Current progress in layered double hydroxide-based electrocatalysts for urea oxidation: insights into strategies and mechanisms

The urea oxidation reaction (UOR) presents a more favorable alternative to the conventional oxygen evolution reaction (OER) for hydrogen production due to its lower thermodynamic potential. This method offers advantages over traditional hydrogen production approaches due to favorable operating conditions and potentially lower costs. However, the complex 6-electron transfer process in UOR limits its performance. Researchers are tackling this challenge by designing advanced electrocatalysts with optimized properties, such as porosity, heterostructures, controlled defects, surface functionalization, and fine-tuned electronic structures. This significant progress in UOR catalyst design holds promise for the future of clean energy technologies. In view of this, layered double hydroxides (LDHs) are attracting significant interest for their potential role in urea electrolysis due to the synergistic cooperation of metals, flexible configuration, tunable electronic composition and unique layered structure. This review examines the recent significant advancements in the design and synthesis of LDH-based UOR catalysts. Beyond highlighting recent breakthroughs in UOR catalysts, this review critically stresses the design strategies and challenges in urea electrolysis towards energy conversion. Moreover, this comprehensive approach provides a valuable forward-looking perspective on future research directions.