Aggregates of Ni/Ni(OH)2/NiOOH Nanoworms on Carbon Cloth for Electrocatalytic Hydrogen Evolution.

The development of an efficient electrocatalyst for hydrogen evolution reaction (HER) is essential to facilitate the practical application of water splitting. Here, we aim to develop an electrocatalyst, Ni/Ni(OH)2/NiOOH, via electrodeposition technique on carbon cloth, which shows efficient activity and durability for HER in an alkaline medium. Phase purity and morphology of the electrodeposited catalyst are determined using powder X-ray diffraction and electron microscopic techniques. The compositional and thermal stability of the catalyst is checked using X-ray photoelectron spectroscopy and thermogravimetry analysis. Electrodeposited Ni/Ni(OH)2/NiOOH material is an efficient, stable, and low-cost electrocatalyst for hydrogen evolution reaction in a 1.0 M KOH medium. The catalyst exhibits remarkable performance, achieving a current density of 10 mA/cm2 at a potential of -0.045 V vs reversible hydrogen electrode (RHE), and the Tafel slope value is 99.6 mV/dec. The overall electrocatalytic water splitting mechanism using Ni/Ni(OH)2/NiOOH catalyst is well explained, where formation and desorption of OH- ion on the catalyst surface are significant at alkaline pH. The developed electrocatalyst shows significant durability up to 200 h in a negative potential window in a highly corrosive alkaline environment along with efficient activity. The electrocatalyst can generate 165.6 μmol of H2 in ∼145 min of reaction time with 81.5% faradic efficiency.