Synergetic effects of hydrophilic surface modification and N-doping for visible light response on photocatalytic activity of TiO2

• N-doping was carried out on TiO2 via thermal treatment under constant NH3 gas flow.
• Surface of TiO2 was modified by PDMS-coating and subsequent vacuum annealing.
• Both process enhanced the MB adsorption as well as visible-light response of TiO2.
• Visible-light response was dominant for N-doping and the opposite for h-modification.
• N-doping and h-modification had synergy effect on MB removal under visible-light.

We made attempts to improve photocatalytic activity of TiO2 nanoparticles under visible light exposure by combining additional treatments. N-doping of TiO2 by ammonia gas treatment increased absorbance of visible light. By coating thin film of polydimethylsiloxane, and subsequently vacuum-annealing, TiO2 surface became more hydrophilic, thereby enhancing photocatalytic activity of TiO2. These two treatments were combined for the first time in this work and photocatalytic activity under visible light irradiation exceeded sum of individual effects of N-doping and hydrophilic modification.

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