Effect of amination of titanium dioxide in the TiO2/rGO composite on the efficient photocatalytic removal of gaseous formaldehyde at room temperature

In order to obtain the advanced photocatalyst with high performance for removing the gaseous formaldehyde, a new strategy with amination of titanium dioxide (TiO2) and combination with reduced graphene oxide (rGO) is proposed in this work. TiO2 was first aminated into amino-TiO2 and then combined with rGO by an electrostatic self-assembly process to form the amino-TiO2/rGO photocatalysts. The structure and morphology were characterized by XRD, FTIR, and SEM, respectively. Physicochemical properties were measured by EIS, XPS, ESR, PL, and photocurrent measurements. The mechanism of the photocatalytic reaction was studied. Optimal aminoTiO2/rGO catalyst exhibits high catalytic activity and recyclability. The reaction rate constant of HCHO over this catalyst is approximately 9.8 x 10-3 L mol- 1 .min-1, which is 10.5 times higher than that of the commercial Degussa P25 TiO2. The analysis results from XPS and ESR indicates that the high catalytic activity could be mainly attributed to the imine formed by chemisorption of amino and HCHO. The reaction speed of formaldehyde photolysis increases as the concentration of HCHO on the photocatalyst surface increased. In addition, the introduction of graphene enhances carrier separation efficiency so that leads to more reactive radicals such as hydroxyl radicals (.OH) and superoxide radicals (.O2- ), leading to improved performance on formaldehyde photolysis. This could provide a useful method for highly efficient formaldehyde photocatalysis.

Automated summary

A new strategy of aminating titanium dioxide and combining it with reduced graphene oxide was proposed for the preparation of an advanced photocatalyst with high efficiency in removing gaseous formaldehyde. The optimal catalyst demonstrated significantly improved catalytic activity and recyclability in formaldehyde photolysis compared to commercial TiO2. The enhanced performance was attributed to the formation of imine by chemisorption of amino and formaldehyde, as well as the introduction of graphene to enhance carrier separation efficiency. This strategy offers a useful method for highly efficient formaldehyde photocatalysis.