Amino Acid Derived Fe Composited Electrocatalyst Towards Highly Efficient Oxygen Reduction Reaction

Global economic crisis and increased ecological concerns for clean and sustainable energy have emphasized on development of several energy conversion and storage devices such as water electrolysers,fuel cells and metal air batteries.In an effort to deploy the technological advancement,the development of novel energy materials is substantially vital.The fundamental aspect of these energy conversion devices is a series of electrochemical processes and among the imminent commercialized technologies,the sluggish cathode kinetics of oxygen reduction reaction limits the overall performance efficiency of fuel cells.The current technologies utilize platinum and its alloys but the scarcity,high price and instability due to low tolerance of methanol crossover hinders its mass commercialization.In pursuit for development of high performance non-precious electrocatalyst to replace Pt catalyst,this research work explores the synthesis and activity performance of renewable derived several amino acids codoped with Fe salts towards oxygen reduction reaction and zinc-air battery.Firstly,fourteen different amino acids doped with ferrous lactate salt were synthesized by template assisted hydrothermal mixing and two step pyrolysis at high temperature.The synthesized samples exhibited a wrinkled structure and dense aggregation of particle with moderate to poor performance towards ORR.Based upon the morphology,modification in precursors loading for Fe NC-Arginine,-Tryptophan and-Histidine improved half wave potential by 0.026 V,0.055 V and 0.018 V in comparison to the unmodified samples and morphology changed to a sponge like network and better dispersion.The improved activity performance attributed to the porous morphology and higher percentage of nitrogen doping.This work provides a platform that by further tuning the morphology and doping content amino acids can be utilized as potential materials for towards oxygen electro-reduction probing metal-air and batteries fuel cells.On basis of previous work,the second part of research utilize Histidine amino acid as single source of carbon and nitrogen precursor for facile synthesize of Fe-N-C electrocatalysts.Their detailed electrochemical performance is linked to the advance structural characterization of Fe-nitrogen interaction and mesoporous carbon framework The outstanding performance of Fe NC-L1 and Fe NC-A1 is comparable to benchmark Pt/C with E_1/20.816V and 0.840V V vs.RHE and corresponding j _L as5.4 m A cm^-2 and 5.71 m A cm^-2 along with superior stability performance（c.a response 88.2%and 95.0%）is linked to XPS spectral results to higher%of doped nitrogen as pyridinic content and Fe⁺² and Fe⁺³ oxidation state of iron as Fe N₄moieties which reduce oxygen absorption energy barriers to catalyse oxygen reduction reaction.In addition,maximal power density of 114.4 Wm cm^-2 and 98.7Wm cm^-2 of zinc-air battery,observed for Fe NC-A1 and Fe NC-L1.A high BET surface area extending up to 713.67 m²g^-1 and 985.99 m²g^-1 attributed to ultra-thin mesoporous carbon framework.