title: Microwave-assisted self-doping of TiO2 photonic crystals for efficient photoelectrochemical water splitting.
abstract: In this article, we report that the combination of microwave heating and ethylene glycol, a mild reducing agent, can induce Ti(3+) 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 TiO2 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 Ti(3+) 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.
authors: Water Desalination and Reuse Center, Biological and Environmental Science and Engineering Division and ‡Imaging and Characterization Laboratory, King Abdullah University of Science and Technology , Thuwal 23955-6900, Saudi Arabia.
authors: Zhonghai
authors: Z
authors: Zhang
authors: Xiulin
authors: X
authors: Yang
authors: Mohamed Nejib
authors: MN
authors: Hedhili
authors: Elaf
authors: E
authors: Ahmed
authors: Le
authors: L
authors: Shi
authors: Peng
authors: P
authors: Wang