Next, the quenching efficiency of PS by the anionic POM-PtI was compared with the quenching behavior of the charge-neutral [Pt(bpy)I2] reference (Figure ). Here, POM-PtI showed a significantly higher quenching efficiency compared to the reference compound. This supports the suggestion that electrostatic attraction of PS and POM-PtI in solution can be used to enhance electronic interactions of the reaction partners following photoexcitation of the PS. This observation also supports the HER catalytic findings, where POM-PtI shows significantly higher reactivity than the [Pt(bpy)I2] reference (Figure ).