Construction of adjustable dominant {314} facet of Bi5O7I and facet-oxygen vacancy coupling dependent adsorption and photocatalytic activity

In layered Bi-O-X materials, {001} and {110} facets are regarded to be highly active. However, dominant facets in bismuth-rich materials are rarely studied so far. In this paper, the role of main {314} facet of Bi5O7I is investigated for the first time. Bi5O7I samples with adjustable {314} and {008} facet ratios are synthesized using ionic liquid self-combustion method. The inducing growth role of tetramethylammonium iodide for {314} main facet is revealed. Photocatalytic experiments indicate that the activity of Bi5O7I material with {314}/{008} facet ratio of 4.32 are lower than those of Bi5O7I with facet ratio of 5.23 and 4.56, implying the increase of {008} facet proportion could not effectively improve the redox performance. Meanwhile, the controllable oxygen vacancy concentration can be realized by constructing reduction atmosphere. Photoelectrochemical test results show that the synergistic effect of facet ratio and the oxygen vacancies lead to the improvement of charge carriers.