Electrocatalytic Urea Waste Valorization via Water Electrolysis: Transition‐Metal Phosphides for Sustainable Hydrogen Production

As global energy demand continues to grow along with increasing environmental challenges, the development of clean, sustainable, and eco‐friendly energy technologies has become imperative to sustain modern society. Urea‐assisted water electrolysis (UAWE) offers a sustainable hydrogen production pathway with simultaneous wastewater remediation. However, its commercialization is hindered by high cost, toxic intermediates, chemical structural complexity of catalysts, and limited long‐term stability. In recent years, transition metal phosphides (TMPs) have been identified as promising electrocatalysts for UAWE, attributed to their high conductivity, favorable catalytic activity, enhanced energy efficiency, and relatively good stability. The surface passivation, structural reconstruction during electrolysis operation, and the leaching of phosphorus at the electrode–electrolyte interface can significantly affect long‐term stability. In this review, we systematically explored diverse hybrid electrolysis with a specific focus on UAWE as the central platform for TMP electrocatalysts. The coupled HER and UOR mechanisms underlying the fundamental electrochemical principles, key synthesis and materials engineering strategies are discussed in relation to their roles in improving catalytic performance. Further, recent advances in TMPs electrocatalysts for UAWE are comprehensively reviewed with respect to catalytic activity, energy efficiency, durability, and cost‐effectiveness. Future perspectives on functional optimization, industrial scalability, and long‐term sustainability of UAWE processes are outlined.