Facile surfactant-aided sol–gel synthesis of mesoporous-assembled Ta2O5 nanoparticles with enhanced photocatalytic H2 production

• Mesoporous-assembled Ta2O5 nanoparticles were synthesized by a modified sol–gel process.
• Their thermal treatment stability under various temperatures was investigated.
• Physicochemical properties were related to photocatalytic H2 production activity.
• The maximum photocatalytic H2 production activity was observed at 700 °C.
• The optimized Ta2O5 could be reused for several cycles without activity loss.

This work was mainly focused on the investigation of thermal treatment impact of the mesoporous-assembled Ta2O5 nanoparticles synthesized via a facile sol–gel method with the aid of a mesopore-directing surfactant on their photocatalytic hydrogen production activity from a methanol aqueous solution under UV light irradiation. The synthesized Ta2O5 nanoparticles were characterized by X-ray diffraction, N2 adsorption–desorption analysis, elemental carbon analysis, UV–vis absorbance spectroscopy, scanning electron microscopy, transmission electron microscopy, and selected-area electron diffraction. The experimental results strongly supported that the calcination temperature in the range of 500–800 °C significantly affected the physicochemical properties and hydrogen production activity of the synthesized Ta2O5 nanoparticles. The synthesized Ta2O5 nanoparticles exhibited the amorphous-to-crystalline phase transformation at the calcination temperature of 650 °C, at and beyond which the hydrogen production activity improvement was clearly observed. The most photocatalytically active and thermally stable Ta2O5 nanoparticle was obtained at the optimum calcination temperature of 700 °C, and its hydrogen production activity was captivatingly found to be higher than that of the commercial Ta2O5 and P-25 TiO2 powders. In addition, the optimized Ta2O5 nanoparticle exhibited a very good durability for multiple reuses without significant activity loss.

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