Enhancing Electrochemical CO₂ Reduction Activity via Charge Transfer and sp-Band Filling in a Au Thin Layer on Ag

Abstract

Producing practical chemical feedstocks via electrochemical CO 2 reduction is a promising technology for carbon recycling and renewable energy storage. To improve CO 2 reduction performance, electrocatalysts with high activity and selectivity must be developed. In this study, Au layers of varying thicknesses were sputtered on polycrystalline Ag catalysts to promote the selective reduction of CO 2 to CO. The results show that a 2 nm Au layer sputtered on polycrystalline Ag exhibited a faradaic efficiency of 83.9% at −0.9 V versus the reversible hydrogen electrode with a current density of 5.93 mA cm −2 . The superior performance of the layered catalyst resulted from the facile charge transfer from Ag to Au, which enhanced the catalytic activity. Furthermore, because the increased electron population in the sp-band resulted in strong CO surface interactions, the layered catalyst exhibited enhanced selectivity for CO production. Thus, this study presents an efficient approach to develop effective layered catalysts for electrochemical CO 2 reduction.

Decrypting the Electron‐Withdrawing Effect of Au‐Decorated Bi2O3 for Efficient CO2‐to‐Formate Electroreduction

“…[36,37] Accordingly, the electron density of Bi as compared to that of Au 0 . [38,39] The Bi 4f 7/2 and Bi 4f 5/2 peaks assigned to Bi 3+ shift to higher binding energy from 158.1 and 163.4 eV to 158.5 and 163.8 eV. [40] Such red shift (about 0.4 eV) of Bi 4f peaks indicates the close connection for electron transfer from Bi 2 O 3 to Au again, which is in agreement with the Raman spectra (Figure 1c).…”

Thermally Evaporated Ag–Au Bimetallic Catalysts for Efficient Electrochemical CO2 Reduction

“…the CO FE of Au20Ag10 reached to 89.01% at −0.9 V, which was much higher than that of Au20Ag05 (60.58%), Au20 (58.14%), Au20Ag50 (39.69%), Au20Ag100 (36.04%), and Ag100 (34.09%). According the FE order of Au20Ag10 > Au20Ag05 > Au20 > Au20Ag50 > Au20Ag100 > Ag100, a proper ratio between Au and Ag in these bimetallic catalysts had synergistic effects [ 24 ] and promoted the selective CO 2 to CO. Results showed that, with the increase of Ag content, the bimetallic catalytic performance was enhanced first due to the enlarged coupling and synergistic effects between Au and Ag.…”

“…It was reported previously that the synergistic effect in bimetallic catalysts could improve the CO 2 RR performance. [ 24 ] Therefore, X‐ray photoelectron spectroscopy (XPS) was performed to confirm the chemical compositions and electronic interactions in the catalysts. Figure shows the high‐resolution Au 4f spectra of the six catalysts.…”

“…[ 23 ] Guo, et al found that the improved performance Au/Ag polycrystalline catalysts was due to the electronic and structural synergetic effects of Au and Ag. [ 24 ] All these methods require chemical reagents as precursors, and some of them need high temperature and pressure conditions. While, the thermal evaporation method directly uses the metal as the precursor, which is safe and simple.…”