Comparison of photocatalytic activities between Er3 +/Yb3 + and Tm3 +/Yb3 + codoped (CaWO4@(TiO2/CaF2)) near-infrared photocatalysts

• Two kinds of Er3 + and Tm3 + doped NIR photocatalysts are synthesized.
• Tm3 + is better for the improvement of NIR-driven photoactivity compared to Er3 +.
• Er3 +-sample has stronger UV light absorption compared to Tm3 +-sample.
• Er3 +-sample displays higher UV–vis-NIR response photoactivity compared to Tm3 +-sample.

Er3 + and Tm3 + ions are the important lanthanides used in the near-infrared (NIR) photocatalysts with upconversion properties, while their individual contributions to the photocatalytic activities are still unclear yet. Herein, two NIR photocatalysts of Er3 +/Yb3 + codoped (CaWO4@(TiO2/CaF2) (EY-CTC) and Tm3 +/Yb3 + codoped (CaWO4@(TiO2/CaF2) (TY-CTC) are synthesized, and their photocatalytic activities are tested by the methyl orange degradation processes. A higher NIR-driven degradation rate (19.21%) is found over TY-CTC compared to EY-CTC with 12.93%. In contrast, due to the stronger UV light absorption and the more efficient electron–hole pair separation, EY-CTC exhibits better photocatalytic activity (99.02%) compared to TY-CTC (94.43%) under UV–vis-NIR irradiation.

The individual contributions of Er3 + and Tm3 + ions on the photocatalytic activities are compared. A higher NIR-driven degradation rate (19.21%) is found over Tm3 +/Yb3 + codoped (CaWO4@(TiO2/CaF2) (TY-CTC) compared to Er3 +/Yb3 + codoped (CaWO4@(TiO2/CaF2) (EY-CTC) with 12.93%. Due to the stronger UV light absorption and the efficient electron–hole pair separation, better photocatalytic activity is obtained in EY-CTC (99.02%) compared to TY-CTC (94.43%) under UV–vis-NIR irradiation.Figure optionsDownload as PowerPoint slide