WO3/SnO2 n-n Heterojunction Photoanode for Clean Selective Photochemical Preparation of Benzaldehyde.

Benzaldehyde is a vital intermediate for the synthesis of pharmaceuticals and agrochemicals. Traditional chemical synthesis methods are costly and cause environmental pollution. Therefore, developing novel green synthesis approaches is growing increasingly important. A photoelectrochemical (PEC) system was constructed using a WO3/SnO2 n-n heterojunction photoanode, with N-hydroxysuccinimide (NHS) acting as a selective hydrogen-atom-transfer mediator. The preparation parameters were optimized, and the material was characterized by SEM, TEM, XRD, XPS, and UV-vis diffuse reflectance spectroscopy. PEC properties and catalytic performance were evaluated. The optimized WO3/SnO2 exhibited extended light absorption and efficient charge separation. Under ambient conditions, the PEC system delivered 98% yield and 100% selectivity for benzaldehyde without using hazardous oxidants or causing substrate overoxidation. This work provides a green and efficient approach for benzaldehyde synthesis, offering theoretical and technical support for the PEC production of high-value fine chemicals and pharmaceutical intermediates.