Silver Nanoparticles with Surface-Bonded Oxygen for Highly Selective CO2 Reduction

Citation:

Jiang K, Kharel P, Peng Y, Gangishetty MK, Lin H-YG, Stavitski E, Attenkofer K, Wang H. Silver Nanoparticles with Surface-Bonded Oxygen for Highly Selective CO2 Reduction [Internet]. ACS Sustainable Chemistry & Engineering 2017;

Abstract:

The surface electronic structures of catalysts need to be carefully engineered in CO2 reduction reaction (CO2RR), where the hydrogen evolution side reaction usually takes over under a significant overpotential, and thus dramatically lowers the reaction selectivity. Surface oxides can play a critical role in tuning the surface oxidation state of metal catalysts for a proper binding with CO2RR reaction intermediates, which may significantly improve the catalytic activity and selectivity. Here, we demonstrate the importance of surface-bonded oxygen on silver nanoparticles in altering the reaction pathways and improving the CO2RR performances. A comparative investigation on air-annealed Ag (Air-Ag) catalyst with or without the post-treatment of H2 thermal annealing (H2-Ag) was performed. In Air-Ag, the subsurface chemically bonded O species (O–Agδ+) was identified by angle resolved X-ray photoelectron spectroscopy and X-ray absorption spectroscopy techniques, and contributed to the improved CO selectivity rather than H2in CO2RR electrolysis. As a result, though the maximal CO Faradaic efficiency of H2-Ag is at ∼30%, the Air-Ag catalyst presented a high CO selectivity of more than 90% under a current density of ∼21 mA/cm2.

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