Electrospun nanofibers containing titanium dioxide (TiO2) were investigated as a self-detoxifying system consisting of polyacrylonitrile (PAN) and anatase TiO2 nanoparticles. Fibers were prepared by uniaxial and coaxial electrospinning to study the effect of nanoparticle placement on the detoxification activities of the photocatalyst. Coaxially spun fibers had the particles selectively placed in the sheath layer by electrospinning pure PAN solution and PAN/TiO2 solution as the core and sheath layer, respectively. Using scanning electron microscopy, X-ray microanalysis and X-ray photoelectron spectroscopy, it was confirmed that the coaxial approach resulted in the location of nanoparticles near the surface of the fibers compared to the uniform distribution obtained for uniaxial fibers. Photocatalytic activity of the fibers under ultraviolet irradiation was demonstrated by the degradation of aldicarb, as measured by high-performance liquid chromatography. In terms of degradation kinetics, the distribution density of TiO2 nanoparticles in the fiber surface region significantly affected the initial degradation rate, while the final decomposition amounts after 3 h did not differ significantly.