Local hydroxyl enhancement design of NiFe sulfide electrocatalyst toward efficient oxygen evolution reaction

Herein, a local OH- reactant concentration enhancement design is proposed towards efficient oxygen evolution reaction (OER) electrocatalyst. In this strategy, N-doped carbon nanotubes (NCNT), serving as conductive OH- concentration enhancement matrix, are introduced near the adjacent Fe-NiS2 catalyst to accelerate OER reaction by promoting the local mass transfer process. This OH- enhancement effect is originated from the electropositive OH- absorption sites of NCNT and local-electronic field induced by conductive three-dimensional NCNT network that synergistically works with adjacent Fe-NiS2 nanocatalyst. Accordingly, the Fe-NiS2/NCNT catalyst only requires low overpotential of 247 mV at 100 mA cm−2, outperforms most of recently reported OER catalysts. The anion-exchange membrane water electrolyzer reaches 500 mA cm−2 at 1.70 Vcell. Analysis also reveals that, this enhanced local concentration design promotes the conversion of Fe-NiS2 into S, Fe co-doped NiOOH, which is the real OER active component. This work provides an alternative strategy to develop high-efficiency OER electrocatalysts.