Electrospun black titania nanofibers: Influence of hydrogen plasma-induced disorder on the electronic structure and photoelectrochemical performance

This work encompasses a facile method for tailoring surface defects in electrospun TiO2 nano\ufb01bers by employing hydrogen plasma treatments. This amiable processing method was proven with SQUID, EPR, and XPS to be highly e\ufb00ective in generating oxygen vacancies, accompanied by the reduction of Ti4+ centers to Ti3+, resulting in the formation of black titania. The treatment temperature was found to a\ufb00ect the Ti3+/Ti4+ ratios and surface valence, while preserving the original 1D morphology of the titania \ufb01bers. Ab initio DFT calculations showed that a high concentration of oxygen vacancies is highly e\ufb03cient in producing midgap states that enhance the system absorption over the whole visible range, as observed with UV/ vis/NIR di\ufb00use re\ufb02ectance spectroscopy. Pristine TiO2 nano\ufb01bers produced a photocurrent density of 3c0.02 mA/cm2 at 1.23 V vs RHE, whereas the hydrogen plasma treatment resulted in up to a 10-fold increase in the photoelectrochemical performance