One-step preparation of microporous Pd@cPIM composite catalyst film for triphasic electrocatalysis

Triphasic microporous materials (containing solid, liquid, and gas) are of interest in electrocatalysis. In this exploratory study, a polymer of intrinsic microporosity (PIM-EA-TB) is impregnated with PdCl₄ ^{2 −} metal precursor and vacuum‑carbonised to give an electrically conductive microporous heterocarbon with embedded Pd nanoparticles of typically 10–30 nm diameter. This microporous composite catalyst is formed (via spin-coating) as “flakes” of typically 100 nm thickness and 1 to 20 μm diameter that are readily re-deposited onto glassy carbon electrode substrates. Due to the triphasic conditions, Pd@cPIM electrocatalytic reactivity is high but only for gases (H₂ oxidation or O₂ reduction). This selectivity is observed even in the presence of excess formic acid fuel in the aqueous/liquid phase. The potential for application in membrane-less micro-fuel cells is discussed.