Enhanced photocatalytic reduction of hexavalent chromium by using piezo-photo active calcium bismuth oxide ferroelectric nanoflakes

Abstract

Photocatalysis is a promising approach to solving environmental pollution issues using solar energy. Recently, ferroelectric materials have also attracted attention for photocatalysis due to the piezo-photo effect. Here we report the synthesis of ferroelectric calcium bismuth oxide (CBO) nanoflakes and demonstrate the influence of the piezo-photo impact on the improved photoreduction of hexavalent chromium, Cr(VI), under visible light irradiation. The structure, morphological, optical, and ferroelectric characteristics of the CBO nanoflakes were investigated using various characterization techniques. The remanent polarization obtained from the P–E loop is 0.02 μC cm⁻² with a coercive field of 3.7 kV cm⁻¹. The CBO nanoflakes showed an 80% photoreduction of Cr(VI) to Cr(III) after 120 minutes of light exposure. This photoreduction is enhanced to 94% when exposed to ultrasonic vibrations and visible light. A possible mechanism of Cr(VI) photoreduction under visible light irradiation was also proposed. The current research presents a novel and simple method for creating effective nanoflakes for environmental remediation.