Hierarchical trimetallic sulfide FeCo2S4–NiCo2S4 nanosheet arrays supported on a Ti mesh: An efficient 3D bifunctional electrocatalyst for full water splitting

In this work, we report an electrocatalyst of hierarchical trimetallic sulfide FeCo2S4–NiCo2S4 supported on Ti mesh (denoted as NiCoFe–S/Ti) for full water splitting in basic media. The NiCoFe–S/Ti shows an efficient and stable electrocatalytic performance for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). As an OER catalyst, NiCoFe–S/Ti shows a low overpotential of 230 mV at 10 mA cm−2 and a small Tafel slope of ∼65 mV dec−1. As a HER electrocatalyst, it also shows a low potential of −150 mV at 10 mA cm−2, a small Tafel slope of 38 mV dec−1, and a superior durability of maintaining the same catalytical activity for at least 10 h under basic condition. The superior activity and high stability of NiCoFe–S/Ti can be attributed to the highly exposed active sites, excellent charge transfer ability, and good synergistic effect resulted from multi-components. The NiCoFe–S/Ti based overall water splitting exhibits a low onset potential (∼1.47 V), a low splitting potential (∼1.51 V) at 10 mA cm−2 in 1.0 M KOH. This work will pave a way to the development of non-noble-metal, earth-abundant, bifunctional electrocatalyst for overall water splitting under basic conditions.