Exceptionally Active and Stable Spinel Nickel Manganese Oxide Electrocatalysts for Urea Oxidation Reaction

Abstract

Spinel nickel manganese oxides, widely used materials in the lithium ion battery high voltage cathode, were studied in urea oxidation catalysis. NiMn2O4, Ni1.5Mn1.5O4, and MnNi2O4 were synthesized by a simple template-free hydrothermal route followed by a thermal treatment in air at 800 °C. Rietveld analysis performed on nonstoichiometric nickel manganese oxide-Ni1.5Mn1.5O4 revealed the presence of three mixed phases: two spinel phases with different lattice parameters and NiO unlike the other two spinels NiMn2O4 and MnNi2O4. The electroactivity of nickel manganese oxide materials toward the oxidation of urea in alkaline solution is evaluated using cyclic voltammetric measurements. Ni1.5Mn1.5O4 exhibits excellent redox characteristics and lower charge transfer resistances in comparison with other compositions of nickel manganese oxides and nickel oxide prepared under similar conditions.The Ni1.5Mn1.5O4modified electrode oxidizes urea at 0.29 V versus Ag/AgCl with a corresponding current density of 6.9 mA cm(-2). At a low catalyst loading of 50 μg cm(-2), the urea oxidation current density of Ni1.5Mn1.5O4 in alkaline solution is 7 times higher than that of nickel oxide and 4 times higher than that of NiMn2O4 and MnNi2O4, respectively.

Electrochemical Oxidation of Glycine with Bimetallic Nickel−Manganese Oxide Catalysts

“…In brief, the bimetallic spinel oxides such as NiMn 2 O 4 , Ni 1.5 Mn 1.5 O 4, and MnNi 2 O 4 were prepared using three different Ni and Mn molar ratio . Generally different metal precursors were used with various Ni : Mn molar ratios as, Ni 2+ (0.05 M): Mn 2+ (0.1 M), Ni 2+ (0.075 M): Mn 2+ (0.075 M), Ni 2+ (0.1 M): Mn 2+ (0.05 M) to obtain various Ni−Mn oxides viz., NiMn 2 O 4 , Ni 1.5 Mn 1.5 O 4 and MnNi 2 O 4 .…”

“…We propose a bimetallic transition metal oxides catalyst containing non‐precious Ni and Mn oxide through a one‐step template‐free hydrothermal route for making viz ., NiMn 2 O 4, MnNi 2 O 4, and non‐stoichiometric oxides Ni 1.5 Mn 1.5 O 4 . The as‐produced nickel‐manganese oxides reduce the activation energy for the formation of nickel oxyhydroxide and show lower onset potential for urea oxidation reactions . The effect of multivalent manganese oxide on nickel promotes the oxidation.…”

An Insight on the Electrocatalytic Mechanistic Study of Pristine Ni MOF (BTC) in Alkaline Medium for Enhanced OER and UOR

“…[22] Splitting of hydrogen (H 2 ) from urea through urea electrolysis (UE) is closer to WE as urea oxidation reaction (UOR) occurs at 0.37 V vs. RHE (below 1.23 V vs. RHE), which lead to considerable interest in the energy sector for the production of H 2 . [22][23][24][25][28][29][30][31] The newer design and development of efficient UOR catalyst is warranted from the existing catalysts and it may open up newer directions in the future. [22][23][24][25]28] Similar to OER in WE, Ni based catalysts such as nano sized nickel, LaNiO 3 , NiÀFe double hydroxide, Ni 2 P, Ni(OH) 2 , Ni nanoparticles decorated NiFe double hydroxide, Ni x Mn y O 4 show catalytic activity towards UOR.…”

Hollow Sodium Nickel Fluoride Nanocubes Deposited MWCNT as An Efficient Electrocatalyst for Urea Oxidation

“…Also storage of the fuel materials and safety are another concerns for this type of fuel cell. Direct urea/air fuel cell is free from these types of issues and still has the potential to achieve the optimum performance until and unless the search for a better catalyst for urea oxidation and other materials like cathodes and AEMs is exhausted [36][37][38].…”