Anodization of Ni-rich NiTi SMA for enhancing green hydrogen production

The anodization of NiTi shape memory alloy (SMA) is conducted in ethylene glycol-based electrolyte to investigate the influence of anodizing voltage on its electrocatalytic performance for hydrogen evolution in 1 M KOH. The surface properties are significantly altered with increasing voltage. At 30 V, the formation of a much thicker oxide layer accompanied by a highly porous morphology increases surface roughness and active sites. The Ni content remains high (53.28 wt%), likely due to the formation of Ti₃Ni₄ phase. Electrochemical tests show that the 30 V anodized sample exhibits the lowest onset potential (−160 mV vs RHE). Electrochemical impedance spectroscopy (EIS) data confirms a 55 % reduction in charge transfer resistance, indicating improved conductivity and reaction kinetics. The 30 V anodized NiTi also shows excellent stability and corrosion resistance. These findings highlight anodization as a promising strategy to enhance NiTi electrocatalysts for sustainable hydrogen production.