In situ generation and efficient activation of H2O2 for pollutant degradation over CoMoS2 nanosphere-embedded rGO nanosheets and its interfacial reaction mechanism

Muen Han; Lai Lyu; Yinmei Huang; Junrong Liang; Meimei Xue; Tao Wu; Jiayi Li; Meiping Chen; Chun Hu

doi:10.1016/j.jcis.2019.02.062

In situ generation and efficient activation of H₂O₂ for pollutant degradation over CoMoS₂ nanosphere-embedded rGO nanosheets and its interfacial reaction mechanism

J Colloid Interface Sci. 2019 May 1:543:214-224. doi: 10.1016/j.jcis.2019.02.062. Epub 2019 Feb 20.

Authors

Muen Han¹, Lai Lyu², Yinmei Huang³, Junrong Liang⁴, Meimei Xue⁴, Tao Wu⁴, Jiayi Li⁴, Meiping Chen⁴, Chun Hu⁵

Affiliations

¹ Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Institute of Environmental Research at Greater Bay, Guangzhou University, Guangzhou 510006, China; School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China.
² Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Institute of Environmental Research at Greater Bay, Guangzhou University, Guangzhou 510006, China; School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China; Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. Electronic address: lyulai@gzhu.edu.cn.
³ School of Mathematics and Information Science, Guangzhou University, Guangzhou 510006, China.
⁴ School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China.
⁵ Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Institute of Environmental Research at Greater Bay, Guangzhou University, Guangzhou 510006, China; School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China; Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.

PMID: 30802768
DOI: 10.1016/j.jcis.2019.02.062

Abstract

Consumption of additional H₂O₂ is necessary in classical Fenton catalysis. Herein, we report a novel and special nanocatalyst consisting of CoMoS₂ nanosphere-embedded, reduced graphene oxide (rGO) nanosheets (CMS-rGO NSs). This nanocatalyst was discovered to have an impressive reactivity for in situ generation and synchronistical activation of H₂O₂ in different active centers, yielding fast and efficient degradation of the pollutants. The reaction rate is ∼21 times higher than that of conventional Fenton catalysts. The characterization shows that countless flower-like CoMoS₂ nanospheres are uniformly embedded in the rGO nanosheets through MoSC bonding bridges in CMS-rGO NSs, which leads to activation of the π electrons and their transfer from rGO to the metal centers (π → M). The formed MoOCo further leads to a distribution of orientations of the electrons around the metal centers due to the different electronegativity of Mo and Co. During the reaction, the dissolved O₂ is efficiently reduced to HO₂/O₂^- around the electron-rich Mo center, and HO₂/O₂^- is further reduced to H₂O₂ around the Co center. The generated H₂O₂ is finally reduced to OH for degrading dyes in the electron-rich metal (Mo or Co) centers of CMS-rGO NSs. The dye pollutants also act as electron donors, and they are directly degraded in the electron-poor π-center of CMS-rGO NSs, which promote the electron transfer cycle and achieve electron gain-loss balance. This discovery provides a new strategy for H₂O₂ generation-activation and pollutant degradation through constructing electron transfer bridges over the surface of catalysts.

Keywords: Fenton reaction; H(2)O(2) generation; Interfacial reaction mechanism; MoS(2); Water treatment.