Regulating multiscale structures of nickel-iron-based electrocatalysts for efficient water oxidation

The oxygen evolution reaction (OER) has been widely studied as an efficient process in energy conversion, yet the majority of studies focus on the strategies to boost the intrinsic activity of the catalyst, rather than considering the enhancement of its mass transfer ability. Herein, we produce efficient NiFe-based OER electrocatalysts with rich oxygen vacancies and abundant transport channels by an argon plasma-engraving strategy. Compared with pristine NiFe, the obtained best NiFe-plasma catalyst yields a 12.5-fold increased current density (from 80 to ∼1,000 mA cm−2) at an overpotential of 300 mV, surpassing most OER catalysts in alkaline solution. Density functional theory calculations disclose that the introduction of oxygen vacancies improve the intrinsic activity and electronic conductivity, while finite element method calculations demonstrate that the construction of catalytic interface and the creation of nanoscale transport channels facilitates mass transfer.