Understanding the role of dominant crystal facets on heterogeneous catalytic activity of BiOBr nanomaterials: Boosting catalytic efficiency through Fe (III)/Fe(II) incorporation

Herein, we have synthesized three different types of BiOBr nanomaterials (nanosheets, nanoplates and nanoflowers) by simply varying the pH of the solvent medium. Results suggest that the nanosheets contain predominantly (001) plane as the major exposed crystal facets. On the other hand, nanoflowers possess mainly (110) plane as the major exposed facet. However, nanoplates show both (001) & (110) crystal facets predominantly. Detailed morphological and elemental studies have been carried out to investigate the variation of positively charged oxygen vacancies depending on the nature of the predominantly exposed crystal facets. Furthermore, the relative extent of oxygen vacancies was further correlated with the overall surface area and the porosity of the as synthesized nanomaterials. Finally, all these three different types of nanomaterials with varying predominantly exposed crystal facets have been utilized for the catalytic reduction of para-nitrophenol to para-aminophenol as a model system through mild reducing agent NaBH4. A probable mechanism has been proposed to explain the facet dependent catalytic activities of different BiOBr nanomaterials. Finally, Fe (III)/ Fe (II) ions were specifically incorporated in BiOBr nanomaterials. The incorporation of Fe (III)/Fe (II) ions has been further correlated with the detail structural, elemental and optoelectronic properties. Depending on the exposed crystal facets, a huge enhancement has been observed for overall catalytic efficiency upon incorporation of Fe (III)/ Fe (II) ions. A suitable mechanism has been proposed. [Display omitted] •BiOBr nanomaterials with varying predominant crystal facets can be synthesized by changing the pH of the solvent medium.•The oxygen vacancies and porosity of the nanomaterials depends on the nature of predominant crystal facets.•BiOBr nanomaterials with predominantly exposed (001) crystal facet specifically show maximum catalytic activity.•Incorporation of Fe ions further improves the catalytic efficiency BiOBr nanomaterials.