Template-based synthesis of porous and wrinkled Pt-supported MXenes for enhanced bifunctional electrocatalysis of the ORR and HER

Abstract

This study proposes a novel strategy to develop a platinum-supported, highly porous MXene (Pt/PMx) catalyst via a “template-based transformation” approach and evaluates its bifunctional electrocatalytic properties for the oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER). The strategy introduces defects into nitrogen MXene sheets, enhancing their surface area and porosity. The synthesized PMx effectively mitigates the restacking of the MXene sheets and facilitates the uniform dispersion of the ultrasmall platinum nanoparticles across their surface. The Pt/PMx catalyst exhibits excellent ORR activity, achieving an onset potential (E_on) of 0.93 V (E_on for Pt/C = 0.94 V) in an acidic medium and 0.94 V (E_on for Pt/C = 0.92 V) in an alkaline medium, along with superior chronoamperometric stability for 40 000 s. Comprehensive evaluation of intrinsic parameters, including active surface area, mass activity, CO poisoning tolerance, and durability, via accelerated degradation tests confirms the robustness of the electrocatalyst support. The significant interaction between the Pt nanoparticles and the support enhances H⁺ adsorption and charge transport and, thereafter, HER activity, which is attributed to the improved porosity and conductivity of the support. The strong interaction between Pt and PMx was found to be the key for excellent stability towards the ORR (20 000 potential cycles) and HER (∼40 h). This synthesis strategy provides a unique and novel pathway for designing highly porous, conductive, and hydrophilic Pt-based catalyst supports for improved ORR and HER performance.