Heterogeneous In/Mo cooperative bandgap engineering for promoting visible-light-driven CO2 photoreduction

Abstract

Improving the low charge separation efficiency, poor light absorption capacity, and insufficient active sites of photocatalysts are the important challenges for CO₂ photoreduction. In this study, a Mo modified InOOH/In(OH)₃ heterojunction with enhanced CO₂ reduction efficiency was synthesized in situ by using an In(OH)₃ monatomic lamellar material with isolated In atom sites exposed on its surface. And bandgap tuning via the energy levels formed by Mo doping and vacancy defect engineering can simultaneously improve visible light absorption and photogenerated charge separation. The results of experimental characterization and DFT calculation show that the Mo impurity energy levels, O defect energy levels, and surface Mo atoms existing in the InOOH phase can act as an electron transfer ladder in cooperation with the In defect energy levels in the In(OH)₃ phase, thereby promoting electron transfer between heterogeneous interfaces. Under visible light irradiation, the evolution rates of CH₄ and CO of the Mo modified InOOH/In(OH)₃ photocatalyst are more than ∼11 and ∼8 times higher than those of InOOH, respectively. This work provides new insights into the design of the CO₂ photoreduction platform through a collaborative strategy of bandgap tuning, transition metal doping, and heterostructure construction.