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

Piezocatalytic generation of H2 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 H2, 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 H2 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 H2 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 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 H2 evolution. Holes played a major role in H2 generation. The H2 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 H2 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.