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 (lambda >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 Er6%Mn2%/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 <middle dot>O-2(-) 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.