Overcoming energy mismatch of metal oxide semiconductor catalysts for CO2 reduction with triboelectric plasma

Abstract

The activities of semiconductor-based catalytic reactions are limited by mismatch between energy bandgaps of semiconductors and redox potentials of inert small molecules, especially for stable molecules, such as CO2. Herein, a triboelectric plasma catalytic system using metal oxide catalysts has been developed, which reduces CO2 to CO at room temperature and atmospheric pressure. Among the various metal oxide semiconductors, TiO2 catalyst exhibited the best activity, reaching a production rate of 0.14mmol·gcat−1·h−1, and an energy efficiency of 5.3 % for the conversion of electrical to chemical energy. In triboelectric plasma, CO2 molecules were pre-activated to form the transient CO2− anions, and the limiting step of electron transfer between TiO2 and CO2 was avoided, overcoming the energy mismatch between catalyst and CO2. The energy barrier of CO2 dissociation was markedly reduced to 0.18 eV. This work provides an effective strategy to overcome the energy bandgap restriction inherent in semiconductor-based catalytic reactions.