DFT Investigation of Organic Functionalized Titania Membranes

Titania is a photocatalyst under visible and ultraviolet light whose catalytic activity can be altered via doping or functionalization. Performing ab-initio calculations with adsorbed dopamine, infrared and visible light spectra have been calculated and compared to experiment to improve photocatalytic activity. In another use for functionalized catalysts, photo-responsive membranes may be designed by use of poly-acrylic acid (PAA) on titania membranes. PAA expands and contracts in response to changes in pH, caused by changes in charge distribution, similar to a photoexcitation. When adsorbed to titania membranes, this would allow the network structure to change its apparent pore size by changing the light present. Different attachment geometries and lengths of PAA were calculated and their steric effects were observed as a function of changing charge. Steric effects followed the changes in charge, the same as would occur with changing pH. This indicates a photo-responsive membrane can be created from this system.