Ternary NiFeTiOOH Catalyst for the Oxygen Evolution Reaction: Study of the Effect of the Addition of Ti at Different Loadings

The world's shift to the production of energy from sustainable sources requires the development of large energy storage. One of the best methods to store surplus energy produced from environmentally friendly methods is as elemental hydrogen, using electrolysis in alkaline electrolyzers. Currently, this technology is hampered by the sluggish oxygen evolution reaction (OER), which limits its overall efficiency and durability. One of the most popular directions is to develop cheap, durable, and active platinum-group-metal-free (PGM-free) catalysts. In this category, the benchmark catalyst is NiFeOOH. Here, synthetic, electrochemical, spectroscopic, and theoretical methods were used to design, synthesize, and investigate novel PGM-free catalysts with enhanced durability and activity. Using an easy and cheap one-step synthetic precipitation method, titanium atoms in various amounts were introduced in the NiFeOOH structure, forming Ni_xFe_yTi_zOOH. One of these compounds (Ni:Fe:Ti = 85.75:7.70:6.55) shows a very low overpotential on GC (400 mV, at a current density of 10 mA/cm²) and high current density (27.9 mA cm^-2) at a potential of 1.8 V vs RHE. This is a higher activity toward the OER in comparison to the benchmark catalyst; in addition, the compound has higher stability at prolonged exposure to high potentials.