Bifunctional Electrocatalysts Derived from Cluster-based Ternary Sulfides for Oxygen Electrode Reactions

Abstract Applying metal sulfides in the electrochemical systems is a currently emerging field owing to the unique physicochemical properties and low-cost. Although ternary sulfides have been explored as oxygen electrocatalysts, they are usually mono-functional and undergo a complicated preparation process. Herein, via a facile and mild self-assembly method induced by electrostatic interaction, a series of novel ternary sulfide hybrids (denoted as MInS/NH2-CNT, M=Co, Fe or Mn) were fabricated as bifunctional oxygen electrocatalysts using supertetrahedral metal sulfide nanoclusters (T4 clusters) with uniformly distributed ternary component as precursors. The synergistic effect between T4 clusters-aggregated nanoparticles and amino carbon nanotubes (i.e., NH2-CNT) endows the hybrids with oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalytic activity. Among the as-synthesized MInS/NH2-CNT, CoInS/NH2-CNT reveals superior electrocatalytic performance for the OER (overpotential of 398 mV at 10 mA cm−2) and ORR (half-wave potential of 0.76 V vs. RHE). The strategy developed here can be easily adopted to construct other cluster-based hybrid materials for electrocatalysts, thus providing more promising non-noble-metal materials for energy application.