Alloying strategies for tuning product selectivity during electrochemical CO2 reduction over Cu

Asymmetric Local Electric Field Induced by Dual Heteroatoms on Copper Boosts Efficient CO2 Reduction Over Ultrawide Potential Window

Electrocatalytic reduction of CO2 powered by renewable electricity provides an elegant route for converting CO2 into valuable chemicals and feedstocks, but normally suffers from a high overpotential and low selectivity. Herein, Ag and Sn heteroatoms were simultaneously introduced into nanoporous Cu (np-Ag/Sn-Cu) mainly in the form of an asymmetric local electric field for CO2 electroreduction to CO in an aqueous solution. The designed np-Ag/Sn-Cu catalyst realizes a recorded 90 % energy efficiency and a 100 % CO Faradaic efficiency over ultrawide potential window (ΔE=1.4 V), outperforming state-of-the-art Au and Ag-based catalysts. Density functional theory calculations combined with in situ spectroscopy studies reveal that Ag and Sn heteroatoms incorporated into Cu matrix could generate strong and asymmetric local electric field, which promotes the activation of CO2 molecules, enhances the stabilization of the *COOH intermediate, and suppresses the hydrogen evolution reaction, thus favoring the production of CO during CO2RR.

Nanostructured cobalt/copper catalysts for efficient electrochemical carbon dioxide reduction

The search for an efficient and stable catalyst for the electrochemical reduction of CO2 to value-added chemicals is especially critical for lowering the atmospheric CO2 concentration. In this study, self-supported cobalt/copper nanostructured catalysts were designed, where the influences of the elemental composition and acid-etching on their efficiency towards the CO2 reduction reaction were studied. The developed Co/Cu catalysts showed superb catalytic activity with a low onset potential at -0.2 V vs. RHE. Gas and liquid product analysis revealed that formate and CO were the main products. It was observed that lower reductive potentials were favourable for formate production, while higher reductive potentials were more favourable for CO formation. In situ electrochemical FTIR studies were further conducted to gain insight into the CO2 reduction mechanism. The novel synthetic procedure reported in this study leads to promising electrocatalysts with high efficiencies for the conversion of CO2 into valuable products.

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.

Cu-based catalyst designs in CO2 electroreduction: precise modulation of reaction intermediates for high-value chemical generation

The massive emission of excess greenhouse gases (mainly CO2) have an irreversible impact on the Earth's ecology. Electrocatalytic CO2 reduction (ECR), a technique that utilizes renewable energy sources to create highly reduced chemicals (e.g. C2H4, C2H5OH), has attracted significant attention in the science community. Cu-based catalysts have emerged as promising candidates for ECR, particularly in producing multi-carbon products that hold substantial value in modern industries. The formation of multi-carbon products involves a range of transient intermediates, the behaviour of which critically influences the reaction pathway and product distribution. Consequently, achieving desirable products necessitates precise regulation of these intermediates. This review explores state-of-the-art designs of Cu-based catalysts, classified into three categories based on the different prospects of the intermediates' modulation: heteroatom doping, morphological structure engineering, and local catalytic environment engineering. These catalyst designs enable efficient multi-carbon generation in ECR by effectively modulating reaction intermediates.

1D/1D W18O49/Cd0.9Zn0.1S S-scheme heterojunction with spatial charge separation for high-yield photocatalytic H2 evolution

Semiconductor photocatalytic water splitting is a green way to convert solar energy into chemical energy, but the recombination of electron and hole pairs and the low utilization of sunlight restrict the development of photocatalytic technology. By comparing the morphologies and hydrogen production properties of different proportions of solid solutions (Cd_xZn_1-xS), one-dimensional (1D) Cd_0.9Zn_0.1S nanorods (NRs) with the best photocatalytic properties are obtained. In addition, 1D W₁₈O₄₉ nanowires are assembled on the surface of 1D Cd_0.9Zn_0.1S NRs to construct a novel 1D/1D step-scheme (S-scheme) W₁₈O₄₉/Cd_0.9Zn_0.1S heterojunction photocatalyst. The W₁₈O₄₉/Cd_0.9Zn_0.1S heterojunction expands the optical absorption capacity of Cd_0.9Zn_0.1S NRs to provide more energy for the photoexcitation of electrons. The optimal hydrogen production rate of W₁₈O₄₉/Cd_0.9Zn_0.1S NRs with W₁₈O₄₉ content of 9 wt% is as high as 66.3 mmol·h^-1·g^-1, which is 5.7 times and 1.6 times higher than that of Cd_0.9Zn_0.1S NRs and 1 wt% Pt/Cd_0.9Zn_0.1S NRs. The apparent quantum efficiency (AQE) of 9 wt% W₁₈O₄₉/Cd_0.9Zn_0.1S reaches 56.0 % and 25.9 % under light wavelength irradiation at 370 and 456 nm, respectively. After the 20 h cycle stability test, the activity of photocatalytic hydrogen evolution does not decrease, due that the severe photo-corrosion of Cd_0.9Zn_0.1S NRs is efficiently inhibited. This work not only provides a simple and controllable synthesis method for the preparation of heterojunction structure, but also opens up a new way to improve the hydrogen evolution activity and stability of sulfur compounds.