Oxygen vacancy in CoO/reduced graphene oxide composite for enhancing long-term effectiveness of photocatalytic CO2 reduction via mediating exciton

Abstract

Photocatalytic reduction of carbon dioxide (CO2) has been expected to be an effective way to reduce carbon emissions. Designing photocatalytic materials with long-term effectiveness is the key of photocatalytic technology. In this work, CoO nanoparticles loaded on the surface of reduced graphene oxide (rGO) membranes on silicon substrate were in-situ fabricated by one-step method. The resulting materials can convert CO2 into carbon monoxide (CO) up to 70 h at a steady rate of ∼185 ± 30 µmol g−1 h−1 with a selectivity of nearly 100%. This material system contained rich oxygen vacancies and generated new oxygen vacancies during the photocatalytic process. Oxygen vacancies mediate the interactions with excitons: (i) promoting the dissociation of free excitons; (ii) leading to form bound excitons under the coupling effect with phonons, inhibiting the recombination of photogenerated electrons and holes as well as enhancing the long-term effectiveness of photocatalytic CO2 reduction. We hope this work can provide valuable insights for the design and optimization of photocatalytic materials.