(c) Titanium dioxide is commonly used as a photocatalyst in the remediation of waste-water, self-cleaning windows and other surface-cleaning applications. (i) Outline the mechanism of metal oxide photocatalysis for the degradation of organic matter on a surface that incorporates a metal oxide film such as titanium dioxide. (ii) (iii) Name two materials that can be added to titanium dioxide to increase its effectiveness as a photocatalyst. Discuss how these two materials lead to such an effect, using a diagram if required. [20 marks] (c) Titanium dioxide is commonly used as a photocatalyst in the remediation of waste-water, self-cleaning windows and other surface-cleaning applications. (i) Outline the mechanism of metal oxide photocatalysis for the degradation of organic matter on a surface that incorporates a metal oxide film such as titanium dioxide. (ii) (iii) Name two materials that can be added to titanium dioxide to increase its effectiveness as a photocatalyst. Discuss how these two materials lead to such an effect, using a diagram if required. [20 marks]