Ultrasound-driven seawater splitting catalysed by TiO2 for hydrogen production
Cherie Wong, Davide Bernardo Preso, Yi Qin, Pankaj S. Sinhmar, Zhiyuan Zong, James Kwan
Abstract
Seawater splitting presents a promising approach for sustainable hydrogen production, yet its application remains limited by competing side reactions and expensive catalyst in electrolysis. In this study, we present an alternative hydrogen production approach using ultrasonic-driven seawater splitting catalysed by TiO 2 at room temperature. The application of high-frequency ultrasound (780 kHz, 5.1 W) with a bespoke sonoreactor, designed to focus pulsed ultrasound waves, induces inertial cavitation and generates highly reactive radicals to produce hydrogen. By optimising acoustic parameters and TiO 2 catalyst concentration of 0.3 mg/mL, the system achieved the highest reported sonochemical efficiency for hydrogen production in both pure and natural seawater, reaching 8086 and 4210 μmol g cat −1 L −1 Whr −1 , respectively. We further investigated the significant decrease in hydrogen production in salty environments. Through bubble dynamics simulations and electron paramagnetic resonance measurements, we attributed the salt-scavenging chemical effect has a dominant role in reducing the efficiency. Our findings demonstrate the potential of sonocatalytic seawater splitting with TiO 2 as a viable alternative for renewable hydrogen production. • Identified optimal acoustic and catalytic conditions for maximised hydrogen yield. • Achieved the record sonochemical efficiency for hydrogen production from seawater. • Demonstrated TiO 2 sonocatalyst's recyclability and resistance to seawater corrosion. • Elucidated salt's physical and chemical effects on hydrogen production efficiency. • Presented sonochemical hydrogen production as a potentially scalable technique.