Bi-phasic photocatalyic particles have been prepared in the form of Janus-like structures (bi-phasic materials with two distinct properties on opposing sides of the particle) using a new synthetic procedure consisting of the sequential layer depositions of semiconductor oxide materials onto soluble substrates. A number of different systems have to date been investigated with an aim of photocatalytic applications. A general synthetic regime consists of utilising simple sol-gel chemistry to deposit sequential layers of photocatalytic material on top of a soluble substrate. The substrate can subsequently be removed yielding extremely fragile disks that fracture into bi-phasic powders of Janus like particles. These particles have two unique sets of properties contained in different faces of the same particle, aimed at the simultaneous reduction and oxidation of toxic species in water. This new synthetic technique is investigated for photocatalyic applications with an eye to efficient water purification, utilising the synergistic effect of the two materials to create highly effective photocatalysts. The photocatalytic activity of anatase/rutile (TiO2) bi-phasic nanoparticle composites enhanced with platinum and deposited on the surface of polycarbonate filters has been successfully demonstrated. Deposition of the photocatalyst on filters overcomes expensive and time consuming recycling processes, adds porosity to the set up and reduces the scattering of nanoparticle dispersions.