In-situ surface self-reconstruction in ternary transition metal dichalcogenide nanorod arrays enables efficient electrocatalytic oxygen evolution

Abstract Water splitting has received more and more attention because of its huge potential to generate clean and renewable energy. The highly active and durable oxygen evolution reaction (OER) catalysts play a decisive factor in achieving efficient water splitting. The identification of authentic active origin under the service conditions can prompt a more reasonable design of catalysts together with well-confined micro-/nano-structures to boost the efficiency of water splitting. Herein, Fe, Co, and Ni ternary transition metal dichalcogenide (FCND) nanorod arrays on Ni foam are purposely designed as an active and stable low-cost OER pre-catalyst for the electrolysis of water in alkaline media. The optimized FCND catalyst demonstrated a lower overpotential than the binary and unary counterparts, and a 27-fold rise in kinetic current density at the overpotential of 300 mV compared to the nickel dichalcogenide counterpart. Raman spectra and other structural characterizations at different potentials reveal that the in-situ surface self-reconstruction from FCND to ternary transition metal oxyhydroxides (FCNOH) on catalyst surfaces initiated at about 1.5 V, which is identified as the origin of OER activity. The surface self-reconstruction towards FCNOH also enables excellent stability, without fading upon the test for 50 h.