Mo-modified (t-m)-ZrO2 with narrowed band gap and strong ability to activate reactants for photocatalytic CO2 reduction

Abstract

ZrO2 is a promising candidate for photocatalytic CO2 reduction due to its high conduction potential, but it suffers from narrow sunlight absorption range and weak activation ability to reactants. Herein, we explore Mo-modified (t-m)-ZrO2 photocatalysts by a one-step hydrothermal method. As compared to bared ZrO2, their photoresponse extends to the visible light region, being attributed to the impurity band of Mo 4d states embedded in the ZrO2 band gap. Meanwhile, PL and electrochemical tests illustrate that the impurity band also leads to an increase in the carrier separation efficiency. MoO3 nanoparticles and doping Mo in Mo-modified ZrO2 photocatalysts promotes H2O and CO2 activation, respectively. Moreover, in situ FTIR and theoretical calculation revealed that Mo modification is also favorable for the generation of *COOH intermediate and the desorption of CO. As a result, the optimized Mo-modified ZrO2 exhibited a 27.3 μmol·g−1 of the CO yield with ∼100% selectivity, being 13 times higher activity than bared ZrO2. This work provides a guidance for the exploitation of wide bandgap semiconductors in the field of photocatalytic CO2 reduction.