Synthesis of NiO thin film on 304-grade stainless steel substrate for oxygen evolution reaction

The use of 304-grade stainless steel (304SS) as a substrate for water splitting is the cheapest way to produce oxygen and hydrogen. But it is essential to activate the surface of 304SS for water splitting. Therefore, in the present work, we deposited nickel oxide (NiO) films on 304SS substrate by a simple hydrothermal method whose water splitting effectiveness is studied here. Morphology and structural changes were obtained with an increase in concentration. X-ray diffraction (XRD) confirms the formation of the monocrystalline NiO phase. The nickel content on 304SS gets converted to NiO at varied temperatures. The morphology was initially characterized by cauliflower-like bulges that changed to pronounced aggregation and a more rugged structure, and finally, a high degree of aggregation was observed for a higher concentration of NiO sample. The electrochemical water activation studies show that NiO at 1M concentration on 304SS showed an excellent oxygen evolution reaction (OER) with good stability (12 hrs 30 min.). NiO on 304SS displays a low overpotential of 133 mV with a Tafel slope of 96.09 mV/dec.