Carbon-encapsulated NiFe nanoparticles as a bifunctional electrocatalyst for high-efficiency overall water splitting

The use of non-noble metal-based electrocatalysts to achieve highly efficient and cost-effective water splitting has encountered major challenges, particularly with respect to catalytic activity, stability, cost, and ease of manufacture. Herein, few carbon-layers-encapsulated NiFe nanoparticles (NiFe@C) were prepared as a simple and effective facile top-down approach when used with the electrical explosion of wire process as a bifunctional electrocatalyst to achieve higher overall water splitting efficiency. Uniformly surrounding the unique structure of NiFe nanoparticles (∼15 nm in diameter) by a small number of carbon layers can be accomplished via one-pot synthesis by exploding NiFe wires in an ethanol media. The simply prepared NiFe@C catalyst exhibits remarkable catalytic activity and stability in alkaline solution for both OER (oxygen evolution reaction) and HER (hydrogen evolution reaction). When bifunctional electrocatalysts are utilized as electrodes for both cathode and anode reactions in a single electrolyzer, outstanding catalytic performance was achieved with an operational voltage of 1.575 V at a current density of 10 mA cm⁻². Most importantly, the electrodes displayed superior catalytic stability in the overall water splitting reaction for 200 h. Consequently, this work proposes and evaluates this effective new strategy for the synthesis of low-cost, highly efficient and stable bifunctional electrocatalysts.