Abstract:

Objective This study aims to investigate the influence of different silk fibroin precursors (woven fabric (F-P), natural cocoon (C-P), degummed silk (D-P), regenerated film (R-P) on catalyst structure and hydrogen evolution reaction (HER) performance. In order to address the issure of textile waste valorization, this research clarifies how precursor morphology regulates metal loading behavior and carbon matrix defects, as an attempt to provide theoretical basis for designing high-performance textile-based electrocatalysts.
Method Silk fabric-derived catalyst (F-C), cocoon-derived catalyst (C-C), degummed silk fibroin-derived catalyst scanning electron microscopy and regenerated film-derived catalyst (R-C) were prepared from silk precursors by KCl activation, Co salt impregnation, and carbonization/sulfidation. Morphology was observed by scanning electron microscopy (SEM), and composition and structure were analyzed by Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction(XRD). Hydrogen evolution reaction (HER) performance was evaluated via double-layer capacitance (C_dl), linear sweep volta mmetry (LSV) polarization curves, Tafel slopes, and electrochemical impedance spectroscopy (EIS) in 0.5 mol/L H₂SO₄ electrolyte.
Results Different forms of precursors exhibited different surface structure characteristics before and after carbonization. The microscopic morphology of the precursor was found to affect the growth of metal sulfides during the impregnation process, with various shapes such as needle-like bouquets, flower buds blocks, strips, and uneven loading. Different forms of precursors formed Co₃S₄ spinel sulfide as the main active component on the surface of the impregnated loaded metal, and the main body of the precursor was transformed into a carbon skeleton after carbonization. The chemical composition of the catalyst materials was basically the same, but with different defect structures and degrees of graphitization, among which the degummed silk fibroin-derived sample D-C showed the highest degree of graphitization. Silk fibroin-based carbon materials exhibited excellent electrocatalytic activity in HER electrocatalysis, but differences exist in Tafel slope and impedance, etc. In general, the catalyst D-C derived from degumming silk fibroin as a carbon precursor demonstrated the best electrocatalytic activity, and the overpotential η₁₀ value was only 235 mV.
Conclusion The loose and smooth degummed silk fibroin fibers significantly enhance activation efficiency and metal loading density, enabling D-C catalysts to achieve high surface area, graphitization, and abundant Co₃S₄active sites for superior HER performance. This study confirms precursor morphology as a key factor in regulating textile-based electrocatalysts, offering a novel approach for silk waste valorization.

Key words: precursor, silk fibroin-based carbon material, hydrogen evolution reaction, silk, electro-catalytic property, catalyst, carbonization