Piezo-Photocatalytic Generation of H2 with MoS2/ZnO/CuFe2O4 Nanosheets

Piezocatalytic generation of H-2 is an emerging technology for the collection and application of mechanical energy and the efficient production of sustainable energy nowadays. To enable high-efficiency and low-energy production of H-2, we prepared three MoS2-based composites (MoS2/ZnO, MoS2/CuFe2O4, and MoS2/ZnO/CuFe2O4) and used them as the catalysts for the green synthesis of H-2 under mild magnetic stirring conditions (namely, hydraulic driving) to replace the conventional ultrasonic vibration. MoS2/ZnO/CuFe2O4 displayed the highest piezo-photocatalytic activity with a notable H-2 production rate of 3963 mu mol g(-1) h(-1) in a 10 vol % methanol-water mixture, accompanied by 1436, 3325, and 2538 mu mol g(-1) h(-1) for MoS2, MoS2/ZnO, and MoS2/CuFe2O4, respectively, at a stirring speed of 400 rpm (hydraulic gradient, 0.123 s(-1)) and 50 W light irradiation. A series of characterizations and analyses were performed to comprehend the insight into the catalytic activity difference and the related reaction mechanisms. The improved piezo-photocatalytic performance of MoS2/ZnO/CuFe2O4 can be ascribed to the enhanced light absorption capability, the reduced electron transfer resistance, and the enhanced separation efficiency of charge carriers, all of which are conducive to H-2 evolution. Holes played a major role in H-2 generation. The H-2 production rate over MoS2/ZnO/CuFe2O4 was far higher than the reported values obtained using ultrasound-driven piezocatalytic slurries. The efficient delivery of hydraulic energy also achieved far lower energy consumption for H-2 production than the reported values. In comparison to the ultrasonic catalytic experiments performed in this work, the hydraulic-driven catalysis was characterized by remarkably lower energy requirements, less noise pollution, and stronger structural stability of the catalysts. This study provides a green and sustainable method for the generation of renewable energy.