Polyacrylonitrile-based electrospun nanofibers carrying gold nanoparticles in situ formed by photochemical assembly

Polyacrylonitrile (PAN) nanofibrous fabrics carrying gold nanoparticles (AuNPs) were prepared via the combination of electrospinning of PAN solution containing HAuCl₄ and in situ gold formation induced by ultraviolet (UV) irradiation. The factors to control the diameter of AuNPs were first investigated, and then their applicability to catalytic reaction using the obtained fibers was presented. The initial contents of Au ranging from 3 to 21 wt% did not exert a significant effect on the size of AuNPs formed in/on the PAN fibers, giving 4.7–5.4 nm in diameter, for 5 days of UV irradiation. On the other hand, the sizes of formed AuNPs were found to change from 5.2 to 2.7 nm with varying UV irradiation time from 5 to 1 day. The first-order rate constants obtained for the reduction of 4-nitrophenol increased from 1.1 × 10⁻³, 3.5 × 10⁻³ to 4.0 × 10⁻³ s⁻¹, under a fixed volume of the fibers with AuNPs as catalysts, with increasing content of Au from 3, 13 to 21 wt%. The PAN catalysts with decreased size of AuNPs obtained through 1 day of UV irradiation gave a higher rate constant of 2.7 × 10⁻² s⁻¹. The highest rate constant per Au content and turnover frequency obtained in this study were 8.3 × 10⁻² s⁻¹ μmol-Au⁻¹ and 71 h⁻¹, respectively.