Fabrication of CdLaS@La(OH)@CoS 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 CdLaS@La(OH)@CoS (CLS@LOH@CS) Z-scheme heterojunction photocatalysts through a facile solvothermal method, which show broad-spectrum absorption and excellent photocatalytic activity. La(OH) nanosheets not only greatly increase the specific surface area of photocatalyst, but also can be coupled with CdLaS (CLS) and form Z-scheme heterojunction by converting irradiation light. In addition, CoS 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 CoS 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 gh, which is 293 times than pristine CLS (0.09 mmol gh). This work will provide a new horizon for synthesizing high efficiency heterojunction photocatalysts through switching the separation and transport modes of photogenerated carrier.