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

Nb2AlC/Nb2C MXene (NAC/NC) heterojunction photocatalysts with Schottky junctions were obtained by se-lective etching of the Al layer, resulting in 146.25 & mu;mol & BULL;g 1 electrons and 15.28 & mu;mol & BULL;g1 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 & mu;mol & BULL;g 1 & BULL;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 contin-uously forms high-energy hot electrons to convert the adsorbed CO2 into *CO2-, b-HCO3, and HCOO. Subse-quently, HCOO releases & BULL;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.

Automated summary

Nb2AlC/Nb2C MXene (NAC/NC) heterojunction photocatalysts with Schottky junctions were prepared, storing electrons and holes in the heterojunction. The NAC/NC thermally coupled photocatalytic reduction of CO2 showed high conversion and selectivity, attributed to the dual LSPR effect of Nb2AlC and Nb2C MXene. The high-energy electrons and holes generated by the LSPR effect promoted the conversion of CO2 into CO.