Synthesis and properties of novel photoactive composites of P25 titanium dioxide and copper (I) oxide with inorganic polymers

Abstract The synthesis of novel composites of spherical Cu2O nanoparticles and P25 TiO2 with aluminosilicate inorganic polymers (geopolymers) is described and the morphology of the homogeneous oxide nanoparticle dispersion within the geopolymer matrix demonstrated by SEM/EDS and TEM. XRD and FTIR confirmed the formation of a well-reacted geopolymer matrix that was unaffected by the insertion of the Cu2O/TiO2 nanoparticles. Experiments in dark conditions and under UV irradiation showed that these materials efficiently remove a model organic pollutant (methylene blue dye) from solution by a dual process of adsorption on the geopolymer matrix, and photodecomposition of the dye without destroying the geopolymer structure. The adsorption kinetics are described by a pseudo-first-order model and Freundlich-type isotherms. Incorporation of 10 wt% Cu2O/TiO2 nanoparticles into the geopolymer composites decreases their adsorption ability by blocking the active adsorption, sites, but at higher Cu2O/TiO2 concentrations, dye adsorption is facilitated, probably by expanding the geopolymer matrix structure. Under UV irradiation, the composites remove the MB dye by a combination of adsorption and photodegradation without destroying the geopolymer structure. The combination of nanosized Cu2O particles and photoreactive P25 titania in an aluminosilicate inorganic polymer matrix is a more efficient photocatalyst under UV irradiation than geopolymer composites containing either of the individual oxides alone. These new geopolymer composites show promise as ecologically-friendly materials which can efficiently remove organic pollutants from water or the atmosphere.