Porous biochar supported Ag3PO4 photocatalyst for “two-in-one” synergistic adsorptive-photocatalytic removal of methylene blue under visible light irradiation

Abstract

The synergistic adsorption and photocatalysis is of importance to pollutant degradation, and thus the design of both adsorption and photocatalytic sites on one site of the catalyst is worthy of investigation. In the work, a bamboo biochar with rich porous structure was synthesized to support Ag3PO4 photocatalyst (AP/PBB) through a ball mill-pyrolysis-precipitation method. Owing to the large surface area of PBB, most of AP nanoparticles were well-dispersed and Ag0 species were in-situ generated in the preparation, which was beneficial for absorbing more visible light. Furthermore, a stronger interaction, i.e., built-in electric field between AP and PBB was observed, and thus the photo-generated electrons transfer quickly from AP to PBB via the Ag0 bridge. Furthermore, the transferred electrons reacted with the surface adsorbed oxygen species on PBB to produce ·OH radicals, and then oxidized the methylene blue (MB) molecules on PBB. Therefore, both adsorption and photocatalytic sites on one site, i.e., “two-in-one” of the AP/PBB photocatalyst exhibited higher MB degradation efficiency (95.6%), compared with AP/common biochar. This work affords a novel strategy for biochar-based photocatalysts for effective contaminant removal.