Issue 8, 2019

Dual metal-free polymer reactive sites for the efficient degradation of diclofenac by visible light-driven oxygen reduction to superoxide radical and hydrogen peroxide

Abstract

Hydrogen peroxide (H2O2) and superoxide radical (O2˙) play a critical role in environmental remediation technologies. Here, we report on metal-free co-catalysts with the in situ incorporation of carbon dots (CDs) into a polymeric O and N co-linked carbon nitride (OCN) framework, which significantly enhanced the synthesis of H2O2 and O2˙ due to dual reactive sites. For the photocatalytic degradation of a typical pharmaceutical and personal care product (PPCP), CDs/OCN demonstrated excellent photocatalytic performance in contrast to g-C3N4 and OCN, which was 11.6 times that of pure g-C3N4. The trapping experiment has shown that O2˙ plays an important role in the degradation of DCF. CDs/OCN exhibited higher electron–hole separation efficiencies than g-C3N4 and OCN, as the result of the excellent transfer and storage performance of the CDs. The yield of H2O2 generation by CDs/OCN was higher than that by g-C3N4 and OCN. Meanwhile, the electron paramagnetic resonance (EPR) spectra revealed that additional O2˙ and ˙OH were generated via the CDs/OCN system. Density functional theory (DFT) and Raman spectroscopy analyses revealed the presence of CD/OCN-resident dual reactive sites, which had distinct selective oxygen reduction capacities. We observed that O2 was more prone to 2-electron reduction on OCN, whereas O2 was more easily reduced to O2˙ on the surface of CDs through the additional e provided by OCN. This study clearly demonstrates a simple strategy for the design and synthesis of metal-free materials in the preparation of H2O2 and O2˙ toward the degradation of organic pollutants.

Graphical abstract: Dual metal-free polymer reactive sites for the efficient degradation of diclofenac by visible light-driven oxygen reduction to superoxide radical and hydrogen peroxide

Supplementary files

Article information

Article type
Paper
Submitted
27 Apr 2019
Accepted
19 Jun 2019
First published
20 Jun 2019

Environ. Sci.: Nano, 2019,6, 2577-2590

Dual metal-free polymer reactive sites for the efficient degradation of diclofenac by visible light-driven oxygen reduction to superoxide radical and hydrogen peroxide

Q. Zhang, C. Tan, X. Zheng, P. Chen, M. Zhuo, T. Chen, Z. Xie, F. Wang, H. Liu, Y. Liu, X. Zhang, W. Lv and G. Liu, Environ. Sci.: Nano, 2019, 6, 2577 DOI: 10.1039/C9EN00482C

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