Highly stability Cu+ species in hollow Cu2O nanoreactors by modulating cavity size for CO2 electroreduction to C2+ products

In Cu-based electrocatalysts, appropriate amount of Cu 0 and high concentration of Cu + are essential for the efficient conversion of CO 2 into C 2+ products. An obstacle of CO 2 electroreduction is the inevitable reduction of Cu + to Cu 0 at cathodic potential. Intermediates confinement is a promising solution to delay Cu + deterioration, in which it is crucial to maintain an appropriate amount of Cu 0 and Cu + species to produce sufficient intermediates to protect most Cu + species. Herein, based on the influence of Cu + /Cu 0 ratio on the reaction process and its feedback, a series of hollow Cu 2 O nanoreactors with different cavity sizes were synthesized to modulate the concentration of intermediates and the coverage degree of Cu + , so as to realize a constant high Cu + /Cu 0 ratio. The optimized hollow Cu 2 O nanoreactors achieved a C 2+ Faradaic efficiency of 70.1 ± 0.2 % at a partial current density of −9.3 ± 0.1 mA cm −2 over 30 h and a large C 2+ -to-C 1 ratio of 9.73. Operando Raman spectra and quasi in - situ Auger electron spectra confirmed that the moderate cavity Cu 2 O nanoreactors led to a full coverage of Cu + and an optimal Cu + /Cu 0 ratio of 8.12:1, which brought the stability of Cu + species and cavity structure, as well as the enhanced C C dimerization.