In situ chemical transformation synthesis of Bi4Ti3O12/I-BiOCl 2D/2D heterojunction systems for water pollution treatment and hydrogen production

Enhancing visible light response and inhibiting the recombination of photogenerated charge carriers are vital for Bi4Ti3O12 nanosheets to achieve high activity in the fields of hydrogen generation and water pollutant treatment. Hence, in this work, Bi4Ti3O12/I-BiOCl 2D/2D heterojunction systems have been constructed successfully for the first time, via a modified in situ ion exchange approach at room temperature. The intimate 2D/2D interface can provide sufficient contact surfaces to enhance the charge transfer rate and the doping of I-ions can dramatically improve the visible light absorption of the composites, ensuring the quantity of photogenerated electron-hole pairs. Moreover, the well-matched band structure can lead to the effective separation of photogenerated charges. Optical and electrochemical measurements are used to prove the above-mentioned points. Bi4Ti3O12/I-BiOCl exhibited highly enhanced visible-light catalytic activity towards hydrogen production and organic pollutant degradation, due to the reduced recombination rate of photogenerated carriers and the dramatically enhanced visible light absorption. The possible photocatalytic mechanism was proposed based on the results of active species trapping experiment and ESR analysis. This work may open up new prospects for constructing other 2D/2D bismuth-based semi-conductor photocatalysts with distinguished visible light response and efficient charge carrier separation rate.