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.

Self-Assembled Hierarchical Nanostructures for High-Efficiency Porous Photonic Crystals

“…1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 11 Control over the optical characteristics of the h1DPC upon thermal treatment is of paramount importance for many applications in which the device fabrication process requires high temperature steps, in order to achieve good crystalline quality and efficient electronic transport (e.g. Dye Sensitized and Perovskite Solar Cells, water splitting, 44 optoelectronic switches and sensors). To simulate this, we annealed a PLD fabricated h1DPC at T=500°C.…”

Management on the location and concentration of Ti3+ in anatase TiO2 for defects-induced visible-light photocatalysis

“…XPS clearly suggests that there is no detectable Ti at lower oxidation state in the surface region of all samples, as indicated by the absence of the shoulder peaks associated with Ti 3+ at 456.8 eV and 462.5 eV for 2p 3/2 and 2p 1/2 core level of Ti 3+ , respectively [39]. It is widely believed that Ti 3+ is easily oxidized by a proper oxidant like O 2 in air or dissolved oxygen in water, and thereby surface Ti 3+ will be consumed rapidly [40].…”

Promoting charge carrier utilization by integrating layered double hydroxide nanosheet arrays with porous BiVO4 photoanode for efficient photoelectrochemical water splitting

“…Metal oxides acting as photoanodes for PEC light conversion, such as TiO2 [5,6], α-Fe2O3 [7][8][9][10], WO3 [11,12], have attracted wide attention because of their low cost, environment-friendliness and stability under oxidizing conditions. Among them, BiVO4 is the top performer due to its relatively small band gap, adequate conduction band edge position and moderate charge transport properties [13][14][15][16][17][18].…”