Localized surface plasmon resonance effect of V4C3-MXene for enhancing photothermal reduction of CO2 in full solar spectrum

Photothermal catalysis in the full solar spectrum has attracted wide attention in alleviating the greenhouse effect and energy crisis. In this work, the V4C3-MXene layered material with 13.87 μmol·g-1 holes on its crystal surface and 119.3 μmol·g-1 electrons inside the crystal was prepared by etching the Al atomic layer of V4AlC3 with HF. Under full-spectrum sunlight irradiation, the electrons and holes in V4C3-MXene are excited to produce resonant excitation, which generates hot holes and high-energy hot electrons lagging behind the holes. High-energy hot holes first dissociate H2 into H+, while the high-energy hot electrons generate *CO2- with the adsorbed CO2, *CO2- then reacts with dissociated •OH and hot electrons to form HCO3-. HCO3- gains electrons and H+ and is further decomposed into •OH and *CO. Finally, *CO desorbs to produce CO. The resonance effect between the holes and the stored electrons of the V4C3-MXene crystal increases the ambient temperature of V4C3-MXene surface to 369 °C, accelerating the photothermal catalytic reduction of CO2 reaction. In the CO2 hydrogenation reduction reaction at 250 °C under the simulated sunlight irradiation for 3 h, the CO yield of V4C3-MXene is 95.68 μmol·g-1·h-1 and the CO selectivity is 96%. This work not only provides experimental validation for the photothermal catalytic conversion of CO2 by V4C3-MXene materials with localized surface plasmon resonance (LSPR) effect, but also a feasible research guidance for the design and synthesis of MXene full-spectrum photothermal catalysts.