Fabrication of CdLa2S4@La(OH)3@Co3S4 Z-scheme heterojunctions with dense La, S-dual defects for robust photothermal assisted photocatalytic performance

Optimize the separation and transport mechanism of photogenerated carriers in heterojunction composites, and make full use of the active sites of each material are key factors to enhance photocatalytic activity. Herein, we successfully synthesize defective CdLa2S4@La(OH)3@Co3S4 (CLS@LOH@CS) Z-scheme heterojunction photo -catalysts through a facile solvothermal method, which show broad-spectrum absorption and excellent photo -catalytic activity. La(OH)3 nanosheets not only greatly increase the specific surface area of photocatalyst, but also can be coupled with CdLa2S4 (CLS) and form Z-scheme heterojunction by converting irradiation light. In addi-tion, Co3S4 with photothermal properties is obtained by in-situ sulfurization method, which can release heat to improve the mobility of photogenerated carriers, and also be used as a cocatalyst for hydrogen production. Most importantly, the formation of Co3S4 leads to a large number of sulfur vacancy defects in CLS, and thus improving the separation efficiency of photogenerated electrons and holes, and increasing the catalytic active sites. Consequently, the maximum hydrogen production rate of CLS@LOH@CS heterojunctions can reach 26.4 mmol g -1h-1, which is 293 times than pristine CLS (0.09 mmol g-1h-1). This work will provide a new horizon for synthesizing high efficiency heterojunction photocatalysts through switching the separation and transport modes of photogenerated carrier.

Automated summary

Optimizing the separation and transport of photogenerated carriers in heterojunction composites and utilizing the active sites of each material are crucial for enhancing photocatalytic activity. In this study, a Z-scheme heterojunction catalyst, CLS@LOH@CS, is successfully synthesized using a simple solvothermal method, exhibiting broad-spectrum absorption and excellent photocatalytic performance. The incorporation of La(OH)3 nanosheets increases the specific surface area and forms a Z-scheme heterojunction with CdLa2S4 (CLS) upon irradiation. Additionally, the in-situ sulfurization method produces photothermal Co3S4, which enhances the mobility of photogenerated carriers and serves as a cocatalyst for hydrogen production. The formation of Co3S4 also introduces sulfur vacancy defects in CLS, improving the separation efficiency of photogenerated electrons and holes and increasing the catalytic active sites. As a result, the maximum hydrogen production rate of CLS@LOH@CS heterojunctions reaches 26.4 mmol g-1h-1, 293 times higher than pristine CLS (0.09 mmol g-1h-1). This work opens up new possibilities for synthesizing high-efficiency heterojunction photocatalysts by modulating the separation and transport modes of photogenerated carriers.