Harvesting Vibration Energy for Efficient Cocatalyst-Free Sonocatalytic H 2 Production over Magnetically Separable Ultra-Low-Cost Fe 3 O 4 .

The cavitation effect is an important geochemical phenomenon, which generally exists under strong hydrodynamic conditions. Therefore, developing an economical and effective sonocatalyst becomes a vital method in capitalizing on the cavitation effect for energy generation. In this study, we first report a novel Fe3 O4 sonocatalyst that can be easily separated using a magnetic field and does not require any additional cocatalysts for H2 production from H2 O. When subjected to ultrasonic vibration, this catalyst achieves an impressive H2 production rate of up to 175 μmol/h/USD (where USD stands for dollars), surpassing most previously reported mechanical catalytic materials. Furthermore, the ease and efficiency of separating this catalyst using an external magnetic field, coupled with its effortless recovery, highlight its significant potential for practical applications. By addressing the key limitations of conventional sonocatalysts, our study not only demonstrates the feasibility of using Fe3 O4 as a highly efficient sonocatalyst but also showcases the exciting possibility of using a new class of magnetically separable sonocatalysts to productively transform mechanical energy into chemical energy.