Composite Metal–Organic Framework-Derived NiCoP/MoS₂ Heterostructure with Superior Electrocatalytic Credentials for Urea and Methanol Oxidation

Abstract

The urea oxidation reaction (UOR) and methanol oxidation reaction (MOR) are the most practical alternative counter-reactions to the hydrogen evolution reaction in the overall electrochemical water splitting process. The thermodynamic gains in terms of lower water-splitting potentials compared to the oxygen evolution reaction (OER) can be cashed in if the kinetics of the UOR and MOR can suitably be controlled. This has called for the development of suitable cost-effective and non-precious catalysts for the processes. Herein, we report the synthesis of a heterostructured composite catalyst that incorporates the versatile NiCoP and MoS 2 components through a composite MOF degradation route for efficient UOR and MOR catalysis in an alkaline medium (0.5 M NaOH). The intimate union of the components generates the strong synergistic influence of catalytically active phosphide and sulfide components toward excellent electrocatalytic UOR and MOR performance. The cyclic voltammetry and linear sweep voltammetry analyses reveal anodic UOR and MOR peak currents of 92.5 and 214.2 mA cm −2 , respectively. Also, a benchmark current of 50 mA cm −2 is achieved at voltages of 1.55 and 1.53 V versus the reversible hydrogen electrode for the UOR and MOR, respectively, which reflects a considerable kinetic facility over the OER. The electrochemical impedance (EIS) measurements reveal considerably enhanced kinetics over the control samples and the OER on the catalyst systems. Additionally, the catalytic synergism is clearly reflected as the catalytic credentials of the composite catalysts surpass those of the individual control samples significantly. The catalytic features compare well with the best catalysts reported for the UOR and MOR in the alkaline medium.

Phosphide‐Based Electrocatalysts for Urea Electrolysis: Recent Trends and Progress

“…Hence, P atoms play a role in adsorption and desorption, improving activity. [52] With these considerations, phosphides and sulfides hetero-structures such as Ni 2 P/Ni 0.96 S, [53] CoP nanoplates with Ni 3 S 2 nanospheres, [54] Ni 3 S 2 @NiP 2 , [55] NiCoP@MoS 2 , [56] Nickel iron phosphosulfide, [57] etc. are been developed and had a contribution in performing urea electrolysis.…”

Critical Role of Interface Design in Acceleration of Overall Water Splitting and Hybrid Electrolysis Process: State of the Art and Perspectives

“…During the anodic potential sweep, the in situ converted metal oxyhydroxide, MOOH (M = Ni, Co, Mn), is the active species for the UOR. Ni based catalysts, like Ni MOF, mesoporous Ni–P, Ni 2 P, NiO, , Ni@NiO nanoparticles, alloyed Ni nanoparticles like Ni–Rh, Ni–Co, and Ni–Mn, Ni sulfide, Ni based bimetallic oxide/hydroxides such as NiMoO 4 , , NiCo 2 O 4 , Ni 0.9 Fe 0.1 O x , Cu:α-Ni­(OH) 2 , and NiMn–OH, NiCo layered double hydroxide, and Ni based heterostructures like NiCoP/MoS 2 , were employed for the UOR. Zhang et al reported NiMo nanotubes as a bifunctional catalyst (Figure A–D) to catalyze the HER and UOR in alkaline electrolyte.…”

Minireview of Coupled Electrochemical Hydrogen Production and Organic-Oxidation for Low Energy Consumption

“…Methanol is a typical alcohol, which can be electrochemically oxidized into CO 2 . Urea is a representative and simple amine, which can be oxidized to CO 2 and N 2 at the anode with H 2 forming at the cathode in a combined system. − In addition, some inorganic reactions can also be used as the institute of OER to combine with HER for energy effective H 2 production. NO is a typical harmful pollutant, which can be oxidized into nitrate in the combined systems with a potential of ∼1.07 V .…”