Dual Localized Surface Plasmon Resonance effect enhances Nb2AlC/Nb2C MXene thermally coupled photocatalytic reduction of CO2 hydrogenation activity

Nb 2 AlC/Nb 2 C MXene (NAC/NC) heterojunction photocatalysts with Schottky junctions were obtained by selective etching of the Al layer, resulting in 146.25 μmol·g −1 electrons and 15.28 μmol·g −1 holes stored in the heterojunction. The average conversion of NAC/NC thermally coupled photocatalytic reduction of CO 2 under the simulated solar irradiation reached 110.15 μmol⋅g −1 ⋅h −1 , and the CO selectivity reached over 92%, which was 1.49 and 1.74 times higher than that of pure Nb 2 AlC and Nb 2 C MXene, respectively. After light excitation, the localized surface plasmon resonance (LSPR) effect of holes distributed on the surface of Nb 2 C MXene crystals in the heterojunction will form high-energy thermal holes to dissociate H 2 to H + and reduce CO 2 to form H 2 O at the same time. The high-energy electrons formed by the LSPR effect of Nb 2 C MXene and the conduction band electrons generated by the photoexcitation of Nb 2 C MXene can be migrated to Nb 2 AlC under the action of the interfacial Schottky junction to supplement the electrons needed for the LSPR effect of Nb 2 AlC, which continuously forms high-energy hot electrons to convert the adsorbed CO 2 into *CO 2− , b-HCO 3 , and HCOO. Subsequently, HCOO releases ⋅OH in a cyclic reaction to continuously reduce to form CO. The dual LSPR effect of Nb 2 AlC and Nb 2 C MXene is used to enhance the hydrogenation activity of thermally coupled photocatalytic reduction of CO 2 , which provides a new research idea for the application of MXene in thermally coupled photoreduction of CO 2 .