2. Electrochemical reduction of MnIII leads to an electroactive MnII species, which binds CO2 and stabilizes the reduced intermediates. This catalyst allows to electrochemically reduce CO2 to acetic acid in a moderate acidic aqueous medium (pH 6) with a selectivity of 63 % and a turn over frequency (TOF) of 8.25 h−1, when immobilized on a carbon paper (CP) electrode. In terms of high selectivity towards acetate, we propose the formation and reduction of an oxalate type intermediate, stabilized at the MnIII‐corrole center. [ABSTRACT FROM AUTHOR]

Abstract: Electrochemical reduction of carbon dioxide (CO2) into value‐added chemicals is a promising strategy to reduce CO2 emission and mitigate climate change. One of the most serious problems in electrocatalytic CO2 reduction (CO2R) is the low solubility of CO2 in an aqueous electrolyte, which significantly limits the cathodic reaction rate. This paper proposes a facile method of catholyte‐free electrocatalytic CO2 reduction to avoid the solubility limitation using commercial tin nanoparticles as a cathode catalyst. Interestingly, as the reaction temperature rises from 303 K to 363 K, the partial current density (PCD) of formate improves more than two times with 52.9 mA cm−2, despite the decrease in CO2 solubility. Furthermore, a significantly high formate concentration of 41.5 g L−1 is obtained as a one‐path product at 343 K with high PCD (51.7 mA cm−2) and high Faradaic efficiency (93.3 %) via continuous operation in a full flow cell at a low cell voltage of 2.2 V. [ABSTRACT FROM AUTHOR]