Is Base-Inhibited Vapor Phase Polymerized PEDOT an Electrocatalyst for the Hydrogen Evolution Reaction? Exploring Substrate Effects, Including Pt Contaminated Au

Studies of the hydrogen evolution reaction (HER) were carried out on base-inhibited vapor phase polymerized (BI-VPP) poly(3,4-ethylenedioxythiophene) (PEDOT)-poly(ethylene glycol) (PEG) thin films synthesized on several substrates, including gold, glassy carbon, and titanium, in an acidic electrolyte. The proton reduction overpotential became smaller and the current−potential (i-E) scans moved toward the thermodynamic potential with time. However, they did not move below the proton reduction potential of the substrate. Collectively, the results suggested to us that the polymer film was porous and that the porosity increased with time when the electrode was immersed in solution, with the hydrogen evolution catalysis taking place on the conducting substrate beneath the polymer rather than on our BI-VPP PEDOTPEG thin films. Comparison of the HER on gold substrates with different impurities was also studied and traces of Pt and Pd at the ppm level significantly improved the HER activity of Au.