A controlled non-radical chlorine activation pathway on hematite photoanodes for efficient oxidative chlorination reactions

Daojian Tang; Lei Wu; Liubo Li; Niankai Fu; Chuncheng Chen; Yuchao Zhang; Jincai Zhao

doi:10.1039/d3sc06337b

A controlled non-radical chlorine activation pathway on hematite photoanodes for efficient oxidative chlorination reactions

Chem Sci. 2024 Jan 16;15(8):3018-3027. doi: 10.1039/d3sc06337b. eCollection 2024 Feb 22.

Authors

Daojian Tang^{1

2}, Lei Wu^{1

2}, Liubo Li³, Niankai Fu^{3

2}, Chuncheng Chen^{1

2}, Yuchao Zhang^{1

2}, Jincai Zhao^{1

2}

Affiliations

¹ Key Laboratory of Photochemistry, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences Beijing 100190 P. R. China yczhang@iccas.ac.cn.
² University of Chinese Academy of Sciences Beijing 100049 P. R. China.
³ Key Laboratory of Molecular Recognition and Function, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences Beijing 100190 P. R. China.

Abstract

Photo(electro)catalytic chlorine oxidation has emerged as a useful method for chemical transformation and environmental remediation. However, the reaction selectivity usually remains low due to the high activity and non-selectivity characteristics of free chlorine radicals. In this study, we report a photoelectrochemical (PEC) strategy for achieving controlled non-radical chlorine activation on hematite (α-Fe₂O₃) photoanodes. High selectivity (up to 99%) and faradaic efficiency (up to 90%) are achieved for the chlorination of a wide range of aromatic compounds and alkenes by using NaCl as the chlorine source, which is distinct from conventional TiO₂ photoanodes. A comprehensive PEC study verifies a non-radical "Cl⁺" formation pathway, which is facilitated by the accumulation of surface-trapped holes on α-Fe₂O₃ surfaces. The new understanding of the non-radical Cl^- activation by semiconductor photoelectrochemistry is expected to provide guidance for conducting selective chlorine atom transfer reactions.