Comments on the paper “Electrooxidation of borohydride on platinum and gold electrodes: Implications for direct borohydride fuel cell” by E. Gyenge, Electrochim. Acta 49 (2004) 965: Thiourea, a poison for the anode metallic electrocatalyst of the direct borohydride fuel cell?

Abstract

The present discussion paper deals with the Gyenge's [E. Gyenge, Electrochim. Acta 49 (2004) 965] suggestion to add thiourea (H 2N–CS–NH 2) to the borohydride fuel of the direct borohydride fuel cell (DBFC). It is expected that thiourea inhibits the hydrogen evolution (stem from the borohydride hydrolysis, a side reaction) that occurs at the anode of the DBFC where in fact it is expected the direct oxidation of borohydride. However, thiourea is an organic sulphur compound and it is well known that the sulphur species are poisons for the metallic catalysts. Hence, the present discussion paper asks a question: may thiourea and the sulphur species stem from its decomposition act as poisons of metallic sites of catalysts used as DBFC anodes?