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 MoS 2 -based composites (MoS 2 /ZnO, MoS 2 /CuFe 2 O 4, and MoS 2 /ZnO/CuFe 2 O 4 ) 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. MoS 2 /ZnO/CuFe 2 O 4 displayed the highest piezo-photocatalytic activity with a notable H 2 production rate of 3963 μmol g –1 h –1 in a 10 vol % methanol–water mixture, accompanied by 1436, 3325, and 2538 μmol g –1 h –1 for MoS 2, MoS 2 /ZnO, and MoS 2 /CuFe 2 O 4, 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 MoS 2 /ZnO/CuFe 2 O 4 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 MoS 2 /ZnO/CuFe 2 O 4 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.