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Sun C, Chen T, Huang Q, Duan X, Zhan M, Ji L, Li X, Wang S, Yan J. Biochar cathode: Reinforcing electro-Fenton pathway against four-electron reduction by controlled carbonization and surface chemistry. Sci Total Environ 2021; 754:142136. [PMID: 32911157 DOI: 10.1016/j.scitotenv.2020.142136] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 08/31/2020] [Accepted: 08/31/2020] [Indexed: 06/11/2023]
Abstract
Porous biochars have attracted tremendous interests in electrochemical applications. In this study, a family of biochars were prepared from cellulose subject to different carbonization temperatures ranging from 400 to 700 °C, and the biochars were in-situ activated by a molten salt (ZnCl2) to construct a hierarchically porous architecture. The activated porous biochars (ZnBC) were used as a carbocatalyst for electro-Fenton (EF) oxidation of organic contaminants. Results showed that high-temperature carbonization improved the activity of biochar for four-electron oxygen reduction reaction (ORR) due to the rich carbon defects, while the mild-temperature treatment regulated the species and distribution of oxygen functional groups to increase the production of hydrogen peroxide (H2O2) via a selective two-electron ORR pathway. ZnBC-550 was the best cathode material with a high ORR activity without compromise in H2O2 selectivity; a high production rate of H2O2 (796.1 mg/g/h) was attained at -0.25 V vs RHE at pH of 1. Furthermore, Fe(II) addition induced an electro-Fenton system to attain fast decomposition of various organic pollutants at -0.25 V vs RHE (reversible hydrogen electrode) and pH of 3 with a satisfactory mineralization efficiency toward phenolic pollutants. The EF system maintains its excellent stability for 10 cycles. Hydroxyl radicals were identified as the dominant reactive oxygen species based on in situ electron paramagnetic resonance (EPR) analysis and radical quenching tests. This study gains new insights into electrocatalytic H2O2 production over porous biochars and provides a low-cost, robust and high-performance electro-Fenton cathode for wastewater purification.
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Affiliation(s)
- Chen Sun
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
| | - Tong Chen
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China.
| | - Qunxing Huang
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
| | - Xiaoguang Duan
- School of Chemical Engineering and Advanced Materials, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Mingxiu Zhan
- College of Metrology and Measurement Engineering, China Jiliang University, Hangzhou 310018, China
| | - Longjie Ji
- National Engineering Laboratory for Site Remediation Technologies, Beijing Construction Engineering Group Environmental Remediation Co. Ltd., Beijing 100015, China; State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Xiaodong Li
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
| | - Shaobin Wang
- School of Chemical Engineering and Advanced Materials, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Jianhua Yan
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
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