Photocatalytic activity of germanosilicate glassceramics containing Ga2O3 nanostructures

Photocatalysis is a crucial process in sustainable environmental technologies and in the development of next generation hydrogen production lines. The opportunity of having photocatalytic activity in glasses and glassceramics may open the way to the design of novel photocatalytic systems based on optical fiber geometry as well as self-cleaning windows and containers. Here we show the photocatalytic performances of nanostructured glassceramics with an amorphous germanosilicate matrix embedding nanoparticles of gallium oxide in the gamma phase. The latter is a wide band gap oxide with known photocatalytic activity. In this study we have investigated glasses obtained by melt quenching method and with molar composition 7.5%Li2O-2.5%Na2O-20%-Ga2O3-25%SiO2-45%GeO2. The nanocrystallization has been achieved according to a two-step thermal treatment (18 hours at 570 °C followed by 30 min at 651 °C) which maximize the number of nanoparticles per volume with an average size of less than 10 nm. Photocatalytic degradation of rhodamine dye in water under UV illumination was performed using powdered samples. The results evidence a photocatalytic activity of the system which follows a mixed kinetics of the 0th and 1st order. Interestingly, the performances of the recovered powders after the first cycle show better results with respect to pristine sample. The formation of defects probably responsible of such an enhancement has been detected by photoluminescence experiments.