Tailored graphenic structures directly grown on titanium oxide boost the interfacial charge transfer

Abstract

Highlights Tailored graphenic structures, dots rods and continuous films, were successfully fabricated directly on TiO 2 substrates using an extremely clean synthesis protocol by Plasma Assisted Chemical Vapor Deposition. Chemical analysis demonstrates undoubtedly the formation of Ti-O-C bonds in the interface of carbon-TiO 2 hybrid materials. High photocurrent density is generated upon illumination through the carbon-TiO 2 contact proving an efficient charge transfer. AbstractThe successful application of titanium oxide-graphene hybrids in the fields of photocatalysis, photovoltaics and photodetection strongly depends on the interfacial contact between both materials. The need to provide a good coupling between the enabling conductor and the photoactive phase prompted us to directly grow conducting graphenic structures on TiO 2 crystals. We here report on the direct synthesis of tailored graphenic structures by using Plasma Assisted Chemical Vapour Deposition that present a clean junction with the prototypical titanium oxide (110) surface. Chemical analysis of the interface indicates chemical bonding between both materials. Photocurrent measurements under UV light illumination manifest that the charge transfer across the interface is efficient. Moreover, the influence of the synthesis atmosphere, gas precursor (C 2 H 2 ) and diluents (Ar, O 2 ), on the interface and on the structure of the as-grown graphenic material is assessed. The inclusion of O 2 promotes vertical growth of partially oxidized carbon nanodots/rods with controllable height and density. The deposition with Ar results in continuous graphenic films with low resistivity (ρ=6.8·10 -6 Ω·m). The synthesis protocols developed here are suitable to produce tailored carbonsemiconductor structures on a variety of practical substrates as thin films, pillars or nanoparticles.

High-Efficiency Flexible Perovskite Solar Cells Enabled by an Ultrafast Room-Temperature Reactive Ion Etching Process

“…In stark contrast, HT-mp-TiO 2 shows a slight reduction in PL intensity and decay time. This PL decay phenomenon is commonly observed in TiO 2 -ETL-based PSCs. − According to previous studies, a slight reduction in PL intensity and decay time occurs when excited electrons in the perovskite layer cannot be efficiently extracted into the TiO 2 layer because of the interfacial electron transport barrier at the mp-TiO 2 /perovskite interface, which is the main cause of hysteresis in TiO 2 ESL-based PSCs. , Therefore, we attribute the small hysteresis of the RIE-PSCs to excellent electron extraction at the RIE-mp-TiO 2 /perovskite interface.…”

“…XPS analyses of C 1s spectra for both mp-TiO 2 also show consistent results. As shown in Figure S5a,b, the C 1s peaks collected from the samples were resolved into three peaks at the binding energies of 284.5, 285.5, and 288.5 eV, which were assigned to C–C, C–O–C, and O–CO bondings, respectively. ,, These C 1s peaks are detected from general samples. However, in this work, the ratio of peak area corresponding to each bonding is different.…”

TiO2–NGQD composite photocatalysts with switchable photocurrent response

“…This disappearance is likely due to the binding of the NGQDs to the surface of the TiO 2 , converting the Ti–OH bonds to Ti–O–C at approximately 530.9 eV. 39–41 The intensity of this peak increases in the 8% NGQD sample as more of the TiO 2 surface is likely to be bonding with NGQDs. The positive shift observed in the high-resolution Ti 2p and O 1s spectra for TiO 2 –NGQD composites compared with pure TiO 2 can be attributed to a transfer of electron density once the composite is formed.…”