Construction of noble-metal alloys of cobalt confined N-doped carbon polyhedra toward efficient water splitting

The quest for an efficient electrocatalyst for a water splitting reaction to produce hydrogen has driven researchers to develop new eco-friendly catalysts. Herein, we report a universal avenue to synthesize alloys of Co encapsulated within nitrogen-doped carbon (NC) polyhedra along with short carbon nanotubes (CNTs) derived from the metal-organic framework (MOF). The reported synthesis stands out being an environmentally benign way to synthesize such hybrids in situ since it is a one-step, hydrogen-free method and uses a single source precursor that successfully overcomes the hurdles of traditional synthesis methods. The as-synthesized MCo@NC (M = Pt, Pd, Ru) shows bifunctional catalytic activity competing with the state-of-the-art catalyst Pt/C (20 wt%) and RuO2 towards the hydrogen evolution and oxygen evolution reactions (HER and OER), respectively, in alkaline media. The best HER activity is observed for PtCo@NC (E@10 mA cm(-2) = 38 mV), whereas the best OER activity is observed for RuCo@NC (E@10 mA cm(-2) = 280 mV). A total water splitting electrolyzer set up with PtCo@NC||RuCo@NC (cathode||anode) showed an impressive 1.52 V of onset potential. A synergistic effect between the bimetallic MCo@NC moiety, Co-N-x centers, and Co nanoparticles wrapped in N-doped graphitic layers (Co@NC) is believed to be the cause for enhanced catalytic activity.