Facet engineering of TiO2 nanocrystals for solar energy conversion

Pan, Jian (2014). Facet engineering of TiO2 nanocrystals for solar energy conversion PhD Thesis, School of Chemical Engineering, The University of Queensland. doi:10.14264/uql.2015.51

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Author Pan, Jian
Thesis Title Facet engineering of TiO2 nanocrystals for solar energy conversion
Formatted title
Facet engineering of TiO2 nanocrystals for solar energy conversion
School, Centre or Institute School of Chemical Engineering
Institution The University of Queensland
DOI 10.14264/uql.2015.51
Publication date 2014-11-30
Thesis type PhD Thesis
Open Access Status Other
Supervisor Lianzhou Wang
Total pages 104
Language eng
Subjects 0912 Materials Engineering
1007 Nanotechnology
0904 Chemical Engineering
Formatted abstract
The ever-growing energy crisis and environmental pollution are the most challenges we are facing nowadays. Solar energy, as an inexhaustible natural resource, has the largest potential to replace fossil fuel and satisfy the global energy consumption in future. Photocatalysis and photovoltaic device are two effective ways of converting solar energy into chemical energy and electric energy, respectively. Due to the unique electronic structure, semiconductors have been widely studied and utilized in the field of solar energy conversion. In the past 40 years since Fujishima and Honda’ pioneering work, titanium dioxide (TiO2) has always been one of the most studied semiconductors for solar energy conversion, due to its advantages such as high efficiency, good stability, nontoxicity and low-cost etc. In order to obtain the optimized performance of TiO2 photocatalyst, numerous studies have been conducted involving crystal growth, doping and heterostructuring. The morphology control and surface exposed of photocatalysts have great influence on their performance. In this thesis, we mainly focus on the study of the facet engineering of anatase TiO2, including the synthesis of anatase TiO2 crystals with tailored facet, the properties of different TiO2 facets and the applications of faceted TiO2 in solar energy conversion.

In Chapter 4, a set of anatase TiO2 single crystals with different percentage of {001}, {010} and {101} facet was synthesized. By comparing their performance in a series of experiments, it was found that clean {001} exhibits lower reactivity than {101} in photooxidation reactions for OH radical generation and photoreduction reactions for hydrogen evolution, while the {010} facets showed the highest photoreactivity due to the surface atomic structure and corresponding electronic structure.

In Chapter 5, single crystalline anatase TiO2 rods with dominant reactive {010} facets are directly synthesized by hydrothermally treating Cs0.68Ti1.83O4/H0.68Ti1.83O4 particles. The nanosized rods exhibited a comparable conversion efficiency as photoanode comparing with P25 in dye-sensitized solar cells (DSCs), and a superior photocatalytic conversion of CO2 into methane to the benchmark P25 TiO2 nanocrystals.

In Chapter 6, a new class of TiO2 single crystals with dominant {010}, {301} and {101} facet, respectively, was obtained. Intrinsic activities of anatase {010}, {301} and {101} facets were revealed in photocatalytic hydrogen evolution. Without loading co-catalyst Pt, the sample with dominant {010} facets exhibited a superior activity comparing to others.

In Chapter 7, boron-containing anatase TiO2 microsphere with dominant {001} facet was employed to build a hybrid photoanode with P25 for DSCs. By deliberately design three structural configurations in photoanodes, the hybrid photoanode exhibited higher light harvesting and better charge collection and diffusion properties than that of pristine P25 in DSCs with ~ 23% efficiency improvement. Detailed characterizations revealed that the B-TiO2 microspheres played a dual role in not only offering excellent light scattering effect owing to its large particle size and exposed {001} facets, but also promoting conductivity of the microsphere because of the presence of heteroatom boron within the microsphere.

The thesis concludes with a brief summary of the key findings in this program and an outlook for future research directions.
Keyword Titanium dioxide
Faceted control
Solar energy
Water splitting
Dye-sensitized solar cells

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Created: Fri, 21 Nov 2014, 17:06:48 EST by Jian Pan on behalf of Scholarly Communication and Digitisation Service