Hyperbranched Polymer-Hemin/TiO₂ Composite Photocatalyst and Its Photocatalytic Performance

With the increasing severity of environmental pollution issues, the development of efficient and environmentally friendly photocatalysts for the degradation of organic pollutants has become a hot topic of research. This study modified titanium dioxide (TiO₂) with hyperbranched polyglycerol (HPG) and hemin to prepare a new type of visible light-responsive photocatalyst, HPG-hemin/TiO₂. A series of HPG-hemin/TiO₂ composite materials were synthesized via the sol-gel method, and the influence of the mass fraction of HPG on the photocatalytic performance was systematically investigated. Characterization results from X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS) indicated that the introduction of HPG did not alter the anatase crystal phase of TiO₂ and effectively enhanced the material's light absorption capability in the visible light region. Photocatalytic degradation experimental results showed that under visible light irradiation, the degradation efficiency of HPG-hemin/TiO₂ for methylene blue (MB) reached up to 88.52%, significantly superior to that of pure TiO₂. Further electron paramagnetic resonance (EPR) testing confirmed that HPG-hemin/TiO₂ generated a large amount of hydroxyl radicals (•OH) and superoxide anion radicals (\text•\textO_2^- ) in the photocatalytic reaction to degrade MB, thereby enhancing the photocatalytic performance. This study provides new insights into the modification of TiO2-based photocatalysts and has significant application prospects for environmental pollution control and the treatment of organic pollutants.