Synthesis of heteroatom incorporated porous carbon encapsulated Fe-doped Co9S8 as an efficient bifunctional electrocatalyst for overall water splitting
Javid Khan, Heng Liu, Jiamin Xiao, Yanlin Zhu, Asif Hayat, Hameed Ullah, Gulzar Ahmed, Handong Zhang, Yanyan Sun, Lei Han
Abstract
Doping metal ions into cobalt sulfide is a promising strategy to improve its performance as a cheap, green, highly active and sustainable electrocatalyst for overall water splitting. Herein, cauliflower-like, noble metal-free bifunctional electrocatalysts composed of S, N, and O atoms co-incorporated porous carbon (SNOPC) encapsulated Fe doped Co 9 S 8 nanoparticles are successfully synthesized by direct pyrolysis of S, Co, and Fe-based polypyrrole ( S – Co –Fe-PPYs) precursors for efficient overall water splitting. Specifically, the optimal catalyst (Fe 0-33 -Co 9 S 8 @SNOPC) shows excellent electrocatalytic performance in an alkaline electrolyte , requiring ultra-low overpotentials of 275 and 258 mV to reach a current density of 10 mA cm −2 for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively, with exceptional stability for 50 h. Furthermore, when applied for overall water splitting as a bifunctional electrolyzer, it generates a current density of 10 mA cm −2 at an extremely low cell voltage of 1.595 V. The exceptional electrocatalytic activity of Fe 0-33 -Co 9 S 8 @SNOPC can be credited to the synergistic effect produced by Fe doped Co 9 S 8 core and multi-atom incorporated porous carbon shell.