Heterogeneous CoFe-Co8FeS8 nanoparticles embedded in CNT networks as highly efficient and stable electrocatalysts for oxygen evolution reaction

It is essential to explore high-efficiency and low-cost electrocatalysts to replace noble metal based electrocatalysts for promoting the efficiency of water splitting and obtaining clean hydrogen energy. Herein, for the first time, self-assembled heterogeneous CoFe-Co8FeS8 nanoparticles embedded in CNT networks (CoFe/Co8FeS8/CNT) are synthesized via a facile microwave-assisted sulfidation and annealing process. Compared to CoFe/CNT or Co8FeS8/CNT, the CoFe/Co8FeS8/CNT delivers much better performance for oxygen evolution reaction (OER): it shows an Ultralow Tafel slope of 38 mV dec(-1); it affords a large current density of 10 mA cm(-2) only requiring a small overpotential of 290 mV; in addition, it demonstrates good long-term stability. The outstanding OER performance of CoFe/Co8FeS8/CNT is attributed to its unique porous nanoarchitecture constructed by heterogeneous CoFe-Co8FeS8 nanoparticles homogenously embedded in highly conductive CNT networks, which can not only enable full utilization of electrocatalytic active sites and provide conductive pathways for efficient charge transfer between nanoparticles and CNT, but also accelerate gas bubbles evolving and releasing. This work provides insight into microwave-assisted synthesis of highly efficient non-precious transition metal sulfide based electrocatalysts with rationally designed nanoarchitecture for OER.