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Photothermal effect: an important aspect for the enhancement of photocatalytic activity under illumination by NIR radiation.

ABSTRACT: A key auxiliary role of photothermal effect (PTE) in the enhancement of photocatalytic activity under illumination to near-infrared (NIR) radiations has been experimentally revealed. It was found that the photoexcitation of electrons, required for the process of photocatalysis does not occur in presence of NIR radiations alone without the support of both UV and visible radiations. Herein, a binary heterogeneous nanophotocatalyst, GR-ZnO was fabricated by a novel approach using hydrothermal process. In which ZnO nanotrapezoids were deposited over the surfaces of graphene nanosheets. In the reported unique approach, reduction of graphene oxide to graphene has been accomplished using water by an entirely alternative mechanism compared to traditional reduction processes those employ the hazardous reducing agents. Thus produced GR-ZnO photocatalyst has exhibited the excellence in rapid degradation of industrially voluntarily employing perilous dye, methyl orange. It is explored that PTE is mainly responsible for the rapid degradation of methyl orange transpired under illumination to NIR laser. Further, it has been established that PTE could not emerge with NIR radiations alone without the support of both UV and visible radiations. In consideration of its importance, PTE of GR-ZnO nanocatalyst has been revealed and compared with its individual components, viz., graphene and ZnO. Moreover, the photothermal conversion efficiency of GR-ZnO nanocatalyst was evaluated. Overall, the excellent catalytic activity found in GR-ZnO nanocatalyst was accounted for its decreased band gap, transpired by hybridization of ZnO with graphene could efficiently prevent the recombination of photo-generated charge carriers. In addition, admired catalytic activity of GR-ZnO nanocatalyst was attributed to improved optical absorption and enhancement in the adsorption affinity to methyl orange molecules.

SUBMITTER: Neelgund GM

PROVIDER: S-EPMC6601625 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature

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Photothermal effect: an important aspect for the enhancement of photocatalytic activity under illumination by NIR radiation.

Neelgund Gururaj M GM Oki Aderemi A

Materials chemistry frontiers 20171010 1

A key auxiliary role of photothermal effect (PTE) in the enhancement of photocatalytic activity under illumination to near-infrared (NIR) radiations has been experimentally revealed. It was found that the photoexcitation of electrons, required for the process of photocatalysis does not occur in presence of NIR radiations alone without the support of both UV and visible radiations. Herein, a binary heterogeneous nanophotocatalyst, GR-ZnO was fabricated by a novel approach using hydrothermal proce ...[more]

PMID: 31263562

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Project description:Rationale: Intraoperative visualization in small surgical cavities and hard-to-access areas are essential requirements for modern, minimally invasive surgeries and demand significant miniaturization. However, current optical imagers require multiple hard-to-miniaturize components including lenses, filters and optical fibers. These components restrict both the form-factor and maneuverability of these imagers, and imagers largely remain stand-alone devices with centimeter-scale dimensions. Methods: We have engineered INSITE (Immunotargeted Nanoparticle Single-Chip Imaging Technology), which integrates the unique optical properties of lanthanide-based alloyed upconverting nanoparticles (aUCNPs) with the time-resolved imaging of a 25-micron thin CMOS-based (complementary metal oxide semiconductor) imager. We have synthesized core/shell aUCNPs of different compositions and imaged their visible emission with INSITE under either NIR-I and NIR-II photoexcitation. We characterized aUCNP imaging with INSITE across both varying aUCNP composition and 980 nm and 1550 nm excitation wavelengths. To demonstrate clinical experimental validity, we also conducted an intratumoral injection into LNCaP prostate tumors in a male nude mouse that was subsequently excised and imaged with INSITE. Results: Under the low illumination fluences compatible with live animal imaging, we measure aUCNP radiative lifetimes of 600 μs - 1.3 ms, which provides strong signal for time-resolved INSITE imaging. Core/shell NaEr0.6Yb0.4F4 aUCNPs show the highest INSITE signal when illuminated at either 980 nm or 1550 nm, with signal from NIR-I excitation about an order of magnitude brighter than from NIR-II excitation. The 55 μm spatial resolution achievable with this approach is demonstrated through imaging of aUCNPs in PDMS (polydimethylsiloxane) micro-wells, showing resolution of micrometer-scale targets with single-pixel precision. INSITE imaging of intratumoral NaEr0.8Yb0.2F4 aUCNPs shows a signal-to-background ratio of 9, limited only by photodiode dark current and electronic noise. Conclusion: This work demonstrates INSITE imaging of aUCNPs in tumors, achieving an imaging platform that is thinned to just a 25 μm-thin, planar form-factor, with both NIR-I and NIR-II excitation. Based on a highly paralleled array structure INSITE is scalable, enabling direct coupling with a wide array of surgical and robotic tools for seamless integration with tissue actuation, resection or ablation.

Dataset Information

Photothermal effect: an important aspect for the enhancement of photocatalytic activity under illumination by NIR radiation.

Publications

Photothermal effect: an important aspect for the enhancement of photocatalytic activity under illumination by NIR radiation.

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