Bimetallic Ni–Fe nanoparticles encapsulated with biomass-derived N-doped graphitic carbon core-shell nanostructures an efficient bifunctional electrocatalyst for enhanced overall seawater splitting and human urine electrolysis

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Producing green hydrogen from abundant natural resources such as seawater and human urine is a viable solution for energy and industrial applications. However, the field of electrocatalysis faces challenges in developing cost-effective metal catalysts for efficient electrolysis of seawater and urea sewage. Here, we reported bimetallic NiFe nanoparticles encapsulated in a biomass derived N-doped graphitic carbon core shell structure (NiFe@BNGC-700) as a stable and effective catalyst for seawater and human urine electrolysis. NiFe@BNGC-700 exhibits remarkable electrocatalytic performance, with a low overpotential requiring 300 mV for OER and 297 mV for HER in alkaline 1.0 M KOH + seawater and 1.36 V for UOR in alkaline 1.0 M KOH + human urine at 50 mA cm−2 current density, respectively. The active bifunctional NiFe@BNGC-700 electrocatalyst symmetry pair facilitates the construction of a seawater electrolyser, achieving a cell voltage of 1.74 V at 50 mA cm−2 current density. Furthermore, the human urine-mediated electrolyser employing NiFe@BNGC-700//NiFe@BNGC-700 achieves a cell voltage of 1.64 V at the same current density, maintaining stability over 12 h with negligible potential deviation. Continual evolution of hydrogen and oxygen is feasible in a solar seawater a cell assembled with NiFe@BNGC-700 electrocatalyst, delivering at cell voltage of 1.74 V, enabling sustained and effective green hydrogen delivery on a large scale. This study proposes a sustainable strategy for fabricating electrodes consisting of non-precious metals, thereby permitting the economical and extensive generation of green hydrogen on a large scale.