Microwave-assisted self-doping of TiO2 photonic crystals for efficient photoelectrochemical water splitting

In this article, we report that the combination of microwave heating and ethylene glycol, a mild reducing agent, can induce Ti3+ self-doping in TiO2. A hierarchical TiO2 nanotube array with the top layer serving as TiO2 photonic crystals (TiO2 NTPCs) was selected as the base photoelectrode. The self-doped TiO2 NTPCs demonstrated a 10-fold increase in visible-light photocurrent density compared to the nondoped one, and the optimized saturation photocurrent density under simulated AM 1.5G illumination was identified to be 2.5 mA cm-2 at 1.23 V versus reversible hydrogen electrode, which is comparable to the highest values ever reported for TiO2-based photoelectrodes. The significant enhancement of photoelectrochemical performance can be ascribed to the rational coupling of morphological and electronic features of the self-doped TiO 2 NTPCs: (1) the periodically morphological structure of the photonic crystal layer traps broadband visible light, (2) the electronic interband state induced from self-doping of Ti3+ can be excited in the visible-light region, and (3) the captured light by the photonic crystal layer is absorbed by the self-doped interbands. © 2013 American Chemical Society.

Citation

Zhang, Z., Yang, X., Hedhili, M. N., Ahmed, E., Shi, L., & Wang, P. (2013). Microwave-Assisted Self-Doping of TiO2 Photonic Crystals for Efficient Photoelectrochemical Water Splitting. ACS Applied Materials & Interfaces, 6(1), 691–696. doi:10.1021/am404848n

Acknowledgements

This work was supported by KAUST baseline fund. Z.Z. is thankful for a SABIC Postdoctoral Fellowship.