Waste as Feedstock, Electrolyte, and Target: Closing the Loop in Electrochemical H2O2 Water Treatment

Abstract Electrochemical H2O2 production is increasingly positioned as an on-site route for water oxidation, disinfection, and resource recovery. However, its environmental translation remains constrained by a basic design mismatch between catalyst development in clean electrolytes and deployment in chemically variable waste streams. This Perspective argues that progress should move beyond catalyst-centered performance metrics toward a closed-loop, waste-centered framework. The key issue is not how to isolate H2O2 electrosynthesis from wastewater complexity but when and how that complexity can be engineered. Solid and liquid waste streams can provide carbon, heteroatoms, and metals for impurity-resilient electrodes. Meanwhile, wastewater constituents can regulate interfacial ion distribution, water structure, oxygen transport, proton availability, intermediate stabilization, and side reactions. Electrogenerated H2O2 can be routed to contaminant transformation, disinfection, detoxification, and metal recovery. We discuss design principles for converting heterogeneous waste feedstocks into catalytic interfaces, defining wastewater operating windows, matching reactor architectures with real water matrices, and evaluating circularity through life-cycle and techno-economic accounting. We identify critical benchmarks─matrix descriptors, durability mechanisms, byproduct control, reactor-treatment matching, and transparent environmental safeguards─needed to turn circular H2O2 concepts into verifiable water-treatment technologies.