Iron, Tungsten Dual‐Doped Nickel Sulfide as Efficient Bifunctional Catalyst for Overall Water Splitting

Abstract

Abstract Developing low‐cost and highly efficient bifunctional catalysts for both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) is a challenging problem in electrochemical overall water splitting. Here, iron, tungsten dual‐doped nickel sulfide catalyst (Fe/W‐Ni 3 S 2 ) is synthesized on the nickel foam, and it exhibits excellent OER and HER performance. As a result, the water electrolyze based on Fe/W‐Ni 3 S 2 bifunctional catalyst illustrates 10 mA cm −2 at 1.69 V (without iR ‐compensation) and highly durable overall water splitting over 100 h tested under 500 mA cm −2 . Experimental results and DFT calculations indicate that the synergistic interaction between Fe doping and Ni vacancy induced by W leaching during the in situ oxidation process can maximize exposed OER active sites on the reconstructed NiOOH species for accelerating OER kinetics, while the Fe/W dual‐doping optimizes the electronic structure of Fe/W‐Ni 3 S 2 and the binding strength of intermediates for boosting HER. This study unlocks the different promoting mechanisms of incorporating Fe and W for boosting the OER and HER activity of Ni 3 S 2 for water splitting, which provides significant guidance for designing high‐performance bifunctional catalysts for overall water splitting.