Vertically Aligned Pt/MXene/Carbon Nanotubes Aerogels for Superior Hydrogen Evolution Reaction

Herein, we propose a one-step directional-freezing strategy to fabricate 3D vertically aligned aerogel (VA) of Ti3C2Tx MXene/carbon nanotubes (MC) decorated with small Pt species (denoted as Pt@MC-VA) as a self-standing electrode for robust electrocatalytic hydrogen evolution reaction (HER) at ampere-level current density. Numerous small Pt nanoclusters and single-atoms species are spontaneously reduced and anchored on the aerogel skeleton, revealing high intrinsic activity. The MXene nanosheets firmly fixed by carbon nanotubes cooperatively construct the porous frameworks, which greatly reinforces the overall mechanical strength and serves as high-speed path for electron transport. Moreover, the 3D self-supported and super-wettable frameworks with vertically aligned and run-through microchannels significantly facilitate the electrolyte infiltration and the immediate removal of gaseous products at high current densities. Based on these combined advantages, the Pt@MC-VA electrode exhibits a significantly improved electrocatalytic activity with overpotentials as low as 208 and 249 mV to reach high current densities up to 500 and 1000 mA cm-2, respectively, and a good long-term stability for at least 24 h at 500 mA cm-2.