A versatile strategy to fabricate MOFs/carbon material integrations and their derivatives for enhanced electrocatalysis

Abstract

We developed a new versatile strategy to fabricate metal–organic frameworks (MOFs)/carbon materials (CMs) integrations (rather than direct mixtures) based on the non-selective adhesive action and bidentate chelating action of polydopamine (PDA) for the first time. More significantly, the resultant MOFs/CMs integrations can be bridged based on the remaining self-polymerization action of dopamine. The final morphology of the integration depends on the shape of the chosen CMs. Based on this strategy, we successfully synthesized a new 3D network composed of bridged multi-walled carbon nanotubes (MWCNTs) with omnibearing wrapped side-by-side ZIF-8 crystals (one typical MOF) on them. After calcination, the metal-free integration can be utilized as an oxygen reduction reaction (ORR) electrocatalyst without any modification. The most remarkable features of our catalyst are the high porosity derived from the remaining ZIF-8 crystal structure, the sufficient and uniform exposed nitrogen-containing active sites derived from PDA and ZIF-8, and the extensive conductive pathway derived from the bridged MWCNT support. As a result, our catalyst, which is devoid of any metals, exhibits high ORR activity comparable to that of existing state-of-the-art Pt/C catalysts in alkaline solution (half-wave potential of −0.19 V, current density of 5.68 mA cm⁻²) as well as superior durability and tolerance to methanol than Pt/C catalyst.