Crack-Free and Thickness-Controllable Deposition of TiO2–rGO Thin Films for Solar Harnessing Devices

Abstract

The use of thin films consisting of TiO2 and reduced graphene oxide (TiO2–rGO) in solar harnessing devices is gaining momentum thanks to improved charge-transporting characteristics. In this report, we propose a facile spin-coating methodology for the deposition of crack-free and thickness-controllable TiO2–rGO thin films. A range of characterization techniques were utilized to confirm the formation of the TiO2–rGO thin film. Improved charge-transporting properties of TiO2–rGO composite thin films were confirmed by measuring their photoelectrochemical (PEC) activity under simulated solar light illumination. In particular, it was found that the TiO2–rGO composite thin film yielded a better photocurrent response (~151.3 µA/cm2) than the bare TiO2 thin film (~71.6 µA/cm2) at 1.23 eV vs. the reversible hydrogen electrode (RHE). The obtained results suggested that rGO addition remarkably improves the charge-transporting properties in TiO2 films.

Deposition of inverse opal-like TiO2 thin film with enhanced photoelectrochemical activity by a spin-coating combined with a dip-coating method

“…The 2θ peaks at 25.3°and 48.1°can be readily assigned to characteristic (101) and (200) planes of anatase TiO 2 (JCPDS card no. 21-1272) [11,17]. The intensity of peaks has slightly increased, indicating an improvement in crystallinity.…”

“…= 280 nm) was measured as it is shown in figure 5(b). In general, the broad peak in the UV range (∼315-380 nm) is usually attributed to direct electron-hole recombination [11,27]. The intensity of dip-coated TiO 2 was noticeably lower, implying a reduced charge carrier recombination.…”

“…Anhydrous isopropanol (99.5%), titanium (IV) isopropoxide (TIP, 97%), and other high-purity reagents were procured from Merck & Co. An aqueous suspension of plain polystyrene spheres (0.35 μm, 2.5% w/v) was purchased from Polysciences Inc. A slurry paste containing TiO 2 nanoparticles (∼20-26 nm) was prepared according to the literature [11]. The concentration of TiO 2 nanoparticles was ∼60 mg per 1 ml of the paste.…”

“…For example, a slurry paste mixture of TiO 2 nanoparticles and PS/ PMMA particles can be reliably deposited on conducting glass substrates and further converted to inverse opallike structures upon heat treatment. On the other hand, it is well-known that electron transport in TiO 2 nanoparticle-based films is hampered by the effects of grain boundary scattering, charge trapping, and recombination [10,11]. To address this issue, one can also consider finding a way to better connect TiO 2 nanoparticles between each other.…”

Recent Progress on Photoelectrochemical Water Splitting of Graphitic Carbon Nitride (g−CN) Electrodes

“…These include SnO 2 /g−CN [73], NiO/g−CN [200], Sn-doped In 2 O 3 /g−CN [201], Cu 2 O/g−CN [202], MoO 3 /g−CN [203], and all of them showed enhanced PEC activity compared to pure g−CN. The construction of metal oxide-based thin films containing 2D structures is also an effective way to improve PEC activity [204,205]. Reprinted with permission from ref.…”