3-D hierarchical Ag/ZnO@CF for synergistically removing phenol and Cr(VI): Heterogeneous vs. homogeneous photocatalysis

He Liang; Tianren Li; Jun Zhang; Dandan Zhou; Chengzhi Hu; Xiaoqiang An; Ruiping Liu; Huijuan Liu

doi:10.1016/j.jcis.2019.09.105

3-D hierarchical Ag/ZnO@CF for synergistically removing phenol and Cr(VI): Heterogeneous vs. homogeneous photocatalysis

J Colloid Interface Sci. 2020 Jan 15:558:85-94. doi: 10.1016/j.jcis.2019.09.105. Epub 2019 Sep 27.

Authors

He Liang¹, Tianren Li², Jun Zhang³, Dandan Zhou⁴, Chengzhi Hu⁵, Xiaoqiang An⁶, Ruiping Liu⁷, Huijuan Liu³

Affiliations

¹ State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; School of Environment, Northeast Normal University, Changchun 1l30117, Jilin, China.
² Key Laboratory of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130021, Jilin, China.
³ Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
⁴ School of Environment, Northeast Normal University, Changchun 1l30117, Jilin, China.
⁵ State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100039, China. Electronic address: czhu@rcees.ac.cn.
⁶ Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China. Electronic address: xqan@tsinghua.edu.cn.
⁷ State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100039, China.

PMID: 31585225
DOI: 10.1016/j.jcis.2019.09.105

Abstract

Synergistic photocatalysis offers great potential for simultaneously treating organic and heavy metal pollutants. Although considerable progress has been made, this technology is seriously restricted by the poor photoactivity of heterogeneous catalysts, and the contribution from homogeneous intermoleculars has been overlooked. In this paper, the Ag/ZnO@CF with 3-D hierarchical porous structure was fabricated and used to synergistically remove phenol and Cr(VI) from water. Due to the enhanced mass transfer and cocatalysts-facilitated charge separation, 3-D photocatalysts exhibited significantly improved activity for heterogeneous photocatalysis. Furthermore, both experimental characterizations and DFT calculations evidenced the formation of phenol-chromate(VI) esters with ligand-to-metal charge transfer from benzene ring to central chromium ion under photoexcitation. Thereafter, the effects of heterogeneous and homogeneous photocatalysis on the treatment efficiency of multiplex pollutants were investigated. In an ideal scenario, 2.4 and 2.3 times higher phenol and Cr(VI) removal rate were achieved compared to single catalytic reactions. This work not only offers new material strategy for photocatalyst exploration, but also provides new insights into the multiphase homogeneous catalysis contributed by intermolecular interactions.

Keywords: Hierarchical porous structure; LMCT; Multiplex pollution; Phenol-chromate(VI) ester; Photocatalysis.