Copper Vacancy and LSPR-Activated MXene Synergistically Enabling Selective Photoreduction CO₂ to Acetate

Photocatalytic CO2 conversion towards C2+ fuels is a promising technology for simultaneously achieving carbon neutrality and alleviating the energy crisis. However, this strategy is inefficient due to the difficulty of both multi-electron transfer and C-C coupling during C2+ formation. In this work, CuInS2/MXene heterostructure with Cu vacancy is rationally designed by in situ hydrothermal synthesis. The V-Cu-CuInS2/MXene heterostructure has a suitable band structure and tight interface contact. Catalytic performances under different testing conditions, in situ spectroscopy, and COMSOL simulation reveal that LSPR-activated MXene promotes the formation of crucial intermediate CH2* and triggers the C-C coupling process under near-infrared light, as the key to acetate. Moreover, in situ XPS analysis, DFT calculations, and photoelectrochemical characterizations unveil that copper vacancy can promote charge transfer from CuInS2 to MXene and boost local electron aggregation on the MXene, further enhancing the photocatalytic efficiency and selectivity of C-2 products. Contributing to the synergistic effect of copper vacancy and plasmonic MXene, V-Cu-CuInS2/MXene achieved excellent CO2RR activity with an acetate evolution rate of 250.0 mu mol/h/g and a selectivity of 97.5 % under the full spectrum irradiation, which is 38.8 and 3.3 times higher than that of V-Cu-CuInS2 and CuInS2/MXene, respectively.