Atomically thin Pt nanolayers were synthesized on the surface of Mo₂TiC₂ MXenes and used for the catalytic dehydrogenation of ethane and propane into ethylene and propylene, two important chemicals for the petrochemical industry. As compared with Pt nanoparticles, the atomically thin Pt nanolayer catalyst showed superior coke-resistance (no deactivation for 24 h), high activity (turnover frequencies (TOFs) of 0.4–1.2 s⁻¹), and selectivity (> 95%) toward ethylene and propylene. The unique Pt nanolayer has a similar geometric surface to Pt nanoparticles, enabling the investigations of the electronic effect on the catalytic performance, where the geometric effect is negligible. It is found that the electronic effect plays a critical role in dehydrogenative product selectivity and catalyst stability. The metal–support interaction is found dependent on the substrate and metal components, providing wide opportunities to explore high-performance MXene-supported metallic catalysts.

Hydrogen economy, as the most promising alternative energy system, relies on the hydrogen production through sustainable water splitting which in turn relies on the high efficiency electrocatalysts. PtAuCu A1-phase alloy has been predicted to be a promising electrocatalyst for the hydrogen evolution. As such preferred phase of Pt-Au-Cu is not thermodynamically favored, herein, we stabilize PtAuCu alloy by engineering the high-entropy phase in the form of nanowire. Density functional theory (DFT) calculations indicate that, in comparison with the ordered phase and segregated phases with discrete hydrogen binding energy, the high-entropy phase provides a diverse combination of site composition to continuously tune the hydrogen binding energy, and thus generate a series of highly active sites for the hydrogen evolution. Reflecting the theoretical prediction, electrochemical tests show that the A1-phase PtAuCu nanowire significantly outperforms its nanoparticle counterpart with phase segregation, toward the electrocatalysis of hydrogen evolution, offering one of the best hydrogen evolution electrocatalysts.