In addition, we investigated whether the trace amounts of palladium detected by ICP-OES act as co-catalysts during photocatalysis. To that end, we treated TT-TAB with tetramethylethylenediamine (TMEDA), a potent chelating agent, to remove accessible palladium from the polymer matrix. After three days of TMEDA extraction, the palladium content in TT-TAB dropped by 28% (from 1.19 wt% to 0.86 wt% as determined by ICP-OES). Commensurately, we observed a 31% drop in the rate of hydrogen evolution using the Pd-depleted photocatalyst (Figure ). Longer periods of TMEDA-treatment did not result in a further, significant decrease of Pd-content (up to 0.76% after six days), indicating a thermodynamic and kinetic limit to the amount of palladium which can be removed using this diffusion-controlled method. We surmise that in our SBP samples palladium assumes the role of an efficient co-catalyst, in particular, since further addition of conventionally-used platinum does not lead to significant improvement of photocatalytic action.