Doping Method Research Articles

Synthesis of Mn-doped hollow octahedron ZnIn2S4 to enhance photocatalytic hydrogen production performance utilizing metal-organic framework as template.

Designing semiconductor photocatalysts with unique structures can improve the transfer efficiency of solar energy to hydrogen (H2). In this study, a dual modification method of element doping and morphological control was used. The Mn-doped hollow octahedron ZnIn2S4 (ZHO-Mn) was synthesized by a simple one-pot solvothermal method using the octahedral Mn-based metal-organic framework (Mn-MOF) as a template. Experiments and theoretical calculations show that the ZHO-Mn has additional active sites, strong light absorption ability and good photoelectric performance. The H2 production performance of optimized ZHO-Mn10 was the best (11.9 mmol h-1 g-1), which was 7.4 times that of monomer ZnIn2S4 (1.6 mmol h-1 g-1). This study provides a new one-step method for the dual control of doping and morphology of ZnIn2S4 photocatalyst.

Electronic and magnetic properties of the HfO2 monolayer engineered by doping with transition metals and nonmetal atoms towards spintronic applications.

Doping two-dimensional (2D) materials is a vitally important method to modulate their electronic and magnetic properties. In this work, doping with transition metals (TM = Mn and Fe) and nonmetal atoms (X = B and C) is proposed to engineer the magnetism in the HfO2 monolayer. The pristine monolayer is an intrinsically nonmagnetic insulator with a large band gap of 4.85 (6.43) eV as calculated using the PBE (HSE06) functional. Doping with Mn and Fe atoms induces monolayer magnetization with total magnetic moments of 3.00 and 4.00μ B, respectively. Herein, Mn- and Fe-3d electrons produce mainly magnetic properties and regulate the electronic nature by forming new mid-gap energy states. Similarly, the 2p orbital of impurities plays a key role in determining the electronic and magnetic properties of B- and C-doped systems. Mn and B doping leads to the emergence of magnetic semiconductor nature, while the half-metallicity is obtained by doping with Fe and C atoms. Further, the substitution of the Hf-O pair with the TM-X pair is also studied. In these cases, both TM and X impurities induce the system magnetism, exhibiting an antiparallel spin orientation. Consequently, pair-atom-doped systems have smaller total magnetic moments in comparison with single-atom-doped systems. Interestingly, doping with all four Mn-B, Mn-C, Fe-B, and Fe-C pairs induces a magnetic semiconductor nature, where spin-dependent energy gaps are determined by the doping-induced multiple mid-gap energy states. When incorporated into the HfO2 monolayer lattice, transition metals lose charge, while nonmetal impurities act as charge gainers. This study demonstrates the effectiveness of the doping method to engineer the magnetism in the HfO2 monolayer for spintronic applications.

Reconfiguration of Intrinsic Depletion-Mode Characteristics of MoS2 Field-Effect Transistors to High-Performance Enhancement-Mode Operation Using an Argon Plasma-Induced p-Type Doping Technique.

The intrinsic n-type behavior and unavailability of the appropriate p-type doping method for MoS2 allows only n-type conduction with depletion mode (D-mode) characteristics and forbids the implementation of p-type field-effect transistors (FETs). The D-mode characteristic results in a high off-current (IOFF) at zero gate bias, which limits the usage of MoS2 FETs for industry-scale (n-channel metal-oxide semiconductor) NMOS/(complementary metal-oxide semiconductor) CMOS-logic-based applications due to significant power dissipation. Both these issues, i.e., i) missing technique for p-type doping and ii) D-mode operation are addressed here through the application of argon (Ar) plasma and subsequent O2 bath. Here, Ar plasma results in the physical removal of sulfur (S) atoms from the MoS2 surface, introducing sulfur vacancies, and the O2 bath results in the chemical bonding of O2 molecules with molybdenum (Mo) atoms at the introduced S vacancy sites. This leads to the formation of shallow acceptor states near the valance band (VB) of MoS2, resulting in p-type doping and enhancement mode (E-mode) characteristics of MoS2 FETs. Moreover, using Ar plasma results in the reduction of contact resistance (RC) of E-mode MoS2 FETs and hence facilitates achieving high-performance top-gated E-mode MoS2 FETs with IOFF (at zero gate bias) in tens of picoamperes and ION/IOFF in seven orders.

Internal Doping and Surface Coating: Mn/La-HCF @ Fe-HCF Composites as High-Performance Cathode Materials for Sodium-Ion Batteries

Manganese-based Prussian blue analogue (Mn-HCF) has outstanding advantages such as a high discharge platform, high discharge capacity and high energy density compared with other PB and PBAs, which is a very valuable cathode material for sodium-ion batteries. However, the rapid decrease in capacity in the cycle process by the Jahn–Teller effect caused by [Formula: see text] is the main obstacle to the commercialization of Mn-HCF. In this work, Mn/La-HCF @ Fe-HCF was synthesized by doping La element into the Mn-HCF phase to suppress the Jahn–Teller effect of Mn ions and coating the Fe-HCF phase outside to protect the Mn-HCF phase from electrolyte corrosion. Benefiting from the inhibition of the Jahn–Teller effect of [Formula: see text] by the abundant electronic energy level structure of La element and the protection of Fe-HCF phase relative to Mn-HCF phase, the initial discharge capacity of Mn/La-HCF @ Fe-HCF can reach 135.6 mAh [Formula: see text] at current density of 0.1 C, and it still has a high discharge capacity of 112.2[Formula: see text]mAh [Formula: see text] at current density of 5 C. After 300 cycles at a current density of 2 C, the reversible capacity of 117.6[Formula: see text]mAh [Formula: see text] is maintained (capacity retention rate is 86.1%). The results show that this method of internal doping and outsourcing can greatly improve the electrochemical performance of Mn-HCF, and provide feasible ideas for the commercialization of Mn-HCF.

Doping Elemental 2D Semiconductor Te through Surface Se Substitutions.

The development of two-dimensional (2D) semiconductors is limited by the lack of doping methods. We propose surface isovalent substitution as an efficient doping mechanism for 2D semiconductors by revealing the evolution of the structure and electronic properties of 2D Se/Te. Because of the different electronegativity of Se and Te, Se substitution for Te at the specific lattice sites introduces electric dipoles and leads to charge redistribution, which lowers the work function and tunes the Te films from p-type to n-type semiconductors. This differs from the gap enlargement of alloy films with random Se-Te substitutions. This doping method minimizes the change of lattice structure and surface roughness, which benefits structure stacking. Further increasing the Se content leads to the formation of two types of 2D semiconducting Se polymorphs.

Research on enhancing thermal conductivity of phase change microcapsules with nano-copper

Abstract The unique ability of phase change materials (PCMs) to store and release heat makes their integration into building materials promising for reducing energy consumption and enhancing sustainability. In this work, a novel high-thermal-conductivity microencapsulated phase change material was studied, with nano-copper embedded in the microcapsule structure. This modification enhanced thermal conductivity while largely preserving the material’s latent heat storage capacity. Poly(ethyl acrylate) (PEA) is chosen as the capsule shell, whereas a eutectic mixture of decanoic acid (CA) and lauric acid (LA) serves as the core material. The analysis results indicate that as the shell-core mass ratio decreases, the microcapsule size increases, and both thermal conductivity and thermal diffusivity gradually decrease. Moreover, the latent heat capacity of microencapsulated phase change material (MEPCM) increases. When the shell-core mass ratio is 1:1.5, the melting latent heat and solidification latent heat are 81.85 J g−1 and 88.68 J g−1, respectively. nano-copper doping enhances the material’s thermal conductivity and thermal diffusivity by 47.5% and 50%, respectively, leading to a 20.3% improvement in heat storage efficiency. After 200 cycles of testing, the material maintains good thermal reliability and chemical stability. Mortar-based composite materials containing microcapsules were prepared. The mortar composite materials containing microcapsules exhibited minimal influence from heating and cooling, with those containing nano-copper microcapsules demonstrating superior thermal response speeds. The method of doping and modifying MEPCM with nano-copper is a promising approach for effectively reducing the impact of temperature fluctuations on the internal comfort of buildings, improving energy utilization efficiency, and providing reliable solutions for temperature-sensitive applications.

The Influence of Nickel Doping on the Metal-Oxide in Solution-Processed Transistors Based on Indium Zinc Oxide

Solution-processing of nickel zinc oxide (IZO) thin-film transistors (TFTs) is gaining traction as a cornerstone of future display technology, promising cost-effective production. However, achieving stability in the off-current state of IZO without using Ga, a less eco-friendly dopant, remains a challenge. This study proposes a solution-based doping method for IZO semiconductors employing a Ni carrier suppressor and examines the impact of Ni on transistor operation. By leveraging the similar size of Ni2+ to Zn2+, an optimal Ni concentration selectively substitutes Zn sites, leading to a reduction in hydroxide groups bonded to Zn and enhancing the bonding strength of Ni with O. Conversely, excessive Ni addition impedes the formation of a smooth thin film. Ni-doped IZO TFT devices with optimized Ni concentrations exhibit superior performance, characterized by significantly lower off-state currents while maintaining high on-state currents compared to conventional IZO TFTs. This approach expands the repertoire of solution-processed metal oxide semiconductors, offering a sustainable alternative for carrier suppression and facilitating the cost-effective and straightforward fabrication of TFTs.

Highly Porous Nitrogen and Phosphorus Dual-Doped Carbon with Increased Phosphorus Content As an Efficient Oxygen Reduction Electrocatalyst

Fuel cells and metal-air batteries have attracted the attention of many researchers because of their high power density and large energy density. Carbon materials are typically used as catalyst supports and conductive agents at the cathodes in fuel cells and metal-air batteries. However, pure carbon exhibits low electrocatalytic activity for the oxygen reduction reaction (ORR) at the cathodes. Single doping of heteroatoms, such as nitrogen and phosphorus, has been investigated as a simple method to improve the ORR activity of carbon materials. Moreover, compared with single doping, dual doping of nitrogen and phosphorus can further enhance the ORR performance due to the synergetic effect of the dopants [1]. Acetylene blacks (ABs) are readily available and widely used in industry for pigments, reinforcing rubber, and battery electrodes. However, the content of heteroatoms doped into AB by conventional heat treatment is low [2]. Recently, mechanochemical treatments have received increasing attention because they are more robust and simpler than conventional methods. Some studies have been conducted on solid-gas mechanochemical treatment under an air atmosphere as a nitrogen doping method for graphite and graphite-based materials [3]. In this study, nitrogen and phosphorus dual-doped carbon (NPC) was synthesized by a two-step method: solid-gas mechanochemical treatment using a planetary ball mill at a rotation speed of 600 rpm for 1 h to prepare nitrogen-doped carbon (NC), followed by heat treatment with ammonium dihydrogen phosphate (ADP) at 800 °C for 12 h to dope the NC with phosphorus. For comparison, phosphorus-doped carbon (PC) was synthesized by heat treatment of AB with ADP at 800 °C for 12 h.X-ray photoelectron spectroscopy was used to identify the doping states and concentrations of the samples. NPC has high concentrations of nitrogen (1.60 at%) and phosphorus (1.91 at%). In contrast, PC has a low phosphorus concentration (0.14 at%). Scanning electron microscopy revealed that mechanochemical treatment using a ball mill broke the particles and reduced their size from 35 nm in AB to approximately 10 nm in NC and NPC. The surface areas of NC and NPC significantly increased to 424 m2 g−1 and 540 m2 g−1, respectively, compared with that of AB (64.7 m2 g−1), mainly due to particle size reduction. Furthermore, NC and NPC exhibit high porosity with a maximum at 3.6 nm (Fig. 1a). The primary pores of NC and NPC constitute spaces between the particles. Electrochemical measurements were performed using a rotating disk electrode (RDE) in O2-saturated 1.0 M KOH. Linear sweep voltammetry curves of samples at an RDE rotation speed of 1600 rpm are shown in Fig. 1b. NC exhibits a much higher kinetic current density of 1.71 mA cm−2 at −0.15 V vs. Hg/HgO calculated from a mass transport correction of RDE than AB (0.04 mA cm−2), suggesting that the doped nitrogen and high porosity in NC significantly promote the ORR process. Furthermore, NPC shows 2.4 times higher kinetic current density of 4.14 mA cm−2 than NC, indicating that additional phosphorus doping into NC can enhance the ORR activity. Owing to the highly porous structure in NC, phosphorus atoms can be effectively doped into the carbon matrix during heat treatment, which may lead to the generation of abundant active sites for the ORR in NPC.

Unveiling Accelerated Oxygen Evolution Reaction through Explosive Reconstruction of Active Species of Coxn@NC

Hydrogen (H2) generation through electrolysis has attracted much attention because of growing global energy needs and the demand for green energy strategies. Hydrogen generation through water electrolysis is accompanied by two half reaction, hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). However, OER has the limitation of lowering the energy efficiency of the entire cell due to its sluggish reaction problem and high overpotential. Also, commercial OER electrocatalysts are limited to noble metal oxide such as IrO2 and RuO2, which are scarce and have stability problems in alkaline solution. Therefore, there is a growing desire to develop an OER electrocatalyst that is abundant, stable, and highly efficient for the superior performance of overall water electrolysis.The doping, alloy, oxide, and nitride of transition metal materials have been reported as abundant materials that exceed the electrolysis efficiency of noble metals during OER. Among them, transition metal nitrides showed superior OER electrocatalytic performance due to their high electrical conductivity, which is derived from their metallic properties. To boost the electrocatalytic activity of transition metal based materials, numerous efforts have focused on modulating electronic structure related to catalytic activity in OER. The d-band center theory which proposed that the position of d-band center (Ed) has close relationship with the catalytic activity has unveiled insights into designing electrocatalysts for OER. However, most researchers have used ion exchange or doping method for modulating d-band center, which requires an additional process and leads to higher difficulty of designing electrocatalysts.Recently, Prussian Blue Analogues (PBAs) have been widely employed as a self-template material for the energy conversion and storage field such as water electrolysis and batteries. PBAs, which are a type of Metal Organic Frameworks (MOFs) composed of CN groups, have emerged as a promising material due to the following characteristics: 1) numerous interstitial sites with unique 3-dimensional structure due to CN group; 2) advantages of synthesizing various compositions; and 3) chemical stability in solution. Due to these advantages, PBAs have a large specific surface area, fast diffusion kinetics, and structural stability when applied as a precursor to water electrocatalysts. Although PBAs-derived electrocatalysts have high electrical conductivity and electrocatalytic performance, they are prone to aggregate and lose their unique morphology after high temperature process. As a breakthrough of the limitation, polydomamine (PDA) coating has been attracting attention as an encapsulation method to achieve hybridization with carbon materials, as well as enhance electrocatalytic performance. PDA is simply synthesized by the polymerization of Dopamine (DA) in Tris-buffer solution, which is beneficial for mass production. In addition, PDA is advantageous for N-doped carbon formation, because it has high nitrogen content, which improves the charge transfer ability during electrocatalytic reaction. Also, because PDA has thermal stability, agglomeration between particles can be prevented when high-temperature heat treatment is performed. Due to these characteristics of PDA, PDA both prevents the aggregation of PBAs during carbonization at high temperature and improves stability in alkaline solution, while increasing reaction sites by forming a high content of N-doped carbon layer.Herein, we present a versatile but promising strategy to synthesize cobalt nitride nanoparticles encapsulated in N-doped carbon (Co/Co4N@NC) nanoboxes as highly efficient and stable OER electrocatalysts by modulating d-band center through the simple nitridation of self-template PBAs encapsulated by PDA. The synthesized Co/Co4N@NC nanoboxes have mesoporous and hollow structure, which provides a large specific surface area and fast charge transfer pathways. Especially, the d-band center of CoxN nanoparticles is strategically modulated to be more metallic and heterogeneous to favor electrocatalytic reactions. Furthermore, the highly conductive N-doped carbon shell derived from PDA coating enables electrocatalysts to have not only numerous active reaction sites and fast charge transfer ability but also long-term durability in alkaline solution during OER. The Co/Co4N@NC nanoboxes showed a remarkable overpotential value of 262 mV and 408 mV at 10 mA∙cm-2 and 100 mA∙cm-2, respectively, and a low tafel slope of 130 mV∙dec-1, which is superior to RuO2 (284 mA∙cm-2 and 470 mA∙cm-2). In addition, the Co/Co4N@NC nanoboxes maintained an overpotential value of 92.6 % after 24 h of stability test at 10 mA∙cm-2, as well as showing outstanding durability for 100 h and at high current density of 100 mA∙cm-2. The DFT calculation also identifies advantages of metallic cobalt nitride and heterogeneous structure derived from the modulated electronic structure of Co/Co4N@NC. Finally, the in-situ XANES during OER of Co/Co4N@NC is clear evidence that the modulated electronic structure of Co/Co4N@NC improves the OER catalytic activity due to reconstruction of Co2+ into Co3+. Figure 1

Large Optical Nonlinearity Enhancement and All‐Optical Logic Gate Implementation in Silver‐Modified Violet Phosphorus

AbstractAs the most stable allotrope of phosphorus, violet phosphorus (VP) has attracted extensive research in the field of all‐optical modulation due to its excellent broadband spatial self‐phase modulation (SSPM) effect. To better exploit the great potential of VP in nonlinear photonics devices, this work explores chemical doping method to artificially enhance the nonlinear optical response of VP. Herein, silver‐modified few‐layer VP (Ag‐VP) is constructed for SSPM experiments. In comparison to pristine VP, a significantly improved third‐order nonlinear susceptibility (χ(3)) and nonlinear optical response for Ag‐VP is obtained in visible light band, and the enhancement ratio increases with the increase of wavelength. Moreover, the excitation threshold of SSPM effect is also significantly reduced, with a reduction ratio up to 3.61. The enhanced nonlinear optical response is attributed to the improved light–matter interaction induced by impurity energy levels. By taking advantage of the outstanding SSPM effect of Ag‐VP, an all‐optical logic gate is designed to demonstrate “OR” logical information transmission. This work provides a new avenue for the design and application of energy‐saving and tunable nonlinear photonic devices in the future.

Analyzing Carrier Density and Hall Mobility in Impurity‐Free Silicon Virtually Doped by External Defect Placement

AbstractImpurity doping at the nanoscale for silicon is becoming less efficient with conventional techniques. Here, an alternative virtual doping method is presented for silicon that can achieve an equivalent carrier density while addressing the primary limitations of traditional doping methods. The doping for silicon is carried out by placing aluminum‐induced acceptor states externally in a silicon dioxide dielectric shell. This technique can be referred to as direct modulation doping. The resistivity, carrier density, and mobility are investigated by Hall effect measurements to characterize the carrier transport using the new doping method. The results thereof are compared with carrier transport analysis of conventionally doped silicon at room‐temperature, demonstrating a 100% increase in carrier mobility at equal carrier density. The sheet density of hole carriers in silicon due to modulation doping remains nearly constant, ≈4.7 × 1012 cm−2 over a wide temperature range from 300 down to 2 K, proving that modulation‐doped devices do not undergo carrier freeze‐out at cryogenic temperatures. In addition, a mobility enhancement is demonstrated with an increase from 89 cm2 Vs−1 at 300 K to 227 cm2 Vs−1 at 10 K, highlighting the benefits of the new method for creating emerging nanoscale electronic devices or peripheral cryo‐electronics to quantum computing.

DFT insights upon Pd assisted MoX2 (X = Se, S, Te) capture of air decomposition products (CO, NO2) in switch cabinet

The MoSe2, MoS2, and MoTe2 substrates are selected for testing the decomposition products of air (CO, NO2) in the switch cabinet. The metal Pd doping method is introduced to improve the detection ability of the substrate. The effect of Pd on the substrate is firstly studied, it is found that Pd can effectively improve the conductivity of the substrate by analyzing the structures, binding energy, band gap and state density changes. The adsorption of the target gases on the initial substrates is physical adsorption, and the addition of Pd enhances the adsorption capacity of the three substrates for CO and NO2 and transforms it into chemical adsorption. After the gas is adsorbed on the three modified substrates, it will cause a decrease in the band gap, and the change caused by NO2 is greater than that of CO. By analyzing the sensitivity and recovery time, it is found that the three modified substrates can effectively distinguish the two gases, and each adsorption system has a suitable recovery time at the corresponding test temperature. The results of this study can provide theoretical support for MoSe2, MoS2, and MoTe2 in detecting the decomposition products of air inside switch cabinet.

Germanium surface segregation in highly doped Ge:β-Ga2O3 grown by molecular beam epitaxy observed by synchrotron radiation hard x-ray photoelectron spectroscopy

We present a study of Ge segregation at the surface of highly germanium-doped gallium oxide (2.5 × 1020 cm−3 nominal doping level) grown by molecular beam epitaxy. We probed the dopant concentration as a function of depth by hard x-ray photoelectron spectroscopy and standard laboratory photoemission spectroscopy. We notably found that there is germanium segregation within the top 2 nm where its concentration is 3 times the nominal doping level. This increased dopant concentration leads to a threefold enhancement of surface conductivity. The results suggest a reliable method for delta doping for power electronics applications.

Istraživanje utjecaja zelenih hibridnih vlakana na žilavost i mehanička svojstva betona od pijeska željezne jalovine

To improve the brittleness and susceptibility to cracking of iron tailings sand concrete, fibre blending was employed to toughen and resist cracking in the material. In this study, two inexpensive and environmentally friendly fibre materials were used: recycled tire steel fibre (RTSF) and coconut fibre (CF). The two fibre materials were blended and the resulting mixture was subjected to a series of performance tests, including compressive, tensile, flexural, impact, and bending tests. The effects of the fibre doping method and amount on the toughness and mechanical properties of iron tailings sand concrete were investigated in terms of the law of effect of the blended fibre admixture on the toughness and mechanical properties of iron tailings sand concrete. The results show that adding two types of fibres can effectively improve the toughness and mechanical properties of the specimen, and the hybrid fibre has a more obvious effect. Compared with the blank control group (Non), the compressive strength, splitting tensile strength, bending strength, impact strength, and bending peak load of the concrete with 0.75 % RTSF and 0.2 % CF increased by 20.8 %, 42.9 %, 40.4 %, 92.4 %, and 37.5 %, respectively. Combined with the theory and fracture surface morphology analysis, it was shown that recycled tire steel fibres play a major role in cracking resistance, while coconut fibres play a toughening role.

Thermal stability of dielectric properties of Dy-doped BaTiO3 for application in the ultra-thin multilayer ceramic capacitors

Rare earth elements are usually used to improve the performance of multilayer ceramic capacitors (MLCC), because their unique chemical and physical properties. Exploring the optimal method of rare earth doping is crucial to address the current performance deficiencies of MLCC. In this study, three samples with different doping levels of Dy and Ho selected to investigate the microstructure, dielectric performance, and reliability. Compared to the co-doping of Dy and Ho, excessive Dy doping exhibited better defect structure, resulting in smoother and more stable temperature coefficient of capacitance (TCC) curves and stronger suppression of oxygen vacancies. As the increase of Dy doping content, the activation energy of oxygen vacancies increased from 59.98 V/μm to 86.79 V/μm. This indicates that appropriate Dy doping has a superior effect on improving MLCC performance compared to co-doping systems. This work validates the complex defect structure induced by Dy doping and its improvement effect on MLCC performance, demonstrating the significant potential of Dy-doped MLCC.

Two-Dimensional MoS2-Based Anisotropic Synaptic Transistor for Neuromorphic Computing by Localized Electron Beam Irradiation.

Neuromorphic computing, a promising solution to the von Neumann bottleneck, is paving the way for the development of next-generation computing and sensing systems. Axon-multisynapse systems enable the execution of sophisticated tasks, making them not only desirable but essential for future applications in this field. Anisotropic materials, which have different properties in different directions, are being used to create artificial synapses that can mimic the functions of biological axon-multisynapse systems. However, the restricted variety and unadjustable conductive ratio limit their applications. Here, it is shown that anisotropic artificial synapses can be achieved on isotropic materials with externally localized doping via electron beam irradiation (EBI) and purposefully induced trap sites. By employing the synapses along different directions, artificial neural networks (ANNs) are constructed to accomplish variable neuromorphic tasks with optimized performance. The localized doping method expands the axon-multisynapse device family, illustrating that this approach has tremendous potentials in next-generation computing and sensing systems.

Solution Doping of PMMA-Based Step-Index Polymer Optical Fibers by Rhodamine B Near Glass Transition Temperature of PMMA

Solution doping is a facile approach to fabricating photoactive polymer optical fibers (POFs). However, previous studies reveal that only the cladding of step-index POFs can be doped by the solution doping method in methanol or aqueous solutions, whereas the fiber core is hardly doped. To dope the fiber core as well as the cladding, this study attempts to dope PMMA-based step-index POFs by raising the doping temperatures to near the Tg of PMMA. The results show that a considerable amount of rhodamine B (RhB) is doped in the fiber core, though the amount is still much less than that in the cladding. The highest content in the fiber core is 0.479 mg/g, which is achieved by doping the POFs in water at 110 °C for 8 h. At the same condition, the RhB content of the cladding is 11.5 mg/g. It is found that the high-temperature doping process leads to dramatic axial shrinkage and radial expansion of the POFs, due to the relaxation of the fiber core. The wrinkled cladding after doping suggests that the macromolecule orientation of the core is much higher than that of the cladding, and high orientation should be the main reason why the core is much more difficult to dope than the cladding. Additionally, the doping process at 90 °C in water does not increase the fiber loss regardless of the tremendous POF structure change. In short, the core of PMMA-based step-index POFs can be doped at a temperature near the Tg of the PMMA, making the solution doping technique more practicable for POF doping.

Supersaturated Doping-Induced Maximized Metal-Support Interaction for Highly Active and Durable Oxygen Evolution.

Metal-support interaction (MSI) is pivotal and ubiquitously used in the development of next-generation catalysts, offering a pathway to enhance both catalytic activity and stability. However, owing to the lattice mismatch and poor solubility, traditional catalysts often exhibit a metal-on-support heterogeneous structure with limited interfaces and interaction and, consequently, a compromised enhancement of properties. Herein, we report a universal and tunable method for supersaturated doping of transition-metal carbides via strongly nonequilibrium carbothermal shock synthesis, characterized by rapid heating and swift quenching. Our results enable ∼20 at. % Ni2FeCo doping in Mo2C, significantly surpassing the thermodynamic equilibrium limit of <3 at. %. The supersaturation ensures more catalytically active NiFeCo doping and sufficient interaction with Mo2C, resulting in the maximized MSI (Max-MSI) effect. The Max-MSI enables outstanding activity and particularly stability in alkaline oxygen evolution reaction, showing an overpotential of 284 mV at 100 mA cm-2 and stable for 700 h, while individual Ni2FeCo and Mo2C only last less than 70 and 10 h (completely dissolved), respectively. In particular, the SD-Mo2C catalyst also exhibits excellent durability at 100 mA cm-2 for up to 400 h in 7 M KOH. Such a significantly improved stability is attributed to the supersaturated doping that led to each Mo atom strongly binding with adjacent heteroatoms, thus elevating the dissolution potential and corrosion resistance of Mo2C at a high current density. Additionally, the highly dispersed NiFeCo also facilitates the formation of dense oxyhydroxide coating during reconstruction, further protecting the integrated catalysts for durable operation. Furthermore, the synthesis has been successfully scaled up to fabricate large (16 cm2) electrodes and is adaptable to nickel foam substrates, indicating promising industrial applications. Our strategy allows the general and versatile production of various highly doped transition-metal carbides, such as Ni2FeCo-doped TiC, NbC, and W2C, thus unlocking the potential of maximized or adjustable MSI for diverse catalytic applications.

High Efficiency n-Type Doping of Organic Semiconductors by Cation Exchange.

Achieving efficient doping in n-type conjugated polymers is crucial for their application in electronic devices. In this study, an n-type doping method is developed based on cation exchange that maintains a high doping level while ensuring a high degree of structural order, leading to significantly improved electrical conductivity. By investigating various dopants and ionic liquids, it is discovered that the choice of dopant influences doping efficiency, while the selection of ionic liquid affects cation exchange efficiency. Through careful selection of suitable dopants and ionic liquids, High doping levels are achieved remarkably in a short period, resulting in the highest conductivity (nearly 1×10- 2Scm-¹) compared to other doping methods for poly{[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (N2200). The findings highlight the robustness and efficiency of cation exchange doping as an effective approach for achieving high-quality n-type doping in conjugated polymers, thereby opening new avenues for the development of advanced polymer-based electronic devices.

Structure and electrical properties of polysilicon films doped with ammonium tetraborate tetrahydrate

Here, p-type polysilicon films are fabricated by ex-situ doping method with ammonium tetraborate tetrahydrate (ATT) as the boron source, named ATT-pPoly. The effects of ATT on the properties of polysilicon films are comprehensively analyzed. The Raman spectra reveal that the ATT-pPoly film is composed of grain boundary and crystalline regions. The preferred orientation is the (111) direction. The grain size increases from 16−23 nm to 21−47 nm, by ~70% on average. Comparing with other reported films, Hall measurements reveal that the ATT-pPoly film has a higher carrier concentration (>1020 cm−3) and higher carrier mobility (>30 cm2/(V·s)). The superior properties of the ATT-pPoly film are attributed to the heavy doping and improved grain size. Heavy doping property is proved by the mean sheet resistance (R sheet,m) and distribution profile. The R sheet,m decreases by more than 30%, and it can be further decreased by 90% if the annealing temperature or duration is increased. The boron concentration of ATT-pPoly film annealed at 950 °C for 45 min is ~3 × 1020 cm−3, and the distribution is nearly the same, except near the surface. Besides, the standard deviation coefficient (σ) of R sheet,m is less than 5.0%, which verifies the excellent uniformity of ATT-pPoly film.