A novel two-step route for synthesizing pure Ta2O5 nanoparticles with enhanced photocatalytic activity

Abstract An innovative and environmentally-friendly procedure has been developed for the successful preparation of Ta2O5 nanoparticles (NPs). This method includes mechanical milling and a subsequent calcination step. The in-situ formation of LiCl/KCl and the partial crystallization of Ta2O5 at low-temperature were observed after milling, confirming the existence of chemical reaction between TaCl5 and LiOH/KOH reagents, and also the mechanochemical synthesis of Ta2O5. By heating at 700 °C during 2 h, complete crystallization of Ta2O5 was achieved. The synthesized Ta2O5 NPs showed flake shape with sizes below 20 nm and SBET of 17 m2 g−1. Furthermore, the proposed method represents an alternative for the straightforward and large-scale production of crystalline Ta2O5 NPs. Moreover, the as-prepared Ta2O5 NPs showed high photocatalytic activity for degrading methylene blue (MB) dye. The Ta2O5 NPs enhanced the degradation rate of MB attaining a degradation percentage of about ⁓ 81% within 180 min under UV–vis irradiation. Herein, trapping experiments demonstrated that holes are the main oxidative species in the MB photodegradation process. After recycling tests, the Ta2O5 NPs showed high stability which demonstrates that this photocatalyst is suitable for use in wastewater treatment.