Scalable Ir-Doped NiFe(2)O(4)/TiO(2) Heterojunction Anode for Decentralized Saline Wastewater Treatment and H(2) Production.

Wastewater electrolysis cells (WECs) for decentralized wastewater treatment/reuse coupled with H(2) production can reduce the carbon footprint associated with transportation of water, waste, and energy carrier. This study reports Ir-doped NiFe(2)O(4) (NFI, ~ 5 at% Ir) spinel layer with TiO(2) overlayer (NFI/TiO(2)), as a scalable heterojunction anode for direct electrolysis of wastewater with circumneutral pH in a single-compartment cell. In dilute (0.1 M) NaCl solutions, the NFI/TiO(2) marks superior activity and selectivity for chlorine evolution reaction, outperforming the benchmark IrO(2). Robust operation in near-neutral pH was confirmed. Electroanalyses including operando X-ray absorption spectroscopy unveiled crucial roles of TiO(2) which serves both as the primary site for Cl(-) chemisorption and a protective layer for NFI as an ohmic contact. Galvanostatic electrolysis of NH(4)(+)-laden synthetic wastewater demonstrated that NFI/TiO(2) not only achieves quasi-stoichiometric NH(4)(+)-to-N(2) conversion, but also enhances H(2) generation efficiency with minimal competing reactions such as reduction of dissolved oxygen and reactive chlorine. The scaled-up WEC with NFI/TiO(2) was demonstrated for electrolysis of toilet wastewater.