In-situ constructing Schottky junction and oxygen vacancy on HNb3O8 nanosheets for rapid charge transfer and enrichment for boosted photocatalytic CO2 reduction towards CH4

Abstract

Photocatalytic conversion of CO2 into CH4 is severely hampered by the kinetically challenging eight-electron transfer process. Herein, a hybrid photocatalyst comprising Pd nanoparticles-decorated HNb3O8 nanosheets with surface oxygen vacancies (Pd/HNb3O8-VO NS) is designed by a simple light-induced hydrogenation strategy. In this design, the introduction of VO is beneficial to the formation of defect energy level within the band gap of HNb3O8-VO NS, which could enhance the visible light absorption efficiency. Meanwhile, the constructed Schottky junction between the Pd nanoparticle and HNb3O8-VO NS accelerates the migration of photogenerated charge from HNb3O8-VO NS to Pd, thus improving the photocatalytic performance of CO2 reduction. The experimental results of photocatalytic CO2 reduction showed that the optimal Pd/HNb3O8-VO NS (0.5% Pd/HNb3O8-VO NS) exhibits a high CH4 production yield of 288.4 μmol·g‒1 with 98.9% selectivity. This CH4 production yield is 37.9, 39.5, and 7.2 times higher than the bare HNb3O8 NS, HNb3O8-VO NS, and 0.5% Pd/HNb3O8 NS, respectively. This work provides a novel light on rationally fabricating high-activity and high-selectivity photocatalysts through integrating Schottky junction and defect engineering design.