Exploring dicyano-ferriprotoporphyrin as a novel electrocatalytic material for selective H2S gasotransmitter detection

Dicyano-ferriprotoporphyrin supported on Pt microelectrodes was investigated as a possible electrocatalytic material capable of selectively oxidizing the gasotransmitter H2S over interfering gasotransmitters CO and NO. The modified microelectrodes were able to detect H2S concentrations as low as 50 nM at a potential of 0.15 V vs. Ag/AgCl and demonstrated a 100–1000× higher sensitivity toward H2S than CO and NO, respectively. However, H2S detection was affected by the presence of CO and NO due, at least in part, to imperfect coverage of the underlying Pt microelectrode by the electrocatalyst. Incomplete CN− coordination and questionable stability of the porphyrin layer are also discussed as possible causes of CO and NO interference. Work is on-going to alleviate these limitations in order to fully develop the material into a practical electrocatalyst capable of selective H2S oxidation.

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► Dicyano-ferriprotoporphyrin ((CN)2-FePP) modified electrodes oxidized H2S at 0.15 V.
► H2S concentrations as low as 50 nM H2S was detected in phosphate buffer saline.
► The sensitivity toward H2S was 100–1000× higher than that toward CO and NO.
► H2S response for modified electrodes decreased when in the presence of CO and NO.