Pt nanoparticles immobilized on a cobalt-doped Zif8 manganese tetraphenylporphyrin bentonite chitosan composite as a durable and poison-tolerant catalyst for ethanol electrooxidation

In this research, a rationally designed multifunctional catalyst, denoted as Pt/Zif8-Co@MnTPP/Bnt-CH, was successfully synthesized. This catalyst integrates platinum nanoparticles within a cobalt-doped Zif8 metal–organic framework, along with manganese tetraphenylporphyrin (MnTPP) immobilized onto a bentonite-chitosan (Bnt-CH) support. The unique architecture of Pt/Zif8-Co@MnTPP/Bnt-CH exploits the high surface area and structural robustness of the Co-doped Zif8 framework, the electron-mediating function of MnTPP for promoting multi-electron transfer, and the dispersive benefits of the Bnt-CH matrix. Comparative electrochemical assessments for ethanol electrooxidation, conducted against Pt/Bnt-CH, Pt-TPP/Bnt-CH, and Pt-MnTPP/Bnt-CH, demonstrate that the newly developed catalyst exhibits superior electrochemically active surface area, anodic mass activity, operational durability, and poison tolerance under prolonged cycling. Mechanistic insights reveal a synergistic interplay among Co centers, MnTPP moieties, and Pt sites in the Zif8-Co framework. This synergy improves the accessibility of active sites, facilitates interfacial electron transfer, mitigates intermediate accumulation, and accelerates charge-transfer kinetics with a lowered activation barrier. The catalyst also displays excellent tolerance to variations in ethanol concentration and reaction temperature. These attributes establish Pt/Zif8-Co@MnTPP/Bnt-CH as a highly promising anode material for advanced direct ethanol fuel cell applications.