Tunable Photocatalytic Selectivity of Hollow TiO₂ Microspheres Composed of Anatase Polyhedra with Exposed {001} Facets

TLDR

The surface chemistry and atomic‑level structure, including ~20 % {001} facets, are key factors in tuning adsorption and photocatalytic selectivity of hollow TiO₂ microspheres toward azo dyes. The study proposes a fluoride‑mediated self‑transformation method to synthesize hollow TiO₂ microspheres composed of anatase polyhedra exposing ~20 % {001} facets. The method involves fluoride‑mediated self‑transformation to produce hollow TiO₂ microspheres with anatase polyhedra exposing ~20 % {001} facets. Fluorinated HTS preferentially decompose methyl orange over methylene blue, while NaOH‑washed or 600 °C calcined HTS favor methylene blue, demonstrating tunable photocatalytic selectivity of the hollow TiO₂ microspheres toward azo dyes.

Abstract

A fluoride mediated self-transformation method is proposed for the synthesis of hollow TiO(2) microspheres (HTS) composed of anatase polyhedra with exposed ca. 20% {001} facets. Importantly, HTS exhibit tunable photocatalytic selectivity in decomposing azo dyes in water. The fluorinated HTS show preferential decomposition of methyl orange (MO) in comparison to methylene blue (MB). In contrast, the surface-modified HTS by either NaOH washing or calcinations at 600 degrees C favor decomposition of MB over MO. The surface chemistry and the surface structure at the atomic level are key factors in tuning the adsorption selectivity and, consequently, photocatalytic selectivity of HTS toward azo dyes.