Gel-like carbon dots: A high-performance future photocatalyst

Yiqun Zhou; Ahmed E ElMetwally; Jiuyan Chen; Wenquan Shi; Emel K Cilingir; Brian Walters; Keenan J Mintz; Christian Martin; Braulio C L B Ferreira; Wei Zhang; Sajini D Hettiarachchi; Leonardo F Serafim; Patricia L Blackwelder; Athula H Wikramanayake; Zhili Peng; Roger M Leblanc

doi:10.1016/j.jcis.2021.04.121

Gel-like carbon dots: A high-performance future photocatalyst

J Colloid Interface Sci. 2021 Oct:599:519-532. doi: 10.1016/j.jcis.2021.04.121. Epub 2021 Apr 28.

Authors

Yiqun Zhou¹, Ahmed E ElMetwally², Jiuyan Chen¹, Wenquan Shi³, Emel K Cilingir¹, Brian Walters⁴, Keenan J Mintz¹, Christian Martin¹, Braulio C L B Ferreira¹, Wei Zhang¹, Sajini D Hettiarachchi¹, Leonardo F Serafim¹, Patricia L Blackwelder⁵, Athula H Wikramanayake⁴, Zhili Peng⁶, Roger M Leblanc⁷

Affiliations

¹ Department of Chemistry, University of Miami, Coral Gables, FL 33146, USA.
² Department of Chemistry, University of Miami, Coral Gables, FL 33146, USA; Petrochemicals Department, Egyptian Petroleum Research Institute, Nasr City, Cairo 11727, Egypt.
³ National Center for International Research on Photoelectric and Energy Materials, School of Materials and Energy, Yunnan University, Kunming, Yunnan 650091, People's Republic of China.
⁴ Department of Biology, University of Miami, Coral Gables, FL 33146, USA.
⁵ Department of Chemistry, University of Miami, Coral Gables, FL 33146, USA; MGS/RSMAS, University of Miami, Key Biscayne, FL 33149, USA.
⁶ National Center for International Research on Photoelectric and Energy Materials, School of Materials and Energy, Yunnan University, Kunming, Yunnan 650091, People's Republic of China. Electronic address: zhilip@ynu.edu.cn.
⁷ Department of Chemistry, University of Miami, Coral Gables, FL 33146, USA. Electronic address: rml@miami.edu.

PMID: 33964697
DOI: 10.1016/j.jcis.2021.04.121

Abstract

To protect water resources, halt waterborne diseases, and prevent future water crises, photocatalytic degradation of water pollutants arouse worldwide interest. However, considering the low degradation efficiency and risk of secondary pollution displayed by most metal-based photocatalysts, highly efficient and environmentally friendly photocatalysts with appropriate band gap, such as carbon dots (CDs), are in urgent demand. In this study, the photocatalytic activity of gel-like CDs (G-CDs) was studied using diverse water pollution models for photocatalytic degradation. The degradation rate constants demonstrated a remarkably enhanced photocatalytic activity of G-CDs compared with most known CD species and comparability to graphitic carbon nitride (g-C₃N₄). In addition, the rate constant was further improved by 1.4 times through the embedment of g-C₃N₄ in G-CDs to obtain CD-C₃N₄. Significantly, the rate constant was also higher than that of g-C₃N₄ alone, revealing a synergistic effect. Moreover, the use of diverse radical scavengers suggested that the main contributors to the photocatalytic degradation with G-CDs alone were superoxide radicals (O₂^-) and holes that were, however, substituted by O₂^- and hydroxyl radicals (OH) due to the addition of g-C₃N₄. Furthermore, the photocatalytic stabilities of G-CDs and CD-C₃N₄ turned out to be excellent after four cycles of dye degradation were performed continuously. Eventually, the nontoxicity and environmental friendliness of G-CDs and CD-C₃N₄ were displayed with sea urchin cytotoxicity tests. Hence, through various characterizations, photocatalytic degradation and cytotoxicity tests, G-CDs proved to be an environmentally friendly and highly efficient future photocatalyst.

Keywords: Carbon dots; Degradation; Mineralization; Photocatalysis; Wastewater treatment.