As a first step, TiO2|Pt photocatalyst panels were prepared by a modified literature method. Frosted glass panels (4.5 × 4.5 cm 2 ) were cleaned by sonication in MilliQ ® water, isopropanol and acetone, 15 min in each, respectively and then dried under gentle N2 flow. The TiO2|Pt photocatalyst was dispersed in ethanol (20 mg mL -1 ) by probe-sonication (10 min, pulses of 30 s at 100% amplitude followed by 5 s pauses) followed by the addition of 1 vol.% Nafion TM solution (5 wt.%) to the resultant mixture. The dispersion was carefully drop-casted onto clean frosted glass (total of 16 µL cm -2 at a time) and dried for 10 min before the addition of subsequent layers (a total of 6 layers were added; final catalyst loading of ~1.92 mgcat cm - 2 ). The prepared TiO2|Pt panels were then annealed at 80 ºC overnight in air.