Three-dimensional functional carbon nanotube architecture as a highly efficient and active indirect catalyst for degradation of 4-chlorophenol

• Published in: Separation and purification technology 2022-08, Vol.295, p.121277, Article 121277
• Main Authors: Feng, Yu, Wang, Yanan, Pang, Zijin, Zhuang, Yunqing, He, Yu-Shi, Zhang, Weimin, Mu, Jinglin, Huang, Xin
• Format: Article
• Language: English
• Subjects: 4-chlorophenol degradation; Carbonaceous catalyst; Electro-Fenton; Iron sludge-free
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2022.121277

•1. A functional carbon nanotubes (CNTs) architecture catalyst was synthesized.•2. The catalyst shows a superior ability for the removal of 4-chlorophenol.•3. The electrode is highly efficient for generating H2O2 and hydroxyl radicals.•4. Pollutants could be degraded efficiently in a wide initial pH range of 2.33–12.0. Electro-Fenton (EF) is a promising and green technology for environmental remediation. However, traditional EF often suffers from iron sludge production, leading to poor pH adaptation and secondary pollution. In this work, we synthesized a three-dimensional (3D) carbon nanotube architecture containing nitrogen and oxygen heteroatoms on carbon fibre paper (3D-NOCNTs/CFP) as an indirect catalyst for a metal-free EF process for the removal of 4-chlorophenol (4-CP). The dependence of the content and the type of the functional groups in the carbon plane on the pyrolysis temperature was studied through XPS measurements. This binder-free electrode has been identified as a bifunctional catalyst that can catalyze a high H2O2 yield process and a subsequent in-situ generation of ⋅OH via an O2 reduction reaction (ORR). Thus the generated ⋅OH radicals can directly participate in the oxidative degradation of 4-CP and the utilization of iron can be avoided in the EF process. The optimized electrode could remove 99.3 % 4-CP in 120 min and exhibits a broad suitability upon pH, an excellent capability, and a prominent stability for the degradation of 4-CP. The mechanism was explained by density function theory (DFT) calculations and the controlled experiments. Such a metal-free EF process features a promising green technology for the oxidative degradation of organic pollutants.