Enhancing the Removal Efficiency of Rhodamine B by Loading Pd onto In2O3/BiVO4 Under Visible Light Irradiation

Abstract

A simple method for synthesizing novel Pd-In2O3/BiVO4 composites by using a hydrothermal technique is proposed. The synthesized samples showed a monoclinic phase and featured homogeneously dispersed Pd and BiVO4 dopants on In2O3, as confirmed by XRD, SEM, and XPS analyses. The Pd-In2O3/BiVO4 composite exhibited notable improvements, such as broadened visible-light absorption (up to 596.1 nm) and a narrowed band gap (2.08 eV vs. 2.82 eV for pure In2O3), a more compact and integrated morphology observed by SEM, which are expected to promote improved light harvesting and facilitate charge separation during photocatalysis. Under visible-light irradiation, the optimized 1 wt% Pd-In2O3/BiVO4 achieved 99% degradation of Rhodamine B (10 mg/L) within 40 min, while pure In2O3 showed less than 10% removal after 60 min—highlighting the strong synergistic effect of dual doping. Additionally, the composite demonstrated excellent stability and reusability over multiple cycles. A plausible photocatalytic mechanism for this process is proposed, providing insights into the design of efficient photocatalysts for wastewater treatment.