Abstract
The large-scale hydrogen production and application through electrocatalytic water splitting depends crucially on the development of highly efficient, cost-effective electrocatalysts for oxygen evolution reaction (OER), which, however, remains challenging. Here, a new electrocatalyst of trimetallic Fe–Co–Ni hydroxide (denoted as FeCoNiOxHy) with a nanotubular structure is developed through an enhanced Kirkendall process under applied potential. The FeCoNiOxHy features synergistic electronic interaction between Fe, Co, and Ni, which not only notably increases the intrinsic OER activity of FeCoNiOxHy by facilitating the formation of *OOH intermediate, but also substantially improves the intrinsic conductivity of FeCoNiOxHy to facilitate charge transfer and activate catalytic sites through electrocatalyst by promoting the formation of abundant Co3+. Therefore, FeCoNiOxHy delivers remarkably accelerated OER kinetics and superior apparent activity, indicated by an ultra-low overpotential potential of 257 mV at a high current density of 200 mA cm−2. This work is of fundamental and practical significance for synergistic catalysis related to advanced energy conversion materials and technologies.