Transition Metal‐Based Catalysts for Urea Oxidation Reaction (UOR): Catalyst Design Strategies, Applications, and Future Perspectives

Abstract

Urea oxidation reaction (UOR) has garnered significant attention in recent years as a promising and sustainable clean‐energy technology. Urea‐containing wastewater poses severe threats to the environment and human health. Numerous studies hence focus on developing UOR as a viable process for simultaneously remediating wastewater and converting it into energy. Moreover, UOR, which has a thermodynamic potential of 0.37 V (vs reversible hydrogen electrode, RHE), shows great promise in replacing the energy‐intensive oxygen evolution reaction (OER; 1.23 V vs RHE). The versatility and stability of urea, particularly at ambient temperatures, make it an attractive alternative to hydrogen in fuel cells. Since UOR entails a complex intermediate adsorption/desorption process, many studies are devoted to designing cost‐effective and efficient catalysts. Notably, transition metal‐based materials with regulated d orbitals have demonstrated significant potential for the UOR process. However, comprehensive reviews focusing on transition metal‐based catalysts remain scarce. In light of this, the review aims to bridge the gap by offering an in‐depth and systematic overview of cutting‐edge design strategies for transition metal‐based catalysts and their diverse applications in UOR. Additionally, the review delves into the status quo and future directions, charting the course for further advancements in this exciting field.

Interface Enables Faster Surface Reconstruction in a Heterostructured CuSey/NiSex Electrocatalyst for Realizing Urea Oxidation

“…This current density is higher than that obtained in solutions containing 1 M KOH + 0.1 M urea (68 mA cm –2 ), 1 M KOH + 0.2 M urea (101 mA cm –2 ), and 1 M KOH + 0.5 M urea (66 mA cm –2 ). This phenomenon arises from the dependency of UOR catalysis on diffusion control at lower urea concentrations . When the concentration of urea is higher than a certain value, it may be a kinetically controlled process .…”

“…Substituting the thermodynamically unfavorable OER with UOR presents a promising approach to enhance the energy conversion efficiency of electrochemical devices. , Furthermore, UOR has been extensively utilized in treating urea-rich wastewater while also recovering energy. , However, urea electrolysis faces challenges due to slow kinetics caused by the 6 e – transfer process (CO­(NH 2 ) 2 + 6OH – – 6e – → CO 2 + N 2 + 5H 2 O), complex intermediate species, and numerous gas-desorption steps, which significantly limit its practical application . There is a pressing need for highly active UOR catalysts to enhance the exchange of intermediate species and accelerate the reaction.…”

“…Jin et al recently constructed a heterostructures catalyst of Ni-TPA@NiSe/NF, demonstrating outstanding electrocatalytic performance and offering insights into the mechanism and pathway of UOR. Therefore, the modulation of electronic structures stands as a pertinent approach to improve the electrocatalytic efficiency of transition-metal-based UOR electrocatalysts. , …”

Recent progress in transition metal based catalysts and mechanism analysis for alcohol electrooxidation reactions

“…This potential arises from their well-regulated d orbitals and abundant presence on Earth. 20 The review specifically summarizes the electrooxidation processes of monohydric alcohols and polyols in the context of AOR. Additionally, characteristic comparisons between representative AOR and OER are provided in Table 1.…”

Amorphous conversion in pyrolytic symmetric trinuclear nickel clusters trigger trifunctional electrocatalysts

“…In the era of next-generation energy, water splitting for hydrogen production and fuel cell applications has garnered a lot of attention. 1 Overall water splitting requires the oxygen evolution reaction (OER), 2 while fuel cells necessitate the urea oxidation reaction (UOR) 3 and methanol oxidation reaction (MOR). 4 Multifunctional electrocatalysts are materials that can efficiently catalyze multiple electrochemical reactions, such as OER, UOR and MOR.…”