In addition to HOR and ORR activity, the catalyst stability under real electrochemical conditions is also a crucial factor to consider. In commercial Pt/C catalyst, Pt NPs undergo dissolution and aggregation (sintering) during long-term operation. The carbon support also becomes corroded under high oxidizing potentials which in turn promotes further NP sintering. This results in a loss of surface area and hence in a performance degradation. A good support thus should prevent sintering, dissolution, oxidation and corrosion under harsh electrochemical conditions. A strong orbital hybridization between cluster and support is required to stabilize the cluster, as well as excellent electrical conductivity to ensure a fast electron transport. On the above basis, twodimensional (2D) materials have recently emerged as promising novel support materials. 2D materials show unique properties compared with their analogous 3D counterparts for a number of reasons. First, they have a maximal surface to bulk ratio, providing a vast density of active sites. Second, they have excellent mechanical, carrier mobility, thermal diffusion, optical and phonon properties. And third, all these properties are highly tunable by introducing surface modifications owing to their anisotropy, i.e., they are confined to the 2D plane.