Valence-mixed iron phthalocyanines/(100) Bi2MoO6 nanosheet Z-scheme heterojunction catalysts for efficient visible-light degradation of 2-chloro-phenol via preferential dechlorination

It is vital for selectively preferential dechlorination by visible-light photocatalysis to eliminate high-risk 2-chlorophenol (2-CP) contaminant. However, selective adsorption and efficient charge separation remain challenging. Herein, ultrathin (100) facet-exposed Bi2MoO6 (BMO) nanosheets (~6 nm thickness) with enhanced selective adsorption for 2-CP due to the Bi-Cl interaction and highly visible-light activity for 2-CP degradation have been synthesized via a pH-controlled microwave-assisted hydrothermal process. The visible-light activity could be improved by modifying iron phthalocyanines (FePc) via H-bond induced assembly and subsequent H2 thermal treatment. The visible-light activity of as-optimized H2-treated heterojunction (H-FePc/BMO) was 4.5 and 2.5time higher than BMO and FePc/BMO. Raman spectra, X-ray photoelectron spectrum, electron paramagnetic resonance, photoelectrochemical measurements, radical trapping experiment and ion chromatography, confirmed that the improved photoactivity of H-FePc/BMO could be attributed to the selective adsorption of 2CP inducing photogenerated-holes as dominating active species with nearly 100% preferential dechlorination, the enhanced charge separation via Z-scheme transfer and the promoted O2 activation from valence-mixed Fe0/ Fe2+ species in FePc after H2 treatment. This study may open up a new way to the high-efficiency degradation of chlorophenols using bismuth-containing oxide-based photocatalysts.

Automated summary

This study demonstrates the synthesis of ultrathin (100) facet-exposed Bi2MoO6 nanosheets with enhanced selective adsorption and high visible-light photocatalytic activity for 2-CP degradation. The improved photoactivity is attributed to the selective adsorption of 2-CP inducing photogenerated-holes as the dominant active species, enhanced charge separation, and promoted O2 activation from valence-mixed Fe0/Fe2+ species after H2 treatment.