Active Sites Intercalated Ultrathin Carbon Sheath on Nanowire Arrays as Integrated Core-Shell Architecture: Highly Efficient and Durable Electrocatalysts for Overall Water Splitting.

The development of active bifunctional electrocatalysts with low cost and earth-abundance toward oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) remains a great challenge for overall water splitting. Herein, metallic Ni4 Mo nanoalloys are firstly implanted on the surface of NiMoOx nanowires array (NiMo/NiMoOx ) as metal/metal oxides hybrid. Inspired by the superiority of carbon conductivity, an ultrathin nitrogen-doped carbon sheath intercalated NiMo/NiMoOx (NC/NiMo/NiMoOx ) nanowires as integrated core-shell architecture are constructed. The integrated NC/NiMo/NiMoOx array exhibits an overpotential of 29 mV at 10 mA cm-2 and a low Tafel slope of 46 mV dec-1 for HER due to the abundant active sites, fast electron transport, low charge-transfer resistance, unique architectural structure and synergistic effect of carbon sheath, nanoalloys, and oxides. Moreover, as OER catalysts, the NC/NiMo/NiMoOx hybrids require an overpotential of 284 mV at 10 mA cm-2 . More importantly, the NC/NiMo/NiMoOx array as a highly active and stable electrocatalyst approaches ≈10 mA cm-2 at a voltage of 1.57 V, opening an avenue to the rational design and fabrication of the promising electrode materials with architecture structures toward the electrochemical energy storage and conversion.