Different electrode modification protocols for evaluating the water-splitting properties of a P(V)-metalloporphyrin

Water electrolysis is currently a notable research domain, having the identification of highly active, stable, and low-cost electrocatalysts as one of its most important pursuits. Herein, an A4 P(V)-centered metalloporphyrin ? (5,10,15,20-tetraphenylporphinato) dichlorophosphorus (V) chloride ? was evaluated in terms of its electrocatalytic water-splitting activity in acidic, neutral and alkaline media. The experiments were performed on electrodes modified with the porphyrin complex using different protocols, and the most electrocatalytically active sample was the one obtained by applying a catalyst ink containing the metalloporphyrin and carbon black on glassy carbon. The best results were observed for the strongly alkaline medium (1 mol L-1 KOH), in which the electrode exhibited a hydrogen evolution reaction overpotential of 0.77 V and a Tafel slope of 0.135 V dec-1. Its stability was outlined by chronoamperometry and Raman spectroscopy. The results supplement the available data regarding the properties and applicative potential of metalloporphyrins and outline the implications of using different electrode manufacturing procedures.