High-Performance Organometallic Catalyst Based on Nickel Porphyrin/Carbon Fibre for the Oxygen Reduction Reaction

Abstract

Development of efficient non-precious metals catalysts for the oxygen reduction reaction (ORR) has attracted considerable attention. A composite catalyst based on nickel- 5,10,15,20-tetra(p-thioanisole) porphyrin complex (Ni-TPT-P) and carbon fibres (CF) is here investigated for the ORR. The porphyrin is synthesised by a one-pot multi-step approach. Ultraviolet-visible (UV–vis) and fourier-transform infrared (FTIR) techniques are used to confirm the synthesis of the Ni-TPT-P complex. The metalloporphyrins (Ni-TPT-P) are non-covalently adsorbed on the CF via π − π stacking interaction. The composite catalyst shows well-defined redox peaks attributed to the Ni2+/Ni3+ redox couple in O2-saturated 0.1 M KOH solution. The area under the reduction peak is used to calculate a surface coverage ( Г ) of 2.43 × 1015 for the Ni2+/Ni3+ species on the catalyst surface area. The rotating ring disk electrode (RRDE) technique is used to assess the performance of the catalyst towards the ORR. Key performance indicators such as the onset potential, average number of electrons and HO 2 − yield are found to be, 0.82 V vs RHE, 3.6 electrons and 22.0% respectively.