Single-atom Electrocatalysts for Urea and Furfural-assisted Water Electrolysis

This chapter explores the emerging role of single-atom catalysts (SACs) in hybrid water electrolysis, where the hydrogen evolution reaction (HER) at the cathode is coupled with an anodic conversion of low-value feedstocks. By replacing the energy-intensive oxygen evolution reaction (OER) with the electrooxidation of urea or furfural, hybrid electrolysis enables simultaneous green hydrogen generation and chemical valorization, enhancing both energy efficiency and sustainability. Urea, abundant in wastewater, and furfural, a biomass-derived platform molecule, can be selectively transformed into value-added products such as furoic, maleic, and succinic acids while reducing environmental burdens. While SACs already show strong potential in urea oxidation, their application in furfural oxidation is still in its early stages, offering fertile ground for innovation. Leveraging strategic support materials, such as functionalized carbon, metal oxides, or metal–organic framework (MOF)-derived frameworks, SACs provide high atomic efficiency, tunable coordination environments, and robust metal–support interactions (MSIs) that stabilize active sites and direct reaction pathways under harsh electrochemical conditions. Beyond catalyst design, progress in decentralized electrolyzer development, even at small scales, is crucial to enable modular, in-situ integration with production plants where residual urea or furfural streams are generated. This chapter highlights design strategies, mechanistic insights, and emerging challenges, positioning SAC-based hybrid electrolysis as a promising route toward circular-economy solutions.