Photothermal Transfer Research Articles

ZIF-67@MXene structure synergistically improve heat storage and photothermal conversion of phase change material

How to design and construct the MOF-based composite phase change materials (PCMs) with simultaneously enhanced heat storage and photothermal conversion to meet the performance requirement of solar energy utilization still remains a challenge. Herein, the polyethylene glycol was selected as PCM, the ZIF-67@MXene acted as supporting structure, a series of polyethylene glycol/ZIF-67@MXene form-stable composite PCMs (PZM fs-CPCMs) with improved latent heat and photothermal conversion were designed and prepared. All the PZM fs-CPCMs showed obvious heat storage and release characteristics, and their latent heat reached ∼106.01 J/g. Furtherly, the latent heat loss of PZM40 was only 1 % after 100 phase change cycles, indicating outstanding thermal reliability, which was closely related to the structure and morphology of the PZM fs-CPCMs. More importantly, during irradiation, the maximum surface temperature of PZM fs-CPCMs regularly increased (42.5–45.2 °C) with increasing ZIF-67@MXene content, while during cooling, it regularly decreased (27.4–23.2 °C). Based on the surface temperature distribution results, the photothermal conversion ability and heat transfer rate of PZM fs-CPCMs were effectively improved, which was mainly attributed to the remarkable light absorption and conversion ability and high thermal conductivity of MXene. Meanwhile, the PZM fs-CPCMs showed good chemical compatibility, crystallinity characteristic and thermal stability, which was conducive to the solar energy utilization.

Photo-thermal design and analysis of a novel CPC coupled solar air evacuated tube collector

The conventional evacuated tube solar air collector can’t reach a higher temperature due to poor heat transfer between absorber and air. To maintain a low heat loss at medium temperature and enhance heat transfer, a novel evacuated tube solar air collector coupled with a compound parabolic concentrator is proposed. The matching shape is designed and optimized for the concentrator reflecting surface using non-imaging optics, and by ray tracing, the optical performance is obtained. The corresponding photothermal conversion and heat transfer models are established, and numerical simulation is conducted for thermal performance analysis. The results show that the thermal performance is mainly affected by the air flow rate, the inlet temperature, and the heat source energy density. Compared with the existing single-pass evacuated tube collector, the novel collector has advantages in heat output temperature, thermal efficiency, adaptability to flow rate changes, and potential for series temperature rise under most conditions. When concentrated solar power density is 800–1600 W/m2, the maximum outlet temperature of a novel collecting evacuated tube can reach to a limiting value of 181.17 ℃, representing its thermal insulation performance, while that of the contrast one is 153.25℃. Under normal inlet temperature of 25℃, the maximum output temperature of a single tube of the novel collector is 146.05℃ at a flow rate of 1.02 m3/h, and the maximum thermal efficiency of 59.21% can be achieved at a flow rate of 3.58 m3/h.

Influence of Preparation Characteristics on Stability, Properties, and Performance of Mono- and Hybrid Nanofluids: Current and Future Perspective

Nanofluids (NFs) synthesized via the suspension of diverse nanoparticles into conventional thermal fluids are known to exhibit better thermal, optical, tribological, and convective properties, photothermal conversion, and heat transfer performance in comparison with traditional thermal fluids. Stability is pivotal to NF preparation, properties, performance, and application. NF preparation is not as easy as it appears, but complex in that obtaining a stable NF comes with the harnessing of different preparation parameters. These parameters include stirring duration and speed, volume, density, base fluid type, weight/volume concentration, density, nano-size, type of mono or hybrid nanoparticles used, type and quantity of surfactant used, and sonication time, temperature, mode, frequency, and amplitude. The effect of these preparation parameters on the stability of mono and hybrid NFs consequently affects the thermal, optical, rheological, and convective properties, and photothermal conversion and heat transfer performances of NFs in various applications. A comprehensive overview of the influence of these preparation characteristics on the thermal, optical, rheological, and properties, photothermal conversion, and heat transfer performance is presented in this paper. This is imperative due to the extensive study on mono and hybrid NFs and their acceptance as advanced thermal fluids along with the critical importance of stability to their properties and performance. The various preparation, characterization, and stability methods deployed in NF studies have been compiled and discussed herein. In addition, the effect of the various preparation characteristics on the properties (thermal, optical, rheological, and convective), photothermal conversion, and heat transfer performances of mono and hybrid NFs have been reviewed. The need to achieve optimum stability of NFs by optimizing the preparation characteristics is observed to be critical to the obtained results for the properties, photothermal conversion, and heat transfer performance studies. As noticed that the preparation characteristics data are not detailed in most of the published works and thus making it mostly impossible to reproduce NF experimental studies, stability, and results; future research is expected to address this gap. In addition, the research community should be concerned about the aging and reusability of NFs (mono and hybrid) in the nearest future.

A Mathematical Study of a Semiconducting Thermoelastic Rotating Solid Cylinder with Modified Moore–Gibson–Thompson Heat Transfer under the Hall Effect

This research aims to investigate photo-thermoelastic interactions in a rotating infinite semiconducting solid cylinder under a high magnetic field acting along its axis with the Hall current effect. The boundary surface is subjected to a variable heat flux generated by an exponential laser pulse. The governing equations are expressed using a new photo-thermoelastic model generalized in the Moore–Gibson–Thompson photo-thermal (MGTPT) heat transfer model for a semiconducting medium. The Moore–Gibson–Thompson (MGT) equation is obtained by introducing a thermal relaxation parameter into the Green–Naghdi (GN III) model. The Laplace transform is utilized to determine the mathematical expressions for the components of displacement, carrier density, temperature field, and thermal stresses in the transformed domain. The numerical inversion technique is used to obtain the expressions in the physical domain. The impacts of thermal relaxations, different theories of thermoelasticity, the Hall current, and rotation on the displacement, temperature, thermal stresses, and carrier density are represented graphically using MATLAB software.

Recent Development of Polydopamine Anti-Bacterial Nanomaterials.

Polydopamine (PDA), as a mussel-inspired material, exhibits numerous favorable performance characteristics, such as a simple preparation process, prominent photothermal transfer efficiency, excellent biocompatibility, outstanding drug binding ability, and strong adhesive properties, showing great potential in the biomedical field. The rapid development of this field in the past few years has engendered substantial progress in PDA antibacterial materials. This review presents recent advances in PDA-based antimicrobial materials, including the preparation methods and antibacterial mechanisms of free-standing PDA materials and PDA-based composite materials. Furthermore, the urgent challenges and future research opportunities for PDA antibacterial materials are discussed.

Photothermal heating and heat transfer analysis of anodic aluminum oxide with high optical absorptance

Abstract Photothermal heating with metallic nanostructures has the unique property of generating heat at the nanoscale owing to plasmon resonances. In this study, the heat transfer of anodic aluminum oxides (AAOs) coated with plasmonic titanium nitride (TiN) of 80 nm thickness are experimentally, numerically, and analytically studied, wherein TiN photothermally generated heat. High optical absorptance and photothermal heating efficiency are observed for the samples with pore sizes in the range of 161–239 nm, and the sample with the pore size of 239 nm exhibits the highest absorptance and photothermal heating efficiency. In addition, the numerical and analytical heat transfer analyses using the effective thermal conductivities for AAO-TiN samples are in reasonable agreement with experimental results, indicating the validity of effective thermal conductivities, which consider the periodic nature. These results can be extended to design other optically absorbing periodic structures for photothermal heating applications.

Influence of enclosure filled with phase change material on photo-thermal regulation of direct absorption anaerobic reactor: Numerical and experimental study

Direct absorption methane reactor can maintain the fermentation process of microorganism by utilizing solar absorption and scattering of media in biogas reactor to improve the slurry temperature. However, direct absorption heating alone can save the corresponding electric energy and ensure the normal fermentation process of the biogas slurry in the reactor, but there are still problems of big temperature fluctuation and low solar heat absorption efficiency. In order to improve the stability of the fermentation process, it is proposed to optimize the design of this kind of reactor by filling paraffin PCM (phase change material). In this paper, a novel transient model for simulating the photo-thermal transfer process of the reactor with PCM structure was proposed. Experimental and numerical methods were utilized to analyze the effect of PCM parameters on photo-biochemical transformation process and solar heat absorption efficiency. The results show that filling paraffin phase change material in the enclosure of direct absorption reactor can effectively improve its thermal insulation and thermal storage performance, so as to improve the rate of volatile fatty acids (VFA) and gas production by anaerobic fermentation by maximum 31.1%. The average solar heat absorption efficiency of reactor equipped with PCM is bigger than 50%. Thicknesses of 4 cm and 2 cm for side and top structure were selected, respectively.

Adsorption Characteristics of Vanadium Ion on Wool, and Photothermal Conversion and Heat Transfer of Vanadium-Treated Wool Depending on Humidity

Adsorption Characteristics of Vanadium Ion on Wool, and Photothermal Conversion and Heat Transfer of Vanadium-Treated Wool Depending on Humidity

Solar water sterilization enabled by photothermal nanomaterials

Pathogen ingestion through drinking water bring about severe health threats to human beings. Recently innovative nanotechnology and their integrated systems provide new opportunities to address the challenges of solar water sterilization by killing pathogens. Of particular interest in this context, we aim to review the-state-of-art knowledge on solar water sterilization by use of photothermal nanomaterials to enhance the efficiency and affordability of water treatment. The basic principle of solar water sterilization is firstly described from the photothermal conversion and heat transfer physics to thermal sterilization mechanism. The engineering design of photothermal materials is then summarized from the aspects of light absorption, heat localization and other synergistic sterilization actions. The links between the photothermal properties of materials and their sterilization performance are highlighted by using solar energy. Furthermore, rationally orienting photothermal nanomaterials in reactor configurations including batch or continuous flow reactor and its crucial role in improving sterilization performance is analyzed depending on the reaction mechanism. Finally, the future challenges and prospects are outlined for further development of solar sterilization technology. This work discusses physical understanding and engineering design of photothermal nanomaterials and reactors by use of solar energy for water sterilization. ● Photothermal mechanism and heat transfer physics are revisited. ● The basic principle of solar water sterilization is stressed. ● The engineering design of photothermal materials is fully summarized. ● Nanomaterials integrated in batch or continuous flow reactors are discussed. ● Future challenges and prospects are highlighted for further development.

Large-Scale and High-Resolution Patterning Based on the Intense Pulsed Light Transfer of Inkjet-Printed Light-Emitting Materials

In this study, we present a hybrid fabrication method using the intense pulsed light transfer of inkjet-printed light-emitting materials for large-scale and high-resolution patterning. The surface morphology of inkjet-printed thin film is improved by introducing a newly synthesized non-sublimable additive to the conventional light-emitting materials. Finally, we also demonstrate successful photothermal transfer from a light-to-heat-conversion donor substrate to the target device substrate with a 1000 PPI resolution pattern.

Fabrication of gold nanoshells for improvement of cell apoptosis and its application in photothermal cancer therapy

For cancer diagnosis and therapeutics, we adopted a novel strategy and established a new approach by using transarterial administration of gold nanoshells on silica nanorattles (GSNs) for multifunctional biomedical application. The GSNs exhibit high biocompatibility and stability in vitro and in vivo. It was found that an arterial administration of GSNs showed six-fold higher efficiency than the venous method. In this study, we found that the system of using GSNs had a high near-infrared (NIR) absorbance and excellent photothermal transfer capability for cancer photothermal therapy (PTT) efficiently. More importantly, the GSN treatment method, involving interventional procedures and nanomaterials, showed great potential to promote tumor apoptosis in all research. Using CT imaging technology, we monitored the volume change of tumors and confirmed cell apoptosis by TUNEL staining and immunohistochemistry. Furthermore, arterial administration of GSNs combined with NIR irradiation was established, and the related proteins was examined by Western blotting. Caspase-3 and 9 showed an high expression level within tumor tissues. Finally, a comparative study of biodistribution and safety was performed in vivo, and the biocompatibility was carefully evaluated. This GSN-based method was ultimately shown to be a promising approach for cancer therapy.

Controlling the laser induction and cutting process on polyimide films for kirigami-inspired supercapacitor applications

The recently emerging laser-induced graphene (LIG) technology, with one-step processing and designable features, has been widely used in the fabrication of wearable/portable electronics. Herein, by taking inspiration from kirigami, we designed a stretchable supercapacitor (SC) step by step through controlling laser induction and cutting process on the polyimide (PI) film, with the use of one single CO2 laser source. Firstly, the carbonized basic geometric units of lines were produced on PI films to investigate the processing-structure relationships. Then, the complex photothermal conversion and heat transfer progress involved in the carbonized process were simulated by a photothermal model. Both experimental and theoretical results suggested that the laser power, scan rate and focus condition have great influence on the size, shape and morphology of the carbonized lines. Finally, we optimized the parameters of laser induction and cutting process to fabricate the kirigami-inspired SCs with reliable electrochemical properties and editable mechanical flexibility, showing great potential in the field of flexible electronics.

Silver–Gold Bimetallic Alloy versus Core–Shell Nanoparticles: Implications for Plasmonic Enhancement and Photothermal Applications

Bimetallic plasmonic nanoparticles enable tuning of the optical response and chemical stability by variation of the composition. The present numerical simulation study compares Ag-Au alloy, Ag@Au core-shell, and Au@Ag core-shell bimetallic plasmonic nanoparticles of both spherical and anisotropic (nanotriangle and nanorods) shapes. By studying both spherical and anisotropic (with LSPR in the near-infrared region) shapes, cases with and without interband transitions of Au can be decoupled. Explicit comparisons are facilitated by numerical models supported by careful validation and examination of optical constants of Au-Ag alloys reported in literature. Although both Au-Ag core-shell and alloy nanoparticles exhibit an intermediary optical response between that of pure Ag and Au nanoparticles, there are noticeable differences in the spectral characteristics. Also, the effect of the bimetallic constitution in anisotropic nanoparticles is starkly different from that in spherical nanoparticles due to the absence of Au interband transitions in the former case. In general, the improved chemical stability of Ag nanoparticles by incorporation of Au comes with a cost of reduction in plasmonic enhancement, also applicable to anisotropic nanoparticles with a weaker effect. A photothermal heat transfer study confirms that increased absorption by the incorporation of Au in spherical Ag nanoparticles also results in an increased steady state temperature. On the other hand, anisotropic nanoparticles are inherently better absorbers, hence better photothermal sources and their photothermal properties are apparently not strongly affected by the incorporation of one metal in the other.

Eco-friendly coffee-based colloid for performance augmentation of solar stills

Recently, nanofluids have been extensively used in water desalination systems because of their superior photo-thermal properties and heat transfer characteristics. Most of inorganic nanoparticles such as metal, metal oxides and carbon have adverse environmental impacts due to the risk related to their production and disposal processes as well as the toxicity of some types of them. In addition, their high production cost is another issue that motivates researchers to find low cost and eco-friendly alternatives to inorganic nanoparticles. In this study, coffee-based colloid has been proposed as an organic, low cost, and eco-friendly alternative to conventional inorganic-based nanofluids to augment the fresh water productivity of solar stills (SS). The performance of the modified solar still (MSS) has been experimentally investigated and compared with another conventional solar still (CSS) under the same conditions. The daily freshwater productivity obtained from the MSS was 4865.73 ml/m2 which was greater than that of CSS by 35.14 %. Energy and exergy efficiencies of MSS were improved by 35.34 % and 46.44 %, respectively, compared with that of CSS. Finally, the economic evaluation of the MSS is carried out via performing cost analysis. The cost of distilled water per liter produced by the modified solar still is 0.0136 $/l.

The impact of size and surface ligand of gold nanorods on liver cancer accumulation and photothermal therapy in the second near-infrared window

Gold nanorods (GNRs) with longitudinal surface plasmon resonance (LSPR) peaks in second near-infrared (NIR-II) window have attracted a great amount of attention as photothermal transducer because of their inherently excellent photothermal transition efficiency, high biocompatibility and versatile surface functionalization. One key question for the application of these GNRs against tumors in vivo is which size/shape and surface ligand conjugation are promising for circulation and tumor targeting. In this study, we prepared a series of gold nanorods (GNRs) of similar aspect ratio and LSPR peaks, and thus similar photothermal transfer efficiency under irradiation of 980 nm laser, but with tunable size in width and length. The obtained GNRs were subjected to surface modification with PEG and tumor targeting ligand lactoferrin. With these tailor-designed GNRs in hand, we have the chance to study the impact of dimension and surface property of the GNRs on their internalization via tumor cells, photothermal cytotoxicity in vitro, blood circulation and tissue distribution pattern in vivo. As a result, the GNRs with medium size (70 nm in length and 11.5 nm in width) and surface PEG/LF modification (GNR70@PEG-LF) exhibit the fastest cell internalization via HepG2 cells and best photothermal outcome in vitro. The GNR70@PEG-LF also display long circulation time and the highest tumor accumulation in vivo, due to the synergetic effect of surface coating and dimension. Finally, tumor ablation ability of the GNRs under irradiation of 980 nm light were validated on mice xenograft model, suggesting their potential photothermal therapy against cancer in NIR-II window.

Specific Core-Satellite Nanocarriers for Enhanced Intracellular ROS Generation and Synergistic Photodynamic Therapy.

The deficiency of reactive oxygen species (ROS) is the main reason for the current poor efficiency of tumor photodynamic therapy (PDT). To solve this problem, a simple light-triggered core-satellite nanoplatform (UPSD@Au) has been developed by loading Au nanoparticles on the surface of mesoporous silica-coated upconversion nanoparticles. Small molecules DC50 (C17H14BrF2N3OS) and photosensitizer (silicon phthalocyanine dihydroxide, SPCD) were loaded into the silica shell to improve ROS production. Meanwhile, PDT can be triggered through facile near-infrared laser irradiation given the occurrence of a moderate photothermal transfer process between upconversion nanoparticles and Au. The reasonable increment in temperature induced by Au resulted in the timely release of DC50. The inhibition of copper transfer by DC50 results in reduced ROS scavenging and thus improves light-triggered ROS accumulation. Notably, the expression levels of the human copper-trafficking proteins Atox1 and CCS in cancerous cells exceed those in normal cells, and thus enhanced ROS accumulation effect was achieved in cancerous cells. In vitro and in vivo results demonstrate that the synergism between DC50 and SPCD coloaded in the UPSD@Au nanoplatform increases the efficiency of PDT. The UPSD@Au platform represents an efficient codelivery method for hydrophobic small molecules and improves sensitization to specific cancer therapy.

A numerical model to investigate non-gray photothermal characteristics of paraffin-containing glazed windows

Most of numerical methods developed for the photothermal transfer researches of the paraffin-containing glazed windows adopt the gray-body model, in which the spectrum properties of glass and paraffin are generally not taken into account, even though scholars are aware of the fact that glass and paraffin are spectrum selective. Therefore, in this work, a one-dimensional photothermal model that accounts phase dependent thermophysical properties and spectrum dependent optical properties was developed based on the finite difference method, which is utilized to study the heat transfer through the glazed units incorporating paraffin. The results of the established model including non-gray characteristics of glass and paraffin with different spectrum bands were compared with the experimental results in terms of transmittance and temperature. It was observed that 4-band spectrum can accurately simulate the heat transfer process. Then, the photothermal performance of the double-layer glazed windows was studied with the verified model for different melting temperatures of paraffin under summer conditions and paraffin layer thicknesses under both summer and winter conditions, and the transmitted energy from the window units for the considered parameters was quantified. The results showed that inappropriate selection of melting temperature or paraffin layer thickness may defeat the purpose of energy saving. For the studied climatic conditions, the photothermal performance of the paraffin-containing glazed window is better when the melting point of paraffin was 18–26 °C, and the recommended paraffin layer thicknesses is 6–12 mm considering the transmitted energy.

Development of poly-vinyl alcohol stabilized silver nanofluids for solar thermal applications

Nanofluids offer the potential to address the low thermal conductivities found in conventional heat transfer fluids, through their unique electrical, optical and thermal properties, but their implementation remains restricted due to absorption and stability limitations. Here, we characterize and exploit the distinctive plasmonic properties exhibited by polyvinyl-alcohol stabilized silver nanostructures by tuning their absorption and thermal properties through controlling the nanoparticle size, morphology and particle-size distribution configuration at the synthesis stage. The photo-thermal efficiency of different water-based silver nanofluids under a standard AM1.5G weighted solar spectrum were explored, the influence of each of these components on the resulting fluids performance within a direct absorption solar thermal collection system being considered. Nanofluids, containing an extensive ensemble of particle size-distributions (5 nm–110 nm in diameter) in addition to anisotropic particle morphologies (e.g. prisms, hexagons and other non-spherical geometries), exhibited a significant enhancement in the absorption and photo-thermal energy transfer. Enhancements of 5%–32% in the photo-thermal conversion efficiency were achieved, the enhancement being dependent upon the presence of multiple particle size-distributions and the particle concentration. The enhancement is influenced by the interactions occurring between the individual particle size-distributions but also by the collective behaviour of the particles ensemble. The critical particle diameter, above which the photo-thermal characteristics of the nanofluid become dominated by the larger sized particles present, was identified as 150 nm. The increased performance of these nanofluids, which adopt a more complex particle-size configuration, suggests that they can represent suitable candidates for solar-thermal applications.

Acid-Triggered in Situ Aggregation of Gold Nanoparticles for Multimodal Tumor Imaging and Photothermal Therapy.

Photothermal agents with high photothermal transfer efficiencies in the near-infrared (NIR) region are important for enhanced photothermal therapy (PTT) of tumors. Herein, we developed a strategy for the acid-triggered in situ aggregation of a system based on peptide-conjugated gold nanoparticles (GNPs). In an acidic environment, the GNPs formed large aggregates in solution, in cell lysates, and in tumor tissues, as observed by transmission electron microscopy (TEM). As a consequence of the aggregation, their UV-vis absorbance in the NIR region was greatly increased, and laser irradiation of the GNPs resulted in a dramatic increase in the temperatures of solutions and tumors that contained the GNP system. When exposed to NIR irradiation, the aggregates formed by the GNP system under acidic conditions were capable of producing a sufficient level of hyperthermia to destroy cancer cells both in vitro and in vivo. Interestingly, the GNP aggregates showed enhanced properties in multiple imaging modalities, including computed tomography (CT), photoacoustic (PA), and photothermal (PT) imaging. Thus, we have developed a novel probe for enhanced multimodal tumor imaging. These findings prove that a strategy involving the acid-triggered in situ aggregation of a GNP system can increase the photothermal transfer efficiency for low to high energy conversion, thus boosting the therapeutic specificity and antitumor efficacy of PTT and facilitating multimodal imaging.

Engineering biocompatible benzodithiophene-based polymer dots with tunable absorptions as high-efficiency theranostic agents for multiscale photoacoustic imaging-guided photothermal therapy.

To date, photoacoustic imaging (PAI) and PAI-guided photothermal therapy (PTT) have been performed for noninvasive cancer diagnosis and precise ablation of tumors. To conduct concurrent PAI and PTT, it is essential to develop theranostic agents with strong optical absorption and high photothermal transfer efficiency. In this study, we have engineered theranostic agents with tunable absorptions based on conjugated polymer dots (Pdots) with different structures via the simple precipitation method. The as-synthesized Pdots exhibit strong absorption, high biocompatibility, and superior stability. In addition, the Pdots demonstrate that they can serve as contrast agents for multiscale PAI in vitro and in vivo. More importantly, a high photothermal conversion efficiency up to 40% is reached under irradiation with LED light, resulting in effective cancer treatment with extremely low light dose. Consequently, they show the potential as imaging-guided therapeutic agents for clinical cancer treatment and various biomedical applications.