UV-light-assisted green preparation of Bi/BiOBr/RGO composites with oxygen vacancies toward enhanced photocatalytic removal of organic dye

Abstract

The concomitant formation of metallic Bi nanoparticles and oxygen vacancies was successfully achieved within Bi/BiOBr/RGO composites by facile and green UV-light exposure. Detailed characterization showed that Bi nanoparticles with an average size of ca. 25 nm and oxygen-vacancies were fabricated simultaneously in this preparative process. The photocatalytic activity in aqueous methylene blue (MB) solution showed that the Bi/BiOBr/RGO composites revealed superior performance over the counterparts and their photocatalytic activities were highly dependent on the light irradiation time of the preparation process. Among all the as-prepared samples, the sample prepared under UV-light irradiation of 40 min exhibited the highest photocatalytic activity and the removal rate of MB was 99.9% under visible-light within 240 min. The mechanism study proved that the improvement in the photocatalytic efficiency of Bi/BiOBr/RGO composites could be ascribed to the synergy of the surface plasmon resonance (SPR) effect of Bi, conductive RGO and oxygen vacancies, all of which enhanced the visible light harvesting and effective separation of electron–hole pairs. The present work not only provided a facile green and low-cost method to simultaneously incorporate Bi and oxygen vacancy into composites but also confirmed that UV-light irradiation was one effective method to tune the photocatalytic performance of the composites.