Promoting Active Sites in Core-Shell Nanowire Array as Mott-Schottky Electrocatalysts for Efficient and Stable Overall Water Splitting (vol 28, 1704447, 2018)

Developing earth-abundant, active, and robust electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) remains a vital challenge for efficient conversion of sustainable energy sources. Herein, metal-semiconductor hybrids are reported with metallic nanoalloys on various defective oxide nanowire arrays (Cu/CuOx, Co/CoOx, and CuCo/CuCoOx) as typical Mott-Schottky electrocatalysts. To build the highway of continuous electron transport between metals and semiconductors, nitrogen-doped carbon (NC) has been implanted on metal-semiconductor nanowire array as core-shell conductive architecture. As expected, NC/CuCo/CuCoOx nanowires arrays, as integrated Mott-Schottky electrocatalysts, present an overpotential of 112 mV at 10 mA cm(-2) and a low Tafel slope of 55 mV dec(-1) for HER, simultaneously delivering an overpotential of 190 mV at 10 mA cm(-2) for OER. Most importantly, NC/CuCo/CuCoOx architectures, as both the anode and the cathode for overall water splitting, exhibit a current density of 10 mA cm(-2) at a cell voltage of 1.53 V with excellent stability due to high conductivity, large active surface area, abundant active sites, and the continuous electron transport from prominent synergetic effect among metal, semiconductor, and nitrogen-doped carbon. This work represents an avenue to design and develop efficient and stable Mott-Schottky bifunctional electrocatalysts for promising energy conversion.