Precious-Group-Metal-Free Energy-Efficient Urea Electrolysis: Membrane Electrode Assembly Cell Using Ni₃N Nanoparticles as Catalyst

Abstract

The sluggish kinetics of the anodic oxygen evolution reaction (OER) limit the overall efficiency of green hydrogen production. The proposed strategy to overcome this is to replace OER with other kinetically favorable anodic reactions like urea oxidation reaction (UOR). Herein, we develop an organometallic synthesis of nickel nitride nanoparticles supported on carbon (Ni3N–C) as the catalyst for both UOR and hydrogen evolution reaction (HER). A precious group metal-free electrolyzer based on Ni3N–C catalyst (as both anode and cathode) is implemented for the first time, and the urea electrolyzer cell has a 200 mV lower overpotential compared to that of the water electrolyzer.

Ultralow Pt Catalyst Loading Prepared by the Electroreduction of a Supramolecular Assembly for the Hydrogen Evolution Reaction

“…5,6 Except for the state-of-the-art noble metal-based catalysts, a lot of novel materials have been reported as efficient HER electrocatalysts in the last few years. 7,8 For example, MoS 2 has been considered an excellent noble metal-free alternative for HER, which has been intensively studied in the last decade. Recently, carbides, phosphides, metal oxides, and carbon materials have been widely studied as pH-universal HER catalysts.…”

Cu-Doping Effect on the Electrocatalytic Properties of Self-Supported Cu-Doped Ni3S2 Nanosheets for Hydrogen Production via Efficient Urea Oxidation

“…Therefore, tremendous attempts have been devoted to exploring earth-abundant alternatives with ample electrocatalytic active sites and superb stability for urea electrolysis, such as transition-metal sulfides, selenides, phosphides, and oxides and their composites. Among them, nickel-based electrocatalysts have received increasing attention, such as Ni­(OH) 2 , , NiMoO 4 , NiTe 2 , Co x Mo y S, Ni 3 Se 4 , Ni-MOF, Ni-Mn LDH, nickel nitrides, and nickel sulfides. , …”

“…6 Therefore, tremendous attempts have been devoted to exploring earth-abundant alternatives with ample electrocatalytic active sites and superb stability for urea electrolysis, such as transition-metal sulfides, 7 phosphides, 9 and oxides 10 and their composites. Among them, nickel-based electrocatalysts have received increasing attention, such as Ni(OH) 2 , 11,12 NiMoO 4 , 13 NiTe 2 , 14 Co x Mo y S, 15 Ni 3 Se 4 , 8 Ni-MOF, 16 Ni-Mn LDH, 17 nickel nitrides, 18 and nickel sulfides. 7,19 Nickel sulfides, such as NiS and Ni 3 S 2 , have attracted considerable interest as UOR catalysts owing to their low cost, facile preparation, excellent conductivity, and unique structural configurations.…”

Hexagonal NiMoO4-MoS2 nanosheet heterostructure as a bifunctional electrocatalyst for urea oxidation assisted overall water electrolysis

“…For a slow OER, overpotential is required to overcome the high activation energy potential, and urea can accelerate the reaction of OER during electrolysis. 3,4 Compared to different substances, urea has the advantages of less toxicity, low cost and convenient transportation and is considered an ideal candidate for the anode reaction. The combination of UOR and HER can also be referred to as integral water electrolysis, to highlight the role of urea in the promotion, as overall water and urea electrolysis.…”