Enhanced photocatalytic CO₂ reduction via MXene synergism: constructing an efficient heterojunction structure of g-C₃N₄ /Nb₂C /CsPbBr₃

Slow charge kinetics and high activation energy seriously hinder the efficiency of photocatalytic CO₂. Synergies are a commonly used strategy. Nevertheless, common synergies have been limited to improving catalytic results. Herein, we synthesize a novel nanocomposite ternary heterojunction material, which forms a low interlayer electrostatic potential within the heterojunction through the MXene synergistic. A strong internal electric field from the outside to the inside is formed within the series layer heterojunction, which provides the inner driving force for the effective spatial separation of photoinduced electron-hole pairs. Under visible-light irradiation, the ternary heterojunction exhibited a maximum CO production rate of 53.07 µmol g⁻¹ h⁻¹, surpassing the rates of pure g-C₃N₄, CsPbBr₃ QDs, and the binary composite of g-C₃N₄/CsPbBr₃ by approximately 8.4, 10, and 2 times, respectively. Experimental results and theoretical analysis reveal the significance of 2D Nb₂C MXene as an electron transporter, benefiting from lower electrostatic potential. This characteristic synergistically facilitated the rapid extraction of photoinduced electrons, enhancing the reduction ability of CO₂ to CO. This research not only provides a novel insight into MXene utilization for designing ternary heterojunction nanocomposite photocatalysts but also presents the potential of utilizing synergism ternary composites to improve solar energy conversion efficiency.