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

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. Er6%Mn2%/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 Er6%Mn2%/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, Er6%/BiVO4, and Mn6%/BiVO4. The kinetic rate constant (0.0312 min−1) of Er6%Mn2%/BiVO4 was 1.3, 2.2, and 4.7 times higher than those of Er6%/BiVO4, Mn6%/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 Er6%Mn2%/BiVO4 for five cycles of photodegradation experiment. This work highlights that Er6%Mn2%/BiVO4 has great potential as a candidate for treating organic pollutants in water.