Efficient charge separation in Z-scheme heterojunctions induced by chemical bonding-enhanced internal electric field for promoting photocatalytic conversion of corn stover to C1/C2 gases
摘要
The direct conversion of corn stover into high value-added C1/C2 gases using photocatalysis is a challenging and prospective endeavor. In this work, a sulfur/oxygen dual-vacancies CdS/Co3O4 (CdS-Sv/Co3O4-Ov) Z-scheme heterojunction was designed for direct raw corn stover powder (RCSP) conversion in a photoreactive system. The internal electric field (IEF) formed in CdS-Sv/Co3O4-Ov can effectively promote the photogenerated charge separation and transfer, and the chemical bond formed at the heterogeneous interface can be used as a channel for the directional migration of photogenerated charges to accelerate the inter-interface charge transfer. Experimental results combined with DFT calculations confirmed the formation of Z-scheme heterojunction and IEF. The results of the photocatalytic RCSP reaction showed that the CO, CH4, C2H6, and C2H4 evolution rates of the proposed catalytic system were as high as 691.99, 2057.69, 202.93, and 187.29 µmol/g, with the corresponding CH4 selectivity and total hydrocarbon selectivity of 65.53% and 77.96%, respectively. What is more, we propose a photocatalytic reaction mechanism in which raw biomass undergoes depolymerization and cascading oxidation to high value-added products. This study provides a new idea for high-performance photocatalytic direct conversion of RCSP into high-value-added C1/C2 gases through the rational design of photocatalysts and reaction systems.
Graphical AbstractA sulfur/oxygen dual-vacancies CdS/Co3O4 Z-scheme heterojunction for the one-step photocatalytic conversion of raw corn stover powder into high-value-added C1/C2 gases