A special synthesis of BiOCl photocatalyst for efficient pollutants removal: New insight into the band structure regulation and molecular oxygen activation

Exploitation of efficient photocatalytic materials is a vital matter to settle the energy and environmental crisis we are facing. In this work, BiOCl with oxygen vacancy (OV-BOC) is synthesized by solvothermal modification method. According to the acquired DRS, VB-XPS, ESR results, solvothermal modification synthesis can not only introduce oxygen vacancy which supports the generation of O-1(2) but regulate the band structure, giving rise to the valance band down-shift and hence the photogenerated h(+) possesses higher oxidation capacity, which brings about desirable photodegradation efficiency on organic pollutants. It is unexpected that the degradation rate can be promoted by 2.6, 3.1 and 2.4 times after adding a little H2O2 towards rhodamine B, methyl orange and phenol, respectively, which benefits from the increased production of O-center dot(2)-. These increased O-center dot(2)- comes from activated H2O2 through the direct attack of holes which possesses higher oxidation capacity because of valance band down-shift (H2O2 + h(+) -> center dot O-2(-) + 2H(+)), as certified by analyses of free radicals and band positions. Radical species capturing and ESR experiments are used to reveal the mechanisms involved by reactive oxygen species and the results show that h(+), O-1(2) and O-center dot(2)- species are all responsible for photocatalytic degradation. This study may give some guidance on architecting photocatalysts on band structure regulation and molecular oxygen activation simultaneously.