Understanding the bifunctional catalytic ability of electrocatalysts for oxygen evolution reaction and urea oxidation Reaction: Recent advances and perspectives

Significant progress has been made in the discovery of bifunctional electrocatalysts for energy storage and conversion systems. Particularly, high-performance bifunctional catalysts for oxygen evolution reaction (OER) and urea oxidation reaction (UOR) provide a distinct avenue for simultaneously achieving the energy-saving hydrogen production and urea-containing wastewater degradation. Over the past decade, various materials engineering strategies have been developed to improve catalytic performance in terms of activity and stability. However, the mechanisms of reported bifunctional catalysts vary depending on the types of materials. This review provides a comprehensive overview of the latest development of bifunctional electrocatalysts toward the OER/UOR, including candidates like oxides, (oxy)hydroxides, sulfides, selenides, phosphides, and metal–organic frameworks. A special focus is given on the in-depth understanding of the related reaction mechanisms to further enhance the bifunctional performance. Perspectives on future research directions are also discussed, including exploring new materials, avoiding the competition between the OER and UOR, tuning the selectivity, and enabling larger-scale applications of bifunctional OER/UOR electrocatalysts. We expect that this review can provide guidelines for the development of bifunctional OER/UOR electrocatalysts to achieve a sustainable energy and environmental future.