Efficient Photocatalytic CH₃NH₂ Degradation by Regulating Surface Acidic Sites and the Crystalline Phase of H₂Ti₃O₇/TiO₂ Nanotubes

Hydrogen titanate nanotubes (H-TNTs) were fabricated via a hydrothermal approach, followed by calcination, to obtain a series of titanate nanotubes (TNTs). The prepared (H−)TNTs were applied in the photocatalytic degradation of methylamine (CH3NH2). The H-TNTs calcined at 350 °C (TNTs-350) showed the best photocatalytic activity of over 85% within 3 h. Experimental results indicated that the surface acidic sites and the crystalline phase are key factors that influence their photocatalytic activities. Although H-TNTs possess abundant surface hydroxyl groups and acidic sites, which favor the adsorption of CH3NH2, enhanced photocatalytic performance is obtained by balancing the number of acidic sites and the anatase TiO2 quantity.