PdAg bimetallic electrocatalyst for highly selective reduction of CO2 with low COOH* formation energy and facile CO desorption
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For electrocatalytic reduction of CO2 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 CO2 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/cm2) than Ag (−0.76 V), but also delivers a CO/H2 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 CO2 reduction.
KeywordsCO2 reduction bimetallic low overpotential CO desorption
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This work was supported by the National Key R&D Program of China (Nos. 2016YFA0202801 and 2017YFA0700101), the National Natural Science Foundation of China (Nos. 21872076, 21573119, 21590792, 21890383, and 91645203) and Beijing Natural Science Foundation (No. JQ18007). The aberration-corrected TEM studies were conducted at the National Center for Electron Microscopy in Beijing for Information Science and Technology.
- Dinh, C. T.; Burdyny, T.; Kibria, M. G.; Seifitokaldani, A.; Gabardo, C. M.; García De Arquer, F. P.; Kiani, A.; Edwards, J. P.; De Luna, P.; Bushuyev, O. S. et al. CO2 electroreduction to ethylene via hydroxide-mediated copper catalysis at an abrupt interface. Science2018, 360, 783–787.CrossRefGoogle Scholar
- Feaster, J. T.; Shi, C.; Cave, E. R.; Hatsukade, T.; Abram, D. N.; Kuhl, K. P.; Hahn, C.; Nørskov, J. K.; Jaramillo, T. F. Understanding selectivity for the electrochemical reduction of carbon dioxide to formic acid and carbon monoxide on metal electrodes. ACS Catal. 2017, 7, 4822–4827.CrossRefGoogle Scholar