Sandwich-Structured MXene/Carbon Hybrid Support Decorated with Pt Nanoparticles for Oxygen Reduction Reaction

Carbon supports for cathodic catalysts in proton-exchange membrane fuel cells suffer from rapid corrosion and instability; therefore, alternative supports with a stable structure and a high electric conductivity are highly required. In this paper, a three-dimensional support hybridized by MXene and Ketjen Black is developed, in which Ketjen Black is sandwiched between MXene nanosheets (MCM). After decorating with Pt nanoparticles by a facile wet-chemical approach, a three-dimensional (3D) Pt/MCM catalyst is obtained. The intercalated Ketjen Black prevents the stacking of MXene nanosheets, thus increasing the specific surface area of the catalyst and exposing the active sites. The strong interaction between functionalized MXene nanosheets and Pt nanoparticles further enhances its intrinsic electrocatalytic activity. Pt/MCM demonstrated encouraging ORR activity with the half-wave potential and specific activity of 0.892 V and 0.377 mA·cm^-2, respectively, surpassing the state-of-the-art Pt/C catalysts. Especially, Pt/MCM achieves ultrahigh durability with a 1 mV decrease in half-wave potential and a 1.73% decrease in mass activity after an accelerated durability test. Given the performance and structure-activity relationships of Pt/MCM, it holds great potential for various energy and catalysis-related applications.