Scientists have identified a new catalyst that can oxidise urea and lower the energy demand for hydrogen generation by urea-assisted water splitting.
Electrolytic generation of hydrogen at cathode, while inherently clean and green, has been hampered by the energy demands of the oxygen evolution reaction at the anode (counter electrode). A viable solution emerges from replacing the oxygen evolution reaction with other anodic processes such as urea electro-oxidation reaction (UOR) possessing lesser overall cell potential. By adding urea to water, it has practically been shown to reduce the energy demand for electrochemical hydrogen production by about 30 per cent. This not only reduces the electrical energy input and hence, the cost for hydrogen generation from water but also holds promise for remediating urea from wastewater in conjunction with energy generation while converting urea into nitrogen, carbonate and water. Despite the potential advantages, the catalysts developed so far are not stable to COx poisons (by-products of UOR) posing barriers to industry-scale implementation of this process.
A team of scientists from Centre for Nano and Soft Matter Sciences (CeNS), Bengaluru – Nikhil N Rao, Dr Alex Chandraraj and Dr Neena S John, have demonstrated a non-noble metal catalyst, Ni3+-rich – Neodymium Nickelate (NdNiO3) with metallic conductivity that efficiently oxidises urea, thereby lowering the energy demand for hydrogen generation by urea-assisted water splitting. The team used neodymium nickelate as an electrocatalyst for UOR, and using techniques such as X-ray absorption spectroscopy, electrochemical impedance spectroscopy and Raman spectroscopy performed operando (under operating conditions), substantiated that the catalyst drives the reaction specifically through a ‘direct mechanism’.