Nickel films were electroplated onto carbon fibers in an electrolyte irradiated by 2.45 GHz, referred to as Ni/Cf, and subsequently partly oxidized to form NiO in air. The resulting carbon fibers with oxidized Ni films were incorporated into calcium aluminate cement to create cement-based composites, known as NiO-Ni/CFRC. The impact of oxidation temperatures and fiber mass fractions of the Ni/Cf on the thermoelectric properties of NiO-Ni/CFRC was investigated. The results revealed that the NiO-Ni/CFRC doped with 1.5 wt% prepared at a oxidation temperature of 450 degrees C for 2 h exhibited the most favorable thermoelectric properties. Specifically, the Seebeck coefficient and electric conductivity were found to be 6,651 mu VK-1 and 0.13 Sm-1, respectively, at an ambient temperature of 30 degrees C. The resulting dimensionless constant ZT value of the NiO-Ni/CFRC peaked at 2.7x10-3, marking a 6.7-fold increase compared to Ni/Cf. Moreover, the compressive strength of Ni-NiO/CFRC could maintain 65.1 MPa, representing a 10.9% increase, and the compressive strain could reach 0.43%, marking an 8% improvement, compared to pure cement. These results suggest Ni-NiO could offer new opportunities for the application of sustainable energy technologies and smart materials in the field of buildings and construction in future cities.

Hydroxyapatite (HA) coatings on carbon fiber-reinforced carbon (Cf/C) composites hold promise for orthopedic implants. However, the interface between HA and Cf/C is prone to delamination, limiting its application. To address this, a polydopamine (PDA)-polyvinyl alcohol (PVA)-graphene oxide (GO) transition layer was introduced to reinforce and toughen HA coatings on Cf/C composites (PDA-PVA-GO/Cf/C) via hydrothermal electro-deposition/post-hydrothermal treatment. For comparison, the PDA and PDA/PVA transition layers were also prepared on Cf/C, designated as PDA/Cf/C and PDA-PVA/Cf/C, respectively. The precursor and transformed coatings obtained were monetite and HA. XRD analyses revealed that PDA and PVA infiltrated the monetite lattice without affecting the HA lattice parameters. Remarkably, scratch tests demonstrated that the HA/PVD-PVA-GO coating on Cf/C exhibited a dense configuration and compact interfacial structure, achieving a maximum critical load of 51.5 N, surpassing other reported electrochemically prepared HA coatings. Moreover, scratch tests indicated a more homogeneous scratch pattern with no sudden delamination of the coating from the matrix. In vitro assessments revealed that all HA coatings with the transition layer exhibited enhanced bioactivity and cell compatibility compared with HA alone. In particular, PDA/PVA/GO-Cf/C exhibited the best superior efficacy in promoting the proliferation of mouse embryonic osteoblast precursor (MC3T3-E1) cells and significantly increased Alkaline phosphatase (ALP) production in rat bone marrow mesenchymal stem cells (BMSCs). These findings underscore the potential of PDA-PVA-GO/Cf/C as a promising biomaterial for bone regeneration.

Ni films with a high density of edge dislocations were successfully produced on carbon fibers using the microwave electrodeposition method, in comparison to Ni films deposited using the conventional electrodeposition method which had fewer edge dislocations. The two types of Ni film/carbon fiber composites were denoted as MNi/Cf and Ni/Cf, with and without microwave involvement, respectively. The results revealed that M-Ni/Cf exhibited superior tensile performance but lower electrical conductivity compared to Ni/Cf. When incorporated into calcium aluminate cement, labeled as M-Ni/CFRC and Ni/CFRC with/without microwave involvement, respectively, M-Ni/CFRC demonstrated outstanding compressive performance with a strength of 84.6 MPa, slightly higher than Ni/CFRC. Additionally, the power factor and thermoelectric figure of merit (ZT) of M-Ni/ CFRC reached 0.838 mu W m- 1 K- 2 and 4.01 x 10-4, respectively, approximately four times greater than that of Ni/CFRC. The improvement in compressive and thermoelectric performances was attributed to the dislocation strengthening effect and the scattering of carriers by dislocations.

We present a novel design of gallium nitride (GaN) Schottky barrier diodes (SBDs) with a vertical micropillar structure. The micron-scale electrode design can effectively enhance the on-state current density and reduce the specific on-resistance (Ron,Sp). In addition, it allows for a reduction in the turn-on voltage (Von) by minimizing the spacing between the electrodes. This phenomenon can be explained by the intensified electric field coupling between the electrodes, as confirmed from the technology computer aided design simulations. By controlling the distance between the micron pillars, the Von of the SBD varies from approximately 0.35 V to 0.46 V. These results showcase the potential of our SBD design with micropillar contacts in efficient high-power applications.

At present, the low volumetric capacitance of anode materials limits the further advancement of supercapacitors. Free-standing electrode materials do not require binders or current collectors, thus designing and preparing freestanding electrode materials can theoretically advance the volumetric capacitance of the electrode materials. In this work, a phosphomolybdic acid/coal-based composite activated carbon foam (PMo12/ACCF) with a crossscale hierarchical porous structure as free-standing anode material was successfully prepared by combining high-pressure pyrolysis, KOH activation and hydrothermal methods. The coal-based activated carbon foam (ACCF), as a structural framework of phosphomolybdic acid (PMo12) load, not only provides a large ionaccessible area but also contributes to double-layer capacitance. PMo12 provides pseudocapacitance for the composite as well as significantly enhances its electrochemical surface activity. The symmetrical device assembled with PMo12/ACCF exhibits an ultra-high volumetric capacitance of 21.79 F cm-3 at 0.025 A cm- 3, an energy density of 5.76 mWh cm- 3 at 12.51 mW cm- 3, and a capacitance retention rate of 83.19 % after 10,000 cycles.

In this article, we report the investigation into the stability of p-GaN gate high electron mobility transistors (HEMTs) with an internal integrated gate circuit that led to the design of a capacitance-based circuit to address threshold voltage shifts (ΔVTH). Pulse I–V measurement revealed a notable positive gate VTH shift of 0.7 V as the drain voltage increased from 0 to 650 V, highlighting the impact of drain bias on VTH instability. Through the investigation of drain bias-induced VTH instability and the behavior of carriers being transported within the gate region, it was found that the maximum ΔVTH is 0.4 V when a 200-V drain bias is applied; after stress removal, ΔVTH diminishes gradually due to the discharge of capacitance, and holes enter the p-GaN layer to mitigate the depletion of holes. The integration of passive components and p-GaN gate HEMT circuits is suggested to address VTH instability in enhancement-mode HEMT devices. The reliability of power devices is essential for their acceptance in emerging applications.

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A microwave anodic deposition process was developed to prepare MnO2/Ni-doped MnO2 films on carbon fibersfor the fillers of cement composites (CFRC) to enhance both thermoelectric and compression performances simultaneously. The resulting CFRCs were designated as M-MnO2/ CFRC and M-Ni-MnO2/CFRC, respectively. The results showed that the M-Ni-MnO2/CFRC exhibited the best thermoelectric performance at 313K, achieving a Seebeck coefficient of -873.9 mu V/K, electrical and thermal conductivities of 3.42 S/m and 0.613 W/mK, respectively, and thus ZT and PF values of 1.69 x 10-3 and 3.42 mu W/(m center dot K2), respectively. The superior thermoelectric performance of the M-Ni-MnO2/CFRCs compared to that of the M-MnO2/CFRCs or the MnO2/CFRCs without microwave involvement in electrodeposition was attributed to the increased density of states at the Fermi level in MnO2 due to Ni doping, and the better interfacial scattering electron carrier effect. Surprisingly, the compression strength of the M-Ni-MnO2/CFRC reached 82.5 MPa, marking a 171.2 % increase, while the elongation reached 1.71 %, a 3.50 times increase compared to pure cement.

In this work, we investigated the stability of a p-GaN gate with high electron mobility transistors (HEMTs) including an internal integrated gate circuit. A circuit was designed to improve p-GaN gate stability by using capacitance to release the hole into the p-GaN layer to mitigate the threshold voltage shift. Through pulse I-V measurement and positive bias temperature instability (PBTI) test, the carrier transporting behavior in the gate region achieved dynamic equilibrium at 5 V gate bias. The positive gate shift δVTH) of 0.4 V is observed with increasing voltage from 3 V to 8 V; δVTH initially drops smoothly after release stresses by external capacitance discharge. Finally, integrated passive components and p-GaN gate HEMT circuit are recommended to mitigate the VTH instability for E-mode HEMT.

The development of efficient photocatalysts with effective charge separation and numerous active sites is a key challenge in photocatalysis. ZnIn2S4 based binary and ternary composite photocatalysts were successfully synthesized using microwave hydrothermal and calcination techniques, exhibiting excellent hydrogen production capabilities. Among these, the FeP/Cu3P/ZnIn2S4 composite photocatalysts demonstrated the highest hydrogen production performance, with an average rate of 1.613 mmol g- 1 h-1, which was 4.42 times greater than that of pure ZnIn2S4. The enhanced hydrogen production of the FeP/Cu3P/ZnIn2S4 photocatalysts was attributed to the establishment of a p-n heterojunction at the ZnIn2S4 interface. Furthermore, the presence of FeP lowered the hydrogen production barrier in the system and provided additional active sites for the catalytic reaction.

The construction of a non-homogeneous photocatalyst system with the advantages of both efficient photo generated charge separation efficiency and abundant number of active sites remains a major challenge in the field of photocatalysis. A new ternary MnCdS-based photocatalyst combined with FeWO4 and CoP modifications was successfully prepared by chemical precipitation and thermal reduction methods. The ternary FeWO4/CoP/Mn0.5Cd0.5S photocatalyst exhibited a maximum hydrogen evolution activity of 30.45 mmol.g(-1).h(-1), which was 6.86 times higher than that of pureMn(0.5)Cd(0.5)S. The enhancement of the hydrogen production performance of the FeWO4/CoP/Mn(0.5)Cd(0.5)Sphotocatalyst was attributed to the p-n heterojunction constructed at the interface of FeWO4 and Mn0.5Cd0.5S, which strengthened the charge separation ability of the system. On the other hand, the decoration of CoP remarkably diminishes the hydrogen evolution potential of the system and supplies richer active sites for the catalytic reaction.

The strategy of Plasmon-Induced Resonance Energy Transfer (PIRET) holds promise in mitigating the recombination of photo-generated electron-hole pairs, thereby amplifying the efficiency of an electrode in photoelectrochemical (PEC) reactions geared towards solar-driven PEC. Nevertheless, the PIRET mechanism, particularly from the view of charge separation and extraction dynamics, remains unclear. Herein, we examined PEC water splitting activities of Au nanoparticles decorated α-Fe2O3 nanoarrays (α-Fe2O3/Au NRs) and systematically investigated the PIRET mechanism by the combination of ultraviolet-visible spectra, field distribution simulation, and transient absorption spectroscopy. The PIRET effect of Au nanoparticles (NPs) generates a localized electromagnetic field near the surface of the α-Fe2O3 NRs and the significant near-field coupling between α-Fe2O3 NRs and Au NPs promotes cross-sectional absorption that markedly enhances plasmonic energy transfer from Au NPs to α-Fe2O3 NRs. TA measurement uncovers the proximate electric field around α-Fe2O3 NRs, which emanates from the Au NPs' PIRET, orchestrates the instantaneous segregation of electrons and holes upon their formation and births enduring photogenerated holes in α-Fe2O3/Au NRs. Additionally, the FeOOH overlayers, as cocatalyst, are effective in boosting hole transfer kinetics. Consequently, the photocurrent density exhibited by the α-Fe2O3/Au/FeOOH arrays is amplified by 3.5 times in comparison to the pristine α-Fe2O3 NR arrays.

The preparation of two-phase electrode materials of Co9S8@Ni(OH)(2) typically involves a laborious three-step process. In this study, a two-step cathode microwave electrochemical method was proposed for the fabrication of Co9S8@Ni(OH)(2) electrode materials for supercapacitors, eliminating the need for precursor synthesis. This approach not only simplified the preparation process and saved time but also successfully produced a p-n heterostructure electrode material consisting of Co9S8@Ni(OH)(2) phases, where the Co9S8 phase has a chemical formula of Co9S3(OH)(5.) This unique structure is capable of inducing an internal electrical field by facilitating the transfer of charge carriers from Co9S3(OH)(5) to Ni(OH)(2), thereby enhancing charge transfer kinetics. As a result, the electrode exhibited remarkable supercapacitive performance, achieving a high specific capacitance of 255.4 mAh g(-1) (7.56 F cm(-2)) at 1 A g(-1). Even at a 20-fold increase in charge/discharge current density, the specific capacitance remained high at 218.9 mAh g(-1) (6.48 F cm(-1)), retaining 85.8 % of the initial capacity. Furthermore, the Co9S3(OH)(6)@Ni(OH)(2) electrode materials demonstrated excellent durability, enduring 10000 cycles with a capacitance retention of 92.9 % of the initial value. An asymmetric supercapacitor constructed with Co9S3(OH)(5)@Ni(OH)(2) as the anode and a commercial active carbon film as the cathode was able to power a red light diode continuously emitting light for up to 42 min.

The microwave electrodeposition/microwave NaOH aqueous solution treatment was developed for the first time to prepare MnO2 modified carbon fiber/cement composite (MCFC). The effects of the MnO2 modified carbon fiber (MCF) content and alkali treatment temperatures on the thermoelectric properties of the cement composites were investigated. The results show that the composite with the MCF content of 3.75 wt% has the optimal thermoelectric performance. After microwave alkali treatment at 333K, this composite has a Seebeck coefficient of -2308.9 mu V/K, electrical and thermal conductivities of 2.72 S/m and 0.632 W/mK, and as a result, the ZT value of 7.73 x 10-3 could be achieved, which is the best value among the reported carbon fiber cement composites. Moreover, the composite has a compressive strength and strain of 38.6 MPa and 2.8%, respectively, which are 15.2% and 75% higher than those of the original cement, and shows good toughness.

In this work, vertical gallium nitride (GaN) Schottky barrier diodes (SBDs) with an ultra-low turn-on voltage VON (0.37 V) were demonstrated. Due to the process of O2 plasma treatment, GaON was formed on the surface of GaN and further modified the surface potential of the material surface, which made the VON decrease from 0.62 to 0.37 V. Spin-on-glass was deposited on top of devices to form the floating guard ring, which was used to improve the breakdown voltage to 681 V (at J = 1 A/cm2) by reducing the electric field distribution. The vertical GaN SBDs exhibit a specific on-resistance (RON) of 2.6 mΩ cm2. Deterioration of the device under different stress time changes slightly showed great stability of the devices.

Electroactive electrode materials for cement-based structural supercapacitors suffer from poor interface contacts with ceramic electrolytes and current collectors due to their poor adhesive to the current col-lectors and severe reactions during cement hydration process, leading to their inferior capacitive per-formance relative to conventional supercapacitors. Herein, microwave hydrothermal electrodeposition was developed to deposit a robust composite film of Ni2(CO3) (OH)2/Co(OH)2 as an electroactive elec-trode material onto nickel foam. Effects of Ni/Co molar ratio of 0.5,1, 1.5, and 2 on the microstructure and electrochemical properties of the film electrode were investigated in detail. Subsequently, the film electrode with the optimal electrochemical performance was compared with that by hydrothermal deposition with no microwave involvement. The results showed all the resultant films by microwave hydrothermal electrodeposition showed a crooked sheet morphology with a polycrystalline structure containing lots of dislocations. Among them, the film of a Ni/Co molar ratio of 1 presented the optimal capacitive performance (a specific capacity of 632.8 (1.88) C/g(F/cm2) at 1 (2.97) A/g (mA/cm2), a su-perlong cycling life of 30,000 cycles at 10 A/g with a capacity retention of 80.4%) and demonstrated better electrochemical and adhesive properties than that prepared by hydrothermal electrodeposition with no microwave involvement. Finally, this optimal film electrode was employed as the cathode, active carbon as the anode and polyacrylic acid (PAA)-KOH-aluminate cement as the structural electrolyte, an hybrid structural supercapacitor device was assembled, and exhibited a compressive strength of as high as 37.2 MPa and a ionic conductivity of 8.2 mS/cm, and deliver excellent electrochemical performance (specific capacitance of 415.31 mF/cm2 at 0.5 mA/cm2 , and 80.1% capacitance retention of after 8000 cycles at 1 mA/cm2), which is the best capacitive performance among the reported cement-based structural supercapacitors in the form of civil engineering. Our experimental results reveal that micro-wave hydrothermal electrodeposition could be utilized to fabricate high-performance electrode mate-rials on nickel foam for structural supercapacitors.(c) 2022 Elsevier Ltd. All rights reserved.

In this article, an ohmic contact structure based on indium tin oxide (ITO)/Ti/Al/Ni/Au is explored for high-performance GaN-on-GaN Schottky barrier diode (SBD) for the first time. Owing to the ultrathin ITO interfacial layer, the Fermi-level pinning (FLP) effect in metal-semiconductor interface could be mitigated, thus the specific contact resistivity ( $\rho _{c}{)}$ on N-polarity was reduced from $3.32\times 10^{-{3}}$ to $7.36\times 10^{-{5}}\,\,\Omega $ cm2, and the specific ON-resistance ( ${R}_{\text {ON}}{)}$ of the device was reduced from 3.14 to 1.17 $\text{m}\Omega $ cm2 under the same testing condition. With the Helium ion implantation technology, a high breakdown voltage ( ${V}_{\text {BR}}{)}$ of 1100 V, low turn-on voltage ${V}_{\text {ON}}$ of 0.63 V, and a high figure of merit ( ${V}_{\text {BR}}^{{2}}/{R}_{\text {ON}}{)}$ of 1.04 GW/cm2 were achieved in this work. The vertical GaN SBD with ITO interfacial layer fabricated in this work achieved the lowest $\rho _{c}$ in the reported GaN-on-GaN SBDs with an indicated anode size.

Designing cost-effective photocatalysts with remarkable performance is a foresighted strategy to foster the evolution of H-2 in water splitting. In this study, a p-n heterojunction FeWO4/Mn-0.5Cd0.5S photocatalyst modified by low-cost and non-toxic FeWO4 was synthesized using hydrothermal and calcination methods. The hydrogen evolution activity of Mn0.5Cd0.5S was strengthened by varying the amount of FeWO4 loading. The hydrogen production rate of FeWO4/Mn0.5Cd0.5S photocatalyst loaded with 10% FeWO4 can reach 9.63 mmol g(-1) h(-1), which is equivalent to 2.16 times of pure Mn0.5Cd0.5S. The enhancement of the H-2 evolution activity was primarily contributed to a p-n heterojunction formed at the interface of FeWO4 and Mn0.5Cd0.5S. It provides a fast pathway for the migration and separation of photogenerated charges and effectively inhibits the photo-corrosion of Mn0.5Cd0.5S. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

The work temperatures have a crucial influence on the performance of supercapacitors. However, temperature effects on pseudocapacitive behaviors are rarely studied for flexible high-performance fiber supercapacitors. Herein, we systematically investigated the electrochemical responses of all-solid-state fiber-based supercapacitors composed of carbon nanotube fiber (CNF) electrodes decorated with porous carbon nanotubes (CNTs)/polyaniline (PANI) and gel electrolyte at various ambient temperatures between −5 °C and 55 °C. The results show that the capacitance of the supercapacitor first enhances with the rising temperature under 40 °C and declines at 55 °C. The internal resistance presents a gradual downward trend and the self-discharge behavior accelerates at high operating temperatures. CNTs/PANI-modified flexible fiber supercapacitors are also far from unsatisfactory for cycling stability tests in a high-temperature environment. After experiencing 5000 charge–discharge cycles at 55 °C, the capacitance retains only 43.86 %, far below the counterpart at low temperatures. This study provides a fundamental comprehension of the temperature dependence of pseudocapacitive behaviors of PANI-based fiber supercapacitors.