N-Doped Reduced Graphene Oxide Composites for Hydrogen Generation in Presence of Chloride Ion Impurities in Alkaline Medium

Abstract

The depletion in fossil fuel reserve leads to the search for a clean, alternate fuel which can replenish the energy demand without causing greater harm to the environment. Hydrogen is one such kind of promising sustainable energy fuel which can be produced from very cheap resources like water. The major hurdle behind the efficient and economical production of hydrogen through electrochemical conversion of water is the large thermodynamic overpotential related to it. Enormous volume of researches has been carried out towards the development of catalysts, improving support materials efficiency and electrochemical environment related to hydrogen evolution reaction (HER). In this work we are going to present a catalyst which shows appreciable enhancement in the electrochemical activity towards HER in alkanine medium and can withstand very high chloride ion impurities in operating conditions. Often, the performance and durability of a fuel cell are greatly influenced by the presence of impurities present in the feed stock, air stream or other components of fuel cell. Among the different contaminants chloride (Cl-) ion is one of the serious impurities which can diffuse through the gas diffusion system and can poison the electrocatalysts and membrane and ultimately leads to the decrease performance of the fuel cell system. Hence it is important to develop a robust catalyst which will have dual functionalities. Along with enhanced performance, it also should be able to withstand the extreme poisoning effect during hydrogen evolution reaction. In comparison to un-doped reduced graphene oxide (RGO)–Pt composites and commercial Pt /C catalysts, the nitrogen-doped graphene oxide (NGO)-Pt composites show low overall potential towards HER both in acidic and alkaline environment. Electro-catalytic performance of the prepared cathodes has been investigated by hydrogen evolution reaction in 0.1M perchloric acid, 0.5 M sulfuric acid and 0.1molar KOH solution. The controlled exposure of chloride ion impurities shows under similar condition NGO-Pt shows better stability and less reduction of electrochemical surface area (ESA) and hence less susceptible towards chloride poisoning under identical conditions. The loss of electrochemical surface area (ESA), before and after chloride poisoning, is much less in case of NGO-Pt . Figure 1 shows the comparison between the RGO-Pt,commercial-Pt and NGO-Pt for loss of ESA. Figure 1