Hydrothermal synthesis and photocatalytic properties of modified and unmodified zinc oxide nanoparticles

Zinc oxide (ZnO) nanoparticles have been modified using caprylic acid and n‐butylamine as surface modifiers through in situ surface modification under mild hydrothermal conditions (T = 150–250°C; P = autogenous). The surface modification was carried out using different molar concentrations of ZnO (1–4M) in the starting materials with an acidic mineraliser like 1 N HCl. The resultant products obtained were either hydrophobic or hydrophilic depending upon the surface modifier used. The ZnO nanoparticles synthesised were subjected to a systematic characterisation using powder X‐ray diffraction, Fourier transform infrared spectroscopy, SEM, ultraviolet–visible spectroscopy and photocatalytic degradation studies. The hydrophilic ZnO was used in the photocatalytic degradation of indigo carmine dye, and it shows 98% efficiency with a residence time of 4 h.