High-Performance Organometallic Catalyst Based on Nickel Porphyrin/Carbon Fibre for the Oxygen Reduction Reaction
Ibrahim Elghamry, Abdulrahman S. Alablan, Mohammed A. Alkhalifah, Mamdouh E. Abdelsalam
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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>π</mml:mi> <mml:mo>−</mml:mo> <mml:mi>π</mml:mi> </mml:math> stacking interaction. The composite catalyst shows well-defined redox peaks attributed to the Ni 2+ /Ni 3+ redox couple in O 2 -saturated 0.1 M KOH solution. The area under the reduction peak is used to calculate a surface coverage ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="normal">Г</mml:mi> </mml:math> ) of 2.43 × 10 15 for the Ni 2+ /Ni 3+ 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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi mathvariant="normal">HO</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> yield are found to be, 0.82 V vs RHE, 3.6 electrons and 22.0% respectively.