Application of amine-functionalized titanium dioxide wrapped in reduced graphene oxide in photocatalytic degradation of methylene blue

Abstract

This research investigated the effect of reduced graphene oxide (rGO) addition to amine-functionalized titanium dioxide (APTMS-TiO2). The loading amount of rGO was varied from 0 to 0.05 %wt. Also, the effect of the amount of 3-aminopropyltrimethoxysilane (APTMS) was studied. To synthesize TiO2/rGO catalysts, the amount of APTMS was varied at 2.21 and 22.1 mmol. TiO2 catalyst was synthesized via a sol-gel method. Next, the surface of TiO2 was modified with APTMS by refluxing. Then graphene oxide was wrapped around APTMS-TiO2 and was reduced to rGO using hydrazine and ammonia. In the experiment, the catalyst was dispersed in methylene blue solution before being exposed to either UV or visible light. An increase in the amount of rGO in the catalyst improved photocatalytic activity for degradation of methylene blue. The amount of rGO that produced the highest conversion is 0.04% with the amount of APTMS of 2.21 mmol. Its highest efficiencies were 70.63 % under UV light and 31.06 % under visible light. The conversions of methylene blue degradation over various TiO2/rGO and TiO2/rGO* photocatalysts were in agreement with the results of PL and UV-Vis. Increasing the rGO content resulted in slower recombination rate of change carrier and better light absorption. Moreover, reducing the APTMS content resulted in narrower bandgap.