The up-conversion effect induced NIR-photocatalytic performance of Bi2−XErXWO6 photocatalysts

Bi2−XErXWO6 photocatalysts were synthesized by a microwave solvothermal-calcination method. The Er3+ ions were doped into the crystal of Bi2WO6 and the photocatalysts show an up-conversion effect of the Er3+ 4f electrons: 4I15/2 → 4F7/2, 4I15/2 → 2H11/2, 4I15/2 → 4S3/2 and 4I15/2 → 4F9/2. The Er3+ ions absorb NIR light and convert it into visible light so that extra photons and electrons-holes are generated. The degradation rates of the Bi2−XErXWO6 photocatalyst reach 96% within 270 min and 95% within 30 min under the simulated sunlight and NIR light, which confirms the enhancement of the degradation performance by the up-conversion effect.