Son, Aseom Cho, Hyekyung Seid Mingizem, Gashaw Han, Jiyun Moon, Byeong Cheul Lee, Jaesang BYUN, JEE HYE HONG, SEOK WON 2025-06-24T02:00:07Z 2025-06-24T02:00:07Z 2025-06-23 2025-08 0043-1354 https://pubs.kist.re.kr/handle/201004/152671 This study presents a paired photoelectrochemical (PEC) system using dual photoelectrodes designed for comprehensive total nitrogen (TN) removal by converting NO3 - into non-toxic N2 gas. Utilizing spaced TiO2 nanotube arrays (STNA) optimized for precise metallic site engineering, bimetallic Pd-Cu and RuO2 catalysts were tailored onto the STNA for the photocathode and photoanode, respectively. This configuration enabled the selective reduction of NO3 - to NH3 at the photocathode, while the NH3 was simultaneously oxidized to N2 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 h 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 that of 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. English Elsevier BV Paired photoelectrochemical system for total nitrogen removal via engineered active sites in spaced TiO2 nanotube platform Article 10.1016/j.watres.2025.123915 1 Water Research, v.282 Water Research 282 N scie scopus 001504783600001 2-s2.0-105006992804 Engineering, Environmental Environmental Sciences Water Resources Engineering Environmental Sciences & Ecology Water Resources Article NITRATE REMOVAL REDUCTION HYDROGEN ELECTROLYSIS GENERATION EVOLUTION CARBON RATE CONSTANTS Metallic site engineering Spaced TiO2 nanotube arrays Photoelectrochemical system Total nitrogen removal Dual photoelectrode