Self-Supported Mn-Ni 3 Se 2 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 (H 2 ) generation. Herein, we demonstrate the facile hydrothermal synthesis of self-supported Mn-Ni 3 Se 2 on Ni foam for overall water splitting under wide pH conditions. With the optimized concentration of Mn in Ni 3 Se 2 , 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 Ni 3 Se 2 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/cm 2 . Finally, the prepared nanostructured Mn-Ni 3 Se 2 @NF acts as an electrocatalyst for overall water splitting under wide pH conditions and urea electrolysis for energy-saving hydrogen production and wastewater treatment.