Influence of Hierarchical and Conformal Electrodeposition of NiCo₂O₄ Electrocatalyst on Carbon Cloth for Water Oxidation

To achieve net-zero emissions, consideration of various energy resources is essential for future energy needs. In this regard, green hydrogen production via water electrolysis using renewable energy sources is an attractive route for providing a cleaner energy mix. Water electrolysis has been intensively studied with limited success to produce hydrogen at a very competitive price point. The major bottleneck for widely adopting such a green technology is to find cost-effective electrocatalysts that can efficiently oxidize water and produce hydrogen at practical cost. The best-known oxide electrocatalysts for water evolution reaction (OER) compose of precious metals such as Ru and Ir, which are expensive and impractical for large-scale production. Thus, searching for alternative electrocatalysis based on transition metal oxide is an attractive approach for low-cost electrolysis processes. In this regard, we developed highly efficient hierarchical NiCo2O4 porous electrocatalysts on electrochemically treated carbon cloth (CC) using facile and green electrodeposition method. X-ray diffraction spectra and scanning tunneling microscope images confirm the formation of hierarchical NiCo2O4 porous structure under study. TEM images of peeled off NiCo2O4 particles from CC show that the electrodeposited structure compose of defined nano-sized crystallites of NiCo2O4. Additionally, the developed electrode exhibits improved electrocatalytic performance with low overpotential of ~ 290 mV at J = 10 mA/cm2 and low Tafel slope of 76 mV/dec. Its superior catalytic activities and durability for OER in alkaline media is mainly attributed to the special hierarchically porous nanostructure that led to enhanced charge transport to more accessible active sites.