Rapid flash Joule heating synthesis of Pt-doped carbon fibers for efficient hydrogen evolution in acidic and alkaline media

초록

Developing highly active, pH-universal electrocatalysts for the hydrogen evolution reaction (HER) is challenging because water dissociation kinetics are slow in alkaline environments. This work introduces a scalable Flash Joule Heating (FJH) method to synthesize efficient Pt-doped carbon nanofiber (Pt-CF) catalysts for HER in both acidic and alkaline electrolytes. Characterization results show that adjusting the FJH voltage allows precise control of the Pt electronic structure and the metal-carbon interface. The 150 V/Pt-CF sample exhibited a higher platinum loading (5.41 wt%) and primarily consisted of metallic Pt0. In comparison, 200 V/Pt-CF catalyst showed a lower Pt loading (3.61 wt%) and contained both Pt0 and Pt2+. The results indicate that applied voltage influences the Pt oxidation state and surface chemistry. Electrochemical measurements reveal clear pHdependent behavior. In acidic media (0.5 M H2SO4), 200 V/Pt-CF catalyst shows faster HER kinetics, indicated by a lower Tafel slope (23.43 mV dec-1) and a slightly reduced overpotential (56 mV at 10 mA cm-2). Under alkaline conditions (1.0 M KOH), 150 V/Pt-CF catalyst performs better, requiring only 25 mV to reach 10 mA cm2, with improved kinetics and higher intrinsic activity. This work provides a scalable strategy for designing highperformance metal-carbon electrocatalysts that are effective over a wide pH range via flash Joule heating.

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