Electro-oxidation of tri(ammonium) phosphate: New hydrogen source compatible with Ni-based electro-catalysts

摘要

Predominantly, the reported Ni-based electro-catalysts are not applicable anode materials for the alcohols-based proton exchange membrane fuel cells due to the high onset potentials. Alternatively, these non-precious materials can be exploited for hydrogen generation from alcohols with small biases. However, as the nickel oxy(hydroxide) active species is a reactant in the alcohols electro-oxidation reactions, so these materials are exhausted and have to be regenerated. Recently, hydrogen could be extracted from tri(-ammonium) phosphate using Ni/C nanostructures as effective catalysts in a simple batch reactor. In this study, electro-oxidation of tri(ammonium) phosphate using Ni-decorated graphene is investigated. The utilized catalyst has been prepared by simple one-pot synthesis procedure; calcination of well mixed nickel acetate/commercial sugar composite. The results indicated that the prepared Ni-decorated graphene is an effective electro-catalyst for tri(ammonium) phosphate oxidation when the nickel content is optimized; 3 wt metal is the best composition. Moreover, chronoamperometry analysis results indicated that the active layer is not being consumed during the electro-oxidation reaction of the tri(ammonium phosphate) which creates a distinct advantage for this fertilizer over alcohols. Stability of the active layer is attributed to performing Ni(OH)_2/Ni(OOH) redox reaction during tri(ammonium) phosphate electro-oxidation process. Overall, the study opens a new avenue for utilizing hydrogen-rich, cheap and available substances for hydrogen generation using continuously-active non-precious electrodes.