Fe-doped Co9S8 nanosheets on carbon fiber cloth as pH-universal freestanding electrocatalysts for efficient hydrogen evolution

Heteroatom doping is a feasible approach to adjust catalytic performance of the HER catalysts. In this work, we report a design of Fe-doped Co 9 S 8 nanosheets grown on carbon cloth (Fe-Co 9 S 8 NSs/CC) as a hydrophilic 3D monolithic electrocatalyst for efficient hydrogen evolution under all pH. The water contact angle and electrochemical measurements proved that the resultant material was hydrophilic for its nano hierarchitectures and dopant Fe enhanced the catalytic capability of singular Co 9 S 8 . In 1.0 M KOH, the Fe-Co 9 S 8 NSs/CC possessed a relatively small Tafel slope (95.3 mV dec −1 ) and required the overpotential of 83 mV to achieve 10 mA cm −2 . To drive the same current density, the overpotentials were 65 and 192 mV in 0.5 M H 2 SO 4 and 1.0 M PBS, respectively. Meanwhile, it showed good cycle stability and durability over 20 h static test at alkaline and neutral condition. The flexible freestanding catalyst has great potential in practical applications.