Work

Paired photoelectrochemical system for total nitrogen removal via engineered active sites in spaced TiO2 nanotube platform

Year: 2025

Type: article

Abstract: This study presents a paired photoelectrochemical (PEC) system using dual photoelectrodes designed for comprehensive total nitrogen (TN) removal by converting NO 3 ⁻ into non-toxic N 2 gas. Utilizing spaced TiO 2 nanotube arrays (STNA) optimized for precise metallic site engineering, bimetallic Pd-Cu and RuO 2 catalysts were tailored onto the STNA for the photocathode and photoanode, respectively. This configuration enabled the selective reduction of NO 3 ⁻ to NH 3 at the photocathode, while the NH 3 was simultaneously oxidized to N 2 via reactive chlorine species (RCS) generated under light illumination. The paired PEC system achieved a TN removal efficiency of over 99.2% over eight cycles, totaling 32 hours of continuous operation without metal leaching and by-products formation. Even in complex real wastewater matrices, the paired photoelectrode system maintained a TN removal efficiency of 96.3%, demonstrating consistent performance in practical applications. Furthermore, the system exhibited a specific electric energy consumption (SEEC) approximately 7 times lower than conventional electrochemical (EC) systems, indicating improvements in cost-effectiveness and energy efficiency. This study establishes a foundation for advancing PEC systems in nitrogen removal and provides insights into the application of tailored metallic site engineering on photoelectrodes for environmental applications.

Source: Water Research

DOI: 10.1016/j.watres.2025.123915