We have fabricated partially aligned free-standing mesoporous pure anatase TiO2 nanofiber mats (TiO2-NF) for photocatalysis by electrospinning on a rotating drum collector using a blend of titanium isopropoxide (Ti(OiPr)4), with a carrier polymer, polyvinylpyrrolidone (PVP) in acetic acid and ethanol. Calcination removes PVP and generates mesoporous TiO2-NF with fiber diameters in the range of 25-75 nm by optimizing the electrospinning parameters such as electric field strength, polymer concentration, and flow rate of solution, etc. The band gap energy of TiO2 nanofibers from the UV-vis absorption spectra is found to increase with an increase in the calcination temperature, thus allowing band gap engineering for different applications. The surface morphology, phase composition, crystallinity, surface area, and porosity of the TiO2-NF are also investigated. We demonstrate the efficient and reusable photocatalytic action of the partially aligned pure electrospun TiO2-NF and residual carbon containing TiO2-NF mats with an average fiber diameter similar to 40 nm in the photocatalytic degradation of a polycyclic aromatic hydrocarbon (PAH) dye, naphthalene. Small carbon residue (2.54%) containing TiO2-NF is found to be about twice as efficient as the pristine TiO2-NF in photodegradation of a PAH dye, but the effectiveness declined at higher carbon content.