Well-dispersed NiCoS2 nanoparticles/rGO composite with a large specific surface area as an oxygen evolution reaction electrocatalyst

Developing efficient oxygen evolution reaction (OER) electrocatalysts such as transition metal sulfides (TMSs) is of great importance to advance renewable hydrogen fuel toward further practical applications. Herein, NiCoS 2 nanoparticles well decorated on double-sided N-doped reduced graphene oxide sheets (NiCoS 2 /rGO) are prepared from an Al-containing ternary NiCoAl-layered double hydroxide precursor (NiCoAl-LDH) grown on GO support as an OER electrocatalyst. The Al-confinement-assisted sulfurization, followed by selective acid treatment, endows the resulting NiCoS 2 /rGO composite with the advantages: well-dispersed NiCoS 2 nanoparticles, dual-sided rGO support, as well as a large specific surface area of 119.4 m 2 ·g –1 and meso-/macroporous size distribution. The NiCoS 2 /rGO electrocatalyst exhibits an overpotential of 273 mV at 10 mA·cm –2 and a good stability of 24 h, which outperform those of the counterparts of NiS 2 /rGO and CoS 2 /rGO. The results of electrochemical active surface area and electrochemical impedance spectra experimentally provide convincing rationales of the information of active sites and good conductivity, both underpin the enhanced electrocatalytic performances. Graphical abstract