Electrochemical hydrogen evolution on polypyrrole from alkaline solutions

Thin films of conductive polypyrrole (PPy) were formed electrochemically from aqueous sulfuric acid. The films showed good electrocatalytic properties towards hydrogen evolution (h.e.r) from alkaline solutions on planar and packed-bed iron electrodes. Current–potential relations were measured at various temperatures and KOH concentrations on Fe, Ni and Fe/PPy planar electrodes. The current was found to be constant during 40 h of operation. SEM micrographs showed no difference in the morphology before and after this period. The activation energy for h.e.r. was found to be 50.2, 58.5 and 33.4 kJ mol^–1 for Fe, Ni and Fe/PPy planar electrodes, respectively. The results showed that Fe/PPy can be used to produce hydrogen at both ambient and relatively high temperatures 70 C. The polypyrrole coating on iron screens was found to reduce the potential required to sustain a specific rate of hydrogen generation and, hence, the energy consumed during the process.