Activated carbon is synthesized using orange peel as precursor through chemical activation using H3PO4 and its ability as electrocatalyst support for ORR reaction is examined. The prepared material was subjected to various structural, compositional, morphological and electrochemical studies. For ORR activity, the platinum loaded on activated carbon (Pt/OP-AC) was investigated by cyclic voltammograms (CVs) recorded in N2 and O2 saturated 0.1 M aqueous HClO4. For supercapacitor performance, three electrode systems was tested in aqueous H2SO4 for feasibility determination and showed electrochemical double layer capacitance (EDLC) behaviour which is expected for activated carbon like materials. Electrochemical surface area (ECSA) of the activated carbon from orange peel is measured using CV. The physical properties of the prepared carbon are studied using SEM (scanning electron microscope), XRD (X-ray diffraction), Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy. The AC derived from orange peels delivered a high specific capacitance of 275 F g−1 at 10 mV s-1 scan rate. Hence, this study suggested that orange peels may be considered not only as a potential alternative source for synthesizing carbon supported catalyst for fuel cell application but also highlight the production of low-cost carbon for further applications like supercapacitors

High cost of benchmarked platinum-based electro-catalyst restricts their extensive usage in various energy technologies such as fuel cell. To overcome this, we report a simple, economical and facile synthesis route for a series of edge-defective nitrogen doped graphene (NG) from graphene oxide in the presence of melamine as a nitrogen precursor. The oxygen reduction reaction activity of NG in alkaline medium is studied with varying GO to melamine ratio to optimize the N-content in the graphene sheet. Cyclic voltammograms and linear sweep voltammograms have been recorded in N₂/O₂ saturated 0.1 M aqueous KOH electrolyte. It is observed that N-doped graphene exhibits a favorable formation of hydroxide ions through a four electron transfer process as confirmed from both rotating disk and rotating ring-disk electrode measurements. The stability of the optimized NG catalyst is ascertained by cycling the potential between −0.8 and 0.2 V vs. Ag/AgCl upto10,000 potential cycles and found to have better durability in comparison to the commercial Pt/C catalyst. The resultant N-doped graphene is used as cathode catalyst for fabricating membrane electrode assembly (MEA) and the performance is evaluated in an anion exchange membrane fuel cells (AEMFCs) at 60°C under ambient pressure.

Nitrogen and fluorine co-doped graphite nanofibers (N/F–GNF) and their cumulative effect with Fe and Co have been developed as an alternative non-precious metal catalyst for efficient oxygen reduction reaction (ORR) in acidic media. The synergistic effect between the doped hetero atoms and the co-ordinated Fe and Co towards ORR activity and durability of the catalyst is deeply investigated. A high ORR onset potential comparable with commercial Pt/C catalyst is observed with the Fe–Co/NF–GNF catalyst, which indicates that this catalyst is a potential alternative to Pt/C. A fivefold increase in mass activity is achieved by the Fe–Co/NF–GNF catalyst compared to the simple N/F–GNF catalyst, which endorses the significant role of transition metal atoms in enhancing ORR activity. The advanced Fe–Co/NF–GNF catalyst also exhibits complete tolerance to CH₃OH and CO. The Fe–Co/NF–GNF catalyst also exhibits excellent durability towards the ORR with only a 10 mV negative shift in its half wave potential after a 10 000 repeated potential cycling test, whereas in the case of a commercial Pt/C catalyst there was an ∼110 mV negative shift under similar environmental conditions. More stringent corrosive test cycles were also performed by maintaining the cell as high as 1.4 V with a later decrease to 0.6 V vs. RHE for 300 cycles, which showed the excellent durability of the Fe–Co/NF–GNF catalyst in comparison with the Pt/C catalyst. XPS analysis of the Fe–Co/NF–GNF catalyst presents the ORR active chemical states of N (pyridinic-N and graphitic-N) and F (semi-ionic-F) and the co-ordinated sites of Fe and Co species with the dopants. The excellent performance and durability of the Fe–Co/NF–GNF catalyst is due to the synergistic effect between the hetero atoms dopants (N and F) and strong co-ordinating bonds of M–N–C, which protect the graphene layers around the metallic species and greatly mitigates the leaching of Co and Fe during the long term cycling test. The high activity and long term durability of the Fe–Co/NF–GNF catalyst make it a promising ORR electrocatalyst for the fuel cell cathode reaction.