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 amino-TiO2/rGO catalyst exhibits high catalytic activity and recyclability. The reaction rate constant of HCHO over this catalyst is approximately 9.8 × 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. •Amino-TiO2/rGO composite prepared by electrostatic self-assembly methods.•XPS and EPR show that imine was formed, ·OH and O2− were active substances.•-NH2 increase concentration of HCHO and kinetics of catalytic reaction.