Enhanced electrocatalytic performance of electrodeposited NiCu alloy as an efficient Bi-functional electrode by prolonged potentiostatic activation

The challenges in electrocatalytic water splitting are to develop a bifunctional catalyst and the role of fabricating catalyst is for commercialization purposes. For that, a simple electrodeposition technique can be used to fabricate the electrode. In this work, the NiCu electrocatalyst was fabricated using a simple electrodeposition technique in which a highly stable binder-free electrode was deposited. The fabricated films were deposited at different current densities and deposition temperatures to improve the efficiency of the electrode for water splitting. The fabricated electrode shows an excellent oxygen evolution reaction (OER) and Hydrogen evolution reaction (HER). Then the sample is subjected to the electrocatalytic Oxygen Evolution Reaction (OER) and Hydrogen Evolution Reaction (HER) studies in 1 M KOH which shows excellent activity. The film prepared at 15 A/cm2 shows outstanding OER and HER than the samples prepared at the current density of 5 A/cm2, 10 A/cm2, 15 A/ cm2 @50 degrees C and 15 A/cm2@70 degrees C. The film prepared at 15 A/cm2 shows an overpotential of 310 mV@ 10 mA for OER and 131 mV@10 mA for HER with Tafel values of about 40 mV/dec and 94 mV/dec respectively. The charge transfer kinetics of the prepared catalyst was analysed using the Tafel slope, and lower Tafel slopes were observed for 15 A/cm2 which was lower than other catalysts. To check the stability of the fabricated film, a prolonged PSTAT analysis was carried out for 12 h. After the PSTAT analysis, an increase in the activity of the sample was observed. This is due to prolonged activation of the surface which enhances the activity of the OER and HER. The larger shift in the overpotential toward cathodic and anodic is due to the PSTAT activation which activates the catalyst and results in a compressive strain of about 6.085 % expansion in the lattice significantly enhancing the activity. The film prepared at 15 A/cm2 shows an overpotential of 280 mV@ 10 mA for OER and 65 mV@10 mA for HER. A shift of about 66 mV in HER and a shift of about 30 mV in OER was observed. Prolonged activation results in the increased activity show that the catalyst can be used as an alternate electrode for future application.