Effective Formation of Oxygen Vacancies in Black TiO₂ Nanostructures with Efficient Solar-Driven Water Splitting

Abstract

Black TiO2 nanomaterials have attracted considerable attention since they usually exhibit excellent photocatalytic activities. Herein, we report the facile preparation of black TiO2 nanostructures with ultrathin hollow sphere morphology, high crystalline quality, small grain size (∼8 nm), and ultrahigh surface area (168.8 m2 g–1) through Al reduction. Electron paramagnetic resonance (EPR) spectra demonstrate the existence of oxygen vacancies in black TiO2 nanostructures, which could increase the donor density and effectively promote the separation and transportation of photogenerated electron–hole pairs. The black TiO2 nanostructures exhibit a high solar-driven hydrogen generation rate (56.7 mmol h–1 g–1) under the full spectrum of solar light, which is nearly 2.5 times than that of pristine TiO2 nanostructures and superior to those kinds of black TiO2 photocatalytic materials reported previously.

Enhancing Photocatalytic Activity of NO Removal through an In Situ Control of Oxygen Vacancies in Growth of TiO2

“…Photoluminescence (PL) measurements further confirm the presence of different types of defects in those samples. As shown in Figure a, m‐0 has a significant fluorescence emission peak at 380.64 nm that due to the near‐band‐edge emission . The sample m‐350 exhibits a broad emission peak around 400 nm, which is probably related to the surface O vacancies (Figure b).…”

Engineering oxygen vacancy on rutile TiO2 for efficient electron-hole separation and high solar-driven photocatalytic hydrogen evolution

“…Because the rutile TiO 2 is extremely stable thermodynamically and has less surface defects than the anatase TiO 2 , constructing rutile TiO 2 with surface defects is promising to have enhanced photocatalytic activity. Surface oxygen vacancy (V O ), as one of the most important surface defects of TiO 2 , receives extensive attention [31][32][33][34][35]. Too low or high content of V O defects are not conducive to narrowing the bandgap and improving the separation efficiency of photogenerated electron-hole pairs.…”

Black Titania with Nanoscale Helicity

“…This shift could result from the surface reduction of the titania structure by ascorbic acid . These results verify that the black product is partially reduced anatase titania crystals formed by incomplete surface reduction of Ti ions by ascorbic acid . Infrared (IR) spectra (Figure S18, Supporting Information) of the prepared black TiO 2 −x also show small stretching bands of CO at ≈1705 cm −1 , CC at ≈1600 cm −1 , and CO at ≈1250 cm −1 , indicating that the reduced surface of the purified black TiO 2 −x was adsorbed by some ascorbic acid‐based compounds.…”