Table of contents

The remarkable flexibility, stable chemical structure, and extraordinary thermal, electrical, and optical properties of carbon nanotubes (CNTs) are promising for a variety of applications in flexible and/or high-temperature electronics, optoelectronics, and thermoelectrics, including wearables, refractory photonics, and waste heat harvesting. However, the long-standing problem in the preparation of CNT ensembles is to maintain the extraordinary properties of individual CNTs on a macroscopic scale; the polydispersity and randomness remain two main challenges. In this topical review, we will discuss three ways of creating wafer-scale aligned CNTs: direct growth of aligned CNTs by chemical vapor deposition, production of ultrahigh-conductivity CNT fibers through solution spinning and coating, and spontaneous formation of wafer-scale aligned CNT films via controlled vacuum filtration. We will then describe flexible and high-temperature applications of these materials, such as flexible CNT broadband detectors, flexible strain sensors, spectrally selective thermal emitters, and thermoelectric devices.

The kinetic effects of non-equilibrium excitation by direct electron impact on low-temperature oxidation of CH₄ were investigated by experiment and simulation. We focused on the vibrational-electronic-chemistry coupling of methane and oxygen molecules under conditions of immediate reduced electric field strengths of 30–100 Td in an RF dielectric barrier discharge. A detailed plasma chemistry mechanism governing the oxidation processes in an He/CH₄/O₂ combustible mixture was proposed and studied by including a set of electron impact reactions, dissociative recombination reactions, reactions involving vibrationally- and electronically- excited species, and important three-body recombination reactions. A linear increase in reactant consumption with an increase in plasma power was observed experimentally. This suggested the presence of decoupling between the molecular excitation by plasma and the low-temperature chemistry. However, CO formation showed a non-linear trend, with its formation increasing with lower energy inputs and decreasing at higher energy inputs. By modelling the chemical kinetic sensitivity and reaction pathways, we found that the formation of radicals via the chain propagation reactions CH₄  +  O(¹D)  →  CH₃  +  OH, and O₂(a¹Δ_g)  +  H  →  O  +  OH was mainly accelerated by the electronically excited species O(¹D) and O₂(a¹Δ_g). The numerical simulation also revealed that under conditions of incomplete relaxation, the vibrational species CH₄(v) and O₂(v) enhanced chain propagating reactions, such as CH₄(v)  +  O  →  CH₃  +  OH, CH₄(v)  +  OH  →  CH₃  +  H₂O, O₂(v)  +  H  →  O  +  OH, thus stimulating the production of active radicals and final products. Specifically, for an E/N value of 68.2 Td in a stoichiometric mixture (0.05 CH₄/0.1 O₂/0.85 He), O(¹D), CH₄(v13), and O₂(v) were estimated to contribute to 12.7%, 3.6%, and 3.8% of the production of OH radicals respectively. The reaction channel CH₄(v13)  +  OH  →  H₂O  +  CH₃ was estimated to be responsible for 1.6% of the H₂O formation. These results highlight the strong roles of vibrational states in a complex plasma chemistry system and provide new insights into the roles of excited species in the low-temperature oxidation kinetics of methane.

Plasma synthesis of ammonia (NH₃) is a potential and sustainable pathway for nitrogen fixation. In this study, non-thermal plasma (NTP) synthesis of NH₃ was conducted in a packed-bed dielectric barrier discharge (DBD) reactor. Different catalysts, including alumina (Al₂O₃), light magnesium oxide (L-MgO), heavy magnesium oxide (H-MgO), Ru/Al₂O₃ and Ru/L-MgO, were filled in the reactor and compared for NH₃ production. Various characterization techniques were used to determine the specific surface area and pore size, surface morphology, and surface acidity of the catalysts. The effects of reaction conditions on NH₃ production were examined. Results showed that the optimal N₂/H₂ volume ratio was 2:1 since a greater quantity of N₂ favored the generation of plasma-excited nitrogen species. The synthesized NH₃ can be adsorbed by the acid sites on Al₂O₃, which reduced the NH₃ yield. Higher total gas flow rate improved the NH₃ production over various catalysts, mainly due to the reduced external diffusion resistance. More plasma-excited nitrogen and hydrogen species for NH₃ synthesis were formed at higher discharge power, yet the increasing rate of NH₃ yield became slower when the discharge power was higher than 32 W. Additionally, the NH₃ desorption from the catalyst was enhanced at higher temperature, which resulted in higher NH₃ yield.

This study applied the combination of plasma-activated water (PAW) and mild heat (40 °C and 55 °C) for the decontamination of Bacillus cereus spores in rice (Oryza sativa L. ssp. japonica). In this study, PAW combined with 40 °C and 55 °C (PAW-40 and PAW-55) achieved 1.54 and 2.12 log₁₀ CFU g⁻¹ reductions of B. cereus spores in rice after 60 min exposure, which was significantly higher than the inactivation level (0.72 log₁₀ CFU g⁻¹) induced by PAW treatment alone. The assays for the leakage of intracellular contents (nucleic acids, proteins, dipicolinic acid-DPA) and the propidium iodide (PI) fluorescence probe confirmed that the combination of PAW and mild heat caused significant damages on the intact multilayered structure of B. cereus spores than the individual PAW did. The application of scanning electron microscope (SEM) and transmission electron microscope (TEM) provided a direct observation for the visible disruption of external structure and leakage of intracellular components caused by the combination of PAW and mild heat. Besides, the combination of PAW and mild heat caused no adverse effect on the texture and sensory qualities of the rice after cooking. These findings provide some knowledge for the application of PAW combined with mild heat for the decontamination of spores in rice.

Ferromagnetic nanowires have attracted extensive interest in the development of monolithic microwave integrated circuits for future microwave reciprocal and non-reciprocal devices. The aim of the present investigation is to explore the magnetization dynamics in NiFe nanowires using a field sweep ferromagnetic resonance (FMR) technique. We also fabricated microwave devices, such as phase shifters and notch filters, on these ferromagnetic nanowired (FMNW) substrates in microstrip transmission line geometry. 1D NiFe nanowires have been synthesized by a dc electrodeposition technique in anodic alumina oxide membranes. Detailed microstructural and magnetic properties of deposited nanowires were investigated. The FMR technique was used to study the dynamic properties in the frequency range from 15 to 25 GHz. The angular variation of resonance field yields the intrinsic parameters such as gyromagnetic ratio and effective field. The resonance field increases up to 7 kOe for changing the nanowire's axis from parallel to perpendicular direction. The stop-band frequency can be modulated up to 30 GHz and phase shifter showed a differential phase shift of 80 deg cm⁻¹ at higher frequency band with an external magnetic field of 5.3 kOe. It is observed that the superlative frequency which corresponds to the highest differential phase shift for NiFe nanowires improved considerably above 33 GHz.

In this paper, we demonstrate a three-axis atomic magnetometer based on parametric oscillations, which can measure the three magnetic field components simultaneously and independently. A circularly polarized pump beam is applied to create the spin polarization, and another linearly polarized probe beam is used to detect the dynamics of the polarized spin under a magnetic field. With a closed-loop system to keep the magnetic field in resonance with the atoms, three components of magnetic field are measured by their feedback signals. We achieve a magnetometer sensitivity of 6 pT ()⁻¹, 25 pT ()⁻¹, and 60 pT ()⁻¹ along three axes in the frequency range from 100 Hz to 1 kHz with a bandwidth better than 1 kHz under an unshielded environment. Furthermore, this magnetometer is free of optical modulation, which reduces the complexity of experimental setups. The methods we present here provide a prototype all-electrical three-axis atomic magnetometer.

This paper reports a novel concept of a low voltage low power temperature sensor with a 300–370 K operating temperature range, based on a silicon-on-insulator (SOI) nanowire FET with standard SOI CMOS technology. The novel design combines a top-down silicon nanowire and an electrostatically formed nanowire, capacitively coupled to a back-gate electrode. A surface charged silicon nitride layer is used to deplete the upper part of the nanowire, while a back-gate controls the size and location of the electrostatically formed nanowire. The device operates in a regime similar to the subthreshold regime of a nanowire transistor and features a very high temperature response, expressed by the temperature coefficient of current (TCC  =  6 % K⁻¹ at 0.4  <  I_DS  <  5 pA for a single nanowire). The device can be easily integrated into a nanowire-based sensor array.

Palladium diselenide (PdSe₂) films exhibit a high charge carrier mobility and sensitivity in photodetection. In this work, wafer-scale PdSe₂ thin films with controllable thickness have been synthesized by the selenization of Pd films. A PdSe₂-based photodetector can detect a broad wavelength ranging from 420 nm to 1200 nm. The responsivity and detectivity can reach 1.96  ×  10³ A W⁻¹ and 1.72  ×  10¹⁰ W Hz^−1/2 at V_SD  =  3 V, respectively. The figure of merit of the photodetection are comparable to the mechanically exfoliated PdSe₂ based photodetector. This work demonstrated that selenization is a facile method to synthesize PdSe₂ films in large scale and the films are promising for broadband photodetection.

Various surface treatment methods have been previously applied on the GaN high electron mobility transistor (HEMT). In this study, the effects of N₂O surface treatment on the electrical properties of InAlN/GaN HEMT were studied. With this surface treatment, the ideality factor of the gate Schottky barrier diode decreases from 7.70 to 1.30, and the barrier height of SBD increases from 0.508 eV to 1.053 eV (~two folds), an indication of the improved Schottky contact characteristic. Negative-shifted threshold voltage, decreased gate capacitance and two-dimensional electron gas (2DEG) electron density were observed. Both the intrinsic transconductance and 2DEG electron mobility are improved. The 2DEG electron mobilities limited by various scattering mechanisms are extracted using two-dimensional (2D) scattering theory. It is found that N₂O surface treatment results in the increase of the 2DEG electron mobility due to the weakened polar optical phonon, interface roughness, and polarization Coulomb field scatterings. This study offers a feasible way to further enhance InAlN/GaN HEMT performances by using N₂O surface treatment.

The tapered long-period fiber grating (TLPFG) and rotated chiral long-period fiber gratings (CLPFG) heated by a CO₂ laser were fabricated by periodically tapering and rotating standard single-mode fibers (SMF). The temperature sensing characteristics of the TLPFG and CLPFG between 30 °C and 60 °C were experimentally investigated, and the slopes of the wavelength shift corresponded to 0.115 nm °C⁻¹ and 0.04 nm °C⁻¹, respectively. The graphene films were coated on gratings to fabricate graphene-coated TLPFG (GTLPFG) and graphene-coated CLPFG (GCLPFG). Given the thermal effects of graphene, the slopes of the resonance dip shift of the GTLPFG and GCLPFG between 30 °C and 60 °C increased to 0.196 nm °C⁻¹ and 0.113 nm °C⁻¹, respectively. Additionally, the high temperature sensing properties of TLPFG and CLPFG between 100 °C and 1000 °C were investigated. The slopes of the higher-order resonance dips of the TLPFG and CLPFG corresponded to 0.119 nm °C⁻¹ and 0.09 nm °C⁻¹, respectively, during the heating process, and to 0.116 °C⁻¹ and 0.09 nm °C⁻¹, respectively, during the cooling process. In the low and high temperature zones, the TLPFG exhibited higher sensitivity when compared to that of the CLPFG, while the CLPFG exhibited higher sensing precision with linearity approaching 1. Given the simple and unsophisticated fabrication process and the high quality and sensitivity of the fabricated gratings, the proposed sensors can play an important role in high-precision temperature-sensing applications.

Significant a-type dislocation movement was directly observed in AlN films using a transmission electron microscope (TEM). Most of the a-type dislocations are arranged in arrays, which are similar in structure to the low-angle grain boundaries, and are unable to move under electron beam irradiation. Only a small number of bending dislocations, away from those dislocation arrays, could be excited to glide by electron beam irradiation. These moving dislocations can travel a rather long distance along the 〈0001〉 direction until their movements are stopped by the free surface or by the interface of the sample, and in some cases, by dislocation arrays. Finally, this letter presents a comprehensive analysis of electron-irradiation-enhanced dislocation glide in AlN, with the role of the stress state in the dislocation movement under uniaxial stress conditions particularly emphasized.

White organic light emitting diodes (WOLED) employing blue, green and red thermally activated delayed fluorescence (TADF) emitters of DMAC-DPS(B), 4CzIPN(G) and 4CzTPN-Ph(R) and various emission layer (EML) structures of G/B, G/R/B and R:G(4CzTPN-Ph(R) doped in 4CzIPN(G) host)/B are fabricated and the effects of the EML structure, including EML thickness and 4CzTPN-Ph(R) dopant concentration, on the electroluminescence (EL) performance are investigated. It is found that the WOLED with the simple EML structure of G(20 nm)/B(10 nm) demonstrates maximum power efficiency (PE) around 16 lm/w and color rendering index (CRI) of 81. Meanwhile, R:G/B EML exhibits better EL performance than that of G/R/B EML. Especially, striking high CRI of 90 together with maximum PE around 13 lm/w can be obtained for R(1 wt%):G(20 nm)/B(10 nm) EML by meticulously modulation of EML thickness and 4CzTPN-Ph(R) dopant concentration, indicating the achievement of balance between EL efficiency and CRI for non-doped TADF emitter-based WOLED. Furthermore, the stacked EML of G(20 nm)/R(0.1 nm) and G(20 nm)/R(0.1 nm)/B(10 nm) reveal much more serious obstruction of delayed fluorescence (DF) compared to mixed EML of R(1 wt%):G(20 nm) and R(1 wt%):G(20 nm)/B(10 nm), implying more intensified quenching effects from the sandwiched 0.1 nm 4CzTPN-Ph(R) layer which will lead to deterioration of EL performance. Different energy transfer routes are derived based on the transient photoluminescence decaying dynamics of R(1 wt%):G(20 nm)/B(10 nm) and G(20 nm)/R(0.1 nm)/B(10 nm) EML and the sandwiched 4CzTPN-Ph(R) ultrathin layer is found to be critical. The decaying dynamics responsible for such EML structure dependent EL performance is discussed in detail.

We present a tunable terahertz (THz) band-pass filter based on electrostatically actuated microelectromechanical systems reconfigurable metamaterials. The unit cell of the filter consists of a U-shaped structure and a fat-T shaped structure. The fat-T shaped structure connects with a movable frame which is actuated by two columns of electrostatic comb actuators. Initially, the filter has two passbands whose central resonance frequencies locate at 0.66 THz and 1.31 THz, respectively. When the actuators are biased with direct currents (DC) voltages, the fat-T shaped structures will move to the U-shaped structures. Thus, the transmition of the peak at 0.66 THz will decrease, and the modulation depth can reach 84.4%. Meanwhile, the resonance frequency of the high-frequency passband shows distinct blueshift, and the largest frequency shift arrives to 0.195 THz. The simulation results obtained from the finite-intergration-technology show that these two resonance peaks are produced by two LC resonators on the two arms and one resonator on the bottom of the U-shaped structure. A flinite element analysis method is introduced to study the electromechanical performance of the actuator, and a displacement of 4 µm is achieved at DC 120 V. The tunable THz band-pass filter can be applied in THz communication, THz frequency selection and THz sensing.

The dielectric/semiconductor interface in organic field effect transistors (OFETs) is critical to their performance. Modification of this interface with functional molecules provides a wide range of possibilities for their applications as sensors. In this work, boronic acid molecules were used to modify the SiO₂ dielectric surface in dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene based OFETs. The device parameters, including most notably the threshold voltage, were significantly improved. The dielectric/semiconductor interface was analyzed using various measurement techniques, such as contact angle and atomic force microscopy. Our work provides evidence that easily functionable boronic acid derivatives improve the device performance of OFETs, which lays the foundation for further studies of such interface modified OFETs for use in sensing applications.

A three-section optical diode amplifier is simulated, whose sections have different amplitude-phase coupling coefficients R (linewidth enhancement factors). We show that it is possible to change the output wave phase for a constant output power due to only a difference in the value of this coefficient. In a single-mode amplifier, the first section has a horizontal waveguide formed by the gain (gainguided), and the other two sections are formed by change of the refractive index (index-guided). The values of the current in the first two sections are found, at which the phase changes by more than 2π at a constant output power of 2W. Such amplifiers can be integrated into single-crystal bars, which makes them adaptive for use in kilowatt laser systems with a coherent combining of beams.

The development of the novel semiconductor heterogeneous functional materials is playing an ever more important role in materials and efficient devices with new properties and functions. In this work, heterostructures of Au/Ti/Ni decorated zinc oxide nanobelts were synthesized. The amount and diameter of metal nanoparticles were controlled by the sputtering time or the deposition time. The photoluminescence of metal/ZnO heterostructures has been investigated. Very strong enhancement of near-band-edge emission and simultaneous attenuation of visible emission were observed for ZnO nanobelts decorated with Au, Ti and Ni nanoparticles. But both the NBEUV and DL emission intensities of Ni/ZnO heterostructures decrease dramatically initially. A novel mechanism is proposed to explain observed kinds of experimental results based on characteristic of metal nanoparticles, LSPR, Purcell effects and work function change of nanosize induced. The Mg decorated zinc oxide nanobelts were synthesized for the first time. Then the entire mechanism was testified by the investigation on Mg/ZnO and Ni/ZnO heterostructures due to its much lower and higher work functions compared with that of ZnO nanobelts, respectively. The mechanism will facilitate the technical application of metal-nanoparticles decorated heterostructures, and be very useful for the creation of highly efficient optoelectronic devices.

In this paper, a novel method is proposed to realize perfect anomalous reflection and refraction utilizing a metasurface composed of binary Pancharatnam–Berry (P–B) phase elements. Previous studies on perfect anomalous reflection usually suffer from low efficiency and complicated calculations. In contrast, the proposed method, which combines the metagrating theory and array antenna theory, use only two kinds of unit cell structures for both perfect anomalous reflected and refracted beams generation. As a proof-of-concept, two binary P–B phase element based metasurfaces are designed and simulated to show that the incident wave can be reflected from θ_i  =  60° to θ_r  =  60° for the perfect anomalous reflective metasurface, while the incident wave can be refracted from θ_i  =  60° to θ_t  =  60° for the anomalous refractive metasurface. The simulated results show good accordance with our theoretical predictions, indicating the anomalous reflection and refraction can be realized with high efficiency. Our method may open a new route for manipulating the propagation of the electromagnetic (EM) wave.

Surface dielectric barrier discharge (SDBD) is very efficient for the production of reactive species to degrade gaseous pollutants, but the streamer propagation only along the dielectric surface limits the gas treatment capacity. In our experiments, an additional ground electrode pasted on a dielectric was arranged over the surface electrode to form a hybrid volume-surface DBD (V-SDBD) configuration for enlarging the spatial distribution of discharge plasma. The current waveforms, discharge images and power measurements indicate that the V-SDBD configuration produced more steamer channels and induced the development of discharge filaments towards the air gap, leading to more production of ozone and higher benzene degradation efficiency compared to SDBD configuration. At the conditions of 16 kV applied voltage, 2.8 mm air gap spacing and 1 l min⁻¹ air flow rate, the ozone concentration and benzene degradation efficiency of V-SDBD configuration were 3.45 times and 2.15 times that of SDBD configuration, respectively, which may be contributed to the enhanced electric discharge and the enlarged spatial plasma distribution in V-SDBD device compared to SDBD device.

Composition of species is one of the key parameters in calculating the plasma properties and assessing the plasma chemical processes. Unlike the calculation of LTE plasma composition, the calculation of 2T plasma composition still remains in dispute. Different researchers have chosen different methods which lead to different results. In this work, we compare two kinds of methods for calculating 2T plasma composition: the mass action law methods and extremum searching methods. The former methods include the two described by Potapov and van de Sanden et al mass action laws, respectively. The latter methods include those of searching minimum Gibbs free energy and maximum entropy of a plasma system respectively. The entropy maximization method is first reported in this work and has the same power as the commonly used Gibbs free energy minimization method. We demonstrate both mathematically and numerically that the method of 2T Gibbs free minimization is completely the same as the 2T Potapov mass action law, and the method of 2T entropy maximization is exactly consistent with the 2T van de Sanden et al mass action law if we assume that the term μ_i/T_i is independent of the number density n_i. It is also found that the assumption of number density-independent μ_i/T_i mainly affects the density of charged particles. When the plasma reaches the LTE state, the composition obtained by the methods of entropy maximization with and without this assumption will be exactly the same.

The assumption of gaseous species is not always valid in non-LTE plasmas. This requires the consideration of condensed phases in the determination of plasma composition. In this work, we compare two methods for calculating 2T multi-phase plasma composition: the Gibbs free energy minimization method and the entropy maximization method. The latter method is first reported in this work and has the same power as the former method for the calculation of 2T plasma composition taking into account condensed species. Based on these two methods, we present a case study of the multi-phase compositions of N₂–Cu, CO₂–Cu, and C₂F₄–Cu plasmas. It is found that the 2T entropy maximization method is less sensitive to the non-equilibrium degree than the 2T Gibbs free energy minimization method. This leads to the large difference between the composition predicted by the two methods, for example, in the phase transition temperature. The case study shows that due to the high electron temperature at large non-equilibrium degree, the ionic species (e.g. Cu⁺ and C⁺) can be generated directly from the condensed species (e.g CuF₂, Cu₂O, Cu, and C). Such ionization does not occur if the copper proportion is very low (e.g only 1%).

Because of the limitations of thin-layer plasma for electromagnetic wave attenuation, a new PS-AWV (plasma-superimposed artificial wave vector) metasurface structure is proposed. We also introduced the design principle of increasing the propagation distance of electromagnetic waves in plasma using artificial wave vector metasurface. We designed a X band artificial wave vector metasurface by geometric phase dispersion control such that the incident electromagnetic wave abnormally reflected, and the reflection angle reached 55° when measured at normal incidence. Using an electromagnetic finite element method, we established a coupling model of the PS-AWV metasurface structure attenuated electromagnetic wave using CST (Computer Simulation Technology). We analyzed the variation law of reflectivity under different plasma parameter distribution, and the experiment was performed in a microwave darkroom. We also measured the reflectivity of the wave-vector metasurface structure. Both simulation and experimental results show that the artificial wave vector metasurface can effectively increase the attenuation effect of plasma on electromagnetic waves and improve the attenuation effect of electromagnetic waves because of thickness reduction; thus, it can reduce the plasma thickness required for plasma stealth and improve its application in practical scenarios.

Due to the emergence of 5G technology and wide applications for the internet of things (IoT), metamaterials are expected to have stronger adaptability and higher performance. However, numerous previous metamaterials based on indium tin oxide (ITO) film fail to be electrically tunable and need external power. In this work, we propose an optically transparent and reconfigurable metasurface based on ITO film with varactor diodes. By varying the capacitances of varactors incorporated into the elements, the phase responses can be modulated as desired. In addition, based on these designed elements, we present four schemes to realize distinct scattering fields. In order to achieve an autonomous power supply for the metasurface, we integrate a solar cell by using the transparency of ITO. The simulated and measured results have good accordance, which demonstrates the excellent performance of the proposed metasurface. This work facilitates the flexibility of metasurfaces and paves the way for applications in outside communications.

We present a water-immersed ultrasound high-efficiency Fresnel lens based on the theory of extraordinary acoustic transmission of plate-wave resonance. We studied, experimentally and numerically, the acoustic pressure gain of the Fresnel lens with and without gratings on the back. We found that the transmission coefficient of the incident acoustic waves through the lens with gratings on the back was much higher than that of the lens without gratings, thus increasing the acoustic pressure gain at the focal point of an impedance-mismatched Fresnel lens by 14.1 dB. We then optimized the grating width in the structure, thereby increasing the acoustic pressure gain by 16.3 dB. This lens has potential applications in acoustic imaging and medical diagnosis.

As a 'new organ' in the human body, an interstitial structure distributes throughout the body and constitutes an operational framework of the interstitial fluid. Research into interstitial structure and its fluid behavior are conducive to revealing the operation law of interstitial fluid and establishing a complete operation system model for life fluid. In this paper, magnetoacoustic tomography with magnetic induction (MAT-MI) with liquid metal as a marker of the interstitial fluid channel is proposed as an imaging research method for the fluid behavior of interstitial structures. For the huge differences in the physical properties between liquid metal and bio-tissue, we studied the distribution characteristics of induction current in liquid metal under pulsed magnetic field stimulation, as well as the acoustic field propagation characteristics and the signal received by the transducer in acoustic inhomogeneous materials. Finally, experimental studies were carried out to verify the theoretical analysis. This work provided a basis for the extraction of effective measurement signals, which is conducive to the identification of acoustic field signals and the position imaging of the liquid metal.

Herein, a simple and facile two-step sonication method was developed for the preparation of nanosheets-like MoS₂ wrapped graphene nanohybrids for energy storage and hydrogen evolution reaction (HER) applications. TEM and HR-TEM images revealed that the 120 nm sized lateral diameter of sheet-like MoS₂ was completely immobilized on the surfaces of graphene via the probe sonication method. The resultant nanohybrid exhibited bifunctional activities of supercapacitor and HER. With this tailored bifunctional nanoarchitecture, the nanohybrid based electrode showed an improved specific capacitance of 350 F g⁻¹ for a current load of 1 A g⁻¹ with a cyclic efficiency of 85 % in 6 M KOH electrolyte solution. Additionally, the developed MG11 nanohybrid was tested as an electrocatalyst for HER. The latter exhibited a low onset potential of ~125 mV with a Tafel slope of 41 mV/decade. Thus, MG11 nanohybrid presents an excellent prospect for a low-cost electrode for a supercapacitor and an electrocatalyst for hydrogen evolution reaction.

The crystallization and distribution of the materials in the active layer has a large effect on performance of solution-processed bulk heterojunction organic solar cells (OSCs). In this work, polyethylene glycol (PEG) is doped to the active layer as a common and inexpensive additive to modulate the crystallization and distribution of the material in the vertical direction. The effect of the addition of PEG on the active layer is confirmed by measuring the contact angle, grazing-incidence wide-angle x-ray scattering, and surface morphology. A performance improved device with power conversion efficiency (PCE) of 11.30% was achieved by doping 4 wt% PEG, which has 20% improvement over control devices (9.44%). It is important to note that the devices show strong tolerance to film thickness, the unpackaged devices with 300 nm thick active layer exhibit PCE of 8.58% (with PCE of ~80% compared with control devices). Also, devices show strong tolerance to high humidity environment, devices placed in 60% RH for 10 d still has 80% PCE. Moreover, green solvent was used to investigate the effect of PEG on the preparation of the device in the atmosphere, devices doped with PEG exhibit greater tolerance to the environment in preparation. This work provides a convenient way to improve device performance, tolerance to thickness, and stability at high humidity.

By performing a two-step coordinate transformation, an N-sided polygonal bifunctional thermal device with nonsingular homogeneous material parameters is proposed based on transformation thermodynamics. The presented device could function as not only a concentrator with heat flux concentration effect, but also an illusion device with a scattering amplification effect. Moreover, to further eliminate the anisotropy of thermal conductivity tensors, multilayer realization of the device through isotropic materials is also investigated. The effectiveness of the design method and the performance of the devices are validated by the full-wave simulations. This work paves a new way for the design of easy-to-implement bifunctional devices and has broad application prospects in such fields as thermal-energy harvesting and thermal camouflage.