The NTU team, led by Professor Lydia Wong, designed the device to address two challenges: the energy intensity of conventional electrolysis and the difficulty of treating hydrazine-contaminated wastewater. Conventional electrolysis requires external electricity and produces oxygen as a waste by-product. Instead, the researchers developed an anode equipped with a catalyst containing iron, cobalt, and chromium that breaks down hydrazine into nitrogen gas while generating additional hydrogen. This reaction requires less energy than producing oxygen, improving overall hydrogen-production efficiency.
The cathode uses lead-halide perovskites to absorb light and generate electricity, making the system self-powered. The researchers protected the moisture-sensitive perovskite with a conductive epoxy layer and titanium foil, then coated the titanium with platinum to facilitate hydrogen production. In tests using simulated and real seawater with hydrazine, the device operated for over 72 hours without significant performance drop. A larger version reduced hydrazine concentration from 0.5 M to 0.5 ppb in about 30 hours. Outdoor tests under natural sunlight produced hydrogen and nitrogen bubbles, confirming real-world viability.
However, the system has limitations. The anode requires hydrazine to function, restricting its use to contaminated wastewater rather than general seawater electrolysis. The lead content raises concerns about long-term stability and leakage. The device remains at the proof-of-concept stage, with scaling and durability beyond 72 hours yet to be demonstrated.
“The breakthrough here lies not simply in producing solar hydrogen but in demonstrating a practical route towards multifunctional photoelectrochemical systems,” said James Durrant, Professor of Photochemistry and Sustainable Energy at the University of Oxford, who was not involved in the research. The researchers acknowledge the need to improve long-term durability and scaling for industrial applications.