Ultrathin cobalt-based nanosheets containing surface oxygen promoted near-complete nitrate removal

Ding Li; Xin-Yu Zhang; Jia-Fang Xie; Jie-Jie Chen; Quan-Bao Zhao; Lin Liu; Wei-Kang Wang; Wen-Wei Li; Han-Qing Yu

doi:10.1016/j.jcis.2024.06.020

Ultrathin cobalt-based nanosheets containing surface oxygen promoted near-complete nitrate removal

J Colloid Interface Sci. 2024 Oct 15:672:383-391. doi: 10.1016/j.jcis.2024.06.020. Epub 2024 Jun 4.

Authors

Ding Li¹, Xin-Yu Zhang², Jia-Fang Xie³, Jie-Jie Chen², Quan-Bao Zhao¹, Lin Liu¹, Wei-Kang Wang⁴, Wen-Wei Li², Han-Qing Yu⁵

Affiliations

¹ CAS Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, China.
² CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Technology, University of Science and Technology of China, Hefei 230026, China.
³ CAS Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, China; Research Center of Urban Carbon Neutrality, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China. Electronic address: jfxie@iue.ac.cn.
⁴ Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, Shanghai Engineering Research Center of Biotransformation of Organic Solid Waste, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, China.
⁵ CAS Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Technology, University of Science and Technology of China, Hefei 230026, China. Electronic address: hqyu@ustc.edu.cn.

PMID: 38848622
DOI: 10.1016/j.jcis.2024.06.020

Abstract

Electrocatalytic nitrate removal offers a sustainable approach to alleviate nitrate pollution and to boost the anthropogenic nitrogen cycle, but it still suffers from limited removal efficiency at high rates, especially at low levels of nitrate. Herein, we report the near-complete removal of low-level nitrate (10-200 ppm) within 2 h using ultrathin cobalt-based nanosheets (CoNS) containing surface oxygen, which was fabricated from in-situ electrochemical reconstruction of conventional nanosheets. The average nitrate removal of 99.7 % with ammonia selectivity of 98.2 % in 9 cyclic runs ranked in the best of reported catalysts. Powered by a solar cell under the winter sun, the full-cell nitrate electrolysis system, equipped with ultrathin CoNS, achieved 100 % nitrogen gas selectivity and 99.6 % total nitrogen removal. The in-situ Fourier Transform Infrared included experiments and theoretical computations revealed that in-situ electrochemical reconstruction not only increased electrochemical active surface area but also constructed surface oxygen in active sites, leading to enhanced stabilization of nitrate adsorption in a symmetry breaking configuration and charge transfer, contributing to near-complete nitrate removal on ultrathin CoNS. This work provides a strategy to design ultrathin nanocatalysts for nitrate removal.

Keywords: Electrochemical nitrate reduction; Electrochemical reconstruction; In-situ spectroscopy characterization; Surface oxygen; Ultrathin nanosheets.