PdAg bimetallic electrocatalyst for highly selective reduction of CO2 with low COOH formation energy and facile CO desorption

• Published in: Nano research Vol. 12; no. 11; pp. 2866 - 2871
• Main Authors: Lin, Rui, Ma, Xuelu, Cheong, Weng-Chon, Zhang, Chao, Zhu, Wei, Pei, Jiajing, Zhang, Kaiyue, Wang, Bin, Liang, Shiyou, Liu, Yuxi, Zhuang, Zhongbin, Yu, Rong, Xiao, Hai, Li, Jun, Wang, Dingsheng, Peng, Qing, Chen, Chen, Li, Yadong
• Format: Journal Article
• Language: English
• Published: Beijing Tsinghua University Press 01.11.2019
• Subjects: Atomic/Molecular Structure and Spectra; Bimetals; Biomedicine; Biotechnology; Carbon dioxide; Carbon monoxide; Carbon monoxide poisoning; Catalysts; Catalytic activity; Chemical reduction; Chemistry and Materials Science; Condensed Matter Physics; Density functional theory; Desorption; Electrocatalysts; Electrolysis; Energy; Energy of formation; Free energy; Heat of formation; Materials Science; Nanotechnology; Palladium; Performance enhancement; Poisoning; Research Article; Silver; Surface stability; low overpotential; CO; reduction; CO desorption; bimetallic
• ISSN: 1998-0124; 1998-0000
• DOI: 10.1007/s12274-019-2526-1

For electrocatalytic reduction of CO 2 to CO, the stabilization of intermediate COOH* and the desorption of CO* are two key steps. Pd can easily stabilize COOH*, whereas the strong CO* binding to Pd surface results in severe poisoning, thus lowering catalytic activity and stability for CO 2 reduction. On Ag surface, CO* desorbs readily, while COOH* requires a relatively high formation energy, leading to a high overpotential. In light of the above issues, we successfully designed the PdAg bimetallic catalyst to circumvent the drawbacks of sole Pd and Ag. The PdAg catalyst with Ag-terminated surface not only shows a much lower overpotential (-0.55 V with CO current density of 1 mA/cm 2 ) than Ag (−0.76 V), but also delivers a CO/H 2 ratio 18 times as high as that for Pd at the potential of -0.75 V vs. RHE. The issue of CO poisoning is significantly alleviated on Ag-terminated PdAg surface, with the stability well retained after 4 h electrolysis at -0.75 V vs. RHE. Density functional theory (DFT) calculations reveal that the Ag-terminated PdAg surface features a lowered formation energy for COOH* and weakened adsorption for CO*, which both contribute to the enhanced performance for CO 2 reduction.