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 Ta 2 O 5 nanoparticles (NPs). This method includes mechanical milling and a subsequent calcination step. The in-situ formation of LiCl/KCl and the partial crystallization of Ta 2 O 5 at low-temperature were observed after milling, confirming the existence of chemical reaction between TaCl 5 and LiOH/KOH reagents, and also the mechanochemical synthesis of Ta 2 O 5. By heating at 700 °C during 2 h, complete crystallization of Ta 2 O 5 was achieved. The synthesized Ta 2 O 5 NPs showed flake shape with sizes below 20 nm and S BET of 17 m2 g−1. Furthermore, the proposed method represents an alternative for the straightforward and large-scale production of crystalline Ta 2 O 5 NPs. Moreover, the as-prepared Ta 2 O 5 NPs showed high photocatalytic activity for degrading methylene blue (MB) dye. The Ta 2 O 5 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 Ta 2 O 5 NPs showed high stability which demonstrates that this photocatalyst is suitable for use in wastewater treatment. Highlights • Ta 2 O 5 nanoparticles were synthesized by an innovative and green route. • The crystallization of Ta 2 O 5 was achieved at low-temperature during milling. • Ta 2 O 5 nanoparticles showed flake shapes with sizes below 20 nm. • Ta 2 O 5 enhanced the MB photodegradation efficiency achieving ⁓ 81% within 180 min. • The two-step route is an alternative for the easy and large-scale production of Ta 2 O 5. [ABSTRACT FROM AUTHOR]