Large-Scale Preparation of Ultrathin Bimetallic Nickel Iron Sulfides Branch Nanoflake Arrays for Enhanced Hydrogen Evolution Reaction

Developing the large-scale preparation of non-noble metal catalysts with high performance is crucial for promoting the electrochemical production of hydrogen from water. In this work, a novel TiO2@FeNi2S4 (TiO2@FNS) branch nanoflake array on Ni foam can be prepared at a large scale (50 cm2) by combining an atomic-layer-deposited (ALD) TiO2 skeleton with one-step facile low-temperature (<100 °C) sulfurization method. As-prepared TiO2@FNS arrays exhibit excellent hydrogen evolution reaction (HER) performance with an overpotential of 97 mV at 10 mA cm−2, superior to the FNS counterpart (without TiO2 coating) and other reported catalysts. The enhanced HER catalytic performance of TiO2@FNS is attributed to the increased specific surface area and improved structural stability due to the introduction of TiO2 coating. Moreover, theoretical calculations also show that the bimetallic NFS structure is more favorable to the dissociation of water molecule and the desorption of H than the monometallic Ni3S2 counterpart. With the combination of experimental results and theoretical calculations, this work has enlightened a new way of exploring high-efficient catalysts for HER.