Hollow porous Co–Ni spinel nanosheet arrays with rich oxygen defects on carbon cloth toward highly efficient and selective CO2 photofixation

Abstract

There is still a great challenge to simultaneously achieve high efficiency and selectivity of photocatalytic CO2 reduction. Here, a MOF-derived and defect-controllable strategy is used to rationally design a flexible hollow porous Co–Ni spinel nanosheet array ([email protected]) containing abundant oxygen defects and highly concentrated accessible active sites toward efficient and selective photocatalytic production of CO. Such a structured photocatalyst renders great synergistic effect, in which the oxygen vacancies greatly enhances the light-absorption, activates sturdy CO2 molecules and inhibits the recombination of photogenerated carriers, while the unique hollow porous nanosheet array structure rises the spatial density of active sites with high accessibility and boosts the photogenerated charge transport. In particular, the flexible hollow porous NiCo2O4 arrays ([email protected]) catalyst delivers a high CO yield of 19.8 μmol (about 3.1-fold higher than that of the poor-Ov photocatalysts), high stability, and a prominent selectivity of 95%. It is noted that the superior selectivity ranks one of the best metal oxides-based CO2 reduction catalysts. This work provides a facile strategy to delicately design a flexible film with abundant oxygen defects and active sites, holding great potential application in solar-driven CO2 reduction.