Photocatalytic CO2 reduction enhanced by the thermochromic effect of modified VO2

Abstract

Photocatalytic CO₂ reduction to solar fuels holds great promise for storing renewable energy and mitigating global warming. However, its widespread application is hindered by the low optical absorption and inefficient utilization of charge carriers. One prospective approach to enhance photocatalytic performance involves converting low-energy photons into thermal energy. In this work, we explore the utilization of the thermochromic effect to enhance the selectivity and activity of photocatalytic CO₂ conversion, particularly in scenarios without photosensitizers and sacrificial agents. We have combined Mo-doped VO₂ (M1V), a thermochromic material, with an InVO₄ (IV) photocatalyst to enhance optical absorption and facilitate charge transfer in IV. The M1V-IV composite exhibits exceptional selectivity in solar-driven CO₂ reduction, an excellent selectivity of 99% with a photothermal CO formation rate of 58.4 μmol h⁻¹ g⁻¹ in pure water under 330 mW cm⁻² light irradiation. The CO evolution rate for M1V-IV is 1.5 times higher than that of the VO₂–InVO₄ composite and 6 times higher than that of pure IV. Comprehensive spectroscopic characterization and theoretical calculations disclose that the enhanced performance is attributed to the increased separation of charge carriers and the photocatalytic enhancement of CO₂ reduction due to the thermal effect. We successfully propose a reaction mechanism for CO₂ photoreduction on M1V-IV. This work introduces a novel strategy to enhance photocatalytic performance by leveraging the thermochromic effect in CO₂ reduction.