Highly surface electron-deficient Co9S8 nanoarrays for enhanced oxygen evolution
Haoxuan Zhang, Jingyu Wang, Qilin Cheng, Petr Sáha, Hao Jiang
Abstract
Tailoring valence electron delocalization of transition metal center is of importance to achieve highly-active electrocatalysts for oxygen evolution reaction (OER). Herein, we demonstrate a “poor sulfur” route to synthesize surface electron-deficient Co9S8 nanoarrays, where the binding energy (BE) of Co metal center is considerably higher than all reported Co9S8-based electrocatalysts. The resulting Co9S8 electrocatalysts only require the overpotentials (η) of 265 and 326 mV at 10 and 100 mA cm−2 with a low Tafel slope of 56 mV dec−1 and a 60 h-lasting stability in alkaline media. The OER kinetics are greatly expedited with a low reaction activation energy of 27.9 kJ mol−1 as well as abundant OOH∗ key intermediates (24%), thus exhibiting excellent catalytic performances. The surface electron-deficient engineering gives an available strategy to improve the catalytic activity of other advanced non-noble electrocatalysts.