Single-Layer Graphene Coated-Metal Nanoparticles for Water Splitting

Abstract

Graphene-coated metal nanoparticles (NPs) have attracted great attention owing to their unique structural, photochemical and electrochemical properties based on electron communication between graphene and metal NPs. The development of highly efficient and non-precious metal-based electrocatalysts for water splitting comprising hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is still a big challenge. The hybridization of nitrogen (N)-doped carbon and cost-effective transition metals is a promising approach to produce highly active catalysts for HER and OER. Herein, a highly controllable chemical vapor deposition method is designed for large-scale synthesis of nickel nanoparticle wrapped by single-layer N-doped graphene (Ni@SNG), where silica work as molecule sieve to tactfully assist single-layer graphene growth by depressing diffusion of carbon radicals. The Ni@SNG sample synthesized at 800 oC shows excellent activity for HER in alkaline solution with a low overpotential of 100 mV at 10 mA cm-2, which is close to state-of-the-art Pt/C catalyst. Furthermore, the Ni@SNG catalyst supported on nickel foil is developed as a magnetic adsorption binder-free electrode, which exhibits much improved performance on catalytic activity and stability than common Nafion binder-based electrode. Therefore, magnetism adsorption technique, taking full advantages of magnetic catalysts, will be a greatly promising approach to overcome high electron resistance and poor adhesive stability of polymer binder-based electrodes in actual applications.