Highly exposed ab-facets of BiOCl hierarchical self-assembly for enhanced photocatalysis

BiOCl micro/nanoplates and their hierarchical architectures were selectively synthesized via 24 h of hydrothermal reaction at 180 degrees C and a wide range of solution pH (2-12), where the vital role of solution pH in phase/morphology evolution were elaborated from solution chemistry and crystal facet engineering. It was unambiguously demonstrated that a higher solution pH retarded the binding interaction between H+ and oxygen-terminated {001} facets, and also yielded more oxygen vacancies. Therefore, the ab-dominated hierarchical self-assembly was the result. Analysis of photocatalytic properties further manifested that the significant exposure of ab plane is beneficial to photocatalysis. The best pH = 10 catalyst showed the strongest UV absorption, similar to 98.5 % of removal efficiency toward the methyl orange molecules within 20 min of simulated solar light irradiation and favorable reusability, while the values are only similar to 55.21 % and 50.75 % for the pH = 2 and pH = 12 ones, respectively. This systematic study facilitates a better understanding of photoreaction mechanism of the compound by considering oxygen vacancy defects and electron-hole interaction.