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
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The direct conversion of corn stover into high value-added C 1 /C 2 gases using photocatalysis is a challenging and prospective endeavor. In this work, a sulfur/oxygen dual-vacancies CdS/Co 3 O 4 (CdS-S v /Co 3 O 4 -O v ) 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-S v /Co 3 O 4 -O v 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, CH 4 , C 2 H 6 , and C 2 H 4 production rates of the proposed catalytic system were as high as 691.99, 2057.69, 202.93 and 187.29 µmol/g, with the corresponding CH 4 selectivity and total hydrocarbon selectivity of 65.53% and 77.96%, respectively. What’s 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 C 1 /C 2 gases through the rational design of photocatalysts and reaction systems.
