A novel understanding of morphological anisotropy features of nanorod units in brookite dominated triphase mesoporous TiO2 and its excellent photocatalytic activity in phenol decomposition: The role of synthesis pH and surface hydroxylation

Abstract

Four different photocatalysts were synthesised using brookite enriched but mixed-phase mesoporous titania using the solvothermal technique. The synthesis pH was optimised within 1.0–5.5 during the sample preparation. The present work is the first of its kind that explores the role of synthesis pH on morphological evolution and crystallographic coherence of the synthesised mixed-phase TiO2. Observations reveal that the synthesis pH highly affects the prepared samples' nucleation, growth mechanism, and surface characteristics. Planner defects, structural anisotropy, oriented attachment of the nanocrystals, and surface hydroxylation were drastically enhanced with pH increment. These parameters appeared to have a positive impact on photocatalytic reactions. The synthesised TiO2 (at pH 5.5) was recognised as an efficient photocatalyst (efficiency > 99.5% in 80 min), even better than single-phase anatase and, P25 for phenol decomposition. The prepared photocatalyst could be helpful to degrade organic pollutants in wastewater to protect the environment.