Efficient electrocatalytic nitrate reduction via boosting oxygen vacancies of TiO2 nanotube array by highly dispersed trace Cu doping

Qinan Song; Shuo Zhang; Xiaoshu Hou; Jiacheng Li; Lei Yang; Xiang Liu; Miao Li

doi:10.1016/j.jhazmat.2022.129455

Efficient electrocatalytic nitrate reduction via boosting oxygen vacancies of TiO₂ nanotube array by highly dispersed trace Cu doping

J Hazard Mater. 2022 Sep 15:438:129455. doi: 10.1016/j.jhazmat.2022.129455. Epub 2022 Jun 25.

Authors

Qinan Song¹, Shuo Zhang¹, Xiaoshu Hou², Jiacheng Li¹, Lei Yang¹, Xiang Liu¹, Miao Li³

Affiliations

¹ State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, PR China.
² Chinese Academy for Environmental Planning, Beijing 10012, PR China.
³ State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, PR China. Electronic address: miaoli@tsinghua.edu.cn.

PMID: 35777148
DOI: 10.1016/j.jhazmat.2022.129455

Abstract

Nitrate pollution of water bodies is a serious global-scale environmental problem. The electrocatalytic nitrate reduction reaction (NO₃RR) using Cu-based electrodes allows excellent nitrate removal; however, its long-term operation results in copper leaching, leading to health risks. This study proposes a strategy for efficient nitrate removal through the activation of oxygen vacancies on a highly dispersed Cu-doped TiO₂ nanotube array (Cu/TNTA) cathode via electrodeposition. The mechanism underlying the activation of oxygen vacancies and enhancement in charge transfer at the cathode-pollutant interface upon trace (0.02 wt%) Cu doping is elucidated by electron paramagnetic resonance analysis, UV-visible diffuse reflection spectroscopy, and Raman spectroscopy. The Cu/TNTA-300 exhibits a nitrate removal rate of 84.3% at 12 h; the electrode activity did not decrease after 10 cycles, and no Cu²⁺ was detected in the solution. Electrochemical characterization and density functional theory calculations demonstrate that Cu doping promotes efficient charge transfer between nitrate and the electrode and reduces the energy barrier of the nitrate reduction reaction. This work provides a platform for novel design of cathodes for use in efficient and safe electrocatalytic nitrate reduction in environmental water bodies.

Keywords: Cu-based electrode; Electrocatalysis; Nitrate reduction; Oxygen vacancy.