Photothermal Process Research Articles

Thermal conductivity dependent temperature during photo-thermo-elastic excitation of semiconductor material with volumetric absorption laser heat source in gravitational field

In this following work, a theoretical novel model for exited semiconducting medium is studied in the context of photothermal transport process. The dual-phase-lag (DPL) is used to modify the heat (energy) conduction equation when the thermal conductivity is variable during an initial hydrostatic stresses. The thermal conductivity depends on a temperature. The photo-thermoelasticity theory is introduced in a generalized form under the impact of gravitational field with a volumetric absorption laser which considered a heat source. The governing equations are studied in two-dimensional (2D) deformations and are solved using the harmonic wave technique. The considered physical quantities are obtained completely when are applied some thermal and mechanical loads at the free surface of silicon (Si) semiconductor elastic medium. The considered numerical physical fields are obtained graphically and discussed theoretically. The impacts of various variables are illustrated graphically which based on the thermal relaxation time (memories time, DPL theory). The comparisons are made under the effect of heat source, gravity and the variable thermal conductivity graphically.

Photothermal Membrane Distillation toward Solar Water Production.

Freshwater production is one of the biggest global challenges today. Though desalination can provide a climate-independent source of clean water, the process requires a high energy consumption. Emerging advancement of photothermal nanomaterials and the urgent demand for a green technology transition have reinvigorated the established solar distillation technology. The current development of photothermal vaporization focuses on material innovation and interfacial heating, which largely emphasizes vapor generation efficiency, without considering pragmatic water collection. Moreover, salt accumulation is another critical issue of seawater solar-driven vaporization. The incorporation of photothermal materials into a photothermal membrane distillation (PMD) solar evaporator design harmoniously resolves these issues through combination of renewable energy and efficient interfacial distillation, to achieve the ultimate goal of practical saline water into freshwater conversion. At this juncture, it is imperative to review the recent opportunities and progresses of the PMD system. Here, the fundamental photothermal processes, strategies for efficient evaporator design, evaluation of various criteria for photothermal material incorporation with desired properties, discussions on desalination, water treatment, and energy generation applications are covered. Guidelines in material and system designs to further advance the PMD system that is highly promising in delivering portable water for both large-scale and decentralized systems are provided.

Optical back-action on the photothermal relaxation rate

Photothermal effects can alter the response of an optical cavity, for example, by inducing self-locking behavior or unstable anomalies. The consequences of these effects are often regarded as parasitic and generally cause limited operational performance of the cavity. Despite their importance, however, photothermal parameters are usually hard to characterize precisely. In this work, we use an optical cavity strongly coupled to photothermal effects to experimentally observe an optical back-action on the photothermal relaxation rate. This effect, reminiscent of the radiation-pressure-induced optical spring effect in cavity optomechanical systems, uses optical detuning as a fine control to change the photothermal relaxation process. The photothermal relaxation rate of the system can be accordingly modified by more than an order of magnitude. This approach offers an opportunity to obtain precise in situ estimations of the parameters of the cavity in a way that is compatible with a wide range of optical resonator platforms. Through this back-action effect, we are able to determine the natural photothermal relaxation rate and the effective thermal conductivity of cavity mirrors with unprecedented resolution.

A basic estimation on the light distribution and thermal behavior of the human skin through transfer matrix method coupled with Pennes’ bio-heat equation

This work is concerned with the investigation of the photo-thermal response of the human skin tissue. A four-layer, one-dimensional air–skin tissue structure has been considered. The considered structure is irradiated by the different light intensities and wavelengths. Light propagation in the skin tissue has been modeled by using a full electromagnetic method. To solve electromagnetic equations numerically, Transfer Matrix Method (TMM) has been used. Inhomogeneity of the multilayer skin tissue structure has been considered by the wavelength dependence of the Complex Optical Refractive Index (CORI). In order to determine the temporal and spatial temperature distribution inside the skin tissue, the TMM has been coupled with Pennes’ bio-heat transfer equation. The equation has been solved semi-analytically with the adiabatic condition by using the Green’s function method. Based on the preliminary findings of this study, the effect of the light intensity and wavelength on the resultant temperature distribution inside the skin tissue structure has been reported. Obtained results could be helpful for designing and improving the practical protocols through the skin photo-thermal therapy process.

Temperature dependent thermal conductivity during photothermal excitation process of semiconductor medium with an internal heat source in gravitational field

In this work, a novel model of semiconducting elastic material is studied during a process of photothermal excitation. The dual phase lag (DPL) for the heat conduction equation is introduced in the context of the variable of the thermal conductivity. The thermal conductivity can be chosen as a linear function of temperature (depend on temperature). The generalized thermoelasticy theory is investigated when an internal heat source is steady with a constant speed in the context of the gravitational field. The harmonic wave technique is used in two-dimensional deformations to obtain the considered physical fields. Some thermal loading subjected to thermal shock and other mechanical forces at the outer free surface of a semi-infinite elastic medium (semiconductor as silicon) are applied. The considered physical fields were illustrated graphically. The influences of some several variables are obtained which based on the DPL (thermal memories) model and the variable thermal conductivity. The results obtained are investigated and are depicted graphically.

Plasmonic Titanium Nitride Nano-enabled Membranes with High Structural Stability for Efficient Photothermal Desalination.

Herein, we demonstrate the desalination performance of a solar-driven membrane distillation (MD) process, where upon light illumination, a highly localized heating of plasmonic titanium nitride nanoparticles (TiN NPs) immobilized on a hydrophobic membrane provides the thermal driving force for the MD operation. The engineered TiN photothermal membrane induces vapor generation directly at the feed-membrane interface upon solar irradiation, thereby eliminating the need to heat the entire bulk feed water. The results indicate that the average vapor flux through the TiN photothermal membrane without any auxiliary feed heating was recorded as 1.01 L m-2 h-1, which corresponds to the solar-thermal efficiency of 66.7% under 1 sun solar irradiance. The superior performance of the photothermal MD process is attributed to the broadband optical absorption and excellent light-to-heat conversion properties of the plasmonic TiN NP layer, which enabled efficient interfacial water heating at the membrane surface and increased the net driving force for vapor transport. Results also reveal the high mechanical stability of the TiN photothermal coating layer during long-term photothermal MD operations. We believe that the TiN photothermal membranes fabricated using a relatively inexpensive and nontoxic material via the simple technique with high stability and photothermal conversion efficiency will provide a path forward for developing the solar-driven MD applications.

Sterilization effects of UV laser irradiation on Bacillus atrophaeus spore viability, structure, and proteins.

Bacillus spores are highly resistant to toxic chemicals and extreme environments. Because some Bacillus species threaten public health, spore inactivation techniques have been intensively investigated. We exposed Bacillus atrophaeus spores to a 266 nm Nd:YVO4 laser at a laser power of 1 W and various numbers of scans. As a result, the UV laser reduced the viability of Bacillus atrophaeus spores. Although the outer coat of spores remained intact after UV laser irradiation of 720 scans, damage inside the spores was observed. Spore proteins were identified by matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry during the course of UV laser irradiation. Photochemical and photothermal processes are believed to be involved in the UV laser sterilization of Bacillus spores. Our findings suggest that a UV laser is capable of sterilizing Bacillus atrophaeus spores.

Accurate SERS monitoring of the plasmon mediated UV/visible/NIR photocatalytic and photothermal catalytic process involving Ag@carbon dots.

The excited carriers (electrons and holes) and heat energy that originate from plasmonic metal nanomaterials are crucial to the enhancement of the photocatalytic performance. In this study, an Ag@carbon dots (Ag@CDs) hybrid has been prepared with excellent Fenton-like photocatalytic and photothermal conversion properties for catalyzing H2O2 to generate hydroxyl radicals (˙OH) for the degradation of crystal violet (CV) dye under full solar spectrum irradiation based on a unique plasmon effect. We have obtained some intrinsic kinetics information, including the reaction rate and apparent activation energy on the surface of the Ag@CDs, through a surface-enhanced Raman scattering strategy to investigate the contributions made by photocatalytic and photothermal effects in the plasmon mediated reaction under irradiation from ultraviolet (UV)/visible/near-infrared (NIR) light. In the visible light region, the Ag@CDs + H2O2 system exhibits the fastest apparent reaction rate owing to the involvement of a large number of hot carriers, which are generated by the strongest plasmon effect, and the presence of the photothermal effect mediated by the plasmonic effect. As the wavelength of the illumination blue-shifts to the UV region, the plasmon effect is weakened, resulting in a decrease in the number of hot carriers. Furthermore, the hot carriers will not be further thermalized because of interband transitions. In addition, the catalytic performance of Ag@CDs in the NIR region is almost dominated by the photothermal effect. This work provides deep insights into understanding the plasmon-mediated photocatalytic mechanism of the Ag@CDs hybrid.

Scattering-mediated photothermal heating in plasmonic PES/Au membranes for heterogeneous catalysis

Scattering-mediated photothermal process in the PES/Au membranes enabled local temperature heating inside the composite membrane to accelerate the kinetics of a model chemical reaction.

Demonstration of the photothermal catalysis of the Sabatier reaction using nickel nanoparticles and solar spectrum light.

The promise of light-to-chemical energy conversion has led researchers to explore photo-thermal processes for chemical reactivity of nanoparticles. Previous work has examined particles as an element of a supported catalyst, but not as an unsupported nanopowder. We present a preliminary examination of a photo-thermal Sabatier reaction performed on suspended Ni nanoparticles. This new system performs a catalytic Sabatier reaction at lower bulk temperatures than reported for a standard reaction, driven by light. This result occurs only when the particles are suspended freely in a gaseous mixture; implying that particle isolation enhances photo-thermal catalysis.

Millisecond photothermal carbonization for in-situ fabrication of mesoporous graphitic carbon nanocomposite electrode films

Binder-free mesoporous graphitic carbon composite films on polymer or metal substrates are attractive for high-surface-area electrodes to achieve superior device performances. However, rapid and large-area fabrication of such materials remains a significant challenge due to the harsh conditions required for the carbonization process. We report an efficient method that combines bottom-up precursor film assembly with photothermal processing using sub-millisecond light pulses generated from a xenon flash lamp. This approach enables the rapid carbonization and graphitization of precursor films over large areas at ambient bulk temperature to yield functional films while avoiding damage to the substrates. The films contain light-absorbing nanoparticles to convert light energy into heat, a block copolymer to template the porous structures via self-assembly, and phenol-fomaldehyde resin to form the carbon skeleton. Graphitic carbon nanoribbons embedded in a porous carbon matrix are created under mild conditions using iron nanoparticles as the catalyst during the millisecond photothermal process. The resulting composite films show excellent electrochemical properties and are demonstrated for use as high capacity lithium ion battery anodes.

Photothermal plasma wave in the theory of two-temperature with multi-phase-lag thermo-elasticity in the presence of magnetic field in a semiconductor with diffusion

In the present study, the wave propagation in a magneto-thermodiffusion semiconductor, in the context of a two-temperature generalized theory of thermo-elasticity with triple-phase-lag, is studied. The governing equations in plasma theory, during the photothermal process, are formulated and solved for a plane-wave solution to obtain a velocity equation. The velocity equation indicates the existence of four coupled longitudinal waves and one shear transverse wave, namely coupled mass diffusion (CD) wave, coupled longitudinal displacement (LD), coupled thermal (CT) waves, coupled plasma (CP) waves, and shear transverse (SV) waves. The speeds of these plane waves are computed for silicon material. The effect of the magnetic field parameter, diffusion parameters, two-temperature parameter, phase lag, thermal conductivity, and frequency on the speed of these waves is depicted graphically.

Refined heat conduction equation of thermomagnetic microtemperature semiconductor material during photothermal excitation process

ABSTRACT In this problem, the coupled between magnetic field and thermal-elastic-plasma waves is studied. The governing equations are taken during photothermal excitation on a surface of semiconductor medium. The medium is exposed to weak external magnetic field during the refined multi-phase-lags of thermal relaxation times. The microelements (microtemperatures) possess due to microstructure of the semiconductor medium is investigated. The normal mode method is applied in one dimension (semiconductor rod) to obtain the main physical fields in this phenomenon for this microtemperature field. The surface is shocked by heating (thermal shock problem) and applying the free traction on its outer surface (mechanical boundary) through transport (diffusion) process of temperature to observe the analytical complete expressions of the main physical fields. The silicon (Si) material is used to make a simulation and obtain the numerical results. The basic physical field quantities are graphed and discussed.

Plasma-elastic-thermal propagation of a rotator semiconductor magneto-electric medium during microtemperature and photothermal excitation processes subjected to mechanical ramp type

ABSTRACT The overlapping between the initial magnetic field and the generalized thermoelasticity theory during the excited semiconductor medium is studied. The microtemperature process in the context of the photothermal theory (due to the thermal effect) is obtained for the main fields of a rotator medium. The disturbances of the elastic-plasma-thermal waves are investigated in two-dimensional (2D) deformation. The governing equations are discussed in the Fourier and Laplace domains when microelements possess microtemperatures. The basic analytical solutions of the main variables are constructed with Laplace transform. The boundary conditions as well as mechanical ramp and isothermal type are applied on the outer surface of the semiconductor elastic medium to obtain the unknown parameters. The complete solutions of the main variables field in the space-time domain are observed when the inversion techniques are used numerically. The effects of parameters of rotation, thermoelectric coupling, and magnetic field are discussed theoretically and graphically in 2D and 3D.

Self-Suspended Photothermal Microreactor for Water Desalination and Integrated Volatile Organic Compound Removal.

Steam generation and photocatalytic degradation of organic pollutants based on solar light are regarded as two important strategies for addressing the water scarcity issues. The water evaporation efficiency was greatly inhibited by the high cost, low stability, and low efficiencies of solar light absorption and photothermal conversion of photothermal materials. Moreover, volatile organic compounds (VOCs) are easily volatilized and enriched in as-distilled water during the photothermal process. Inspired by the structure of biomass materials in nature, a bifunctional solar light-driven steam generation and VOC removal microreactor was explored by coating commercial TiO2 (P25) powders on a carbonized biomass waste Flammulina. With the 3D aligned porous carbon architectures, this microreactor exhibited both a high water evaporation rate (37.0 kg m-2 h-1) and a high energy conversion efficiency (91.2%) under simulated sunlight irradiation (light intensity = 25.5 kW m-2). A high VOC removal rate (80.9% in 40 min) was also achieved during the steam generation process via choosing phenol as the probe pollutant molecules. The nature-inspired designing concept and bifunctional microreactor in this study may open up a new strategy for producing clean distilled water from seawater with an efficient removal of VOCs.

Photothermal Excitation Process during Hyperbolic Two-Temperature Theory for Magneto-Thermo-Elastic Semiconducting Medium

A novel technique is used to study the magnetic field influence in the free surface of an elastic semiconductor medium for a one-dimensional (1D) deformation. The problem is formulated during the hyperbolic two-temperature theory to study the coupled between the plasma, thermo-elastic waves. The investigation is conducted during a photothermal transport processes with the effects of both initial hydrostatic stress and some mechanical force. Using the Laplace transform method, the governing equations of the elastic waves, carrier density, quasi-static electric field, heat conduction equation, hyperbolic two temperature coefficient and constitutive relationships are obtained for the thermo-magnetic-electric medium. The mechanical stresses, thermal and plasma boundary conditions are applied on the interface adjacent to the vacuum to obtain the basic physical quantities in Laplace domain. The inversion of Laplace transform with numerical method is applied to obtain the complete solutions in time domain for the main physical fields under investigation. The effects of thermoelectric, thermoelastic and hyperbolic two temperature parameters of the applied force on the displacement component, carrier density, force stress and temperature distribution have been discussed graphically.

A three-dimensional numerical study of coupled photothermal and photoelectrical processes for plasmonic solar cells with nanoparticles

Base on the GaAs plasmonic solar cell, a three-dimensional numerical model is proposed for the photoelectrical and photothermal processes. In the model, the coupled processes of nanoparticle photothermal conversion and substrate photoelectrical conversion are accounted for with FDTD solver and DEVICE solver. The Finite-Difference-Time-Domain method is used in the FDTD solver to analyze the light absorption process. The light absorption efficiency, quantum efficiency ratio of plasmonic solar cells to bare solar cells, and temperature distributions of the nanoparticles and substrate surface are obtained. A dimensionless coefficient for the substrate temperature rise is proposed to characterize the photothermal performance of the investigated plasmonic solar cell. The nanoparticles create parasitic absorption, increase substrate light scattering, and improve light absorption. Spherical Ag nanoparticles hold a higher photoelectrical conversion efficiency than spherical Au nanoparticles with an acceptable temperature increase, while spherical Au nanoparticles have stronger thermal sensitivity than spherical Ag nanoparticles. The cylindrical nanoparticles (Au or Ag) contribute significantly to the photothermal performance but do not contribute to the enhancement of the overall integrated quantum efficiency ratio. The nanoparticle arrays have accumulated heating and interference effects that enhance the thermal response. Spherical Ag nanoparticles are recommended for photoelectrical devices, while cylindrical Ag and Au nanoparticles are suitable for the development of thermal sensors.

Review of the Photothermal Energy Conversion Performance of Nanofluids, Their Applications, and Recent Advances

Nanoparticles have been thoroughly investigated in the last few decades because they have many beneficial and functional qualities. Their capability to enhance and manipulate light absorption, thermal conductivity, and heat transfer efficiency has attracted significant research attention. This systematic and comprehensive work is a critical review of research on the photothermal energy conversion performance of various nanofluids as well as the recent advances in several engineering applications. Different nanofluids used in the photothermal energy conversion process were compared to identify the suitable applications of each nanofluid in thermal systems. An analysis of the previous investigations based on experimental and numerical studies has established that nanomaterials have the potential to increase the efficiency of solar thermal systems.

Non-Gaussian laser pulse response on photo-thermoelastic interactions in a silicon plate under the light of memory-dependent thermoelasticity theory

In the present article, the wave propagation in a homogeneous semi-infinite silicon plate through photo-thermal process has been comparatively studied under the light of memory-dependent thermoelasticity theories with thermal relaxations. Without neglecting the coupling between the plasma and thermoelastic waves that photo-generated through intensity modulated beam of non-Gaussian laser pulse, a two-dimensional semiconducting medium having homogeneity in thermal and elastic properties is considered. The analytical solutions were observed in the domain of Laplace–Fourier transform by the method of eigenvalues approach. Finally, suitable graphical discussions and conclusions are presented with respect to varied thermal relaxation times.

Thomson effect in thermo-electro-magneto semiconductor medium during photothermal excitation process

ABSTRACT The effect of Thomson heating on semiconductor medium is studied. Analytical discussions in the presence of thermoelectricity and magnetic field, in the context of photothermal transport process, are made. The interactions between plasma, thermoelectric, magnetic and elastic waves are taken into consideration. The governing equations are investigated in two-dimensional deformations of a homogenous, isotropic medium. The density of charge is taken only as a function of time of the induced electric current. The normal mode technique is used to obtain the physical quantities field under investigation. Some electro-mechanical loads and thermal effect through recombination process are applied at the free surface of semiconductor elastic medium. The distributions of physical fields in this phenomenon are discussed and represented graphically. The results have been discussed under the effects of thermoelectric parameter and Thomson parameter.