Fabrication of multiphase MoSe₂ modified BiOCl nanosheets for efficient piezo-photoelectric hydrogen evolution and...

Efficient spatial charge separation plays a crucial role in improving the photocatalytic performance. Therefore, 1T/2H MoSe₂/BiOCl (1T/2H MS/BOC) and 2H MoSe₂/BiOCl (2H MS/BOC) piezo-photocatalysts are synthesized. By combining piezoelectric catalysis and photocatalysis, a highly active piezo-photocatalytic process is realized. The optimal 1T/2H MS/BOC piezo-photocatalyst displays superior diclofenac (DCF) degradation and hydrogen (H₂) evolution activity under the combined action of ultrasound and light. In particular, the DCF degradation kinetic constant (k) of optimal 0.5% 1T/2H MS/BOC under the synergistic effect of ultrasound and light is 0.057 min^-1, which is 8.1 and 6.3 times higher than those of BiOCl (0.007 min^-1) and 0.5% 2H MS/BOC (0.009 min^-1). Moreover, the H₂ evolution rate of 0.5% 1T/2H MS/BOC is 122.5 μmol g^-1 h^-1, which is also higher than those of BiOCl (45.8 μmol g^-1 h^-1) and 2H MS/BOC (49.5 μmol g^-1 h^-1). The dramatic improvement in the DCF degradation and H₂ evolution piezo-photocatalytic performance of 1T/2H MS/BOC catalysts is ascribed to the built-in polarization electric field and abundance of active sites of 1T/2H MS/BOC as well as the advantageous band structure between BiOCl and 1T/2H MoSe₂. Additionally, three probable degradation pathways of DCF were put forward from the results of liquid chromatography-mass spectrometry (LCMS) and density functional theory (DFT) calculations. This study provides the design strategy of high efficiency piezo-photocatalysts in environmental purification and energy-generation fields based on phase and band structure engineering.