Insights on advanced substrates for controllable fabrication of photoanodes toward efficient and stable photoelectrochemical water splitting

Conversion of solar energy into H_(2) by photoelectrochemical(PEC)water splitting is recognized as an ideal way to address the growing energy crisis and environmental issues.In a typical PEC cell,the construction of photoanodes is crucial to guarantee the high efficiency and stability of PEC reactions,which fundamentally rely on rationally designed semiconductors(as the active materials)and substrates(as the current collectors).In this review work,we start with a brief introduction of the roles of substrates in the PEC process.Then,we provide a systematic overview of representative strategies for the controlled fabrication of photoanodes on rationally designed substrates,including conductive glass,metal,sapphire,silicon,silicon carbide,and flexible substrates.Finally,some prospects concerning the challenges and research directions in this area are proposed.

11.2 W/mm power density AlGaN/GaN high electron-mobility transistors on a GaN substrate

In this letter,high power density AlGaN/GaN high electron-mobility transistors(HEMTs)on a freestanding GaN substrate are reported.An asymmetricΓ-shaped 500-nm gate with a field plate of 650 nm is introduced to improve microwave power performance.The breakdown voltage(BV)is increased to more than 200 V for the fabricated device with gate-to-source and gate-to-drain distances of 1.08 and 2.92μm.A record continuous-wave power density of 11.2 W/mm@10 GHz is realized with a drain bias of 70 V.The maximum oscillation frequency(f_(max))and unity current gain cut-off frequency(f_(t))of the AlGaN/GaN HEMTs exceed 30 and 20 GHz,respectively.The results demonstrate the potential of AlGaN/GaN HEMTs on freestanding GaN substrates for microwave power applications.

Influence of substrate effect on near-field radiative modulator based on biaxial hyperbolic materials

Relative rotation between the emitter and receiver could effectively modulate the near-field radiative heat transfer(NFRHT)in anisotropic media.Due to the strong in-plane anisotropy,natural hyperbolic materials can be used to construct near-field radiative modulators with excellent modulation effects.However,in practical applications,natural hyperbolic materials need to be deposited on the substrate,and the influence of substrate on modulation effect has not been studied yet.In this work,we investigate the influence of substrate effect on near-field radiative modulator based onα-MoO_(3).The results show that compared to the situation without a substrate,the presence of both lossless and lossy substrate will reduce the modulation contrast(MC)for different film thicknesses.When the real or imaginary component of the substrate permittivity increases,the mismatch of hyperbolic phonon polaritons(HPPs)weakens,resulting in a reduction in MC.By reducing the real and imaginary components of substrate permittivity,the MC can be significantly improved,reaching 4.64 forε_(s)=3 at t=10 nm.This work indicates that choosing a substrate with a smaller permittivity helps to achieve a better modulation effect,and provides guidance for the application of natural hyperbolic materials in the near-field radiative modulator.

Facile electrochemical surface-alloying and etching of Au wires to enable high-performance substrates for surface enhanced Raman scattering

Surface-enhanced Raman Spectroscopy(SERS)is a nondestructive technique for rapid detection of analytes even at the single-molecule level.However,highly sensitive and reliable SERS substrates are mostly fabricated with complex nanofabrication techniques,greatly restricting their practical applications.A convenient electrochemical method for transforming the surface of commercial gold wires/foils into silver-alloyed nanostructures is demonstrated in this report.Au substrates are treated with repetitive anodic and cathodic bias in an electrolyte of thiourea,in a one-pot one-step manner.X-rays absorption fine structure(XAFS)spectroscopy confirms that the AuAg alloy is induced at the surface.The unique AuAg alloyed surface nanostructures are particularly advantageous when served as SERS substrates,enabling a remarkably sensitive detection of Rhodamine B(a detection limit of 10^(-14)M,and uniform strong response throughout the substrates at 10^(-12)M).

Exploring the mechanisms of calcium carbonate deposition on various substrates with implications for effective anti-scaling material selection

The unexpected scaling phenomena have resulted in significant damages to the oil and gas industries,leading to issues such as heat exchanger failures and pipeline clogging.It is of practical and fundamental importance to understand the scaling mechanisms and develop efficient anti-scaling strategies.However,the underlying surface interaction mechanisms of scalants(e.g.,calcite)with various substrates are still not fully understood.In this work,the colloidal probe atomic force microscopy(AFM)technique has been applied to directly quantify the surface forces between calcite particles and different metallic substrates,including carbon steel(CR1018),low alloy steel(4140),stainless steel(SS304)and tungsten carbide,under different water chemistries(i.e.,salinity and pH).Measured force profiles revealed that the attractive van der Waals(VDW)interaction contributed to the attachment of the calcium carbonate particles on substrate surfaces,while the repulsive electric double layer(EDL)interactions could inhibit the attachment behaviors.High salinity and acidic p H conditions of aqueous solutions could weaken the EDL repulsion and promote the attachment behavior.The adhesion of calcite particles with CR1018 and4140 substrates was much stronger than that with SS304 and tungsten carbide substrates.The bulk scaling tests in aqueous solutions from an industrial oil production process showed that much more severe scaling behaviors of calcite was detected on CR1018 and 4140 than those on SS304 and tungsten carbide,which agreed with surface force measurement results.Besides,high salinity and acidic p H can significantly enhance the scaling phenomena.This work provides fundamental insights into the scaling mechanisms of calcite at the nanoscale with practical implications for the selection of suitable antiscaling materials in petroleum industries.

Enhanced resonance frequency in Co2FeAl thin film with different thicknesses grown on flexible graphene substrate

The flexible materials exhibit more favorable properties than most rigid substrates in flexibility,weight saving,mechanical reliability,and excellent environmental toughness.Particularly,flexible graphene film with unique mechanical properties was extensively explored in high frequency devices.Herein,we report the characteristics of structure and magnetic properties at high frequency of Co2FeAl thin film with different thicknesses grown on flexible graphene substrate at room temperature.The exciting finding for the columnar structure of Co2FeAl thin film lays the foundation for excellent high frequency property of Co2FeAl/flexible graphene structure.In-plane magnetic anisotropy field varying with increasing thickness of Co2FeAl thin film can be obtained by measurement of ferromagnetic resonance,which can be ascribed to the enhancement of crystallinity and the increase of grain size.Meanwhile,the resonance frequency which can be achieved by the measurement of vector network analyzer with the microstrip method increases with increasing thickness of Co2FeAl thin film.Moreover,in our case with graphene film,the resonance magnetic field is quite stable though folded for twenty cycles,which demonstrates that good flexibility of graphene film and the stability of high frequency magnetic property of Co2FeAl thin film grown on flexible graphene substrate.These results are promising for the design of microwave devices and wireless communication equipment.

Recess-free enhancement-mode AlGaN/GaN RF HEMTs on Si substrate

Enhancement-mode(E-mode)GaN-on-Si radio-frequency(RF)high-electron-mobility transistors(HEMTs)were fabri-cated on an ultrathin-barrier(UTB)AlGaN(<6 nm)/GaN heterostructure featuring a naturally depleted 2-D electron gas(2DEG)channel.The fabricated E-mode HEMTs exhibit a relatively high threshold voltage(VTH)of+1.1 V with good uniformity.A maxi-mum current/power gain cut-off frequency(fT/fMAX)of 31.3/99.6 GHz with a power added efficiency(PAE)of 52.47%and an out-put power density(Pout)of 1.0 W/mm at 3.5 GHz were achieved on the fabricated E-mode HEMTs with 1-μm gate and Au-free ohmic contact.

Facile SERS screening of melamine in bovine milk with 2D printed AgNPs/glass fabric filter paper as the flexible substrate

Melamine is one of the most frequently detected adulterants in dairy products.The current study proposes a surface-enhanced Raman spectroscopy(SERS)-based analytical tool for fast and reliable screening of melamine in bovine milk.A hand-held Raman spectrometer was used in conjunction with a substrate composed of silver nanoparticles(AgNPs)that was 2D printed onto glass fiber(GF)filter paper.Under optimized conditions,a sensitive and fingerprint-like signal at 674 cm^(-1) was obtained.The AgNPs/GF substrate exhibited high sensitivity to melamine in milk down to 1.9498×10^(-5)mg/mL,which is well below the USA and EU safety limits(2.5×10^(-3)mg/mL).Remarkably,the proposed technology was also highly reproducible,showing spot-to-spot and block-to-block variations below 3.3%and 4.9%at 674 cm^(-1) in Raman intensity,respectively.The characteristic peak intensity and concentration of melamine showed an acceptable linear relationship(R^(2)=0.9909)within the range of 0.0001-1 mg/mL.Overall,the method established in this study can provide an efficient and effective method for the quantitative target screening and detection of melamine in dairy products.

Reshaping Li–Mg hybrid batteries:Epitaxial electrodeposition and spatial confinement on MgMOF substrates via the lattice‐matching strategy

The emergence of Li–Mg hybrid batteries has been receiving attention,owing to their enhanced electrochemical kinetics and reduced overpotential.Nevertheless,the persistent challenge of uneven Mg electrodeposition remains a significant impediment to their practical integration.Herein,we developed an ingenious approach that centered around epitaxial electrocrystallization and meticulously controlled growth of magnesium crystals on a specialized MgMOF substrate.The chosen MgMOF substrate demonstrated a robust affinity for magnesium and showed minimal lattice misfit with Mg,establishing the crucial prerequisites for successful heteroepitaxial electrocrystallization.Moreover,the incorporation of periodic electric fields and successive nanochannels within the MgMOF structure created a spatially confined environment that considerably promoted uniform magnesium nucleation at the molecular scale.Taking inspiration from the“blockchain”concept prevalent in the realm of big data,we seamlessly integrated a conductive polypyrrole framework,acting as a connecting“chain,”to interlink the“blocks”comprising the MgMOF cavities.This innovative design significantly amplified charge‐transfer efficiency,thereby increasing overall electrochemical kinetics.The resulting architecture(MgMOF@PPy@CC)served as an exceptional host for heteroepitaxial Mg electrodeposition,showcasing remarkable electrostripping/plating kinetics and excellent cycling performance.Surprisingly,a symmetrical cell incorporating the MgMOF@PPy@CC electrode demonstrated impressive stability even under ultrahigh current density conditions(10mAcm^(–2)),maintaining operation for an extended 1200 h,surpassing previously reported benchmarks.Significantly,on coupling the MgMOF@PPy@CC anode with a Mo_(6)S_(8) cathode,the assembled battery showed an extended lifespan of 10,000 cycles at 70 C,with an outstanding capacity retention of 96.23%.This study provides a fresh perspective on the rational design of epitaxial electrocrystallization driven by metal–organic framework(MOF)substrates,paving the way toward the advancement of cuttingedge batteries.

Enhanced performance of solution-processed carbon nanotube transparent electrodes in foldable perovskite solar cells through vertical separation of binders by using eco-friendly parylene substrate

The successful utilization of an eco-friendly and biocompatible parylene-C substrate for high-performance solution-processed double-walled carbon nanotube(CNT)electrode-based perovskite solar cells(PSCs)was demonstrated.Through the use of a novel inversion transfer technique,vertical separation of the binders from the CNTs was induced,rendering a stronger p-doping effect and thereby a higher conductivity of the CNTs.The resulting foldable devices exhibited a power conversion efficiency of 18.11%,which is the highest reported among CNT transparent electrode-based PSCs to date,and withstood more than 10,000 folding cycles at a radius of 0.5 mm,demonstrating unprecedented mechanical stability.Furthermore,solar modules were fabricated using entirely laser scribing processes to assess the potential of the solution-processable nanocarbon electrode.Notably,this is the only one to be processed entirely by the laser scribing process and to be biocompatible as well as eco-friendly among the previously reported nonindium tin oxide-based perovskite solar modules.

Impact of Different Cultivation Substrates on the Growth of Cymbidium goeringii

[Objectives]The paper was to explore the impact of different cultivation substrates on the growth of Cymbidium goeringii.[Methods]The impact of 13 distinct cultivation substrates on the growth of C.goeringii was examined using C.goeringii as the test material.[Results]The combination of burning red clay particles(15%),No.4 pine bark(15%),No.3 pine bark(60%),and perlite(10%),as well as the mixture of burning red clay particles(20%),No.4 pine bark(15%),No.3 pine bark(55%),and perlite(10%),yielded superior results.These formulations resulted in an increased number of new roots in C.goeringii,a reduction in the incidence of decayed roots,and enhancements in the number of tillers,new leaves,and flowers.[Conclusions]The selection of substrates may serve as a valuable reference for the cultivation of C.goeringii.

Screening of Substrate Formulas for Culture of Auricularia auricula Mycelia with Byproducts

[Objectives]This study was conducted to explore the source of substitutive substrate raw materials for cultivation of edible fungi,reduce the cutting and use of woody materials,and realize harmless treatment and resource utilization of byproducts from Chinese medicine production and bamboo processing.[Methods]Traditional Chinese medicine residue and bamboo shavings were used to partially replace hardwood sawdust in the conventional formula,and the growth of Auricularia auricula mycelia in large test tubes under different substrate formulas was studied.[Results]The results showed that the mycelia of A.auricula could grow normally on substrates with byproducts,and the mycelia grew differently with different formulas,and the performance of different strains of the same species was also different.Compared with the conventional formula,the suitable substitution amount of bamboo shavings for A.auricula strains was 10%-30%,and the substitution amount of Chinese medicine residue was 5%-15%.[Conclusions]This study provides reference for the efficient utilization of byproducts and the expansion of raw material sources for production of edible fungi.

Split Addition of Nitrogen-Rich Substrate at Thermophilic and Mesophilic Stages of Composting: Effect on Green House Gases Emission and Quality of Compost

Composting as a solution to the increasing generation of municipal solid waste (MSW), also contribute to GHGs emission when not controlled and could lack some basic nutrients, especially nitrogen. This study assessed the split-additions of nitrogen-rich substrate to composting materials and their effect on GHGs emissions as well as the quality of the composts. Nitrogen-rich substrates formulated from pig and goat manure were co-composted with MSW for a 12-weeks period by split adding at mesophilic (˚C) and thermophilic (>50˚C) stages in five different treatments. Representative samples from the compost were taken from each treatment for physicochemical, heavy metals and bacteriological analysis. In-situ CH4, CO2, N2O gas emissions were also analyzed weekly during composting. It was observed that all the treatments showed significant organic matter decomposition, reaching thermophilic temperatures in the first week of composting. The absence affects the suitable agronomic properties. All nitrogen-rich substrate applied at thermophilic stage (Treatment two) recorded the highest N, P and K concentrations of 1.34%, 0.97% and 2.45%, respectively with highest nitrogen retention. In terms of GHG emissions, CO2 was highest at the thermophilic stage when N-rich substrate was added in all treatment, while CH4 was highest in the mesophilic stage with N-rich substrate addition. N2O showed no specific trend in the treatments. Split addition of the N-rich substrate for co-composting of MSW produced compost which is stable, has less nutrient loss and low GHG emissions. Split addition of a nitrogen-rich substrate could be an option for increasing the fertilizer value of MSW compost.

Localized-states quantum confinement induced by roughness in CdMnTe/CdTe heterostructures grown on Si(111) substrates

This work shows that despite a lattice mismatch of almost 20%, CdMnTe/CdTe/CdMnTe heterostructures grown directly on Si(111) have surprisingly good optical emission properties. The investigated structures were grown by molecular beam epitaxy and characterized by scanning transmission electron microscopy, macro-and micro-photoluminescence. Low temperature macro-photoluminescence experiments indicate three emission bands which depend on the CdTe layer thickness and have different confinement characteristics. Temperature measurements reveal that the lower energy emission band (at 1.48 eV)is associated to defects and bound exciton states, while the main emission at 1.61 eV has a weak 2D character and the higher energy one at 1.71 eV has a well-defined (zero-dimensional, 0D) 0D nature. Micro-photoluminescence measurements show the existence of sharp and strongly circularly polarized (up to 40%) emission lines which can be related to the presence of Mn in the heterostructure. This result opens the possibility of producing photon sources with the typical spin control of the diluted magnetic semiconductors using the low-cost silicon technology.

Active tuning of anisotropic phonon polaritons in natural van der Waals crystals with negative permittivity substrates and its application in energy transport

Phonon polaritons(PhPs)exhibit directional in-plane propagation and ultralow losses in van der Waals(vdW)crystals,offering new possibilities for controlling the flow of light at the nanoscale.However,these PhPs,including their directional propagation,are inherently determined by the anisotropic crystal structure of the host materials.Although in-plane anisotropic PhPs can be manipulated by twisting engineering,such as twisting individual vdW slabs,dynamically adjusting their propagation presents a significant challenge.The limited application of the twisted bilayer structure in bare films further restricts its usage.In this study,we present a technique in which anisotropic PhPs supported by bare biaxial vdW slabs can be actively tuned by modifying their local dielectric environment.Excitingly,we predict that the iso-frequency contour of PhPs can be reoriented to enable propagation along forbidden directions when the crystal is placed on a substrate with a moderate negative permittivity.Besides,we systematically investigate the impact of polaritonic coupling on near-field radiative heat transfer(NFRHT)between heterostructures integrated with different substrates that have negative permittivity.Our main findings reveal that through the analysis of dispersion contour and photon transmission coefficient,the excitation and reorientation of the fundamental mode facilitate increased photon tunneling,thereby enhancing heat transfer between heterostructures.Conversely,the annihilation of the fundamental mode hinders heat transfer.Furthermore,we find the enhancement or suppression of radiative energy transport depends on the relative magnitude of the slab thickness and the vacuum gap width.Finally,the effect of negative permittivity substrates on NFRHT along the[001]crystalline direction ofα-MoO3 is considered.The spectral band where the excited fundamental mode resulting from the negative permittivity substrates is shifted to the first Reststrahlen Band(RB 1)ofα-MoO_(3) and is widened,resulting in more significant enhancement of heat flux from RB 1.We anticipate our results will motivate new direction for dynamical tunability of the PhPs in photonic devices.

Effect of substrate temperature and oxygen plasma treatment on the properties of magnetron-sputtered CdS for solar cell applications

Cadmium sulfide(CdS)is an n-type semiconductor with excellent electrical conductivity that is widely used as an electron transport material(ETM)in solar cells.At present,numerous methods for preparing CdS thin films have emerged,among which magnetron sputtering(MS)is one of the most commonly used vacuum techniques.For this type of technique,the substrate temperature is one of the key deposition parameters that affects the interfacial properties between the target film and substrate,determining the specific growth habits of the films.Herein,the effect of substrate temperature on the microstructure and electrical properties of magnetron-sputtered CdS(MS-CdS)films was studied and applied for the first time in hydrothermally deposited antimony selenosulfide(Sb_(2)(S,Se)_(3))solar cells.Adjusting the substrate temperature not only results in the design of the flat and dense film with enhanced crystallinity but also leads to the formation of an energy level arrangement with a Sb_(2)(S,Se)_(3)layer that is more favorable for electron transfer.In addition,we developed an oxygen plasma treatment for CdS,reducing the parasitic absorption of the device and resulting in an increase in the short-circuit current density of the solar cell.This study demonstrates the feasibility of MS-CdS in the fabrication of hydrothermal Sb_(2)(S,Se)_(3)solar cells and provides interface optimization strategies to improve device performance.

Advances in the structure design of substrate materials for zinc anode of aqueous zinc ion batteries

Aqueous zinc ion batteries(AZIBs) demonstrate tremendous competitiveness and application prospects because of their abundant resources,low cost, high safety, and environmental friendliness. Although the advanced electrochemical energy storage systems based on zinc ion batteries have been greatly developed, many severe problems associated with Zn anode impede its practical application, such as the dendrite formation,hydrogen evolution, corrosion and passivation phenomenon. To address these drawbacks, electrolytes, separators, zinc alloys, interfacial modification and structural design of Zn anode have been employed at present by scientists. Among them, the structural design for zinc anode is relatively mature, which is generally believed to enhance the electroactive surface area of zinc anode, reduce local current density, and promote the uniform distribution of zinc ions on the surface of anode. In order to explore new research directions, it is crucial to systematically summarize the structural design of anode materials. Herein, this review focuses on the challenges in Zn anode, modification strategies and the three-dimensional(3D) structure design of substrate materials for Zn anode including carbon substrate materials, metal substrate materials and other substrate materials. Finally, future directions and perspectives about the Zn anode are presented for developing high-performance AZIBs.

Interfacial behavior of a thermoelectric film bonded to a graded substrate

To improve the thermoelectric converting performance in applications such as power generation,reutilization of heat energy,refrigeration,and ultrasensitive sensors in scramjet engines,a thermoelectric film/substrate system is widely designed and applied,whose interfacial behavior dominates the strength and service life of thermoelectric devices.Herein,a theoretical model of a thermoelectric film bonded to a graded substrate is proposed.The interfacial shear stress,the normal stress in the thermoelectric film,and the stress intensity factors affected by various material and geometric parameters are comprehensively studied.It is found that adjusting the inhomogeneity parameter of the graded substrate,thermal conductivity,and current density of the thermoelectric film can reduce the risk of interfacial failure of the thermoelectric film/graded substrate system.Selecting a stiffer and thicker thermoelectric film is advantageous to the reliability of the thermoelectric film/graded substrate system.The results should be of great guiding significance for the present and upcoming applications of thermoelectric materials in various fields.

Phytochemical Contents and Antioxidant Properties of Ganoderma lucidum Polysaccharides in Relation to Growth Stage and Culture Substrate

[Objectives]To determine physicochemical characteristics and antioxidant activity of Ganoderma lucidum polysaccharides(GLP)in different growth stages and culture media.[Methods]Five polysaccharides(GLP1,GLP2,GLP3,GLPW and GLPB)were extracted and purified from the fruiting body of G.lucidum at three growth stages and culture substrates(wood culture and bag culture).The chemical components and antioxidant activity of the five polysaccharides were determined.[Results]GLP1 contained the highest content of neutral sugar(87.65%)and GLP3 had the highest uronic acid content.All the samples mainly comprised glucose,galactose,mannose,xylose and arabose with different ratios.Moreover,their antioxidant activities were investigated on the basis of DPPH radical,ABTS radical,SOD-like activity,and antihaemolytic activity.Results indicated in all three growth stages GLP2 had the greatest antioxidant properties.In addition,the antioxidant activity of GLPW was significantly higher than that of GLPB.[Conclusions]Overall,by comparison,G.lucidum in growth stage two may have potential health benefits,and wood culture may be a superior choice of artificial cultivation due to their abundance of active polysaccharides.

A Pore-Forming Strategy Toward Porous Carbon-Based Substrates for High Performance Flexible Lithium Metal Full Batteries

Self-standing carbon-based substrates with satisfied structural stability and property adjustability have promising applications in flexible lithium(Li)metal batteries(FLMBs).Current strategies for modifying carbon materials are normally carried out on powder carbon,and very few of them are suitable for self-standing carbon substrates.Herein,a pore-forming strategy based on the redox chemistry of metallic oxide nanodots is developed to prepare two porous carbon substrates for anode and cathode.Starting with cotton cloth,the resulting hollow carbon fibers substrate with nanopores effectively prevents from Li dendrites formation and large volume change in lithium metal anode(LMA).Simulations indicate that the porous structure leads to homogeneous ion flux,Li-ion concentration,and electric field during Li deposition.Li symmetrical cell based on this substrate remains stable for 8300 h with an ultralow voltage hysteresis of 9 mV.Via a similar route,porous carbon cloth substrate is obtained for subsequently seeding V_(2)O_(5)nanowires to prepare the cathode.The assembled FLMBs pouch cell delivers a capacity of 8.2 mAh with a high capacity retention of~100%even under dramatic deformation.The demonstrated strategy has far-reaching potential in preparing free-standing porous carbon-based materials for flexible energy storage devices.