The design and development of efficient TiO 2 -based, hybrid, nanostructured photocatalysts has recently been receiving substantial attention for environmental remediation due to their excellent physiochemical properties. This article provides an overview of the synthesis strategies and characteristics of the next-generation TiO 2 -based hybrid photocatalysts, produced in combination with polymers (e.g., polyaniline, polypyrrole, polythiophene) and carbon nanomaterials (e.g., graphene, GO, CNT, carbon quantum dots, carbon nitride). The structural aspects, nanostructure formation process, parameters affecting catalytic activity, photocatalytic mechanisms and photocatalytic applications of TiO 2 -based catalysts for efficient photocatalytic degradation of gaseous/volatile organic pollutants in water/air are reviewed. Further, current research trends, means to increase catalytic performance and future prospects of high-performance TiO 2 -based hybrid photocatalytic materials, are briefly summarized.

Hybrid nanostructures based on titanium dioxide for enhanced photocatalysis

Complementary in situ X-ray photoelectron spectroscopy (XPS), X-ray diffractometry, and environmental scanning electron microscopy are used to fingerprint the entire graphene chemical vapor deposition process on technologically important polycrystalline Cu catalysts to address the current lack of understanding of the underlying fundamental growth mechanisms and catalyst interactions. Graphene forms directly on metallic Cu during the high-temperature hydrocarbon exposure, whereby an upshift in the binding energies of the corresponding C1s XPS core level signatures is indicative of coupling between the Cu catalyst and the growing graphene. Minor carbon uptake into Cu can under certain conditions manifest itself as carbon precipitation upon cooling. Postgrowth, ambient air exposure even at room temperature decouples the graphene from Cu by (reversible) oxygen intercalation. The importance of these dynamic interactions is discussed for graphene growth, processing, and device integration.

http://pubs.acs.org/doi/pdf/10.1021/nl4023572

Observing Graphene Grow: Catalyst-Graphene Interactions during Scalable Graphene Growth on Polycrystalline Copper

Solvothermal synthesis of hierarchical TiO 2 nanostructures with tunable morphology and enhanced photocatalytic activity

Recent progress on the enhancement of photocatalytic properties of BiPO4 using π-conjugated materials.

Silicon nanorod based radial-junction solar cells are competitive alternatives to traditional planar silicon solar cells. In various silicon nanorods, nanocone is always considered to be better than nanowire in light-absorption. Nevertheless, we find that this notion isn’t absolutely correct. Silicon nanocone is indeed significantly superior over nanowire in light-concentration due to its continuous diameters, and thus resonant wavelengths excited. However, the concentrated light can’t be effectively absorbed and converted to photogenerated carriers, since its propagation path in silicon nanocone is shorter than that in nanowire. The results provide critical clues for the design of silicon nanorod based radial-junction solar cells.

/pdf/a-comparison-of-light-harvesting-performance-of-silicon-2jyyi2tp2h.pdf

A comparison of light-harvesting performance of silicon nanocones and nanowires for radial-junction solar cells.

A novel 3D structure composed of strings of hierarchical TiO2 spheres formed on TiO2 nanobelts with high photocatalytic properties

An important atomic process in the CVD growth of graphene: Sinking and up-floating of carbon atom on copper surface

The electroless etching technique combined with the process of UV/Ozone pretreatment is presented for wafer-scale fabrication of the silicon nanowire (SiNW) arrays. The high-level uniformity of the SiNW arrays is estimated by the value below 0.2 of the relative standard deviation of the reflection spectra on the 4-in. wafer. Influence of the UV/Ozone pretreatment on the formation of SiNW arrays is investigated. It is seen that a very thin SiO2 produced by the UV/Ozone pretreatment improves the uniform nucleation of Ag nanoparticles (NPs) on the Si surface because of the effective surface passivation. Meanwhile, the SiO2 located among the adjacent Ag NPs can obstruct the assimilation growth of Ag NPs, facilitating the deposition of the uniform and dense Ag NPs catalysts, which induces the formation of the SiNW arrays with good uniformity and high filling ratio. Furthermore, the remarkable antireflective and hydrophobic properties are observed for the SiNW arrays which display great potential in self-cleaning antireflection applications.

Wafer-scale fabrication of uniform Si nanowire arrays using the Si wafer with UV/Ozone pretreatment

The ways in which carbon atoms coalesce over the steps on copper (111) surface are ascertained by density functional theory (DFT) calculations in the context of chemical vapor deposition (CVD) growth of graphene. Two strategies, (1) by putting carbon atoms on and under the steps separately and (2) by importing additional carbon atoms between the ones separated by the steps, have been attempted to investigate if an over-step coalescence of carbon atoms could take place. Based on analyses about the optimized configurations and adsorption energies of carbon atoms nearby the steps, as well as the energy evolution curve of the system throughout the geometry optimizations process, we determined the main way in which graphene grows over the steps continuously: the carbon atoms, adsorbed additionally on the locations between the already existing ones which are separated by the steps, link them (these carbon atoms separated by the steps) together. The direct over-step coalescence of the carbon atoms separated by the steps is very difficult, although the energy barrier preventing their coalescence can be weakened by importing carbon atoms on and under the steps gradually. Our results imply potential applications in directing the fabrication of graphene with particular structure by controlling the surface topography of copper substrate.

/pdf/the-over-step-coalescence-of-carbon-atoms-on-copper-surface-3hmc10l2zc.pdf

Yue Yu

Papers

A novel 3D structure composed of strings of hierarchical TiO2 spheres formed on TiO2 nanobelts with high photocatalytic properties

An important atomic process in the CVD growth of graphene: Sinking and up-floating of carbon atom on copper surface

Wafer-scale fabrication of uniform Si nanowire arrays using the Si wafer with UV/Ozone pretreatment

The over-step coalescence of carbon atoms on copper surface in the CVD growth of graphene: density functional calculations

Abnormal thermal effects on the surface plasmon resonance of Ag nanoparticles on the surface of silicon