Abstract
Defect sites are often proposed as key active sites in the design of catalysts. A promising strategy for improving activity is to achieve a high density of homogeneously dispersed atomic defects; however, this is seldom accomplished in metals. We hypothesize that vacancy-rich catalysts could be obtained through the synthesis of quantum dots (QDs) and their electrochemical reduction during the CO2 reduction reaction (CO2RR). Here, we report that QD-derived catalysts (QDDCs) with up to 20 vol % vacancies achieve record current densities of 16, 19, and 25 mAcm−2 with high faradic efficiencies in the electrosynthesis of formate, carbon monoxide, and ethylene at low potentials of –0.2, –0.3, and –0.9 V versus reversible hydrogen electrode (RHE), respectively. The materials are stable after 80 hr of CO2RR. These CO2RR performances in aqueous solution surpass those of previously reported catalysts by 2×. Together, X-ray absorption spectroscopy and computational studies reveal that the vacancies produce a local atomic and electronic structure that enhances CO2RR.
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•QDDCs were synthesized through in situ electrochemical reduction•QDDCs maximize the density and stability of vacancies in metallic nanocrystals•QDDCs produce a local atomic and electronic structure that enhances CO2RR performances•QDDCs provide further avenues to catalyst design and optimization
Using renewable electricity to convert CO2 into value-added carbon-based products and feedstocks simultaneously addresses the needs for storage of intermittent renewable energy sources and reduces greenhouse gas emissions. We report record current densities with high faradic efficiencies in the electrosynthesis of formate, carbon monoxide, and ethylene at the low applied potentials through the synthesis of quantum-dot-derived catalysts (QDDCs). The QDDCs maximize the density and stability of vacancies in metallic nanocrystals and thus the catalytic activity and stability. The catalysts show excellent stability without deactivation after more than 80 h of operation.
A high density of homogeneously dispersed atomic defects has long been believed to be a promising strategy for improving catalytic activity. Taking the defective nature of quantum dots, Liu et al. synthesize vacancy-rich metal nanocrystals through in situ electrochemical reduction of quantum dots. This maximizes the density and stability of vacancies in metallic nanocrystals and achieves record current densities with high faradic efficiencies in the electrosynthesis of formate, carbon monoxide, and ethylene at low applied potentials.