Enhancing the Performance of Titanium Dioxide Compact Layer on Epitaxial Graphene and Fluorine Tin Oxide Heterojunctions

Nelson Mugambi^1, , James Mbiyu Ngaruiya¹ and Simon Waweru Mugo¹

¹Department of Physics, Jomo Kenyatta University of Agriculture and Technology Nairobi, Kenya

Cite this paper:
Nelson Mugambi, James Mbiyu Ngaruiya and Simon Waweru Mugo. Enhancing the Performance of Titanium Dioxide Compact Layer on Epitaxial Graphene and Fluorine Tin Oxide Heterojunctions. American Journal of Energy Research. 2024; 12(2):40-46. doi: 10.12691/ajer-12-2-2

Abstract

We report a facile synthesis of Titanium dioxide (TiO₂) modified compact layers on Fluorine Tin oxide (FTO) and graphene employing the Sol gel Doctor Blade technique, optimized systematically for enhanced solar energy conversion applications. UV-VIS spectrophotometer, a Varian 7000e FTIR, a Scanning Kelvin Probe Microscope, and Hall Effect setup evaluated the as deposited and films subjected to 1 step, 2°C/min and 1°C/min annealing rates. FTIR revealed considerable absorption at low frequencies (less than 798 cm^-1) in TiO₂ on graphene heterojunctions, confirming the occurrence of Ti-O and C-O-Ti bonds. The predominant anatase TiO₂ characteristic was found at 438 cm^-1. The TiO₂ on graphene film annealed at 1 °C/min exhibited the lowest porosity (46%), as well as the highest dispersion energy (11.30 eV). As the annealing rates declined, so did the surface-to-volume energy loss ratio for all the annealed films. Graphene TiO₂ annealed at 1 ^oC/min had a lower VELF/SELF than TiO₂ on FTO, implying that an electron loses less energy when passing through the TiO₂ on graphene layer than it does in TiO₂ on FTO. The light absorption coefficient α and electron diffusion coefficient D of TiO₂ on graphene improved to 4.637 x 10³ and 1.485 x 10^-4 (1 ^oC/min), respectively, whereas TiO₂ on FTO values increased to 4.221 x 10³ and 1.251 x 10^-4 (1°C/min), in that order, with decreasing annealing rates. Higher values of TiO₂ on graphene α and D indicate enhanced electron transition in the films. Hall Effect measurements on as-deposited and annealed TiO₂ on graphene films demonstrated higher conductivity as annealing rates decreased, which was attributed to film recrystallization induced by calcination. Smoluchowski smoothing model, reveal surface scan average work functions (φ) and linear profile scan average work functions (φ) ensemble variations in granular tilts and surface slopes explaining geographic variation and distribution. Local fluctuations in φ triggered by the spatially varying concentrations of electric dipole moments are intrinsic to atomic steps and influence φ. TiO₂ incorporation on graphene photoanode increased h⁺/e^-separation, electron transport, and light absorption. The continuous conduction network on compact TiO₂ nanoparticles acts as an electron leakage barrier, and the porous structure has a large specific surface area.

Keywords:
Graphene TiO₂ Fluorine tin oxide Porosity electron transport

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