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

Abstract

Nb₂AlC/Nb₂C 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 CO₂ 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 Nb₂AlC and Nb₂C MXene, respectively. After light excitation, the localized surface plasmon resonance (LSPR) effect of holes distributed on the surface of Nb₂C MXene crystals in the heterojunction will form high-energy thermal holes to dissociate H₂ to H⁺ and reduce CO₂ to form H₂O at the same time. The high-energy electrons formed by the LSPR effect of Nb₂C MXene and the conduction band electrons generated by the photoexcitation of Nb₂C MXene can be migrated to Nb₂AlC under the action of the interfacial Schottky junction to supplement the electrons needed for the LSPR effect of Nb₂AlC, which continuously forms high-energy hot electrons to convert the adsorbed CO₂ into *CO^2-, b-HCO₃, and HCOO. Subsequently, HCOO releases ⋅OH in a cyclic reaction to continuously reduce to form CO. The dual LSPR effect of Nb₂AlC and Nb₂C MXene is used to enhance the hydrogenation activity of thermally coupled photocatalytic reduction of CO₂, which provides a new research idea for the application of MXene in thermally coupled photoreduction of CO₂.

Keywords: CO(2) reduction; LSPR effect; Nb(2)AlC/Nb(2)C MXene; Selective etching; Thermally coupled photocatalysis.