Influence of oxygen vacancy defect on photoelectrochemical performance in interstitial nitrogen doped titanium dioxide photocatalyst

An interstitial nitrogen doped titanium dioxide (N-TiO 2 ) photocatalyst with high concentration of oxygen vacancies (O v ) defect was synthesised using a dry physical method. The successful O v defect was confirmed by PL, XPS and ESR analyses, where the wavelength at 468 nm representing as band-to-sub-band energy, binding energies at 398.7 and 400.3 eV proving the Ti−O−N−O, Ti−O−N or N−O bonding and g-value was obtained at about 1.988 ± 0.01 and 2.045 ± 0.01, attributed to the trapped electron at the surface of Ti 3+ and confirming the presence of hole trapping site. The presence of O v defects in interstitial N-TiO 2 photocatalyst has been extensively studied by researchers; however, their influence on photoelectrochemical (PEC) activity is not yet fully elucidated. In this work, the O v defect demonstrated a lower resistivity, ca. 2.513 ×103 Ω, which promoted rapid electron transfer, thus lowering the rate of electron-hole recombination proven by PL, EIS, and photocurrent responses. Besides, it proved a larger accumulation of electrons at the interface due to contribution as an electron donor, where the carrier concentration ca. 4.27 ×1018 cm -3 . Hence, the photocatalytic degradation for N-TiO 2 photocatalyst was achieved 3.4 times higher as compared to the unmodified TiO 2 photocatalyst, where the rate photoactivity of N-TiO 2 photocatalyst was determined about 0.138 min -1 .