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The electroreduction of CO2 to methane using renewable energy is a promising approach to achieving carbon neutrality. At commercially relevant current densities (>200 mA cm−2), methane selectivity is however below 50%. Herein, we reported a benzenethiol-modified Cu nanoparticle catalyst that achieved a methane faradaic efficiency of 54.5% at a partial current density of 383 mA cm−2, 1.9-fold higher than that of Cu nanoparticle controls. In situ vibrational spectroscopy and density functional theory calculations showed that the benzenethiol modulated the electronic structure of the Cu surface to enable a lowered coverage of *CO, favouring the formation of *CHO, a key intermediate embarking on the CH4 pathway, over the competing carbon–carbon coupling, the pathway towards multicarbons. [ABSTRACT FROM AUTHOR]

Electrochemical CO2 methanation powered by renewable electricity provides a promising approach to utilizing CO2 in the form of a high‐energy‐density, clean fuel. Cu nanoclusters have been predicted by theoretical calculations to improve methane selectivity. Direct electrochemical reduction of Cu‐based metal‐organic frameworks (MOFs) results in large‐size Cu nanoparticles which favor multi‐carbon products. This study concerns an electrochemical oxidation‐reduction method to prepare Cu clusters from MOFs. The derived Cu clusters exhibit a faradaic efficiency of 51.2 % for CH4 with a partial current density of >150 mA cm−2. High‐resolution microscopy, in situ X‐ray absorption spectroscopy, in situ Raman spectroscopy, and a range of ex situ spectroscopies indicate that the distinctive CH4 selectivity is due to the sub‐nanometer size of the derived materials, as well as stabilization of the clusters by residual ligands of the pristine MOF. This work offers a new insight into steering product selectivity of Cu by an electrochemical processing method. [ABSTRACT FROM AUTHOR]

The cathodic mechanism of Li-N 2 batteries is similar to Li-mediated N 2 reduction (LiNR). Herein, the Li-N 2 , LiNR, and Cu-Li battery were amalgamated to a milliliter-scale Cu(N 2 )-Li system. The utilization of a lithium anode with lithium oxidation reaction (LiOR), ensures an uninterrupted supply of lithium ions to active N 2 . LiOR not only enhances electrolyte stability but also reduces voltage by stripping Li ions, in contrast to the inert platinum anode, commonly employed in LiNR. Notably, an unusual observation of ammonia accumulation within the anode chamber elucidates the presence and role of reaction intermediates. The charging process aimed at lithium regeneration faces high polarization, and a cycling procedure involving low-current charging was proposed to improve cycling. This study integrates insights from three distinct research directions to leverage their respective advantages and scientific insights. The Li-N 2 battery emerges as a highly advantageous strategy for ammonia synthesis due to the progressiveness of lithium anode.

Electrochemical CO 2 methanation powered by renewable electricity provides a promising approach to utilizing CO 2 in the form of a high-energy-density, clean fuel. Cu nanoclusters have been predicted by theoretical calculations to improve methane selectivity. Direct electrochemical reduction of Cu-based metal-organic frameworks (MOFs) results in large-size Cu nanoparticles which favor multi-carbon products. This study concerns an electrochemical oxidation-reduction method to prepare Cu clusters from MOFs. The derived Cu clusters exhibit a faradaic efficiency of 51.2 % for CH 4 with a partial current density of >150 mA cm -2 . High-resolution microscopy, in situ X-ray absorption spectroscopy, in situ Raman spectroscopy, and a range of ex situ spectroscopies indicate that the distinctive CH 4 selectivity is due to the sub-nanometer size of the derived materials, as well as stabilization of the clusters by residual ligands of the pristine MOF. This work offers a new insight into steering product selectivity of Cu by an electrochemical processing method., (© 2021 Wiley-VCH GmbH.)

CO 2 electroreduction powered by renewable electricity represents a promising method to enclose anthropogenic carbon cycle. Current catalysts display high selectivity toward the desired product only over a narrow potential window due primarily to unoptimized intermediate binding. Here, we report a functional ligand modification strategy in which palladium nanoparticles are encapsulated inside metal-organic frameworks with 2,2'-bipyridine organic linkers to tune intermediate binding and thus to sustain a highly selective CO 2 -to-CO conversion over widened potential window. The catalyst exhibits CO faradaic efficiency in excess of 80% over a potential window from -0.3 to -1.2 V and reaches the maxima of 98.2% at -0.8 V. Mechanistic studies show that the 2,2'-bipyridine on Pd surface reduces the binding strength of both *H and *CO, a too strong binding of which leads to competing formate production and CO poison, respectively, and thus enhances the selectivity and stability of CO product.

Surface functionalization with atoms serves as an important strategy to modulate the catalytic activities of low-dimensional nanomaterials. Herein, we developed a facile hydrogen incorporation strategy for improving the catalytic activities of SnS 2 nanosheets toward CO 2 electroreduction. Compared with SnS 2 nanosheets, the hydrogen-incorporated SnS 2 (denoted as H-SnS 2 ) nanosheets exhibited high current density and Faradaic efficiency (FE) for formate. At -0.9 V vs RHE, H-SnS 2 nanosheets displayed a maximum FE of 93% for carbonaceous product, which rivals the activities of most Sn-based catalysts in CO 2 electroreduction. Mechanistic studies disclosed that the incorporation of surface hydrogen induced the electron injection into the structures of H-SnS 2 nanosheets, which largely facilitates the process of CO 2 activation. Density functional theory (DFT) calculations further revealed that hydrogen incorporation decreased the energy barrier for the formation of HCOO* intermediates, thus contributing to the CO 2 -to-formate conversion on H-SnS 2 nanosheets.

Probing and understanding the intrinsic active sites of electrocatalysts is crucial to unravel the underlying mechanism of CO 2 electroreduction and provide a prospective for the rational design of high-performance electrocatalysts. However, their structure-activity relationships are not straightforward because electrocatalysts might reconstruct under realistic working conditions. Herein, we employ in-situ measurements to unveil the intrinsic origin of the InN nanosheets which served as an efficient electrocatalyst for CO 2 reduction with a high faradaic efficiency of 95% for carbonaceous product. During the CO 2 electroreduction, InN nanosheets reconstructed to form the In-rich surface. Density functional theory calculations revealed that the reconstruction of InN led to the redistribution of surface charge that significantly promoted the adsorption of HCOO* intermediates and thus benefited the formation of formate toward CO 2 electroreduction. This work establishes a fundamental understanding on the mechanism associated with self-reconstruction of heterogeneous catalysts toward CO 2 electroreduction.

In CO 2 electroreduction, the critical bottleneck lies in the CO 2 activation which requires high overpotentials. CO 2 activation is related to both the electronic structures of catalysts and those of adsorbates, thus an ideal catalyst should match its electronic structures with those of the adsorbate. Here, we harmonized the electronic structures of the adsorbate and Mn-doped In 2 S 3 nanosheets for efficient CO 2 reduction. The introduction of Mn dopants into In 2 S 3 nanosheets enhanced both the Faradaic efficiency (FE) for carbonaceous products and current density ( j ). At -0.9 V vs RHE, Mn-doped In 2 S 3 nanosheets exhibited a remarkable FE of 92% for carbonaceous product at a high j of 20.1 mA cm -2 . Mechanistic studies revealed that Mn doping enabled the harmonic overlaps between the p orbitals of O atoms and d orbitals of Mn atoms near the conduction band edge of Mn-doped In 2 S 3 nanosheets during the activation of CO 2 . Due to the unique electronic structures of the coadsorbed configurations, Mn-doped In 2 S 3 nanosheets exhibited an energy barrier for CO 2 activation into HCOO* lower than that over pristine In 2 S 3 nanosheets.