Spatial separation of photocarriers and selective adsorption on flower-like core-shell heterojunction of Cr(VI) imprinted polymer@BiOI for boosted photocatalytic Cr(VI) reduction

Abstract

Background

Constructing heterojunction photocatalyst is a well-established strategy for enhancing photocatalytic Cr(VI) reduction due to the heightened separation and transfer of photocarriers. Whereas, aimless and random transfer of photocarriers and low photocarrier utilization rate deriving from the weak interface interaction between heterojunction and Cr(VI) are still limited the photocatalytic reduction performance of Cr(VI).

Methods

Herein, a flower-like core-shell heterojunction photocatalyst was designed by wrapping a pyridine-based Cr(VI) imprinted polymer (PCIP) onto flower-like BiOI to achieve spatial separation of photocarriers and selective adsorption of Cr(VI), resulting in an outstanding photocatalytic reduction performance of Cr(VI).

Significant findings

In the core-shell heterojunction, photocarriers could be spatially separated, and then brought about high-efficient photocatalytic Cr(VI) reduction close to the selective adsorption sites of Cr(VI). After measurement, the optimal PCIP@BiOI core-shell heterojunction, polymerized for ≈30 min, exhibited a robust photocatalytic reduction performance of Cr(VI), without adding any free radical sacrifice agents. Within 1 h, the aqueous solution containing 100 mg/L of Cr(VI) could be completely removed, and the photocatalytic reduction rate constant of Cr(VI) was ≈20 times superior to BiOI. This study presents a methodology for designing core-shell heterojunction photocatalysts on the basis of inorganic/organic conjunction for environmental remediation of high concentrations of Cr(VI).