Facile Synthesis of Sulfur-Doped Mesoporous Carbon Nitride Supported Defect-Rich Cobalt Sulfide for Electrocatalytic Water Oxidation

The synthesis of defect-rich materials is of significant interest for electrochemical energy conversion, including water splitting. Herein, we report a novel strategy for the synthesis of sulfur-doped mesoporous conducting carbon nitride supported defect-rich cobalt sulfide (O-Co3S4@S-MCN). Mesoporous silica material (MCM-41) is used as a template for the synthesis, and it performs dual functions: introducing porosity and providing in situ oxygen to fill the defects. O-Co3S4@S-MCN is highly crystalline and shows characteristic diffractions indicating the formation of defect-rich Co3S4. X-ray photoelectron spectroscopy proves the presence of Co-S (777.9 eV) and Co-O (782.4 eV) bonds in O-Co3S4@S-MCN. Further, Fourier-transform infrared spectroscopy clearly indicates the presence of C.N (1620 cm(-1)) and C.S (1090 cm(-1)) bonds. This composite material, OCo3S4@S-MCN, shows a low onset potential (1.6 V for 10 mA cm(-2)), high mass activity (71 A/g at 1.7 V), high rate (Tafel slope, 52 mV/dec), and excellent stability (only 5% decrease in current density after 2 h continuous electrolysis) for the electrocatalytic oxygen evolution reaction in 1.0 M KOH.