Hierarchical Ni-based alloy electrocatalysts for water splitting

The OER electrocatalyst is a key component for water splitting. However, the OER is a slow and complex process that requires high energy input and efficient catalysts. The mos...st commonly used catalysts are based on noble metals such as IrO2 and RuO2, but they have drawbacks of excessive cost and low stability. Therefore, the development of alternative robust and durable catalysts is needed. Alloying Ni with other metals could be one of the strategies, which can improve the activity and stability of the OER electrocatalyst by modulating the electronic structure, surface area, and morphology of the alloy. Alloying causes multiple changes in the physical and chemical properties of metallic components which influence catalytic activity by ligand, ensemble, and strain effects. The alloying effects can also tune the binding strength of the intermediates on the catalyst surface, which can affect the reaction kinetics and selectivity. Among numerous Ni-based electrocatalysts reported for OER, Ni-based alloys are promising candidates because of their low cost, high activity, and stability. However, most studies on electrocatalysis report the requirement of polymer binders that reduce their conductivity and durability. It also increases the resistance between the catalyst and the current collector and hinders the easy transfer of electrons, thereby deteriorating the conductivity. Moreover, such bonded catalysts are not mechanically stable, and the catalyst easily flakes off under severe oxygen evolution conditions, particularly when higher current densities are applied. These issues need to be solved to understand the full potential of nanostructured catalysts. Therefore, we aim to develop a polymeric binder-less electrocatalytic thin film of Ni combined with other transition metals such as (Fe, Co, or Cu) directly on conducting substrate by following a thin film deposition process based on aerosol-assisted chemical vapor deposition (AACVD) in a designed AACVD setup, which is a cheap and single-step method to fabricate thin alloy film directly on a support surface without any need of binder or reagent. As the catalyst will be directly developed over NF support the inherent conductivity of the catalyst is expected to be retained which will result in a highly active and durable catalyst.