Self-Supported Mn-Ni₃Se₂ Electrocatalysts for Water and Urea Electrolysis for Energy-Saving Hydrogen Production

Recently, there has been a huge research interest in developing robust, efficient, low-cost, and earth-abundant materials for water and urea electrolysis for hydrogen (H2) generation. Herein, we demonstrate the facile hydrothermal synthesis of self-supported Mn-Ni3Se2 on Ni foam for overall water splitting under wide pH conditions. With the optimized concentration of Mn in Ni3Se2, the overpotential for hydrogen evolution, oxygen evolution, and urea oxidation is significantly reduced by an enhanced electrochemical active surface area. Different electronic states of metal elements also produce a synergistic effect, which accelerates the rate of electrochemical reaction for water and urea electrolysis. Owing to the chemical robustness, Mn-doped Ni3Se2 shows excellent stability for long time duration, which is important for its practical applications. A two-electrode electrolyzer exhibits low cell voltages of 2.02 and 1.77 V for water and urea electrolysis, respectively, to generate a current density of 100 mA/cm2. Finally, the prepared nanostructured Mn-Ni3Se2@NF acts as an electrocatalyst for overall water splitting under wide pH conditions and urea electrolysis for energy-saving hydrogen production and wastewater treatment