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 mAcm2 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 23. Together, X-ray absorption spectroscopy and computational studies reveal that the vacancies produce
a local atomic and electronic structure that enhances CO2RR.
