Photocatalytic degradation of benzene over different morphology BiPO4: Revealing the significant contribution of high–energy facets and oxygen vacancies

Wide–band–gap BiPO 4 (BPO) is a promising candidate for photocatalytic degradation of highly stable benzene exhaust. To reveal the effect of the morphology and the oxygen vacancies of BPO on the degradation of benzene, a series of monoclinic BPO samples with the common reported rod– (BPO–R), sheet– (BPO–S), urchin– (BPO–U), and dendrite–like (BPO–D) morphology were synthesized and some oxygen vacancies were introduced in BPO–D. The samples were then used for photocatalytic degradation of gaseous benzene and the mineralization rate of benzene over the samples decreased in order BPO–D (258.6)> BPO–S (48.0)> BPO–U (21.0)> BPO–R (7.3 μmol h –1  m –2 ). BPO–D with a dendritic morphology showed the highest activity. The highly energetic (002), (012), and (031) facets and the oxygen vacancies make great contributions to the high performance of BPO–D, which favor the absorption of BPO–D in long–wavelength range, the adsorption of reactants, the formation of O 2 –· and eventually the interfacial degradation of benzene. The ESR and scavengers tests indicated that O 2 –· and the photogenerated holes are the main active species responsible for the degradation of benzene. This work suggests that increasing the proportion of high–energy crystal facets and introduction of oxygen vacancies are effective strategies to improve the photocatalytic performance of BPO.