Near Infrared Reflectance Properties of Metal Oxide Nanoparticles

Jeevanandam, P.; Mulukutla, Ravichandra S.; Phillips, M. M.; Chaudhuri, S.; Erickson, and L. E.; Klabunde, Kenneth J.

doi:10.1021/jp066363o

Cited by 182 publications

(115 citation statements)

References 29 publications

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“…The reflectance of a material can be affected by a combination of factors, such as chemical composition, particle size, particles distribution, particle shape and refractive index of the material. 11) Refractive index is associated with a material's electronic structure. 12) This means that the doped Cr 2 O 3 green pigments with different amounts of dopant could differ in their ability to reflect in the NIR region.…”

Section: Introductionmentioning

confidence: 99%

Influence of composition on near infrared reflectance properties of M-doped Cr2O3 (M=Ti,V) green pigments

Zhou

Weng

Yuan

et al. 2014

J. Ceram. Soc. Japan

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Ti-Al-V-doped Cr 2 O 3 green pigments could present a higher near-infrared (NIR) reflectance compared to pure Cr 2 O 3 . The amount of Ti and V introduced in the Cr 2 O 3 matrix has been systematically varied respectively, in order to evaluate the effects of Ti and V contents on the NIR properties of the doped Cr 2 O 3 . For comparison, experimental reflectance measurements and mean-NIR reflectance (7802000 nm) of samples are given. The results reveal significant variations in the NIR region as a function of nominal composition for both Ti-doped Cr 2 O 3 and V-doped Cr 2 O 3 . Moreover, the NIR reflectance of a Ti-Al-V-doped Cr 2 O 3 pigment sample was measured. It has been found that it exhibits lower NIR reflectance compared to that reported in previous study. The correlations between electronic structural and spectroscopic features are discussed. For the Ti-doped Cr 2 O 3 samples, the decrease of free carriers and the electronic transitions between defect energy levels within the band gap and the conduction band, could be responsible for the variable NIR reflectance. However, for V-doped Cr 2 O 3 , apart from light absorptions of free carriers, there are new light absorption peaks range from 1190 to 2000 nm, resulting in the variations of the NIR reflectance.

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Section: Introductionmentioning

confidence: 99%

Influence of composition on near infrared reflectance properties of M-doped Cr2O3 (M=Ti,V) green pigments

Zhou

Weng

Yuan

et al. 2014

J. Ceram. Soc. Japan

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“…The aim of the present work is to show the improvement of NIR reflectance on paints (for building roofs and façades) and ceramic tiles (for building façade) by working on the coating nanoscale, tuning the particle size of selected nanostructured oxides [7]. Being the developed prototypes prepared by following traditional processes other variables like abrasion and adhesion resistance have not considered to be critical.…”

Section: Introductionmentioning

confidence: 99%

Nanobased coatings with improved NIR reflecting properties for building envelope materials: Development and natural aging effect measurement

Revel

Martarelli

Bengochea

et al. 2013

Cement and Concrete Composites

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A significant contribution to the reduction of the Urban Heat Island effect and cooling energy demand is given today by the so called cool materials for the building envelope with enhanced reflecting and emitting properties. The present study shows some preliminary results of the EU project COOL-Coverings aiming at developing innovative nanobased coatings with improved Near InfraRed reflecting capabilities. The key idea is to work on a nanoscale by tuning the crystal size and distribution of selected nanostructured oxides . Cool prototypes of brown colored ceramic tiles and green acrylic paints have been developed and compared to conventional ones showing an improvement in solar reflectance without any perceptual difference in color. The material characterization has been based on the measurement of spectral reflectance on a wide wavelength range (300-2200nm) using a UV/Vis/NIR spectrophotometer. In parallel with the development of nanostructured cool materials, natural aging tests on ceramic and painted concrete tiles have been performed with the goal of identifying and measuring the effects of the main aging factors affecting reflective properties. A significant drop of solar reflectance for paints has been noticed from the very beginning of the testing period while ceramic tiles have confirmed excellent resistance to weathering. However, both for paints and tiles the effect of soiling cannot be neglected and, if combined to weathering, it can lead to a solar reflectance reduction as high as 10%. This preliminary study will pave the way to a future development of dedicated accelerated aging testing procedures for cool materials.

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“…Enhanced absorption of visible light at wavelengths larger than the absorption edge can be observed for the AFO-3 and AFO-6 compared to the other two samples. It may be resulting from the enhanced intensity of the scattered light in the photocatalysts with a smaller particle size [28]. The band gap of AgFeO 2 samples are determined based on the Kubelka-Munk method by the following equation:…”

Section: Structure Morphology and Optical Propertiesmentioning

confidence: 99%

A Novel Delafossite Structured Visible-Light Sensitive AgFeO2 Photocatalyst: Preparation, Photocatalytic Properties, and Reaction Mechanism

Yin

Shi

et al. 2016

Catalysts

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Abstract:This work presents a systematic study of a novel efficient visible-light sensitive AgFeO 2 photocatalyst. The photocatalysts were prepared via simple hydrothermal procedure at 160˝C with different reaction time. The structures, morphologies, specific surface areas, and optical properties of the photocatalysts were explored by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Brunauer-Emmett-Teller (BET) model, and UV-vis diffuse reflectance spectra (DRS). Photoluminescence and photocurrent analysis were conducted for the understanding of photogenerated electron-hole pair separation. AgFeO 2 with a six-hour hydrothermal procedure demonstrated the most efficient photocatalytic performance which resulted in 97% degradation of methyl orange (MO) within 180 min. The enhanced photocatalytic activity was attributed to the combined effect of its relatively large surface area and high separation electron-hole pair efficiency. Holes and¨O 2´w ere the dominant reactive species responsible for MO degradation and holes played the leading role according to the quenching effects analysis and detection of active species. The conduction and valence band position of AgFeO 2 were calculated to be´0.5 V and 1.32 V, respectively. Based on active species detection, along with the band structure, the photocatalytic mechanism was proposed.

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Near Infrared Reflectance Properties of Metal Oxide Nanoparticles

Cited by 182 publications

References 29 publications

Influence of composition on near infrared reflectance properties of M-doped Cr<sub>2</sub>O<sub>3</sub> (M=Ti,V) green pigments

Influence of composition on near infrared reflectance properties of M-doped Cr<sub>2</sub>O<sub>3</sub> (M=Ti,V) green pigments

Nanobased coatings with improved NIR reflecting properties for building envelope materials: Development and natural aging effect measurement

A Novel Delafossite Structured Visible-Light Sensitive AgFeO2 Photocatalyst: Preparation, Photocatalytic Properties, and Reaction Mechanism

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