A two-step synthesis of NaTaO3 microspheres for photocatalytic water splitting

• NaTaO3 microspheres were synthesized via a newly developed two-step processing without using any templates or surfactants.
• NaTaO3 microspheres have rough surfaces composed of many tiny particles.
• NaTaO3 microspheres show superior photocatalytic activity for water splitting.
• The rough surface favors the separation of photogenerated charges and the adsorption of water molecules.

NaTaO3 photocatalyst has been successfully synthesized by a two-step synthesis approach, namely, molten salt in combination with hydrothermal processing at a relatively low temperature. The key concept of the approach is using molten salt to convert Ta2O5 to a soluble Ta-precursor, and the aqueous solution of the obtained Ta-precursor is then transferred as a starting source of Ta to synthesize NaTaO3 by a hydrothermal process. The obtained sample was characterized by powder X-ray diffraction (XRD), inductively coupled plasma emission spectrometry (ICP), field emission scanning electron microscopy (FESEM) and ultraviolet–visible (UV–vis) spectroscopy. A spherical morphology for NaTaO3 has been observed by FESEM. Comparative study on hydrogen production from water splitting under UV-light irradiation evinces that the obtained sample exhibits more than 4 times higher photoactivity than its counterpart prepared by a solid state method. In addition, loading of NiO co-catalyst onto the surface of NaTaO3 improves its efficiency for water splitting.

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