Template-sacrificial conversion of MnCO3 microspheres to fabricate Mn-doped TiO2 visible light photocatalysts

This study demonstrates a one-step hydrothermal approach to prepare novel spherical microstructures of Mn-doped TiO2 by the in situ template-sacrificial conversion of MnCO3 microspheres grown in a radial direction. After a hydrothermal reaction, MnCO3 microspheres were completely dissolved by HF as a hydrolysis product of [NH4]2TiF6. Furthermore, the hollow and radially porous structures of Mn-doped TiO2 microspheres were obtained without and with stirring during hydrothermal reaction, respectively. The prepared anatase TiO2 microspheres were fully characterized in terms of particle size, morphology, chemical composition, and porosity by X-ray diffraction, scanning and transmission electron microscopies, X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller method, respectively. The photocatalytic activity of the prepared TiO2 microspheres was evaluated by the degradation of methylene blue under UV and visible light irradiations. Our versatile approach can be used for different types of metal carbonates to fabricate morphology controllable metal oxide nano- and microstructures. [Display omitted] •The template-sacrificial conversion of MnCO3 microspheres leads to hollow and radially porous Mn-doped TiO2 microspheres.•The mechanical stirring step allows the control of Mn-doping content less than 10% in the TiO2 matrix•The Mn-doped TiO2 microspheres achieve a high photocatalytic activity under λ > 435 nm visible light irradiation