Boosting Photocatalytic Hydrogen Evolution Reaction by the Improved Mass Flow and Energy Flow Process Based on Ultrasound Waves

Sun-driven photocatalytic hydrogen production reaction opens up possibilities for renewable energy systems. The reaction is the mass and energy conversion process between materials and the environment. Thus, the proper physical field introduction is the desired serious consideration to improve the mass flow and energy flow process. Here, we propose a piezo-enhanced photocatalytic system based on the ultrasound field to realize the adjustable built-in electric field favoring photo-induced carriers' transfer. As a proof of concept, the piezo-photocatalyst is prepared through a hydrothermal method. On the basis of the photoelectric characterization and theory calculation, the dynamics of mass transfer is enhanced by the ultrasonic field's spatial compression and cavitation effect. Moreover, the surface redox reaction is accelerated because the chemical bond break–reformation process is improved under the support of the cavitation effect. Thus, an impressive hydrogen production rate of up to 13.09 mmol h–1 g–1 has been achieved with a ternary catalyst. A practical demonstration is also designed to actualize hydrogen production in the natural condition, proving the piezo-photocatalytic system's practical advantages.