Abstract
Wastewater electrolysis cells(WECs)for decentralized wastewater treatment/reuse coupled with H2 production can reduce the carbon footprint associated with transportation of water,waste,and energy carrier.This study reports Ir-doped NiFe2O4(NFI,～5 at％Ir)spinel layer with TiO2 overlayer(NFI/TiO2),as a scalable heterojunction anode for direct electrolysis of wastewater with circum-neutral pH in a single-compartment cell.In dilute(0.1 M)NaCl solutions,the NFI/TiO2 marks superior activity and selectivity for chlorine evolution reaction,outperforming the benchmark IrO2.Robust operation in near-neutral pH was confirmed.Electroanalyses including operando X-ray absorption spectroscopy unveiled crucial roles of TiO2 which serves both as the primary site for Cl-chemisorption and a protective layer for NFI as an ohmic contact.Galvanostatic electrolysis of NH4+-laden synthetic wastewater demonstrated that NFI/TiO2 not only achieves quasi-stoichiometric NH4+-to-N2 conversion,but also enhances H2 generation efficiency with minimal competing reactions such as reduction of dissolved oxygen and reactive chlorine.The scaled-up WEC with NFI/TiO2 was demonstrated for electrolysis of toilet wastewater.
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