Enhanced visible light photocatalytic performance of Er, Mn co-doped monoclinic BiVO4 for efficient organic pollutant degradation

Abstract

This study reports the synthesis of Er-doped, Mn-doped, and Er, Mn co-doped monoclinic BiVO₄ photocatalysts via a facile one-pot hydrothermal method. Er_6%Mn_2%/BiVO₄ exhibited a larger specific surface area, bigger pore volume, and smaller average pore size compared to pure BiVO₄ and single-doped BiVO₄. The co-doping of Er³⁺ and Mn²⁺ ions resulted in lattice distortion and crystal particle size reduction of BiVO₄, and generated a new impurity level at the bottom of the conduction band, narrowing the band gap and widening the absorption edge of visible light, thus improving the separation efficiency of photogenerated electron–hole pairs. Photocatalytic experiments on rhodamine B showed that Er_6%Mn_2%/BiVO₄ achieved a degradation efficiency of 97.8% under visible light irradiation (λ >420 nm) within 100 min, which is higher than those of BiVO₄, Er_6%/BiVO₄, and Mn_6%/BiVO₄. The kinetic rate constant (0.0312 min⁻¹) of Er_6%Mn_2%/BiVO₄ was 1.3, 2.2, and 4.7 times higher than those of Er_6%/BiVO₄, Mn_6%/BiVO₄, and BiVO₄, respectively. The study also identified ·O₂⁻ and h⁺ as the predominant active species involved in the photocatalytic degradation of rhodamine B and demonstrated the excellent stability of Er_6%Mn_2%/BiVO₄ for five cycles of photodegradation experiment. This work highlights that Er_6%Mn_2%/BiVO₄ has great potential as a candidate for treating organic pollutants in water.