Constructing a Rod-like CoFeP@Ru Heterostructure with Additive Active Sites for Water Splitting

Graphical Decorating nanorods : We demonstrate the first metal-phosphides-metal system consisting of Ru and FeCoP, which forms unique CoFeP@Ru nanorod using a simple one-pot synthetic method. Due to its optimal dual cation decorating effects, improved conductivity and rod-like morphology, this catalyst shows superior electro-catalytic HER and OER performances, which are superior to those of some recently reported phosphides and close to that of commercial catalysts. Interfacial engineering and defect modulation can provide abundant active sites for catalysts to further boost the catalysis process. In this work, we develop a strategy to grow multi-heterogeneous cobalt phosphide (CoP) nanorods with rich interfaces and defects along the one-dimensional (1D) nanostructure by dual incorporation of Fe and Ru (CoFeP@Ru). Such a catalyst exhibits high activity and stability towards the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), with overpotentials of only 38 mV in 0.5 M H 2 SO 4 and 48 mV in 1.0 M KOH for HER, and an overpotential of 340 mV in 0.1 M KOH for OER at 10 mA cm −2 . Finally, as the bifunctional catalyst, an alkali electrolyzer is assembled and delivers at a low cell voltage, with almost 100 % Faradaic efficiency. Our experimental results demonstrate that Fe incorporation can disturb or even break the periodic structure of cobalt phosphides, causing a redistribution of the electronic structure and electron density of activity sites, while Ru can significantly enhance the catalytic kinetics, as well as electrochemical and mechanical stability.