Catalytic Properties of Free-Base Porphyrin Modified Graphite Electrodes for Electrochemical Water Splitting in Alkaline Medium

Hydrogen generation via electrochemical water splitting is considered an eco-friendly pathway for obtaining this desired alternative energy source, and it has triggered intensive search low cost efficient catalysts. Within context, four free-base porphyrins were studied as heterogeneous catalysts the oxygen hydrogen evolution reactions (OER HER) in alkaline aqueous solutions. TEM STEM analyses of samples obtained by drop-casting from different organic solvents on grids revealed a rich variety aggregates due to self-assembling property porphyrin molecules. Modified electrodes manufactured applying tetrapyrrolic macrocycles various surface graphite supports, one or more layers. Experiments performed 0.1 M 1 KOH electrolyte solutions allowed identification most electrocatalytically active OER HER, respectively. In first case, electrode was three layers 5-(4-pyridyl)-10,15,20-tris(4-phenoxyphenyl)porphyrin substrate N,N-dimethylformamide solution identified overall catalytically superior. second layer 5,10,15,20-tetrakis(4-allyloxyphenyl)-porphyrin benzonitrile displayed HER overpotential value 500 mV at i = −10 mA/cm2 Tafel slope 190 mV/dec.