Selective CO₂‐to‐Syngas Conversion Enabled by Bimetallic Gold/Zinc Sites in Partially Reduced Gold/Zinc Oxide Arrays

Abstract

Electrocatalytic CO2‐to‐syngas (gaseous mixture of CO and H2) is a promising way to curb excessive CO2 emission and the greenhouse gas effect. Herein, we present a bimetallic AuZn@ZnO (AuZn/ZnO) catalyst with high efficiency and durability for the electrocatalytic reduction of CO2 and H2O, which enables a high Faradaic efficiency (FE) of 66.4% for CO (corrected current density of 0.38 mA cm‐2) and 26.5% for H2 and a 3 h CO2‐to‐syngas at ‐0.9 V vs. the reversible hydrogen electrode (RHE). And the CO/H2 ratio shows a wide range from 0.25 to 2.50 over a narrow potential window (‐0.7 V to ‐1.1 V vs. RHE). In‐situ attenuated total reflection surface‐enhanced infrared absorption spectroscopy (ATR‐SEIRAS) combined with density functional theory (DFT) calculations reveals that the bimetallic synergistic effect between Au and Zn lower the activation energy barrier of CO2 molecules and facilitate electronic transfer, further highlight the potential to control the CO/H2 ratios for efficient syngas production using the coexisting Au sites and Zn sites.

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

“…In the high-resolution Zn 2p spectra (Figure d), the two peaks located at 1044.8 and 1021.7 eV were assigned to Zn 2p 1/2 and Zn 2p 3/2 , respectively, indicating the presence of Zn 2+ species. , In comparison with ZnO NW and ZnO NF, the binding energy of ZnO NS shifted to lower values, indicating an increasing lower valence of zinc and higher oxygen vacancy concentration on their surface. In the case of O 1s spectra (Figure e), the peaks at 530.4 and 531.6 eV corresponded to Zn–O–Zn and oxygen atoms in the adjacent oxygen vacancies, respectively. , As presented in Figure f, the integral-area ratios of the peak at 531.6 eV to the peak at 530.4 eV were calculated to be 0.71, 0.42, and 0.55 for ZnO NS, ZnO NW, and ZnO NF, respectively. These results indicated that ZnO NS exhibited the highest concentration of oxygen vacancies compared to those in the other ZnO samples.…”

“…In the case of O 1s spectra (Figure 3e), the peaks at 530.4 and 531.6 eV corresponded to Zn−O−Zn and oxygen atoms in the adjacent oxygen vacancies, respectively. 52,53 As presented in Figure 3f, the integral-area ratios of the peak at 531.6 eV to the peak at 530.4 eV were calculated to be 0.71, 0.42, and 0.55 for ZnO NS, ZnO NW, and ZnO NF, respectively. These results indicated that ZnO NS exhibited the highest concentration of oxygen vacancies compared to those in the other ZnO samples.…”

Femtosecond Laser Combined with Hydrothermal Method to Construct Three-Dimensional Spatially Distributed Wurtzite ZnO Micro/Nanostructures to Enhance Photocatalytic Properties

“…On the other hand, excited state electrons located in the conduction band have strong reducing properties and can interact with dissolved oxygen in the solution to form superoxide ion radicals. These active groups can quickly undergo redox reactions with organic pollutants adsorbed on the surface of the material. − In addition, photogenerated electrons and holes can directly degrade organic pollutants. Therefore, under the same illumination conditions, more electron–hole pairs will be generated on the sample surface to participate in the photocatalytic reaction process.…”

Dual Sites on Graphitic Biochar for Electrocatalytic CO2 Reduction to Ethanol Conversion

“…The band at about 1217.02 cm –1 represents C–O stretching vibrations in *OCCOH . The dimerization of two adjacent *CO to form *OCCOH is introduced as the rate-dependent step for C 2 products because *OCCOH intermediate can generate CH 2 CH 2 , CH 3 CH 3 and C 2 H 5 OH by discarding the O attached to the active site. , …”