Nanotube Nanocomposite Films Research Articles

A novel enzymeless electrochemical sensor based on Ni(OH)2–NiO(OH) nanoelectrocatalyst for sensitive and selective detection of uric acid in PBS simulated body fluid

Neurodegenerative diseases such as Parkinson's disease, Alzheimer's disease, and Huntington's disease are increasing worldwide. Therefore, the development of a low-cost, highly stable, and portable device for rapid and accurate risk assessment of relevant biomarkers, especially uric acid (UA), by electrochemical detection is currently attracting much attention. Herein, an electrochemical enzymeless UA sensor based on highly active Ni(OH)2–NiO(OH) nanoelectrocatalyst decorated on polyaniline–carbon nanotubes (PANI-CNTs) nanocomposite film, which was modified on a commercial screen-printed carbon electrode (SPCE) by electrodeposition method for sensitive and selective detection of UA. The sensing behavior of the modified electrode (named Ni(OH)2–NiO(OH)/PANI-CNTs/SPCE) is examined in a simulated body fluid (phosphate buffer solution-PBS, 0.01 M, pH 7.4) using differential pulse voltammetry (DPV) technique. The obtained results showed that the Ni(OH)2–NiO(OH)/PANI-CNTs/SPCE electrode exhibited outstanding electrocatalytic performance for the detection of UA at low potential (0.33 V vs. Ag/AgCl) without exhibiting interfering signals of dopamine (DA), glucose (Glu), ascorbic acid (AA) and urea. The sensor exhibited extra high sensitivity (386.8 μA mM−1 cm−2), high selectivity, good reproducibility, and durable stability with the ability to detect UA at both low (5–100 μM) and high (100–800 μM) levels with a very low detection limit down to 0.11 μM (individual detection of UA) and 0.29 μM (detection of UA in presence of DA) in a simulated body fluid. The recovery test using the proposed electrochemical sensor showed a high recovery percentage (>99.81 %), making it a viable option for practical applications.

Customized Extrusion Nozzle Assisted Robust Nylon 6/MWCNT Nanocomposite Based Triboelectric Nanogenerators for Advanced Smart Wearables

To meet the growing demand for durable, tough, and electrically conductive polymer nanocomposites driven by the rise of smart devices, e-textiles, wearables, and advanced structures, this study offers a systematic approach to fabricating highly robust Nylon 6/multi-walled carbon nanotubes (MWCNTs) nanocomposite films and fibers. The robustness of the nanocomposite is achieved through a simple straightforward approach involving the selective surface functionalization of MWCNTs with oxygen plasma-assisted tetraethylenepentamine grafting (O2T-MWCNTs) and melt-blending these MWCNTs with Nylon 6 under optimized conditions. The mixture is then processed through a specially designed narrow convergent nozzle attached to the extruder die. The die facilitates the alignment of the CNTs into the matrix in the flow direction and increases the composite strength. The incorporation of just 1 wt% of O2T-MWCNTs into Nylon 6 results in a nanocomposite with a remarkable enhancement, demonstrating a 93.25 % increase in tensile strength (T.S.), a 50.47 % increase in Young’s Modulus (E), and an outstanding 136 % increase in elongation at the break (ε) compared to neat Nylon 6, surpassing contemporary benchmarks. Importantly, this method yields a nanocomposite ∼ 30.2 % stronger than the conventional melt-blending process without a nozzle. When fabricating a triboelectric nanogenerator (TENG) with the nanocomposite, exceptional performance was observed, with an output voltage of 105.7 V, a current of 10.55 μA, and a power density of 465 mW/m2, surpassing many reported values. Moreover, the TENG displays highly stable performance through 20,000 cycles of continuous compression. The nanogenerator also exhibited outstanding capability in harvesting mechanical energy from body movements, as demonstrated by lighting various LEDs and small electronics.

Tuning thermoelectric performance with N-annulated perylene-based small molecules and single-walled carbon nanotube nanocomposite films

Two N-annulated perylene (NP)-based organic small molecules (OSMs) with end groups of di-p-tolylamine (DTA) and phenyl-di-p-tolylamine (PhDTA), namely DDTANP and DPhDTANP, are incorporated into single-walled carbon nanotubes (SWCNTs) to fabricate nanocomposite thin films for thermoelectric (TE) application. The weight ratios of OSMs to SWCNTs range from 1:1 to 1:4. The inherent planar structures of these novel OSMs facilitate strong π-π interactions and charge transfer with SWCNTs. Specifically, the DDTANP/SWCNT nanocomposite films, due to its lower HOMO, induces pronounced energy filtering and, thus, a high Seebeck coefficient (S). At the optimized weight ratio of 1:3, DDTANP/SWCNT nanocomposite thin film exhibits an electrical conductivity (σ) of 214.7 S cm−1, and S of 59.8 μV K−1. The flat structure of DPhDTANP enhances its adhesion to SWCNTs, thereby improving dispersion and increasing σ. Similarly, the DPhDTANP/SWCNT (1:3) nanocomposite thin film achieves 256.4 S cm−1, and an S of 55.8 μV K−1. The DPhDTANP/SWCNT (1:3) nanocomposite film exhibits higher σ, resulting in a power factor (PF) of 79.8 μW m−1 K−2, surpassing the PF of 76.7 μW m−1 K−2 for the DDTANP/SWCNT (1:3) nanocomposite film. These findings offer valuable insights into molecular design for SWCNTs-based composite TE research and contributed to enhancing TE applications.

Development of integrated smartphone/resistive biosensor for on-site rapid environmental monitoring of organophosphate pesticides in food and water

Organophosphate (OP) pesticides remain a worldwide health concern due to their acute or chronic poisoning and widespread use in agriculture around the world. There is a need for robust and field-deployable tools for onsite detection of OP pesticides in food and water. Herein, we present an integrated smartphone/resistive biosensor for simple, rapid, reagentless, and sensitive monitoring of OP pesticides in food and environmental water. The biosensor leverages the hydrolytic activity of acetylcholinesterase (AChE) to its substrate, acetylcholine (ACh), and unique transport properties of polyaniline nanofibers (PAnNFs) of chitosan/AChE/PAnNF/carbon nanotube (CNT) nanocomposite film on a gold interdigitated electrode. The principle of the sensor relies on OP inhibiting AChE, thus, reducing the rate of ACh hydrolysis and consequently decreasing the rate of protons doping the PAnNFs. Such resulted decrease in conductance of PAnNF can be used to quantify OP pesticides in a sample. A mobile app for the biosensor was developed for analyzing measurement data and displaying and sharing testing results. Under optimal conditions, the biosensor demonstrated a wide linear range (1 ppt–100 ppb) with a low detection limit (0.304 ppt) and high reproducibility (RSD <5%) for Paraoxon-Methyl (PM), a model analyte. Furthermore, the biosensor was successfully applied for analyzing PM spiked food/water samples with an average recovery rate of 98.3% and provided comparable results with liquid chromatography-mass spectrometry. As such, the nanosensing platform provides a promising tool for onsite rapid and sensitive detection of OP pesticides in food and environmental water.

Bidirectionally enhanced thermally conductive and mechanical properties MXene nanocomposite film via covalently bridged functionalized single-walled carbon nanotube

The development of thermal interface materials (TIMs) with excellent mechanical properties and efficient heat dissipation capability has become very necessary for the next generation of integrated electronics and flexible devices. Herein, a covalently cross-linked cellulose nanofiber/MXene/single-walled carbon nanotube (CNF/MXene/SWCNT-KH550, K-CMC) nanocomposite film was successfully fabricated by vacuum-assisted self-assembly method. This unique cross-linked ternary narce-like structure greatly promoted the load transfer and energy dissipation between the components, thereby improving the mechanical properties of K-CMC nanocomposite films. CNF/MXene/2wt%SWCNT-KH550(K-CMC2) nanocomposite film exhibits superior tensile strength of 255.1 MPa and satisfactory toughness of 3.9 MJ/m3. Additionally, strong covalent cross-linking network also effectively promotes the transfer of phonons between the components, notably in both vertical and horizontal directions. The K-CMC2 nanocomposite film exhibits in-plane thermal conductivity of 25.06 W m−1 K−1 and through-plane thermal conductivity of 1.64 W m−1 K−1, which enhanced 871% and 680% relative to the pure CNF film, respectively. The effective medium theory (EMT) proves that the formation of covalent cross-linked network effectively reduces the interfacial thermal resistance by 31.35%. These superior comprehensive properties endow the K-CMC nanocomposite films with great potential in the field of high power electronics.

Microwave Attenuation Studies of Polypyrrole-SWCNT Nanocomposite Films for Improved EMI Shielding

In the process of finding stable, lightweight, broadband, cost-effective and improved electromagnetic interference (EMI) shielding material, electromagnetic wave attenuation properties of polypyrrole (PPy)—single-walled carbon nanotube (SWCNT) nanocomposite hybrid films were investigated in X-band region (8.2–12.4 GHz) and reported in the present work. The incorporation of SWCNT as a nanofiller in polymer matrix exhibits enhanced EMI shielding performance as compared to pure polymer films. The substantial values of dielectric loss with good impedance matching contribute to improvement in EMI shielding performance. It is found that with an increase of SWCNT loading in polymer matrix from 0 wt% to 5 wt%, nanocomposite films display a gradual increase in AC conductivity and total shielding effectiveness. The maximum total shielding effectiveness of 32.10 dB and minimum reflection loss of −45.54 dB with a wide bandwidth of 3.1 GHz, were obtained for 5 wt% CNT loading. The present results revealed that the prepared nanocomposite films are appropriate materials for lightweight, broadband EMI shields for radar and stealth applications.

Conjugated Polymer /Multi Wall Carbon Nanotubes Composite Characterisation for Application in Volatile Organic Compounds Sensors

Polyimidazole multi-walled carbon nanotubes (MWCNTs) nanocomposite film were synthesised by chemical oxidation of imidazole monomer and addition of MWCNTs to the conductive polymer (CP) solution in 1:1 ratio. Chemical characterisation using FTIR where there is an increased in intensity of peaks in the control sample from 2823 and 2937 cm-1 to 2833 and 2947 cm-1 in Plm/MWCNTs composite respectively and Raman spectroscopy in which Plm/MWCNTs shows the so-called D-band (attributed to disordered sp2 and non-sp2 carbon defects in graphitic sheets) and G-band (attributed to the C–C vibration with the sp2 hybridized orbital in graphene structures) peaks at 1355 cm-1 and 1593 cm-1, but chemical analysis confirmed the mixing of the polymer and the MWCNTs. Electrical measurements using current voltammetry (CV) that shows a reversible wave that is the typical behavior of conductive surfaces in the presence of the redox couple and Impedance measurements in which the largest semicircle was obtained with Plm/CNTs film that corresponds to a film resistance on the real axis of 350 MΩ which is an indication of a higher electron transfer rate in the redox probe and good electrical behaviour. The overall results have shown that the composite has a significant electrical conductivity and can be applied in sensing volatile organic compounds in the environment.

Room-Temperature ppb-Level H2S Gas Sensors Based on Ag Nanowire/Hollow PPy Nanotube Nanocomposites

H2S gas sensors were fabricated using Ag nanowire/hollow polypyrrole nanotube nanocomposite (Ag NW/hollow PPy NT) film for sensing ppb-level H2S gas at room temperature. The morphology, phase composition and crystalline structure of Ag NW/hollow PPy NT nanocomposites were analyzed via scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometry (XRD) and Fourier-transform infrared spectroscopy (FTIR). TEM and SEM images revealed that Ag NWs were well dispersed in the hollow PPy NT matrix. IR results showed no interaction between Ag NWs and hollow PPy NTs in the Ag NW/hollow PPy NT nanocomposites. The effect of the amount of added Ag NWs on the response of the Ag NW/hollow PPy NT nanocomposites to the ppb-level H2S gas was investigated. Comparative gas-sensing results revealed that the introduction of Ag NWs onto hollow PPy NTs was effective in promoting the sensor response to H2S gas. More importantly, the Ag NW/hollow PPy NT nanocomposite had a strong response to ppb-level H2S gas at room temperature.

Self-assembled cellulose nanofiber-carbon nanotube nanocomposite films with anisotropic conductivity.

In this study, a nanocellulose-based material showing anisotopic conductivity is introduced. The material has up to 1000 times higher conductivity along the dry-line boundary direction than along the radial direction. In addition to the material itself, the method to produce the material is novel and is based on the alignment of cationic cellulose nanofibers (c-CNFs) along the dry-line boundary of an evaporating droplet composed of c-CNFs in two forms and conductive multi-walled carbon nanotubes (MWCNTs). On the one hand, c-CNFs are used as a dispersant of MWCNTs, and on the other hand they are used as an additional suspension element to create the desired anisotropy. When the suspended c-CNF is left out, and the nanocomposite film is manufactured using the high energy sonicated c-CNF/MWCNT dispersion only, conductive anisotropy is not present but evenly conducting nanocomposite films are obtained. Therefore, we suggest that suspending additional c-CNFs in the c-CNF/MWCNT dispersion results in nanocomposite films with anisotropic conductivity. This is a new way to obtain nanocomposite films with substantial anisotropic conductivity.

Impact of CNT Concentrations on Structural, Morphological and Optical Properties of ZnO: CNT Nano composite Films

In this study, zinc oxide: carbon nanotube (ZnO: CNT) nano composite films with varying CNT concentrations (0,3,5,10, and 15) wt percent were generated utilizing the pulsed laser deposition (PLD) procedure on clean glass substrates at room temperature. The impact of CNT concentration on the structural, morphological, and optical features of ZnO: CNT nano thin films as deposited was examined. X-ray diffraction was used to evaluate the structure of the generated ZnO: CNT thin films, while an atomic force microscope was used to explore the morphological features of the nano films (AFM) and field emission scan electron microscopy (FESEM). The optical properties of prepared thin films were characterized and studied using UV-VIS-NIR spectrophotometer. The structures of prepared ZnO: CNT with different concentration of CNT thin films were polycrystalline. ZnO: CNT nano thin films were synthesized in hexagonal phase and the dominate orientation is (101). The crystallite sizes are 32 and 26 nm for (101) and (100)) planes for ZnO and ZnO: 15% CNT nano films respectively. These crystallite size are decreased with increasing CNT (0, 3,5,10 and 15) wt. %. The lowest grain size can be shown for ZnO, while the largest grain size can be seen in ZnO: CNT nano thin with 15% concentration, whereas FESEM micrographs displayed a typically rough, pronounced microstructure, with surface protrusions. The energy gap (Eg) of ZnO: CNT nano thin film with various concentrations is computed. The result analysis shows that Eg decreased with increasing CNT weight concentration. This type of behaviors make the prepared films are good candidate for broad range of applications such as optoelectronic and display devices.

TiO2 Nanotube Hydroxyapatite Nanocomposite as Methanol Sensor

AbstractIn the present work, it has successfully demonstrated the utilization of TiO2 nanotube (TNT) and hydroxyapatite (HAp) nanocomposite films by screen printing techniques material for sensing methanol at lower temperature and lower concentrations. Preparation of modified material using HAp blended with TNT by mechanical mixing in different height percentages. The 2 wt% TNT‐HAp nanocomposite film exhibits pronounced sensing behavior for the detection of alcohol vapor even at 10 ppm. The operating temperature is observed to be 30°C for methanol, whereas for the same nanocomposite material fast response and recovery time are 100 and 30 s, respectively, as compared with pure HAp, TNT. These results concluded that nanocomposite of TNT and HAp is capable to sense alcohol vapors with their existence in ambient as low as 10 ppm concentration.

Mechanical and fracture properties of poly(ethylene terephthalate) with glycol/carbon nanotube nanocomposite films under accelerated weathering conditions

Mechanical and fracture properties of poly(ethylene terephthalate) with glycol/carbon nanotube nanocomposite films under accelerated weathering conditions

Development of Cu/F-MWCNT/ZnO Based Active Layer for Long Term Soil Urea Measurements

There is a significant interest in the detection of nutrient levels in smart agriculture farms. In this paper, we report the development of Zinc oxide (ZnO) modified multi-walled Carbon nanotube (F-MWCNT) nanocomposite thin film layers specifically for soil nitrogenous fertilizers level detection. The nanostructured ZnO loaded over the surface of F-MWCNT forms the nanocomposite active layer. The surface morphology of the F-MWCNT/ZnO is characterized using field emission scanning electron microscopy (FeSEM) and energy-dispersive X-ray spectroscopy (EDS). Crystal phase and orientation of F-MWCNT, ZnO and F-MWCNT/ZnO nanocomposites were examined using an X-ray diffractometer (XRD). The electrochemical sensing characteristics of the Cu/F-MWCNT/ZnO structure was measured using an impedance/gain phase analyzing system and resulting composite structure was found to have a proportional impedance change with soil Urea levels. The performance of the sensor was investigated in the 1- 10 kHz range. The impedance magnitude was found to be a linearly decrease with the Urea levels.

Ultra-Wide Range Pressure Sensor Based on a Microstructured Conductive Nanocomposite for Wearable Workout Monitoring.

Conventional flexible pressure sensors are not suitable for high-pressure applications due to their low saturation pressure. In this study, an ultra-wide range pressure sensor is designed based on the optimized microstructure of the polyimide/carbon nanotubes (PI/CNT) nanocomposite film. The sensing range of the pressure sensor is expanded by adopting polyimide (PI) with a high elastic modulus as a matrix material and its sensitivity is improved through functional sensing film with tip-flattened microdome arrays. As a result, the pressure sensor can measure a wide pressure range (≈ 0-3000kPa) and possesses the sensitivity of ≈ 5.66 × 10-3 -0.23 × 10-3 kPa-1 with high reliability and durability up to 1000 cycles. The proposed sensor is integrated into the hand and foot pressure monitoring systems for workout monitoring. The representative values of the pressure distribution in the hands and feet during the powerlifting are acquired and analyzed through Pearson's correlation coefficient (PCC). The analyzed results suggest that the pressure sensor can provide useful real-time information for healthcare and sports performance monitoring.

Laminated Ag and Ag/CNT nanocomposite films as sensing element for efficient thin film temperature sensors

Thin film sensor (TFS) is one of the most promising candidates for instantaneous temperature measurements owing to their extremely small response time (~milliseconds) aided with fair accuracy. Since they are capable of making quick and precise temperature measurements, they can be also used as heat flux gauges to measure surface heat fluxes in dynamic environments like high speed aerospace applications, gas turbine blades etc. Usual TFS are made by depositing a thin metallic film over insulating substrate. In this work we developed an Ag-Carbon nanotube (CNT) nanocomposite film as the sensing element of a TFS and compare it with pure Ag TFS, both having Macor as substrate. Static calibration established a better temperature coefficient of resistance (TCR) value i.e. better sensitivity, for the nanocomposite TFS. X-ray diffraction (XRD) and Energy Dispersive X-ray (EDX) studies are done to probe behind the increase in sensitivity of the nanocomposite TFS compared to its conventional metallic counterpart.

Fabrication of Zn3(PO4)2/carbon nanotubes nanocomposite thin film via sol-gel drop coating method with enhanced photocatalytic activity

Thin films of Zn3(PO4)2 and Zn3(PO4)2/carbon nanotubes (Zn3(PO4)2/CNT) were fabricated on glass substrate by the simple sol-gel drop coating method. The crystal structure, particle size, morphology and optical properties were characterized by X-ray Diffraction, Field Emission Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy (FT-IR) and Ultraviolet-visible Spectroscopy. The X-ray diffraction results revealed the formation of zinc phosphate crystal without any impurities as well as the average particle size of 24 nm and 19 nm for Zn3(PO4)2 and Zn3(PO4)2/CNT, respectively. FT-IR spectral data confirmed the grafting of the polar carboxylic and hydroxyl functional groups on the surface of nanotubes due to functionalization and also the presence of PO43- group. The formation of heterojunction interface between CNT and Zn3(PO4)2 reduce the fast recombination of charge carriers, which leads to the high photoenergy conversion efficiency. The as-synthesized Zn3(PO4)2/CNT composite thin film showed highest photocatalytic efficiency for the degradation of cationic organic dye methylene blue under ultraviolet (UV) (85%) and visible (53%) light irradiation. Incorporation of CNT with the Zn3(PO4)2 enhanced the photocatalytic efficiency two fold in case of UV and four fold higher in presence of visible light irradiation as high as bare Zn3(PO4)2. We offer that this work will smooth the progress of preparation of innovative phosphate based photocatalysts for degradation of organic pollutants from environment under UV light illumination. Furthermore, a plausible photocatalytic degradation mechanism of an organic pollutant by the synthesized Zn3(PO4)2/CNT composite is proposed.

Fabrication of transparent silica-silica nanotube/PFTS nano-composite thin films with superhydrophobic, oleophobic, self-cleaning and anti-icing properties

Light on optoelectronic devices and solar panels is lost both through reflection at the air/glass interface of the cover glass and through scattering or absorption by accumulated dust, dirt and ice. Therefore, the transparent superhydrophobic thin films can resolve these problems. In this research, silica-silica nanotube nanocomposite thin films were applied on glass substrates by a sol–gel method. To modify the nanocomposite thin film, the samples were immersed in a PFTS solution. The morphology, chemical composition and transparency of the thin films were investigated using FE-SEM, FTIR and UV–VIS–NIR spectrophotometer methods. The water and oil contact angles on the thin film surfaces was measured using a contact angle analyzer. The self-cleaning and stability of the thin films were investigated. The water contact angle results indicated that silica nanotube/PFTS thin films increased water contact angle of the glass substrate from 16° to 152°. The transmittance of the silica-silica nanotube/PFTS coated glass substrate was measured as 87% at 550 nm. The icing test results showed that superhydrophobic coating increased icing time during ice formation on the glass surface from 102 to 874 s.

Green technique solvent-free fabrication of silver nanoparticle–carbon nanotube flexible films for wearable sensors

Fabricating flexible/stretchable physical sensors has emerged as a topic of interest owing to the huge market demand for wearable medical devices and electronic skins for the regular and continuous monitoring of human health information. Herein, we report a green and efficient strategy for constructing a sensitive polydimethylsiloxane-derived wearable piezoresistive sensor, based on silver nanoparticle (AgNP)@multi-walled carbon nanotube (CNT) nanocomposite films. The developed sensing material exhibits good flexibility and electrical conductivity because of the interfacial effect between AgNPs and CNTs, leading to excellent sensing performances with good sensitivity, fast response time, low operating voltage, and mechanical stability, as measured under different pressure loading, bending angle, and percentage elongation conditions. In addition, finger movement recognition is sampled by testing the exceptional resistance change, and its practicality was further proven. Thus, the developed material has potential for application in wearable electronics. Notably, the entire sensor fabrication process is low-cost, environment-friendly, scalable, and industrially available, which is beneficial for industrial applications.

The Preparing and Characterization of Nanocomposite (PTh/SWCNT) for NO2 Gas Sensing

We prepared polythiophene (PTH) with single wall carbon nanotube (SWCNT) nanocomposite thin films for Nitrogen dioxide (NO2) gas sensing applications. Thin films were synthesized via electrochemical polymerization method onto (Indium tin oxide) ITO coated glass substrate of thiophene monomer with magnesium perchlorate and different concentration from SWCNT (0.012 and 0.016) % in the presence130mL of Acetonitrile used. X-ray diffraction (XRD), Field Emission Scanning Electron microscopy (FE-SEM), Atomic Force Microscope (AFM) and Fourier Transform Infrared Spectroscopy (FT-IR) were used to characterized these nanocomposite thin films. The response of these nanocomposite for NO2 gas was evaluated via monitoring the change time in presence 25% NO2 of with electrical resistance at (40, 80,120,160 and 200)°C. We can observe that the PTh/SWCNT films show a higher sensitivity as compare to pure PTH.

Polydimethylsiloxane/multi-walled carbon nanotube nanocomposite film prepared by ultrasonic-assisted forced impregnation with a superior photoacoustic conversion efficiency of 9.98 × 10−4

Polydimethylsiloxane/multi-walled carbon nanotube (PDMS/MWCNT) composite had high photoacoustic transduction efficiency owing to its high light absorption coefficient and low interfacial thermal resistance. The high expansion coefficient and light absorption ability of PDMS/MWCNT nanocomposite films have significant positive effects when it is used as a laser ultrasonic transducer. We introduce an ultrasonic-assisted forced impregnation method for the preparation of PDMS/MWCNT nanocomposite films. PDMS was used as the matrix phase, and MWCNTs were used as the nano-supporting framework. PDMS matrix was introduced into the MWCNT framework by the forced impregnation method. The morphology, thermal, and mechanical properties of the nanocomposite film were analyzed systematically. The photoacoustic conversion efficiency was researched through both experiment and simulation methods. The output sound pressure of our PDMS/MWCNT nanocomposite film reached 7.59 MPa when applied as an ultrasonic transducer under the pulsed laser excitation of 1 mJ / pulse energy. The photoacoustic conversion efficiency of our sample was 9.98 × 10 − 4, three times higher than similar products reported before, which offered the possibility to greatly enhance the photoacoustic signals.