Phosphorus Doping Research Articles

Rational design of Schottky heterojunction with modulating surface electron density for high-performance overall water splitting

The development of non-precious metal electrocatalysts to synergistically expose more active sites and optimize intrinsic activity still remains a huge challenge. Transition metal layered double hydroxide (LDH) has a great potential in electrocatalysis due to its unique sheet-like nanostructure and low cost. However, the poor electrical conductivity and sluggish water dissociation process hinder their development. Herein, the interface effect of Schottky heterostructure between cobalt-iron hydroxide and MXene and surface electron density modification with phosphorus (P) doping provide an efficient method to solve these crucial issues. The novel Schottky heterostructure catalyst (P-CoFe-LDH@MXene/NF) with self-driven charge transfer can enhance electron transport efficiency. In addition, the surface electron density optimized by P-doping will promote the ability of H+/OH- ion adsorption and redox reaction for overall water splitting. The as-prepared P-CoFe-LDH@MXene/NF requires overpotentials of only 85 mV at 10 mA cm−2 for HER and 252 mV at 200 mA cm−2 for OER in 1.0 M KOH, respectively. And under an alkaline electrolyzer, it can be driven 10 mA cm−2 at a low voltage of 1.52 V for overall water splitting with remarkable durability for 100 h. More broadly, this design concept is universal and it can be extended to design other transition metal-based catalysts.

Phosphorus doping and phosphates coating for nickel molybdate/nickel molybdate hydrate enabling efficient overall water splitting

Earth-abundant transition metal-based bifunctional electrocatalysts are promising alternatives to noble metals for overall water electrolysis, but restricted by low activity and durability. Herein, a three-dimensional phosphorus-doped nickel molybdate/nickel molybdate hydrate @phosphates core–shell nanorod clusters on nickel foam self-supported electrode was fabricated by a combined hydrothermal and phosphating process. The phosphorus doping and phosphate coating induced by phosphating process bring in a synergistic effect to improve the electrical conductivity, provide abundant active surface sites and accelerate the surface reaction for nickel molybdate/nickel molybdate hydrate (NiMoO4/NiMoO4·nH2O) heterostructures. These advantages enable the self-supported electrode to exhibit high hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activity in 1.0 M KOH with low overpotentials of 148 and 260 mV at 10 mA cm−2, respectively. When it was employed both as anode and cathode, a cell voltage of 1.62 V is only required to reach the current density of 10 mA cm−2 in alkaline solution. Especially, the self-supported electrode reveals outstanding durability, which could maintain over 25 h at 10 mA cm−2 for HER, OER or overall water splitting. This work provides a novel avenue to enhance the electrocatalytic performance of the catalysts by synergistically modulating the intrinsic electrical conductivity, active surface sites and surface reaction.

Catalytic-conversion behavior of MoS2 for polysulfides by nickel introduction and phosphorous-doping in advanced lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) have aroused remarkable concern as promising energy storage equipments owing to the high theoretical capacity and energy density. Efficient conversion of lithium polysulfides into S as well as Li2S/Li2S2 in the charge and discharge process is a crucial factor to improve the performance of LSBs. Among all the competing polysulfides conversion catalysts, MoS2 is considered as the one of the strongest competitors. Herein, the dual effects of nickel introduction and phosphorus doping on the morphology, structure and electrochemical properties of MoS2 materials are detailedly investigated. It has been found that the Ni-P coordinated sites on the MoS2 can provide the affluent sites for adsorption and conversion of polysulfides. Meanwhile, the phase transition of MoS2 from 2H phase to metallic 1T phase can be distinctly improved owning to nickel introduction, which enhances the electrochemical performances of LSBs. Besides, the P0.1-Mo0.9Ni0.1S2/CNT/S displays a good initial capacity of 742 mAh g−1 with a low fading rate of 0.075% per cycle at 1C as well as the discharge capacity of 463 mAh g−1 at the 500th cycle. Therefore, the strategy of Ni introduction and heteroatom doping can effectively inhibit Polysulfides shuttle and promote the performance of LSBs.

Configuration of phosphorus doping in silicene nanoribbons in the presence of an external electric field

Silicene nanoribbons have been studied a lot in recent years, it is a nanostructure with enormous applications. The doping of another element into the unit cell changes the electrical and magnetic properties of the material, which creates new research directions in materials science. Based on the DFT theory, this work studies the doping phosphorus atoms and in silicene nanoribbons in the presence of an external electric field of about 0.1 V/Angstrom. The work also limited the doping study in two cases: The doping case of one phosphorus atom and the 100% doping configuration. There are two doping positions of a phosphorus atom, the top position, and the valley position, and the formation energy will find the optimal position. The energy band structure and state density will also be drawn, examined, and compared.

Dosimetric Application of Phosphorus Doped Fibre for X-ray and Proton Therapy.

Phosphorous-doped silica optical fibres with a core diameter of 4 µm were tested in X-ray and proton fields for application in cancer therapy dosimetry. Specifically, the radiation-induced attenuation was investigated in terms of linearity in deposited dose in 15 MV and 6 MV photons and 74 MeV protons, as well as Bragg-peak detection along the proton track. Fibres were found to demonstrate linear relative dose response in both radiation modalities, but possible saturation did occur at the high linear energy transfer of the Bragg peak. This demonstrates the possibility to use these fibres as a relative dosimeter for radiation therapy applications.

Highly Efficient Oxygen Evolution Reaction Enabled by Phosphorus Doping of the Fe Electronic Structure in Iron-Nickel Selenide Nanosheets.

The electronic structure of active sites is critically important for electrochemical reactions. Here, the authors report a facile approach to independently regulate the electronic structure of Fe in Ni0.75Fe0.25Se2 by P doping. The resulting electrode exhibits superior catalytic performance for the oxygen evolution reaction (OER) showing a low overpotential (238 mV at 100 mA cm−2, 185 mV at 10 mA cm−2) and an impressive durability in an alkaline medium. Additionally, the mass activity of 328.19 A g−1 and turnover frequency (TOF) of 0.18 s−1 at an overpotential of 500 mV are obtained for P─Ni0.75Fe0.25Se2 which is much higher than that of Ni0.75Fe0.25Se2 and RuO2. This work presents a new strategy for the rational design of efficient electrocatalysts for OER.

Photocatalytic degradation of sulfamonomethoxine by mesoporous phosphorus-doped titania under simulated solar light irradiation

Photocatalytic degradation of sulfamonomethoxine (SMM) by mesoporous phosphorus-doped TiO2 (P–TiO2) was studied under simulated solar light irradiation. The morphological structure and chemical composition of P–TiO2 were analyzed by XRD, SEM, HRTEM, BET, XPS and FTIR. Using the central composite design (CCD) of response surface methodology (RSM), the degradation of SMM was investigated with a range of antibiotic concentrations (4–8 mg L−1), catalyst dosages (400–900 mg L−1), P doping amounts (5–15 wt %) and irradiation time (90–150 min). The Ti–O–P bond formed during the calcination of TiO2, thereby generating plate-like P–TiO2, where P was uniformly distributed. Phosphorus doping can stabilize anatase TiO2, which has a larger specific surface area and a lower average particle and pore size than bare TiO2. The result obtained from the RSM model showed a significant correlation between the predicted values and the experimental results of SMM degradation (P < 0.05). Under the optimal experimental conditions (antibiotic concentration = 6 mg/L, catalyst dosage = 800 mg/L, P doping = 5 wt% and irradiation time = 90 min), the degradation rate of SMM was 99.51%, and the TOC was 50%. Toxicity showed a considerable reduction towards Vibrio-qinghaiensis sp.-Q67 after SMM photocatalytic degradation. Through free radical capture experiments, LC-MS detection and DFT calculations, the possible photocatalytic degradation mechanism of SMM using P–TiO2 as the catalyst was revealed.

Ultrafast dynamics of the surface photovoltage in potassium-doped black phosphorus

Black phosphorus is a quasi-two-dimensional layered semiconductor with a narrow direct band gap of 0.3 eV. A giant surface Stark effect can be produced by the potassium doping of black phosphorus, leading to a semiconductor to semimetal phase transition originating from the creation of a strong surface dipole and associated band bending. By using time- and angle-resolved photoemission spectroscopy, we report the partial photoinduced screening of this band bending by the creation of a compensating surface photovoltage. We further resolve the detailed dynamics of this effect at the pertinent timescales and the related evolution of the band structure near the Fermi level. We demonstrate that after a fast rise time, the surface photovoltage exhibits a plateau over a few tens of picoseconds before decaying on the nanosecond timescale. We support our experimental results with simulations based on drift-diffusion equations.

Pore Modification and Phosphorus Doping Effect on Phosphoric Acid-Activated Fe-N-C for Alkaline Oxygen Reduction Reaction.

The price and scarcity of platinum has driven up the demand for non-precious metal catalysts such as Fe-N-C. In this study, the effects of phosphoric acid (PA) activation and phosphorus doping were investigated using Fe-N-C catalysts prepared using SBA-15 as a sacrificial template. The physical and structural changes caused by the addition of PA were analyzed by nitrogen adsorption/desorption and X-ray diffraction. Analysis of the electronic states of Fe, N, and P were conducted by X-ray photoelectron spectroscopy. The amount and size of micropores varied depending on the PA content, with changes in pore structure observed using 0.066 g of PA. The electronic states of Fe and N did not change significantly after treatment with PA, and P was mainly found in states bonded to oxygen or carbon. When 0.135 g of PA was introduced per 1 g of silica, a catalytic activity which was increased slightly by 10 mV at −3 mA/cm2 was observed. A change in Fe-N-C stability was also observed through the introduction of PA.

Synthesis of Phosphorus Doped Graphenes via the Yucel’s Method as the Positive Electrode of a Vanadium Redox Flow Battery

Improving electrode performances in the high-current cycles is essential to increase the global competitiveness of vanadium redox flow battery (VRFB), a widespread application potential for large-scale energy storage systems. Modifying carbon electrode surfaces with graphene-based materials and even doping of graphene with heteroatoms is a reasonably critical strategy to enhance the reaction activity and reversibility of vanadium redox couples. In this study, phosphorus-doped graphene-based electrodes were produced via Yucel’s method in phosphoric acid solution, and their use as positive electrodes for VRFB was investigated. Various electrochemical, spectroscopic, and morphologic characterization methods were used to analyze the electrodes. The effects of P-doped graphene-based materials as the positive electrode of VRFB were investigated via electrochemical methods such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and cyclic charge-discharge. The VRFB with phosphorous doped graphene-based electrodes prepared in the potential range between −1.0 and +2.1 V (P-GPGE1) exhibited higher discharge capacity as 1.11 Ah l−1, and energy efficiency as 73.1% at the charge and discharge current densities of 8 and 1.6 mA.cm−2, respectively. This paper reveals a promising way to produce phosphorous doped graphene-based electrodes for the next-generation VRFB, a high-power, stable, and efficient operation.

Characterization Analysis of Textured and Diffused Monocrystalline Silicon Wafer

This paper focuses on examining the characteristic analysis of the textured and diffused silicon wafer. Characterization performance of the textured and diffused wafer using surface reflection method, sheet resistance method, SEM, and surface photovoltage method is examined. From the SRM result, it is observed that the reflection of the textured wafer is lower than the raw wafer. This means that the textured wafer forms the pyramid structure, which was measured by SEM. Sheet resistance measures the resistivity of the raw wafer and after phosphorous diffusion into the p-type silicon, the wafer are 2.3 Ω-cm and 0.80 Ω-cm respectively. From the sheet resistance results, it is observed that the phosphorus doping is properly done. The Surface Photovoltage (SPV) result shows that minority carrier diffusion length and lifetime for a solar cell is 86.4μm and 2.8 μsec respectively.

Vacancies and phosphorus atoms assembled in amorphous urchin-like Co3O4 for highly efficient overall water splitting

Designing highly efficient and low-cost electrocatalysts is essential for water splitting. Herein, urchin-like Co3O4 microspheres are firstly grown on nickel foam by a hydrothermal method, then Oxygen vacancies, phosphorus doping are effectively assembled in Co3O4 electrocatalysts. The introduction of oxygen vacancies and phosphorus doping will adjust the electronic structure of Co which increase the intrinsic catalytic activity and improve the adsorption energy of intermediates, simultaneously, progressively transform the crystal into randomly arranged atoms structure with short range order resulting in more active sites participate in the catalytic reaction. Moreover, the catalyst of vacancies Co3O4-Ov and phosphorus doping Co3O4–P demonstrate excellent performance in oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline media, Co3O4-Ov sample served as anode while Co3O4–P as cathode to form an electrolytic cell needs only 1.58 V to reach 20 mA cm−2 for overall water splitting.

Flexible high-energy and stable rechargeable vanadium-zinc battery based on oxygen defect modulated V2O5 cathode

The development of earth-abundant, high-capacity and stable cathode materials for robust aqueous Zn-ion batteries (ZIBs) is an ongoing challenge. With the merits of suitable operating voltage window and highly reversible redox reaction, vanadium oxide has recently emerged as an attractive cathode material. Herein, an oxygen defect modulated binder-free V 2 O 5 nanorods (named as PVO@C) was constructed for aqueous/quasi-solid-state Zn ion battery. Accompanying the fast electron transport ability, increased concentration of oxygen defect and enhanced active sites, the aqueous PVO@C//Zn battery delivers an excellent high capacity of 385.34 mAh g −1 at 0.13 A g −1 and robust long-term life span of 86.7% capacity retention after 5000 cycles with nearly 100% coulomb efficiency. In particular, the assembled quasi-solid-state ZIBs exhibited the high voltage of 1.3 V, yielding an admirable energy density of 10.5 mWh cm −3 at a power density of 33.4 mW cm −3 and admirable cycling performance. What’s more, the solid-state ZIB exhibits extremely high safety, wettability and wear-ability over the lithium ion batteries. It performs well even at a variety of severe hazardous conditions, such as punctured, soaked, bent, sewed, washed, cut, and hammered conditions. This work innovatively proposes the synergistic effect of oxygen defect modulation and phosphorus doping to optimize reaction kinetics, which will lead to further improvements in the performance of metal oxides electrode. This strategy can be extended to electrode materials of other battery systems for the construction of highly efficient flexible energy storage devices and accelerated the commercialization of wearable electronics technology. • An facile hydrothermal method is used to synthesis a binder-free electrode material of PVO@C nanorods. • After the introduction of oxygen defects and phosphor doping, the conductivity and capacity have been considerable improvement. The robust PVO@C//Zn battery demonstrates an excellent capacity of 385.34 mA h g −1 and a long-term cyclability of 86.7% capacity retention after 5000 cycles. • A flexible and high capacitance quasi solid-state PVO@C//Zn battery (SS ZIB) is assembled, achieving an excellent volumetric energy density (10.5 mW h cm −3 ) at volumetric power density (33.4 mW cm −3 ) together with a stable cycling capability. • This SS ZIB manifests an extremely high safety, wettability and wear-ability though working well in a variety of safety related experiments, further proving its wide application prospect.

Enhanced performance of solar cell with n+ emitter by SiO2 nanospheres assisted liquid phosphorus diffusion

In order to improve the quality of n+ emitter fabricated by phosphorus doping, SiO2 nanospheres were added into a phosphoric acid solution for spin-on doping. Through a complete analysis of the trade-off between the diffusion uniformity and sheet resistance, the particle size of SiO2 nanospheres is selected to be 230 nm. It is found that with the increase of phosphoric acid concentration from 50% to 85%, the average sheet resistance decreases from 128.5 Ω/sq to 18.1 Ω/sq, and the diffusion uniformity increased from 95.2% to 98.5%. In a large concentration range, the surface doping concentration of the emitter will increase with phosphoric acid, but when the concentration of phosphoric acid reaches 80%, the surface doping concentration will be almost unchanged. Nevertheless, different from above, the p-n junction depth has little dependence on the phosphoric acid concentration. Moreover, the efficiencies in the solar cell center and edge are enhanced by 40.54% and 88.08% respectively using SiO2 nanospheres assisted diffusion.

Influence of Phosphorus Doping on Triazole-Based g-C3N5 Nanosheets for Enhanced Photoelectrochemical and Photocatalytic Performance.

Triazole-based g-C3N5, a potential catalyst, has received little attention over the years. We prepared phosphorus-doped g-C3N5 with one triazole and two triazine units for the first time to investigate its photoelectrochemical (PEC) and photocatalytic properties. The doping states and crystalline structures of the samples were determined using X-ray techniques, namely, X-ray diffraction, X-ray photoelectron spectroscopy, and X-ray absorption fine structure analysis. Our results suggested that the phosphorus was substituted into carbon sites form P-N/P═N bonds with four coordination, which contribute P 2p level donor states in the band gap to enhance light absorption and reduce charge separation. Therefore, P-doped g-C3N5 exhibited higher PEC current density and better photocatalytic efficiency toward the degradation of rhodamine B dye or tetracycline under light irradiation compared to the undoped g-C3N5 sample. However, excess phosphorus doping resulted in the formation of impurities and disrupted the triazine and triazole units, reducing the PEC and photocatalytic efficiency. In summary, P-doped g-C3N5 was successfully prepared in the present study and represents a promising, facile, and effective catalyst for energy applications and environmental remediation.

Highly efficient BiVO4 single-crystal nanosheets with dual modification: phosphorus doping and selective Ag modification

BiVO4, a visible-light response photocatalyst, has shown tremendous potential because of abundant raw material sources, good stability and low cost. There exist some limitations for further applicaitions due to poor capability to separate electron–hole pairs. In fact, a single-component modification strategy is barely adequate to obtain highly efficient photocatalytic performance. In this work, P substituted some of the V atoms from VO4 oxoanions, namely P was doped into the V sites in the host lattice of BiVO4 by a hydrothermal route. Meanwhile, Ag as an attractive and efficient electron-cocatalyst was selectively modified on the (010) facet of BiVO4 nanosheets via facile photo-deposition. As a result, the obtained dually modified BiVO4 sheets exhibited enhanced photocatalytic degradation property of methylene blue (MB). In detail, photocatalytic rate constant (k) was 2.285 min−1 g−1, which was 2.78 times higher than pristine BiVO4 nanosheets. Actually, P-doping favored the formation of O vacancies, led to more charge carriers, and facilitated photocatalytic reaction. On the other hand, metallic Ag loaded on (010) facet effectively transferred photogenerated electrons, which consequently helped electron–hole pairs separation. The present work may enlighten new thoughts for smart design and controllable synthesis of highly efficient photocatalytic materials.

Nitrogen, phosphorus co-doped porous carbon originated from egg white for advanced lithium-sulfur battery

N, P co-doped micro-/meso-/macroporous carbon originated from egg white using freeze drying followed by carbonization method. The porous carbon derived from protein provides moderate nitrogen and phosphorus doping in carbon matrix. When used for sulfur host and the cathode with a sulfur loading of 0.57 mg cm−2 demonstrates brilliant battery performance with a first capacity of 1635 mAh g−1 at 0.1 A g−1 and kept at 762 mAh g−1 after 100 cycles, remarkable rate capabilities of 1352, 1017, 961 and 701 mAh g−1 at 0.1, 0.2, 0.5 and 1.0 A g−1. The excellent stability and rate performance are due to the N, P co-dopants and porous structure, which have strong adsorption effect to the soluble polysulphides.

Effect of melt flow rate and S/L interface on the P horizontal distribution in silicon

Uniform doping of phosphorus (P) in silicon is always the key and difficult point in the study of n-type solar cells. This paper aims to study the influencing factors for horizontal distribution for P. It is found that the distribution of P in silicon ingot is the results of the combined effect of melt flow and solid-liquid (S/L) interface. With numerical simulation, the melt flow rate in the edge is lower than that of the middle area, which leads to a higher effective segregation coefficient (Keff). For the slightly concave S/L interface, the concentration of P in the molten silicon is lower when the solidification process began at the edge position. The higher Keff and lower concentration make the slightly concave interface has better performance in uniform doping at the early stage of growth. In addition, with the melt flow taken into account, a mathematical model was built to predict P concentration in the molten silicon. This work is helpful to explain the movement of P and achieve uniform distribution in the silicon ingot during production.

Preparation of phosphorus-doped graphitic carbon nitride and its application in lithium-sulfur batteries

Graphite-phase carbon nitride (g-C3N4) was prepared by heat shrinkage polymerization method using urea as raw material, and phosphorus-doped g-C3N4 with different phosphorus content (xP-CN) was prepared by using hydrogen phosphate diamine as a phosphorus source. The effect of doping on the microstructure, morphology, and electrochemical performance of xP-CN/S composites as cathode materials for lithium-sulfur batteries was studied. The studies show that the layer spacing of xP-CN increases after phosphorus doping, the electrical conductivity increases, and the specific surface area becomes larger. The specific surface area of the 10% P-CN reaches 101.741 m2·g−1. The initial discharge specific capacity of the 10% P-CN/S composite at 0.05 C (1 C=1675 mA·h·g−1) reaches 1383.8 mA·h·g−1. The reversible specific capacity after 100 cycles at 0.2 C is 860.0 mA·h·g−1, the reversible specific capacity of g-C3N4/S composite is only 178.3 mA·h·g−1; The specific capacity of 10% P-CN/S composite can be restored to 93.6% at 0.2 C after the rate test, showing good cycle performance and rate performance.

Fabrication of heterogeneous interface and phosphorus doping in MoS2 for efficient hydrogen evolution in both acid and alkaline electrolytes

Reasonable design of non-precious metal electrocatalysts with high catalytic activity plays a crucial role in promoting the sustainable development of hydrogen energy. Herein, to improve both the active sites and intrinsic conductivity of molybdenum disulfide (MoS2), a facile ionic liquid-assisted hydrothermal method and subsequent phosphorization treatment are fabricated for advanced electrochemical hydrogen evolution reaction (HER) performance. The obtained P-CoS1.097@MoS2/CC heterostructure exhibits a low overpotential of 98 mV and 88 mV at the current density of 10 mA cm−2 in 0.5 M H2SO4 and 1 M KOH, respectively. The remarkable performance is due to the synergistic effects of the constructed heterogeneous interface between CoS1.097 and MoS2 as well as sulfur vacancies generated by the phosphorus doping. Therefore, fast electron transfer and large number of catalytic active sites can be achieved by means of such advantageous strategy. This research paves the way for the development of MoS2-based catalysts through the cooperative design of doping and interface engineering toward efficient HER process.