One-step Doping Research Articles

Porous biochar with a tubular structure for photothermal CO2 cycloaddition: One-step doping versus two-step doping

Solar-powered carbon dioxide (CO2) conversion over biomass derived carbon (BC) has shown great promise for alleviating global warming and producing useful chemicals. However, their lack of active sites, rapid recombination of photogenerated electron-hole pairs, and low CO2 uptake abilities pose significant challenges for photo-induced catalysis. Here, we report the fine-tuning of active sites of BC via one-step and two-step calcination of corn stalk with a tubular structure. Strikingly, compared with samples prepared by two-step doping strategies, NB-BC synthesized via a one-step doping process harbors much enhanced activity under relatively mild conditions (Xe lamp, 400 mW cm−2, 1 bar CO2) with a considerable cyclic carbonate yield of 99 %. The high catalytic performance is attributed to the alteration of pore structure, electronic structure, and active sites due to N, B doping. Moreover, this biochar displays excellent recyclability and retains its applicability under simulated flue gas conditions. Various characterizations and control experiments reveal the combination of thermal catalysis and photocatalysis over this N, B co-doped BC catalyst. Our work provides some insights into the effective applications of biochar in the field of CO2 catalytic conversion.

Enhancing the performance of β-Ga2O3 solar-blind photodetectors based on ZnGa2O4 substrate by bottom-up Zn diffusion doping

β-Ga2O3 solar-blind photodetector (SBPD) promises great potential applications in both industrial and scientific fields while it urgently needs performance optimization. Herein, the unique bottom-up Zn diffusion doping engineering was applied to fabricate an ultrahigh-performance β-Ga2O3 planar MSM SBPD. High-quality β-Ga2O3 film was grown by MOCVD heteroepitaxy technology on the cost-effective ZnGa2O4 substrate, and the high-temperature growth process successfully realized the moderate diffusion Zn doping from the substrate to the film. This low-cost one-step doping not only reduces the dark current of the device to 635 fA at 20 V, which is 103 times lower than the β-Ga2O3 film SBPD grown on a c-sapphire substrate under the same conditions, but also maintains the excellent crystal quality of the MOCVD grown film, thus brings the comprehensive performance of the device exceeding most reported β-Ga2O3 SBPDs. The device exhibits a high photo-to-dark-current ratio of 1.18 × 107, high responsivity of 72.35 A/W, considerable rejection ratio (R254 nm/R365 nm) of 107, and extremely fast decay time of 8 ms under 254 nm illumination at 20 V. This work provides novel strategies of β-Ga2O3 film optimization for the future development of high-performance photodetectors.

One-step approach to Quaternary (B, N, P, S)-Doped hierarchical porous carbon derived from Quercus Brantii for highly selective and efficient CO2 Capture: A combined experimental and extensive DFT study

Recently, the enhancement of atmospheric carbon dioxide (CO2) concentration has a negative impact on the environment and human health. Adsorption is well recognized as a promising technology to control CO2 emission in which the design of an optimum adsorbent is one of the most critical challenges. In this article, multi-heteroatoms doped porous carbons have been successfully derived from Quercus Brantii by one-step doping–activation to investigate the textural characteristics and heteroatoms doping effects on CO2 capture application. Based on the physicochemical properties of the adsorbents, which were characterized using varied techniques (FE-SEM, EDS, HR-TEM, XRD, FT-IR, XPS, BET, and BJH), the introduction of heteroatoms provides more active sites in carbon networks and develops the porous architecture of each activated carbon, resulting in diverse CO2 capture performances. The low content of phosphorus (P) incorporated in P-doped activated carbon (PAC) perfected the performance of CO2 capture to reach a high uptake (7.13 mmol g−1 at 1 bar and 20 °C) on a heterogeneous surface. Apart from the high equilibrium and dynamic CO2 uptake, these Quercus Brantii-based carbonaceous adsorbents present superior CO2 selectivity over N2, CH4, and H2, prominent cyclic regeneration capacity, high turnover frequency (TOF) and turnover number (TON) for commercial scale as well as fast kinetic adsorption. The density functional theory (DFT) method was performed to reveal the adsorption mechanisms as well as electronic properties of the systems.

Emitter-Quencher Pair of Single Atomic Co Sites and Monolayer Titanium Carbide MXenes for Luminol Chemiluminescent Reactions.

A facile, one-step doping protocol was adopted to synthesize Co single atomic site catalysts (SASCs) in UiO-66 metal-organic frameworks. In view of highly uniform active sites of Co-O6 moieties, the SASCs specifically contribute to catalyzing the generation of a large amount of singlet oxygen instead of superoxide or hydroxyl radicals, which endows Co SASCs with a the remarkable enhancement effect (∼3775 times) on luminol chemiluminescent (CL) emission. Interestingly, monolayer titanium carbide MXenes can drastically quench the CL signal of the Co SASC-boosted luminol reaction by ∼94.6% as highly efficient luminescent absorbents. Furthermore, the emitter-quencher pair of Co SASCs and titanium carbide MXenes was successfully adopted to develop an immunoassay method for cardiac troponin I (cTnI) on an immunochromatographic test strip platform. With a sandwich immunoreaction mode, a titanium carbide MXene-labeled cTnI tracer antibody was captured on the test line of a test strip, which significantly inhibited the CL response of the Co SACs-boosted luminol system. The dynamic range for quantitating cTnI is 1.0-100 pg mL-1, with a detection limit of 0.33 pg mL-1 (3σ). The test strip was successfully used to detect cTnI in human serum samples collected from cardiopathy patients. This proof-of-principle work manifests both the CL enhancement of SASCs and the quenching behavior of MXenes, which shows the thrilling prospects of combinational usage of the two functionalized nanomaterials for tracking biological recognition events.

Understanding the role of nitrogen and sulfur doping in promoting kinetics of oxygen reduction reaction and sodium ion battery performance of hollow spherical graphene

Here, a simple, economical one-step doping strategy is adopted to prepare N, S co-doped graphene hollow spheres (NSGHS). The NSGHS exhibits remarkable oxygen-reduction-reaction (ORR) activity with a high half-wave potential (E1/2) of 0.847 V vs. RHE and considerable long-term stability. When applied as anode materials for sodium-ion batteries (SIBs), it could deliver a high reversible capacity of 385 mAh g−1 at 500 mA g−1, excellent rate performance of 308 mAh g−1 at even 20 A g−1 and superior cycling performance at 10 A g−1 during 5000 cycles with negligible capacity fade. DFT calculation reveals that the doping of N and S endows the surrounding carbon with high positive charge and spin density, respectively, making them be highly active ORR catalytic sites except for S itself. Despite the possible oxidization of C–S–C active sites, the rest C atoms of NSGHS will still hold a considerably high catalytic activity superior to those of mono-doped or undoped cases. In addition, S doping will improve the binding between Na and graphene substrate to get a high capacity and N doping effectively curbs the rising of oxygen levels and oxidization of S in C–S–C active sites, thus the excellent stability for ORR and SIBs.

Fabrication of Co doped MoS2 nanosheets with enlarged interlayer spacing as efficient and pH-Universal bifunctional electrocatalyst for overall water splitting

Exploring inexpensive and active bifunctional electrocatalysts to produce hydrogen and oxygen from water at all pHs is highly desirable. Herein, we report a facile one-step method to prepare vertically aligned Co doped MoS2 nanosheets with extended interlayer distance on carbon cloth (Co–MoS2@CC) for full hydrolysis in both alkaline and acidic medium. Co–MoS2@CC exhibits long-term durability with overpotentials of 56.6 mV and 130 mV for hydrogen generation and 242 mV and 201 mV for oxygen production at 10 mA cm−2 in basic and acidic conditions, respectively. Moreover, we achieve low voltages of 1.585 V and 1.55 V in basic and acidic conditions respectively for the overall water splitting. We assume that such excellent property of Co–MoS2@CC may be ascribed to the uncovering of more active sites and high porosity resulted from Co doping, which boosts the conductivity and thus reduces MoS2 hydrogen adsorption free energy in HER, as well as benefits to catalytic active sites in OER. This one-step doping approach opens up new ways to regulate the intrinsic catalytic activity to catalyze total hydrolysis at all PHs.

Controllable one-step doping synthesis for the white-light emission of cesium copper iodide perovskites

In this paper, a controllable one-step doping method has been successfully adopted in the cesium copper iodide perovskite’s luminescence, a high-quality white-light emission with Commission Internationale de l´Eclairage (CIE) coordinates of (0.3397, 0.3325), and a color rendering index (CRI) reaching up to 90 was realized in a convenient way. Through adding impurities into the Cs 3 Cu 2 I 5 system, high efficiency and stable CsCu 2 I 3 was synthesized, and the coexistence of varied high luminescence phases realized the white lighting. Strikingly, blue-emitting Cs 3 Cu 2 I 5 and yellow-emitting CsCu 2 I 3 could coexist, and their respective luminescence was not interacted in the compound, which was beneficial for acquiring a single emission and highly efficient white lighting. This work carried out a deep exploration of the Cu-based metal halides, and would be favorable to the applications of lead-free perovskites.

Large specific surface area S-doped Fe–N–C electrocatalysts derived from Metal–Organic frameworks for oxygen reduction reaction

It is highly desired but challenging to develop platinum group metal-free electrocatalysts for oxygen reduction reaction (ORR), which can promote the commercialization of fuel cell technology. To achieve this target, we report a one-step doping method to prepare S-doped Fe–N–C catalysts using zeolite imidazole framework (ZIF-8) and iron (III) thiocyanate (Fe(SCN)3) as precursor. Different from conventional doping approach, i.e. physical mixing, Fe(SCN)3 is in-situ added during ZIF-8 formation which would encapsulate Fe(SCN)3 molecules inside ZIF-8 to avoid structure destruction and create potential replacement of Zn ions by Fe ions to form uniform Fe–N4 complexes. As a result, the prepared S-doped Fe–N–C catalysts own large specific surface areas with a maximum value of 1326 ​m2 ​g−1 and a dual-scale porous structure that benefits mass transport. Significantly, the composition-optimized catalyst exhibits superior ORR activity in both 0.1 ​M HClO4 electrolyte and 0.1 ​M KOH electrolyte, in which the half-wave potential reaches 0.81 ​V and 0.92 ​V (vs. RHE), respectively. Remarkable stability is also attained, which loses 2 ​mV only after 10000 potential cycles in O2-saturated 0.1 ​M HClO4 and remains almost constant in O2-saturated 0.1 ​M KOH, surpassing commercial Pt/C catalyst in both acidic and alkaline medium.

From children’s toy to versatile sensor: One-step doping of Play-Doh with primary amino group for explosive detection both on surfaces and in solution

2,4,6-trinitrotoluene (TNT) sensing on surfaces and in solution is an important issue in sensor fabrication for homeland security and environmental protection. Herein, Play-Doh, a modeling material popular for kids, was proposed as a versatile sensor for on-site fluorescent (FL), visual FL (VFL), and colorimetric detection of TNT both on surfaces and in solution after being doped with –NH2 through a one-step approach. Play-Doh exhibits FL emission due to the main ingredient of flour. After –NH2 doping, amino-Play-Doh (APD) was utilized to construct a FL sensor based on FL resonance energy transfer and inner filter effect for TNT detection. The advantage of APD was that no additional fluorophore was needed compared with the traditional sensors for FL and VFL analysis. The orange complex visible to the naked eye was also recorded for smartphone-based colorimetric detection of TNT. In both cases, the APD demonstrated good analytical performance for TNT. Finally, APD was successfully utilized for TNT sensing on fingerprints, luggage, and in environmental water samples, respectively. Play-Doh might be a potential sensor for future on-site detection of TNT owing to the merits of being cost-effective and versatile.

Doping of donor-acceptor polymers with long side chains via solution mixing for advancing thermoelectric properties

One-step doping of conjugated polymers by solution mixing is typically performed instead of sequential doping because of its simplicity. However, doped polymer solutions often exhibit poor solubility, and the presence of dopants in the produced films can disturb the molecular ordering of polymer structures. In this work, effective pairs of two donor-acceptor (D-A) type polymers and a molecular dopant characterized by high solution stability and good thermoelectric properties of the prepared thin films have been reported. The presence of long side chains in the polymer structures preserves their original solubilities and crystallinity in the solution and thin-film states, respectively, even at large amounts of added dopant (up to 38 mol%). Furthermore, the relatively shallow levels of the highest occupied molecular orbitals of the selected D-A polymers enable efficient charge transfer from the dopant species. Owing to their good charge transport properties, the doped D-A polymers exhibit outstanding thermoelectric properties with a maximum power factor of 31.5 μW m−1 K−2, which is more than an order of magnitude higher than those of the control samples prepared from donor-only poly(3-hexylthiophene).

Enhancing the electrochemical performance of LiNi0.8Co0.15Al0.05O2 by a facile doping method: Spray-drying doping with liquid polyacrylonitrile

In this paper, a simple one-step doping spray method using liquid polyacrylonitrile (LPAN) is reported, for the preparation of LiNi0.8Co0.15Al0.05O2 (NCA) precursor, after calcination, to obtain a loose and porous sphere-shaped NCA (LPAN@NCA). The initial discharge specific capacity was found to be 227.9 mA h g−1 at 0.1C, which is 26.6% higher than that of the pristine sample. Its capacity retention rate was found to be 93.59% after 200 cycles, and the surface morphology of the material grains after the cycles remains intact. X-ray diffraction (XRD) analysis reveals that doping with LPAN can effectively decrease the amount of disorder of Ni2+ in Li + position that gets reduced by 2.72%. The X-ray photoelectron spectroscopy (XPS) analysis shows that after the carbonization of LPAN, the C atoms replace part of O atoms, effectively forming a new compound. The decrease in the impedance of the battery materials before and after the cycle and the increase of lithium ion mobility also confirms the effectiveness of LPAN doping. The LPAN@NCA prepared by in-situ doping of LPAN by spraying method is simple and effective, which exhibits high specific capacities, superior rate performance and excellent recycling stability, that has a good commercial application prospect.

Concurrent Phosphorus Doping and Reduction of Graphene Oxide

Doped graphene materials are of huge importance because doping with electron-donating or electron-withdrawing groups can significantly change the electronic structure and impact the electronic and electrochemical properties of these materials. It is highly important to be able to produce these materials in large quantities for practical applications. The only method capable of large-scale production is the oxidative treatment of graphite to graphene oxide, followed by its consequent reduction. We describe a scalable method for a one-step doping of graphene with phosphorus, with a simultaneous reduction of graphene oxide. Such a method is able to introduce significant amount of dopant (3.65 at. %). Phosphorus-doped graphene is characterized in detail and shows important electronic and electrochemical properties. The electrical conductivity of phosphorus-doped graphene is much higher than that of undoped graphene, owing to a large concentration of free carriers. Such a graphene material is expected to find useful applications in electronic, energy storage, and sensing devices.

Through-Wafer Polysilicon Interconnect Fabrication with In-Situ Boron Doping

AbstractBulk micromachining technology can be used to produce conducting through-wafer polysilicon interconnects, i.e., polysilicon via plugs. This paper presents the process fabrication steps of polysilicon via plugs with in-situ boron doped polysilicon material in order to develop fast one-step doping process, without additional diffusion. The via holes can be processed by high-aspect ratio silicon etching with inductively coupled plasma (ICP). Only one deep ICP etching is required if the wafer is mechanically ground (from the backside) to reduce the wafer thickness of 500 microns to a typical of 400, in order to overcome deep etching sidewall profile problems. After hole formation with ICP the via plug fabrication process continues by growing an insulating thermal oxide layer with a thickness of the order of a micron, followed by an in-situ boron doped LPCVD polysilicon growth to fill the holes with sufficient step coverage. The polysilicon growth temperature at 680°C ensures sufficient step coverage, reasonable furnace process time and enables planarization processing, such as grinding and chemical-mechanical polishing (CMP). The subsequent planar processing typically requires planarization of the polysilicon layer down to the original silicon (or oxide) surface with CMP, and some doping activation step, which usually can be performed together with some additional oxidation step. Applications of the via plugs in the field of silicon-based sensors or actuators enable significant reduction of the front surface wiring density, which opens additional space for denser packing or other desired components.

Influence of channel doping-profile on camel-gate field effect transistors

We report the performance of GaAs camel-gate FETs and its dependence on device parameters. In particular, the performance dependence on the doping-profile of a channel was investigated. In this study, one-step, bi-step, and tri-step doping channels with the same doping-thickness product are employed in camel-gate FETs, while keeping other parameters unchanged, For a one-step doping channel FET, theoretical analysis reveals that a high doping channel would provide a large transconductance which is suitable for logic applications. Decreasing the channel concentration increases the drain current and the barrier height. For a tri-step doping channel FET, it is found that the output drain current and the barrier height remain large and the relatively voltage-independent transconductance is also increased. These are the requirements for the large input signal power amplifiers. A fabricated camel-gate FET with a tri-step doping channel exhibits a large drain current density larger than 750 mA/mm and a potential barrier greater than 1.0 V. Furthermore, the relatively voltage-independent transconductance is as high as 220 mS/mm and the applied gate voltage is up to +1.5 V. A 1.5/spl times/100 /spl mu/m/sup 2/ device is found to have a f/sub t/ of 30 GHz with a very low input capacitance.

Fullerene derivatives and fullerene superconductors

A series of 1:1 C 60 cycloaddition adducts, C 60A (A = anthracene, butadiene, cyclopentadiene and methylcyclopentadiene), has been synthesized. The products are cleanly separated and characterized by use of TGA, 1H-NMR, IR, and mass spectrometry. Among these adducts, C 60, (methylcyclopentadiene) showed the highest thermal stability and was doped with three equivalents of rubidium. The resulting Rb 3C 60 (MeCp) is a semiconductor but can be thermally converted to the superconducting Rb 3C 60 through a retro-Diels-Alder reaction. A one-step doping process to prepare Rb 3C 60 crystals has been developed. The optimal doping condition occurs at 3̃00°C. High superconducting shielding fractions between 60 and 90% and sharp transition widths (Δ T 10- 90between 4 and 0.7 K) were measured for these samples.

Synthesis, superconductivity and ESR characterization of Rb 3C 60 crystals

A one-step doping process of C 60 crystals with three equivalents of rubidium to produce Rb 3C 60 crystals was developed. The T c's for all Rb 3C 60 crystalline samples ( ∼ 30.5 K ) were higher than those of the powder samples (28 to 29.6 K), but consistent with the reported four-probe resistivity result for a doped C 60 crystal (transition midpoint = 30.2 K). High superconducting shielding fractions (between 60 and 90%) and sharp magnetic transition widths (Δ T 10–90 between ∼ 3 K and 0.7 K) were observed for the samples doped with Rb at temperatures of 300 to 450°C. The doping process, as well as the composition, of these samples were studied with the use of an ESR spectrometer. Two major components, RbC 60 and Rb 3C 60, were quantitatively characterized. The superconducting shielding fractions of these samples were found to be linearly correlated with the Rb 3C 60 content obtained from ESR measurements. Higher-temperature doping (> 400°C) favored the formation of Rb 3C 60 at the expense of severe C 60 crystal fragmentation. The optimal doping condition to produce Rb 3C 60 crystals was found to be around 300°C.