Ultrathin PtSe ₂ Nanowires in Single‐Walled Carbon Nanotubes for Hydrogen Evolution Reaction

Platinum selenide (PtSe₂) has shown great potential for application in electrocatalysis. One-dimensional (1D) nanostructures are particularly advantageous for enhancing catalytic performance, as they expose abundant active sites at the edges and enable rapid charge transport. However, the synthesis of 1D PtSe₂ nanostructures for efficient electrocatalysis remains a challenge. Here, we report the controllable synthesis of ultrathin (0.4-2.0 nm) PtSe₂ nanowires (NWs) using single-walled carbon nanotubes (SWCNTs) as a confined template via direct selenization by chemical vapor deposition (CVD). The atom-resolved electron microscope combined with spectroscopy and theoretical calculations revealed that PtSe₂ NWs grow anisotropically along the <110> direction inside the SWCNTs, possessing zigzag edges and higher thermodynamical stability. Owing to the rich-edges with abundant unsaturated Pt atoms, the as-prepared PtSe₂ NWs exhibit excellent hydrogen evolution reaction (HER) activity at an extremely low Pt loading of 4.684 wt%, with an overpotential of 47 mV@10 mA cm^-2 and a Tafel slope of 41.7 mV dec^-1. This work provides a novel strategy for synthesizing 1D ultrathin NWs and offers the potential to achieve low-cost and efficient Pt-based catalysts in the future.