Efficient Visible Light-Driven Photocatalytic Degradation of Pentachlorophenol with Bi2O3/TiO2–xBx

In this study, a new TiO 2 -based photocatalyst with both B doping and Bi 2 O 3 coupling (Bi 2 O 3 /TiO 2– x B x ) was synthesized to degrade pentachlorophenol under visible light (λ > 420 nm) irradiation. The resulting Bi 2 O 3 /TiO 2– x B x sample exhibited much higher photocatalytic performance than the counterparts with only B doping or Bi 2 O 3 coupling or pure TiO 2 . This is because B doping could result in more visible light absorption to produce more photogenerated electron–hole pairs, while Bi 2 O 3 coupling could favor the separation and transfer of photoinduced charge carriers to inhibit their recombination. We interestingly found that the visible light-driven degradation of pentachlorophenol was mainly attributed to photogenerated holes and ·O 2 – other than ·OH as reported previously because the hybridization of B 2p orbital and O 2p orbital could elevate the VB edge of Bi 2 O 3 /TiO 2– x B x as compared to that of pure TiO 2 and thus lower the oxidation ability of photogenerated holes, blocking the pathway of photogenerated holes induced oxidation of surface OH – and water to generate ·OH. The intermediates during the PCP photodegradation were systematically analyzed, ruling out the existence of high toxic polychlorinated dibenzo- p -dioxins and polychlorinated dibenzofurans. These results reveal that the visible light-driven photocatalytic degradation of PCP over Bi 2 O 3 /TiO 2– x B x is an effective and green method to remove highly toxic halogenated aromatic compounds.