Tuning the electronic structure of AuNi homogeneous solid-solution alloy with positively charged Ni center for highly selective electrochemical CO2 reduction

Designing bimetallic electrocatalysts with homogenous element distribution and tunable electronic structure is attractive strategy to enhance the CO selectivity in electrochemical carbon dioxide reduction reaction (CO2RR). Herein, we report a concept of atom-polymer hybridization to synthesize AuNi homogeneous solid-solution alloy nanoparticles (NPs) with positively charged Ni center supported on electrospun carbon nanofibers (CNFs). The nanofibers host can strong restrict the separated growth of Au and Ni nanoclusters during the directly graphitization process, leading to the formation of homogeneous AuNi alloy. In-situ characterizations reveal the formation process and phase evolution of the AuNi alloy during the carbonization. The positively charged Ni when alloying with Au lead to the enhanced local electronic structure on AuNi homogeneous solid-solution alloy due to the electron-withdrawal effect of nearby Au atoms. The AuNi homogeneous solid-solution alloy exhibits a high CO selectivity with an optimal CO Faradaic efficiency (FECO) of 92% at -0.98 V (vs. RHE). Theoretical calculations indicate that the incorporation of Ni into Au can make the d-band center more positive and reduce the free energy barrier for the CO2 activation into *COOH and *CO desorption. Operando Raman spectroscopy provides the evidences that AuNi homogeneous solid-solution alloy can facilitate the activation of CO2 into *COOH and enhance the interaction between *COOH and AuNi (111) due to the change of electronic structure.

Automated summary

The article introduces a new method of atom-polymer hybridization to synthesize AuNi homogeneous solid-solution alloy catalysts, which exhibit excellent CO selectivity and high CO Faradaic efficiency. The positively charged Ni in the alloy enhances the local electronic structure of AuNi, leading to improved CO2 activation and interaction between *COOH and AuNi (111).