Highly efficient photoelectrocatalytic reduction of CO2 on the Ti3C2/g-C3N4 heterojunction with rich Ti3+ and pyri-N species

Abstract

Photoelectrocatalytic (PEC) reduction of CO₂ into chemical fuels in water is a promising route to mitigate the energy crisis and global warming issues. Herein, Ti₃C₂/g-C₃N₄ (TCCN) heterojunctions were fabricated by in situ heat treatment and were applied to PEC CO₂ reduction. These heterojunctions have narrow band gaps (2.3–2.6 eV) and rich Ti³⁺ species, which are beneficial to the absorption of solar light and the separation of electrons and holes. Besides this, the abundant pyri-N species in the TCCN heterojunctions can adsorb CO₂ molecules, which is favourable for CO₂ reduction. The deposition of nanometal particles can accelerate charge transfer. In a two-electrode system of M–TCCN‖BiVO₄, the total formation rate of formate and methanol was as high as 50.2 μM cm⁻² h⁻¹ (25.1 mM h⁻¹ g⁻¹), which is tenfold that of pristine g-C₃N₄. The carbon source of the products was verified by a ¹³CO₂ labeling experiment. These heterojunctions show outstanding PEC performance and stability and are promising candidates in the solar-to-fuel engineering field.