Photothermal Conversion Efficiency Research Articles

Experimental investigation of photothermal conversion and thermal conductivity of broadband absorbing gold nanoblackbodies and graphene oxide nanoparticles for plasmonic photothermal cancer therapy

The choice of nanomaterial is crucial for achieving desired thermal ablation of a tumors, considering nanoparticle dose/concentration and near-infrared (NIR) irradiation parameters during plasmonic photothermal therapy (PPTT). Most studies prioritize use of nanoparticles with high photothermal conversion efficiency (η) for PPTT without emphasizing the thermal conductivity (κ) within a solid tumor. Herein, two broadband absorbing nanoparticles, i.e., gold nanoblackbodies (AuNBs) and graphene oxide (GO) nanoparticles, are compared for η under similar NIR irradiation and nanoparticles dose. Further, the effect of photothermal conversion and κ are studied through tumor-tissue mimicking phantoms mimicking invasive ductal carcinoma embedded with nanoparticles, surrounded by normal tissue region. Under similar conditions, η is higher in AuNBs (73.2%) than GO nanoparticles (63.7%), while κ of GO nanoparticles embedded phantom (0.62 W/mK) surpasses AuNBs embedded phantom (0.59 W/mK) by 5.08%. Photothermal response through tumor-tissue mimicking phantoms shows that GO nanoparticles achieve higher temperatures within the entire tumor region than AuNBs due to their high κ, despite having lower η. This finding suggests that η is not the sole parameter, and it is the coupled effect of η and κ for the choice/suitability of a nanoparticle to attain desired temperatures throughout the tumor for PPTT.

Preparation and performance enhancement of MXene/Na2HPO4·12H2O@SiO2 phase change microcapsule

Currently, the leakage problem of phase change materials can be solved by the microencapsulation technology. Inorganic hydrated salt materials have the advantages of high latent heat density, high thermal conductivity and low cost. How to construct inorganic hydrated salt microcapsules with excellent heat storage capacity and photothermal conversion performance maintains a challenge. In this work, the MXene/Na2HPO4·12H2O@SiO2 (MXene/MPCMs) composite phase change microcapsules were designed and prepared. The Na2HPO4·12H2O was directly used as phase change material and TEOS was used as raw material to generate SiO2 wall material. The MXene played a key and important role in simultaneously enhancing their photothermal conversion efficiency while maintaining available latent heat. The prepared composite microcapsules (MPCM-1) showed more obvious heat storage and release characteristics, and the latent heat reached 169.62 J/g. Besides, when the hydrated salt was encapsulated in silica shell, the supercooling degree of hydrated salt was reduced from 14.2 °C to 10.1 °C. With the increase of MXene content, the maximum surface temperature of microcapsules significantly increased. Based on the results of surface temperature distribution, the photothermal conversion ability and heat transfer rate of microcapsules were effectively improved, which was mainly attributed to the remarkable light absorption conversion ability of MXene. When the MXene was added, the MXene/MPCMs still showed excellent heat storage properties (~ 156.64 J/g). At the same time, the MXene/MPCMs showed good chemical compatibility, crystallization characteristics and thermal stability. Considering available performance enhancement, the prepared microcapsules show good application prospect in solar energy utilization.

Photothermal/photodynamic synergistic antibacterial study of MOF nanoplatform with SnFe2O4 as the core

Drug-resistant bacterial infections cause significant harm to public life, health, and property. Biofilm is characterized by overexpression of glutathione (GSH), hypoxia, and slight acidity, which is one of the main factors for the formation of bacterial resistance. Traditional antibiotic therapy gradually loses its efficacy against multi-drug-resistant (MDR) bacteria. Therefore, synergistic therapy, which regulates the biofilm microenvironment, is a promising strategy. A multifunctional nanoplatform, SnFe2O4-PBA/Ce6@ZIF-8 (SBC@ZIF-8), in which tin ferrite (SnFe2O4, denoted as SFO) as the core, loaded with 3-aminobenzeneboronic acid (PBA) and dihydroporphyrin e6 (Ce6), and finally coated with zeolite imidazole salt skeleton 8 (ZIF-8). The platform has a synergistic photothermal therapy (PTT)/photodynamic therapy (PDT) effect, which can effectively remove overexpressed GSH by glutathione peroxidase-like activity, reduce the antioxidant capacity of biofilm, and enhance PDT. The platform had excellent photothermal performance (photothermal conversion efficiency was 55.7 %) and photothermal stability. The inhibition rate of two MDR bacteria was more than 96 %, and the biofilm clearance rate was more than 90 % (150 μg/mL). In the animal model of MDR S. aureus infected wound, after 100 μL SBC@ZIF-8+NIR (150 μg/mL) treatment, the wound area of mice was reduced by 95 % and nearly healed. The serum biochemical indexes and H&E staining results were within the normal range, indicating that the platform could promote wound healing and had good biosafety. In this study, we designed and synthesized multifunctional nanoplatforms with good anti-drug-resistant bacteria effect and elucidated the molecular mechanism of its anti-drug-resistant bacteria. It lays a foundation for clinical application in treating wound infection and promoting wound healing.

Reinforcing Carrier‐Free Photothermal Nanodrugs Through Flavonol‐Driven Assembly

AbstractCarrier‐free nanodrugs that integrate chemodrugs and other therapeutic agents demonstrate good efficacy and minimized side effects, showing promise for combined therapy. However, a key challenge lies in enhancing the bioavailability and therapeutic potential of the nanodrugs through a controllable assembly process. Herein, a carrier‐free photothermal nanodrug (ZPQ NPs) is constructed through flavonol‐driven assembly with amine‐substituted perylene diimide for enhanced chemo‐photothermal combined cancer therapy. The flavonol, particularly quercetin, facilitates J‐aggregation of perylene diimide derivatives within the nanodrug and contributes to multiple improvements, including red‐shifted absorption, enhanced fluorescence intensity, improved photothermal conversion efficiency as well as excellent photostability. Moreover, the nanodrug also demonstrates enhanced cellular uptake and intracellular reactive oxygen species scavenging capability. The combination of quercetin and photothermal effect effectively kills cancer cells, as well as alleviates inflammation following photothermal therapy. Guided by in vivo fluorescence imaging, the application of ZPQ NPs results in complete tumor elimination and effectively inhibits tumor recurrence through chemo‐photothermal combined therapy. This work presents a straightforward strategy for constructing carrier‐free nanodrugs that exhibit simultaneous enhancements in both photophysical properties and biological activity.

Multi-Functional 2D Covalent Organic Frameworks with Diketopyrrolopyrrole as Electron Acceptor.

2D covalent organic framework (COF) materials with extended conjugated structure and periodic columnar π-arrays exhibit promising applications in organic optoelectronics. However, there is a scarcity of reports on optoelectronic COFs, mainly due to the lack of suitable π-skeletons. Here, two multi-functional optoelectronic 2D COFs DPP-TPP-COF and DPP-TBB-COF are constructed with diketopyrrolopyrrole as electron acceptor (A), and 1,3,6,8-tetraphenylpyrene and 1,3,5-triphenylbenzene as electron donor (D) through imine bonds. Both 2D COFs showed good crystallinities and AA stacking with a rhombic framework for DPP-TPP-COF and hexagonal one for DPP-TBB-COF, respectively. The electron D-A and ordered intermolecular packing structures endow the COFs with broad UV-vis absorptions and narrow bandgaps along with suitable HOMO/LUMO energy levels, resulting in multi-functional optoelectronic properties, including photothermal conversion, supercapacitor property, and ambipolar semiconducting behavior. Among them, DPP-TPP-COF exhibits a high photothermal conversion efficiency of 47% under 660nm laser irradiation, while DPP-TBB-COF exhibits superior specific capacitance of 384Fg-1. Moreover, P-type doping and N-type doping are achieved by iodine and tetrakis(dimethylamino)ethylene on a single host COF, resulting in ambipolar semiconducting behavior. These results provide a paradigm for the application of multi-functional optoelectronic COF materials.

Polydopamine Nanocarriers with Cascade-Activated Nitric Oxide Release Combined Photothermal Activity for the Therapy of Drug-Resistant Bacterial Infections.

Antibiotic abuse leads to increased bacterial resistance, and the surviving planktonic bacteria aggregate and secrete extracellular polymers to form biofilms. Conventional antibacterial agents find it difficult to penetrate the biofilm, remove the bacteria wrapped in it, and produce an excellent therapeutic effect. In this study, a dual pH- and NIR-responsive nanocomposite (A-Ca@PDA) was developed to remove drug-resistant bacteria through a cascade of catalytic nitric oxide (NO) release and photothermal clearance. NO can melt in the outer package of the biofilm, facilitating the nanocomposites to have better permeability. Thermal therapy further inhibits the growth of planktonic bacteria. The locally generated high temperature and the burst release of NO together aggravate the biofilm collapse and bacterial death after NIR irradiation. The nanocomposites achieved a remarkable photothermal conversion efficiency of 47.5%, thereby exhibiting significant advancements in energy conversion. The nanocomposites exhibited remarkable efficacy in inhibiting multidrug-resistant (MDR) Escherichia coli and MDR Staphylococcus aureus, thus achieving an inhibition rate of >90%. Moreover, these nanocomposites significantly improved the wound-healing process in the MDR S. aureus-infected mice. Thus, this novel nanocomposite offers a novel strategy to combat drug-resistant bacterial infections.

Three-dimensional NiO/Ni self-floating porous composite materials for efficient solar interfacial evaporation

The scarcity of freshwater resources and energy crisis are major challenges to the progress of human society. Recently, solar-driven interfacial water evaporation utilizes photothermal conversion materials to convert solar energy into thermal energy, which possesses great application potential in seawater desalination and sewage treatment. Here, we fabricated porous nickel sponge (NSP) composite photothermal material (NiO-NSP) containing abundant NiO nanoneedles array. This in situ-grown NiO with enhanced bonding between photothermal material and substrate can be used as a solar absorber directly without consuming additional photothermal material compared to conventional coating and cladding on the carrier surface. Due to the multi-scattering induced light trapping effect of the semiconductor NiO nanoneedles array on the surface of nickel fibers, resulting in light absorption up to 96.5 %. NiO-NSP evaporators have an abundance of interconnected porous channels for water supply, which results in strong capillary action to pump water to the evaporation interface efficiently. Moreover, the highly dispersed nanoneedles array expand the evaporation surface area. Consequently, the NiO-NSP evaporator delivers an excellent evaporation rate of 1.78 kg m−2 h−1 and a photothermal conversion efficiency of 84.7 % at one sun radiation. In addition, the micron-sized porous mesh structure of NiO-NSP dissolve salt crystals and diffuse them downward into the bulk brine, exhibiting excellent salt resistance and remarkable seawater desalination stability. Moreover, NiO-NSP solar evaporators has been demonstrated to possess excellent ability to purify dye and heavy metal ion wastewater. Therefore, the NiO-NSP high-performance evaporator produced by straightforward process proved to be suitable for solar seawater desalination and wastewater purification.

MXene-modified lemon peel-based composite phase change material with excellent photo-thermal conversion efficiency, thermal storage capacity and thermal conductivity for thermal management of electronic components

The preparation of multifunctional composite phase change materials using green technology to achieve an efficient energy storage and conversion remains an issue of concern. In this paper, a lemon peel-based porous carbon (LPC) composite phase change material (CPCM) was prepared by using polyethylene glycol (PEG) 6000 as a phase change medium and MXene nanosheet-modified carbonized lemon peel as a support carrier. MXene nanosheets were bonded to a lemon peel-based porous carbon skeleton to construct an excellent continuous three-dimensional thermally conductive grid system. What makes it noteworthy is that the presence of MXene nanosheets substantially improves the thermal conductivity (0.66 W/mK) and photo-thermal conversion efficiency (θ = 96.4 %) of MXene-modified lemon peel-based porous carbon/polyethylene glycol composite phase change materials (PEG/LPC@M). It is noteworthy that PEG/LPC@M has remarkable thermal stability and still has high enthalpy after 100 cycles, which further proves the recyclability of PEG/LPC@M and PEG/LPC@M embodies great potential in the field of thermal management of electronic components. In conclusion, a novel multifunctional CPCM was prepared by a simple and green process method in this study, which provides a new idea for waste recycling and reuse, and also has a wide range of applications in thermal management of electronic devices.

Recycling of waste coffee grounds as a photothermal material modified with ZnCl2 for water purification

The aim of this study was to develop a photothermal material modified with carbonization and ZnCl2 impregnation and supported by polyvinyl alcohol (PVA) for water purification using the waste coffee grounds. Scanning electron microscopy (SEM) characterization of the prepared material revealed that a significant surface modification was achieved due to the carbonization and ZnCl2 impregnation. X-ray diffraction analysis (XRD) pattern of the samples showed two broad peaks at 18.4° and 22.2°, this is due to the crystal planes of β-crystal phase structure, which indicates the existence of strong hydrogen bonds between the micro-structures and therefore less suspectable to chemical attack. Additionally, thermogravimetric analysis (TGA) result suggests a slight mass reduction between the temperature range of 65–75 °C implying the thermal stability of the prepared material. The produced modified material had a photothermal conversion efficiency of 74% and could produce vapor at a rate of 1.12 kg/m2h under 980 W/m2 irradiation at 1 sun. A significant reduction in Cu2+ ion concentration (83%), turbidity (91%), total dissolved solids (TDS) (61%), microbial load (95.6%), and total hardness (41.2%) were achieved. Therefore, waste coffee grounds can be considered as a future eco-friendly and low-cost candidate for water purification.

Atomic‐iodine‐substituted polydiacetylene nanospheres with boosted intersystem crossing and nonradiative transition through complete radiative transition blockade for ultraeffective phototherapy

AbstractThe energy dissipation pathways of a photosensitizer for phototherapies, including photodynamic therapy (PDT) and photothermal therapy (PTT), compete directly with that of its fluorescence (FL) emission. Enriching heavy atoms on the π‐conjugated systems and aggregation‐caused quenching are two effective methods to turn off the FL emission of photosensitizers, which is expected to boost the intersystem crossing (for PDT) and nonradiative transition (for PTT) of photosensitizers for maximized phototherapeutic efficacy. Following this approach, an all‐iodine‐substituted polydiacetylene aggregate poly(diiododiacetylene) (PIDA) has been developed, which shows a superior near infrared absorption (ε808nm = 26.1 g−1 cm−1 L) with completely blocked FL, as well as high efficiency of reactive oxygen species generation (nearly 45 folds of indocyanine green) and photothermal conversion (33.4%). To make the insoluble fibrillar PIDA aggregates favorable for systemic administration, they are converted into nanospheres through a pre‐polymerization morphology transformation strategy. The in vivo study on a 4T1 tumor‐bearing mouse model demonstrates that PIDA nanospheres can almost eliminate the tumor entirely in 16 days and prolong the survival time of mice to over 60 days, validating their effective phototherapeutic response through the strategy of inhibiting FL for boosted intersystem crossing and nonradiative transition.

Simultaneous Biofilm Disruption, Bacterial Killing, and Inflammation Elimination for Wound Treatment Using Silver Embellished Polydopamine Nanoplatform.

Due to the presence of spatial barriers, persistent bacteria, and excessive inflammation in bacteria biofilm-infected wounds, current nanoplatforms cannot effectively address these issues simultaneously during the therapeutic process. Herein, a novel biomimetic photothermal nanoplatform integrating silver and polydopamine nanoparticles (Ag/PDAs) that can damage biofilms, kill bacterial persisters, and reduce inflammation for wound treatment is presented. These findings reveal that Ag/PDAs exhibit a broad-spectrum antimicrobial activity through direct damage to the bacterial membrane structure. Additionally, Ag/PDAs demonstrate a potent photothermal conversion efficiency. When combined with near-infrared (NIR) irradiation, Ag/PDAs effectively disrupt the spatial structure of biofilms and synergistically eradicate the resident bacteria. Furthermore, Ag/PDAs show remarkable anti-inflammatory properties in counteracting bacterium-induced macrophage polarization. The in vivo results confirm that the topical application of Ag/PDAs significantly suppress Staphylococcus aureus biofilm-infected wounds in murine models, concurrently facilitating wound healing. This research provides a promising avenue for the eradication of bacterial biofilms and the treatment of biofilm-infected wounds.

A novel treatment modality for rheumatoid arthritis: Inflammation-targeted multifunctional metal-organic frameworks with synergistic phototherapy and chemotherapy

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease with complex pathogenesis. Single chemotherapy struggles to eliminate the disease permanently and reduce the pain owing to drug resistance and inadequate delivery to target cells. This study developed hyaluronic acid (HA)-modified and methotrexate (MTX)-load metal-organic frameworks (denoted as FT-HA-MTX NPs), combining photothermal therapy (PTT), photodynamic therapy (PDT), and chemotherapy to inhibit the progression of RA. In vitro experiments proved that the obtained NPs exhibited good biocompatibility and commendable photothermal conversion efficiency of 36.3 %. Additionally, they promoted ∙OH and O2 production via the Fenton reaction, which dramatically alleviated hypoxia and enhanced ROS generation, and induced substantial mortality in activated RAW 264.7 cells, with cell viability of 31.72 %. Cellular uptake and in vivo imaging confirmed that the modification of HA enabled the NPs to specifically target activated macrophage, ensured prolonged retention of NPs in inflamed synovial tissues, and reduced systemic toxicity. In vivo, after FT-HA-MTX NPs treatment with laser irradiation, the levels of TNF-α and IL-1β in the synovial tissue were reduced by approximately 50 % compared to those in the inflamed synovium, demonstrating a significant enhancement in the anti-inflammatory effect (p < 0.001). In conclusion, FT-HA-MTX NPs are promising inflammation-targeted multifunctional nanoparticles that combine PTT, PDT, and chemotherapy, thereby significantly inhibiting the progression of RA while reducing systemic toxicity.

Nucleus-targeted carbon dots as peroxidase nanozyme for photoacoustic imaging and phototherapy of tumor

High-purity carbon dots (CDs) with a highly π-conjugated sp2-hybridized graphite structure were prepared by the pulse electrolysis method using the graphite plate as raw material. Photoacoustic signal together with photothermal effect was found in the CDs-dispersed suspensions under near-infrared (NIR) irradiation. For the suspension with the CDs concentration of 500 μg/mL, the photothermal conversion efficiency is high up 64.3% and the solution’s temperature can be increased to 82.2 °C under NIR irradiation. Moreover, CDs can be effectively endocytosed by human hepatoma (HepG2) cells with a few hours, act as peroxidase nanozyme to decompose H2O2 and facilitate the production of reactive oxygen species. Under NIR irradiation, CDs exhibit an outstanding apoptosis-inducing effect on HepG2 cells by the photothermal effect. In addition, in vivo experiments show that CDs can be used in photoacoustic imaging (PAI) and guiding the tumor treatment. As a result, the nucleus-targeted CDs with an unique combination of PAI and photothermal effect have potential in cancer diagnosis and treatment.

Self-enhanced regulation of stable organic radicals with polypeptide nanoparticles for mild second near-infrared phototheranostics

Stable organic radicals have emerged as a promising option to enhance fluorescence quantum yield (QY), gaining traction in medical treatment due to their unique electronic transitions from the ground state (D0) to the doublet excited state (D1). We synthesized a stable dicyanomethyl radical with a NIR-II fluorescence QY of 0.86 %, surpassing many NIR-II organic dyes. Subsequently, amphiphilic polymer-encapsulated nanoparticles (NPs) containing the radical were created, achieving a NIR-II fluorescence QY of 0.32 %, facilitating high-contrast bio-imaging. These CNPPs exhibit self-enhanced photothermal properties, elevating photothermal conversion efficiency (PCE) from 43.5 % to 57.5 % under 915 nm laser irradiation. This advancement enables more efficient photothermal therapy (PTT) with lower dye concentrations and reduced laser power, enhancing both feasibility and safety. Through regular fractionated mild photothermal therapy, we observed the release of damage-associated molecular patterns (DAMPs) and an increase in cytokine expression, culminating in combined mild phototherapy (m-PTT)-mediated immunogenic cell death (ICD). Consequently, we developed an immunostimulatory tumor vaccine, showcasing a novel approach for refining photothermal agents (PTA) and optimizing the PTT process.

NIR Absorbing Organic Chromophores Combination with NSAIDs for Remodeling of the Inflammatory Microenvironment to Amplify Tumor Ferroptosis-Photothermal Synergistic Therapy.

Photothermal therapy has emerged as a promising approach for cancer treatment, which can cause ferroptosis to enhance immunotherapeutic efficacy. However, excessively generated immunogenicity will induce serious inflammatory response syndrome, resulting in a discounted therapeutic effect. Herein, a kind of NIR absorption small organic chromophore nanoparticles (TTHM NPs) with high photothermal conversion efficiency (68.33%) is developed, which can induce mitochondria dysfunction, generate mitochondrial superoxide, and following ferroptosis. TTHM NPs-based photothermal therapy is combined with Sulfasalazine (SUZ), a kind of nonsteroidal anti-inflammatory drugs, to weaken inflammation and promote ferroptosis through suppressing glutamate/cystine (Glu/Cys) antiporter system Xc- (xCT). Additionally, the combination of SUZ with PTT can induce immunogenic cell death (ICD), followed by promoting the maturation of DCs and the attraction of CD8+ T cell, which will secrete IFN-γ and trigger self-amplified ferroptosis via inhibiting xCT and simulating Acyl-CoA synthetase long-chain family member 4 (ACSL4). Moreover, the in vivo results demonstrate that this combination therapy can suppress the expression of inflammatory factors, enhance dendritic cell activation, facilitate T-cell infiltration, and realize effective thermal elimination of primary tumors and distant tumors. In general, this work provides an excellent example of combined medication and stimulates new thinking about onco-therapy and inflammatory response.

Solar photothermal self-deicing composite films based on fluorinated polyimide and phosphorene nanoflakes for passive anti-icing of photovoltaic panels

Snow and ice coverage greatly deteriorates the power output of photovoltaic (PV) solar cells due to sunlight obstruction and thus makes a great impact on their electricity generation. To address this problem, we design a type of passive self-deicing composite films based on colorless fluorinated polyimide as a polymeric matrix and phosphorene (PR) nanoflakes as a light absorber for the photothermal deicing of PV panels driven by solar energy. The composite films were successfully fabricated through in situ polycondensation, followed by temperature-programmed thermal imidization. The resultant composite films exhibit a colorless transparent feature along with high transmittance and high absorptivity. The presence of PR nanoflakes enhances the absorption of solar light and conversion of photothermal energy by the composite films, resulting in good photothermal self-deicing effectiveness for solar PV panels. There is an accelerated melting process occurring in the ice covering on the surface of the composite films under solar illumination. The composite film containing 2.0 wt % PR nanoflakes exhibits an optimal photothermal self-deicing performance under a high photothermal conversion efficiency of 92.9 %. The use of this composite film can promote a rapid recovery of the output voltage to an ideal value for the snow- or ice-covered PV panels through fast photothermal self-deicing. This study provides a novel approach for the development of passive self-deicing materials to enhance the power output and electricity generation efficiency of solar PV panels in the snowy and icy weather.

Atomically Precise Nanometer‐Sized Pt Catalysts with an Additional Photothermy Functionality

AbstractAtomically precise ~1‐nm Pt nanoparticles (nanoclusters, NCs) with ambient stability are important in fundamental research and exhibit diverse practical applications (catalysis, biomedicine, etc.). However, synthesizing such materials is challenging. Herein, by employing the mixture ligand protecting strategy, we successfully synthesized the largest organic‐ligand‐protected (~1‐nm) Pt23 NCs precisely characterized with mass spectrometry and single‐crystal X‐ray diffraction analyses. Interestingly, natural population analysis and Bader charge calculation indicate an alternate, varying charge ‐layer distribution in the sandwich‐like Pt23 NC kernel. Pt23 NCs can catalyze the oxygen reduction reaction under acidic conditions without requiring calcination and other treatments, and the resulting specific and mass activities without further treatment are sevenfold and eightfold higher than those observed for commercial Pt/C catalysts, respectively. Density functional theory and d‐band center calculations interpret the high activity. Furthermore, Pt23 NCs exhibit a photothermal conversion efficiency of 68.4 % under 532‐nm laser irradiation and can be used at least for six cycles, thus demonstrating great potential for practical applications.

Atomically Precise Nanometer-Sized Pt Catalysts with an Additional Photothermy Functionality.

Atomically precise ~1-nm Pt nanoparticles (nanoclusters, NCs) with ambient stability are important in fundamental research and exhibit diverse practical applications (catalysis, biomedicine, etc.). However, synthesizing such materials is challenging. Herein, by employing the mixture ligand protecting strategy, we successfully synthesized the largest organic-ligand-protected (~1-nm) Pt23 NCs precisely characterized with mass spectrometry and single-crystal X-ray diffraction analyses. Interestingly, natural population analysis and Bader charge calculation indicate an alternate, varying charge -layer distribution in the sandwich-like Pt23 NC kernel. Pt23 NCs can catalyze the oxygen reduction reaction under acidic conditions without requiring calcination and other treatments, and the resulting specific and mass activities without further treatment are sevenfold and eightfold higher than those observed for commercial Pt/C catalysts, respectively. Density functional theory and d-band center calculations interpret the high activity. Furthermore, Pt23 NCs exhibit a photothermal conversion efficiency of 68.4 % under 532-nm laser irradiation and can be used at least for six cycles, thus demonstrating great potential for practical applications.

Design of CuS composite carbon-based Ni Al-LDH multifunctional phase change composite with electromagnetic shielding performance and heat storage capacity

CuS-based composites are widely used in the fields related to photothermal energy storage and electromagnetic shielding and are excellent candidates for composites with phase change materials. To meet the requirements of micro-integration and electromagnetic resistance of electronic products and optimize the thermal management of electronic products, it is necessary to prepare new flexible composite phase change materials. In this paper, through the design of MPC@Ni Al-LDH/CuS double-layer structure, two-step vacuum filtration method is used, and the highly conductive materials CuS and MPC are introduced into the manufacture of PCM films. With the help of Ni Al-LDH, flame retardancy is introduced. The electromagnetic wave absorption performance is enhanced, and the existence of nano-cellulose (CNF) makes the film have excellent mechanical properties. Ni Al-LDH/MPC and CuS substrates with stable and high mechanical properties are prepared by ultrasonic treatment. According to scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC) and thermogravimetry (TG) characterizations, PEG successfully entered the MPC/CuS skeleton by vacuum filtration, and flexible phase change composite bilayers (MLPC) were obtained. Due to the synergistic effect of structure and components, the obtained composite film has many different excellent functions. Specifically, when MPC@Ni Al-LDH is 15 wt%, the phase transition enthalpy, thermal conductivity, electromagnetic shielding, and electrical conductivity are 146.8 J/g, 1.07 W/m·K, 38.8 dB and 126.4 S/m, respectively. The 3600 s infrared temperature measurement results show that the sample has stable thermal properties. Due to the presence of CuS, when MPC@Ni Al-LDH is 5 wt%, its absorbance can be kept at 1.51 L/(g·cm), and its photothermal conversion efficiency can reach 90.6 %. The MPC/CuS structure in the composite film provides many heat transfer channels, which reduces the phonon scattering in the heat transfer process and significantly increases thermal conductivity. Therefore, this multifunctional flexible phase change film can be used in photothermal conversion devices and for thermal management of electronic equipment, and it has broad application prospects in wearable equipment design due to its excellent electromagnetic shielding ability and infrared thermal stealth ability.

Eutectic phase change composites with MXene nanoparticles for enhanced photothermal absorption and conversion capacity

Phase change composite materials with uniform nanomaterial dispersion are potential solutions for improving thermophysical properties and enhancing latent heat capacity applicable in thermal management. In this study, various transitional carbide-based MXene samples were synthesised via acid etching to augment the heat transfer capacity and efficiency of the solar thermal energy storage (TES). These samples were then uniformly dispersed in a eutectic mixture (1:1) of paraffin wax (PW) and polyethylene glycol (PEG-6000), resulting in the formation of a MePCM composite. The controllable porous structure and hydrogen interactions with the external layer of MXene and long-chain PCM benefitted in the well impregnation of PCM and compatibility impregnated into the composite. An exceptionally higher mass fraction of 1 wt % Ti3C2Tx MXene-based phase change composite unveiled a higher phase change enthalpy of 138.66 J/g in the melting phase and 139.54 J/g in the solidification phase with 89.82 % energy storage efficiency. In contrast to pure eutectic PCM (0.2593 W/mK), the thermal conductivity of MePCM composite is relatively higher and provides a thermal conductivity of 0.9209 W/mK for Ti3C2Tx MXene-based composite. The enhancement of thermal conductivity is ascribed to the increased heat conduction pathway facilitated by the MXene arrangement. The utilisation of spatially constrained eutectic phase change material (PCM) assembly resulted in the development of MePCM, which exhibited enhanced thermal conductivity, chemical and physical stability, and thermal consistency across 500 melting-solidification cycles. Benefitting from the thermal conduction path, the MePCM exhibits an excellent photothermal conversion efficiency of 98.53 %. The thermal responsive tests of Ti3C2Tx and V2CTx MXene composite samples provide better thermal response than eutectic PCM without thermal reduction. With a higher thermal storage capacity and higher heat transfer property, thermally reliable MePCM composites exhibited tremendous potential for photothermal applications.