Improving photocatalytic activity under visible light over a novel food wastes biochar-based BiOBr nanocomposite

Biochar (C) applied in synthesizing photocatalysts to eliminate water pollution has been intensively investigated. Herein we report the first use of biochar pyrolyzed from food wastes at 400 °C (400C) and 700 °C to construct C/BiOBr composites via a facile hydrolysis approach. Photocatalytic performances could be significantly improved by choosing the appropriate carbonization temperature and adjusting the content of C in C/BiOBr composites. The prepared 1%400C/BiOBr exhibited the best photodegradation capacity towards methylene orange (20 mg/L) and tetracycline (50 mg/L). A series of characterization results illustrated that smooth structure and surface properties (oxygen functional groups and persistent free radicals) of 400C played an important role in enhancing the photocatalytic activities. Mechanism exploration suggested that h+ and ˙O2- were the main active species thus contributing to photodegradation. This study provided a new insight into utilization of biochar derived from food wastes in photocatalysis and environmental remediation.