In Situ Construction of a Mn²⁺-Doped Ni₃S₂ Electrode with Highly Enhanced Urea Oxidation Reaction Performance

Abstract

Urea, as a prospective energy source, is rarely utilized for lack of effective catalysts to overcome its sluggish kinetics during its electrolysis. Exploiting low-cost and high-efficiency catalysts to accelerate the urea oxidation reaction (UOR) does make sense as it can relieve not only energy shortage but also the water contamination problems. In this work, the Ni3S2 nanosheets grown on the Ni foam with different amounts of Mn2+ doping were developed as useful electrocatalysts toward UOR. The experimental and computational methods were performed to explore the properties of obtained samples. We found that the doping of Mn2+ could distinctly regulate the charge distribution of Ni3S2 by which the performance was observably optimized. We also compared the behaviors of obtained catalysts with various dopant concentrations of Mn2+. Especially, Ni3S2 grown on the Ni foam with the addition of 0.2 mmol of Mn2+ exhibits splendid properties with a lower potential and superior longevity, which can achieve a current density of 100 mA cm–2 at a voltage of only 1.397 V (vs reversible hydrogen electrode) in 1.0 M KOH containing 0.5 M urea solution, indicating that our findings can serve as promising electrocatalysts for urea electrolysis.

Strategies for designing more efficient electrocatalysts towards the urea oxidation reaction

“…Therefore, compared to acidic or neutral UOR, alkaline UOR is more promising. For alkaline UOR, owing to the intrinsic higher activities, Ni-based catalysts (Ni-containing metals, 80–84 oxides, 85–90 hydroxides, 91–97 sulfides, 98–102 phosphides, 103–105 selenides, 106–108 nitrides, 109–113 etc. ) have been more widely investigated among all transition metal-based catalysts.…”

A Wet Impregnation Strategy for Advanced FeNi‐Based Electrocatalysts towards Oxygen Evolution

“…The Ni 2p 3/2 and Ni 2p 1/2 bands of the catalyst are at 856.3 and 874.1 eV, respectively (Figure 3c). The corresponding satellite peaks are located at 861.9 and 880.6 eV [41–43] . Similar to that of iron, after OER, the bands present obvious red‐shifts.…”

“…The corresponding satellite peaks are located at 861.9 and 880.6 eV. [41][42][43] Similar to that of iron, after OER, the bands present obvious red-shifts. Figure 3d presents the oxygen XPS band for the catalyst Fe 3 + /Ni 2 + À PC-1 : 2 before and after OER.…”

Nickel Selenide Quantum Dot Applications in Electrocatalysis and Sensors

“…Urea is regarded as a potential energy source because it possesses the following: high energy density, high hydrogen content, abundant reserves, highly stable, easily stored and transported [108, 109]. Interestingly, urea is considered as an advanced hydrogen carrier because it utilizes a lower cell potential (0.37 V) than the water‐splitting reaction (1.23 V) [108, 110]. The electrooxidation reaction of urea is shown in Equation 5 and 6 [111]: …”