La–doped FeNiSe4/Fe0.8Ni0.2Se2/NF heterostructure for superior oxygen evolution reaction

It is of great value to explore non-noble and highly active electrocatalysts for oxygen evolution reaction (OER) to obtain reproducible and clean fuels. In this work, a novel La-doped FeNiSe4/Fe0.8Ni0.2Se2/NF (La-FeNi-Se/NF) heterostructure catalyst was prepared by a facile selenization treatment to La-doped FeNi Prussian blue analogue(PBA) in-situ grown on foam nickel (NF). The catalytic performance of La-FeNi-Se/NF was significantly enhanced by the doped La3+. As a result, the optimized La-FeNi-Se-2/NF exhibits superior alkaline OER electrocatalytic activity (overpotential 158 mV at 10 mA cm−2 and Tafel slope 35.6 mV dec−1) than FeNi-Se/NF and Ln-FeNi-Se/NF (Ln = Ce, Gd, Yb), and most reported FeNi-based OER electrocatalysts. The excellent electrocatalytic capability to OER is attributed to the doping FeNi-Se heterostructure with a suitable amount La3+. Also, the unique La-FeNi-Se-2/NF flower-like structure composed of nanograins can produce abundant active sites and enhance charge transfer, thereby further improving the catalytic performance. This work highlights an effective chemical and engineering method to prepare efficient electrochemical catalysts.