Investigation of electrocatalytic activity of nickel borate compounds for water oxidation

Due to the limited availability of fossil-based fuels and their negative impact on the environment, alternative energy sources are seen as a necessity. Hydrogen is seen as a good alternative due to its high energy density. Research on hydrogen production has recently been directed to the development of cost-effective and durable heterogeneous catalysts for water splitting. Non-oxide cobalt-based water oxidation electrocatalysts have attracted attention recently because they are stable in both acidic and basic environments. In this study, four nickel borate compounds with Kotoite crystal structure, stable Ni3(BO3)2, Ni2Co(BO3)2, NiCo2(BO3)2 and Ni2Cu(BO3)2, were synthesized by solid state method. The synthesized compounds were characterized by powder XRD, XPS, Infrared, ICP-OES and SEM-EDX methods. These compounds were used for the first time as electrochemical water oxidation catalysts. The electrocatalytic activities of these compounds were investigated in three stages incluiding: in three different pH solutions on the FTO electrode; in 1 M KOH solution on the CC electrode and finally, hybrid material was prepared with NiCo2(BO3)2, which had the highest activity and CNT on the CC electrode in 1 M KOH solution.