Strong Interactions between Flash Subnanometer Carbide Nanowires and Single-Walled Carbon Nanotubes for Catalysis.

Zhu, Sheng; Li, Lan; Zan, Wenyan; Zhang, Xuehuan; Zhang, Xinrui; Deng, Bing; Han, Gaoyi; Li, Yan · ACS Nano · 2025

basic_science · Level V

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Abstract

The synthesis of transition metal carbides with precise control over their dimension, morphology, and crystallinity at a subnanometer scale presents a significant challenge. Addressing this, a kinetics-controlled confined flash Joule heating method has been developed, characterized by superfast heating (>2000 K ms<sup>-1</sup>) and cooling (>30 K ms<sup>-1</sup>) rates, enabling the millisecond-scale production of subnanometer molybdenum carbide nanowires. These one-dimensional structures are synthesized through a carbothermic reduction of encapsulated polymolybdate cluster arrays, a process that eschews the need for solvents, catalysts, or special gases, utilizing single-walled carbon nanotubes (SWNTs) as both thermal conductors and structural templates. The resulting carbide-encapsulated SWNTs feature a delocalized, electron-rich surface that is ideal for the stable immobilization of iron phthalocyanine (FePc) molecules. The MoC<sub><i>x</i></sub>@SWNT-FePc complex demonstrates enhanced electrocatalytic activity in the alkaline oxygen reduction reaction, boasting a high half-wave potential of 0.91 V and long-term durability in zinc-air batteries, exceeding 450 h. Further, a type of Pt<sub>1</sub>/MoC<sub><i>x</i></sub>@SWNT chainmail catalyst has been achieved and showcases exceptional catalytic efficiency in the acidic hydrogen evolution reaction. It exhibits a high mass activity of 4.84 A mg<sub>Pt</sub><sup>-1</sup>, a low Tafel slope of 37.4 mV dec<sup>-1</sup>, and sustained durability over 350 h.