Carbon quantum dots/TiO2 composites for efficient photocatalytic hydrogen evolution

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 2; no. 10; pp. 3344 - 3351
• Main Authors: Yu, Huijun, Zhao, Yufei, Zhou, Chao, Shang, Lu, Peng, Yong, Cao, Yinhu, Wu, Li-Zhu, Tung, Chen-Ho, Zhang, Tierui
• Format: Journal Article
• Language: English
• Published: 01.01.2014
• Subjects: carbon quantum dots; catalysts; electric current; hydrogen; hydrogen production; hydroxyl radicals; irradiation; light; photocatalysis; photosensitizing agents; titanium dioxide; ultraviolet-visible spectroscopy
• ISSN: 2050-7488; 2050-7496; 2050-7496
• DOI: 10.1039/c3ta14108j

Carbon quantum dots modified P25 TiO₂ composites (CQDs/P25) with a “dyade”-like structure were prepared via a facile one-step hydrothermal reaction. CQDs/P25 exhibited improved photocatalytic H₂ evolution under UV-Vis and visible light (λ > 450 nm) irradiation without loading any noble metal cocatalyst, compared to pure P25. A possible mechanism of the photocatalytic H₂ production activity over CQDs/P25 was proposed based on detailed measurements of the transient photocurrent response, surface photovoltage and hydroxyl radicals. CQDs play dual roles on the improved photocatalytic activity of CQDs/P25. Under UV-Vis light irradiation CQDs act as an electron reservoir to improve the efficient separation of the photoinduced electron–hole pairs of P25. However, under visible light irradiation CQDs act as a photosensitizer to sensitize P25 into a visible light response “dyade” structure for H₂ evolution.