Ni Strongly Coupled with Mo2C Encapsulated in Nitrogen-Doped Carbon Nanofibers as Robust Bifunctional Catalyst for Overall Water Splitting

It is urgently required to develop highly efficient and stable bifunctional non-noble metal electrocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) for water splitting. In this study, a facile electrospinning followed by a post-carbonization treatment to synthesize nitrogen-doped carbon nanofibers (NCNFs) integrated with Ni and Mo 2 C nanoparticles (Ni/Mo 2 C-NCNFs) as water splitting electrocatalysts is developed. Owing to the strong hydrogen binding energy on Mo 2 C and high electrical conductivity of Ni, synergetic effect between Ni and Mo 2 C nanoparticles significantly promote both HER and OER activities. The optimized hybrid (Ni/Mo 2 C(1:2)-NCNFs) delivers low overpotentials of 143 mV for HER and 288 mV for OER at a current density of 10 mA cm −2 . An alkaline electrolyzer with Ni/Mo 2 C(1:2)-NCNFs as catalysts for both anode and cathode exhibits a current density of 10 mA cm −2 at a voltage of 1.64 V, which is only 0.07 V larger than the benchmark of Pt/C-RuO 2 electrodes. In addition, an outstanding long-term durability during 100 h testing without obvious degradation is achieved, which is superior to most of the noble-metal-free electrocatalysts reported to date. This work provides a simple and effective approach for the preparation of low-cost and high-performance bifunctional electrocatalysts for efficient overall water splitting.