Why Do Amorphous-Crystalline Heterostructures Excel in Urea Oxidation Reaction Over Single Phases?

Abstract

Interface engineering of amorphous-crystalline (A-C) heterostructures represents a powerful strategy to boost electrocatalytic performance in the urea oxidation reaction (UOR), a process enabling simultaneous wastewater remediation and hydrogen (H2) production. While amorphous phases provide abundant unsaturated coordination sites, defects, and electronic flexibility for enhanced adsorption and activation of urea intermediates, crystalline phases ensure superior charge transport and structural stability. However, A-C heterostructures uniquely outperform either single phase by harnessing interfacial synergies, including modulated electronic structures, accelerated electron transfer across phase boundaries, and stabilized active sites that mitigate reconstruction during UOR. Despite progress in synthesizing such catalysts, the precise interfacial mechanisms and structure-activity relationships remain poorly understood. As well, a comprehensive review that specifically addresses why A-C heterostructures are demonstrably superior to their single-phase counterparts in boosting UOR kinetics remains scarce. In light of this gap, this review offers an in-depth and systematic overview of cutting-edge design strategies for A-C heterostructures, with a specific focus on their application in UOR. We begin by introducing the fundamental characteristics of A-C heterostructures to provide a scientific foundation for understanding their unique structural properties. Subsequently, we elaborate on the superior performance and current achievements of these heterostructures as highly efficient UOR catalysts. We also critically discuss the challenges and unresolved issues, particularly the need for more in-depth mechanistic studies to fully reveal the role of these unique heterointerfaces in facilitating key reaction steps. The core of this review critically discusses the fundamental perspective -specifically, how the synergistic duo, electronic modulation, and structural integrity at the A-C boundary accelerate the rate-determining step (RDS) of the UOR. Finally, we propose future research directions and opportunities for the rational design and development of next-generation A-C catalysts for clean energy applications.