Oxygen Vacancies and Z-Scheme Heterostructure Synergistic Improve the Photocatalytic Glycerol Reforming to Syngas

Abstract

Photocatalytic glycerol reforming offers significant potential for applications in biomass conversion, but increasing its efficiency remains a critical challenge. While the synergistic effect of oxygen vacancies and Z-scheme heterojunctions have shown substantial potential in photocatalysis, it has not yet been explored in the context of glycerol reforming. The present study proposes the design of a Z-scheme heterojunction (NAL/TiO2-500) composed of oxygen vacancies TiO2 (TiO2-500) and NiAl-LDH to significantly enhance the yield of photocatalytic glycerol dehydrogenation to syngas (H2 and CO) by utilizing the synergistic effect between oxygen vacancy and Z-scheme heterojunction. The efficiency of NAL/TiO2-500 catalyst to convert glycerol to H2 (1368.4 μmol g-1 h-1) and CO (128.3 μmol g-1 h-1) is 2.1 and 5.4 times higher than that of NAL/TiO2 catalyst without oxygen vacancies, respectively. The introduction of oxygen vacancies in TiO2 significantly reduces the band gap and enhances the light absorption efficiency. Meanwhile, the local electronic structure of the Z-scheme heterojunction interface is optimized by utilizing oxygen vacancies, which trigger additional charge transport routes and further enhance the Z-scheme charge separation efficiency. This study emphasizes the crucial role of the synergy between oxygen vacancies and Z-scheme heterojunctions in photocatalytic glycerol reforming, providing novel insights and strategies for future defect- and heterostructure-based photocatalyst designs.

Keywords: Photocatalysis, Z-scheme, oxygen vacancy, Glycerol, Syngas