Ni-Doped MnO₂ Nanosheet Arrays for Efficient Urea Oxidation

Abstract

Urea oxidation reaction (UOR), with a low thermodynamic potential, offers great promise for replacing anodic oxygen evolution reaction of electrolysis systems such as water splitting, carbon dioxide reduction, etc., thus reducing the overall energy consumption. To promote the sluggish kinetics of UOR, highly efficient electrocatalysts are required, and Ni-based materials have been widely investigated. However, most of these reported Ni-based catalysts suffer from large overpotentials, as they generally undergo self-oxidation to form NiOOH species at high potentials, which act as catalytically active sites for UOR. Herein, Ni-doped MnO 2 (Ni-MnO 2 ) nanosheet arrays were successfully prepared on nickel foam. The as-fabricated Ni-MnO 2 shows distinct UOR behavior with most of the previously reported Nibased catalysts, as urea oxidation on Ni-MnO 2 proceeds before the formation of NiOOH. Notably, a low potential of 1.388 V vs reversible hydrogen electrode was required to achieve a high current density of 100 mA cm −2 on Ni-MnO 2 . It is suggested that both Ni doping and nanosheet array configuration are responsible for the high UOR activities on Ni-MnO 2 . The introduction of Ni modifies the electronic structure of Mn atoms, and more Mn 3+ species are generated in Ni-MnO 2 , contributing to its outstanding UOR performance.

Superhydrophilic Dendritic FeP/Cu3P Electrocatalyst for Urea Splitting via the Intramolecular Mechanism

“…Electrochemical treatment of urea-containing wastewater is an effective and feasible technology with the advantages of simple design, high efficiency, and easy operation. 11,12 The whole electrocatalytic process consists of a cathodic hydrogen evolution reaction (HER, eq 1) and an anodic urea oxidation reaction (UOR, eq 2). 13 The overall urea decomposition voltage is only 0.37 V, obviously lower than that of water splitting (1.23 V).…”

Electrocatalysts for the oxygen evolution reaction: mechanism, innovative strategies, and beyond

“…[1][2][3][4][5] A common feature of all these systems is that the cathode region undergoes a reduction reaction while the anode region experiences an oxygen evolution reaction (OER). [6][7][8][9][10] However, the sluggish and multi-step proton-coupled electron transfer process of the OER plays a decisive role, especially in electrocatalytic water-splitting systems. [11][12][13][14][15][16] Water splitting is considered a straightforward, environmentally friendly, and cost-effective approach to hydrogen production instead of hydrocarbon reforming or cracking.…”

“…1–5 A common feature of all these systems is that the cathode region undergoes a reduction reaction while the anode region experiences an oxygen evolution reaction (OER). 6–10…”

Controlled synthesis of M doped NiVS (M = Co, Ce and Cr) as a robust electrocatalyst for urea electrolysis

“…[16][17][18][19] So finding an efficient and stable non-precious metal catalyst is now a more valuable challenge. [20][21][22] Recently, non-precious metal catalysts have received attention mainly focused on sulfides, 23 phosphides, 24,25 oxides/hydroxides, 19 nitrides, 26 etc. What is noteworthy is that sulfides have the advantages of low price and high electrocatalytic efficiency.…”