Sub‐Nanometer Pt Nanowires with Disordered Shells for Highly Active Electrocatalytic Oxidation of Formic Acid

Abstract Controlled synthesis of one‐dimensional materials at atomic‐scale dimensions represents a milestone in nanotechnology, offering the potential to maximize atom utilization while enhancing catalytic performance. However, achieving structural stability and durability at such fine scales requires precise control over material structure and local chemical environment. Here, we introduce dimethylamine (DMA) as a small‐molecule modifier, in contrast to conventional long‐chain surfactants, to interact with surface Pt atoms. This approach facilitates the removal of surface Pt atoms bonded to nitrogen atoms in DMA during solubilization in water, effectively stripping the size of Pt nanowires down to sub‐nanometer. The resulting Pt subnanometer nanowires (subNWs) feature a monoatomic‐layer surface composed of disordered, bonding‐unsaturated Pt atoms, and an interior crystalline core as narrow as 0.58 nm in diameter. These unique structural characteristics confer the Pt subNWs with an electrochemically active surface‐area of 189 m2 ⋅ g−1 during formic acid oxidation. Furthermore, the amorphous‐like surface structure lowers the free energy of *OCOH intermediates and inhibits the formation of toxic byproducts CO, demonstrating exceptional electrocatalytic activity of 18.1 A ⋅ mg−1, surpassing most reported Pt‐based electrocatalysts. Our work introduces a novel strategy for the controlled construction of nanowire‐structures at sub‐nanometer scale, effectively bridging the gap between ultrafine structural design and performance stability.