Phosphorus Co-doping Research Articles

Phosphorus and sulphur co-doping of g-C3N4 nanotubes with tunable architectures for superior photocatalytic H2 evolution

Non-metal doping not only optimizes the energy band structure of g-C3N4 to improve the absorption of visible light, but also exacerbates the distortion of lowest and highest unoccupied molecular orbital plane, causing polarization, thereby improving photocatalytic activity. For the first time, S and P are co-introduced into g-C3N4 network to enhance photocatalytic performance and create various tubular morphologies. The ratio of S to P is crucial to control the tubular morphology and property. In the photocatalytic process, the separation of electrons and holes causes by the polarization of the S and P elements and the synergy of the tubular morphology results in new migration paths for photogenerated electrons and holes. Using optimized preparation conditions, g-C3N4 tubes co-doped with S and P (CNSP) reveal very high H2 generation efficiency (163.27 μmol/h), which is two orders of magnitude higher compared to that of pure g-C3N4 and apparent quantum yield is 18.93% at 420 nm. Fast degradation of Rhodamine B by using CNSP occurs within 5 min under visible light irradiation. Because of the reproducible process, the synthetic strategy provides a novel method for controlling the morphology of g-C3N4-based materials with super activity.

Self-Supported Carbon Nanofiber Films with High-Level Nitrogen and Phosphorus Co-Doping for Advanced Lithium-Ion and Sodium-Ion Capacitors

It is a challenge to achieve the high power/energy densities of portable and flexible energy storage devices. Here, an advanced lithium-ion capacitor (LIC) and sodium-ion capacitor (SIC) were const...

Enhancing thermal oxidation and fire resistance of reduced graphene oxide by phosphorus and nitrogen co-doping: Mechanism and kinetic analysis

The use of reduced graphene oxide (rGO) in high-temperature oxidization (HTO) environment, is limited by its poor thermal oxidation and fire resistance. In this study phosphorus and nitrogen co-doped reduced graphene oxide (PN-rGO) with high oxidation and fire resistance was prepared by hydrothermal and microwave treatment and its thermal oxidation decomposition kinetics and mechanisms were analyzed. Concisely, PN-rGO presents an increment of 162 °C in the decomposition temperature relative to undoped rGO (WrGO), and excellent fire resistance with only a ∼20% mass loss after burning. Thermal oxidation degradation kinetics reveals that WrGO shows continuously increasing activation energy (E) within a range of 119.7–182.9 kJ/mol, while PN-rGO exhibits almost constant E of ∼171.8 kJ/mol during main degradation stage. Moreover, the improved E at initial stage by phosphorus/nitrogen doping, combining with the char analysis, suggested that the introduction of strong chemical bonds replacing the reactive oxygen-containing groups was the key to preventing the oxidation of rGO. As one of the main properties, the electrical conductivity of PN-rGO is well kept after HTO treatment. This work demonstrates that a doping strategy can effectively expand the application of graphene-based devices in HTO environment.

Design of basal plane active MoS2 through one-step nitrogen and phosphorus co-doping as an efficient pH-universal electrocatalyst for hydrogen evolution

The exploration of low-cost, stable, and highly active noble-metal-free electrocatalyst for hydrogen evolution reaction (HER) in a wide pH range is crucial but still challenging task for renewable energy techniques. MoS2-based materials have been considered as a promising electrocatalyst for HER. However, corresponding studies have been hampered by the lack of effective routes to fully utilize the large number of inert basal plane for catalyzing HER, especially under alkaline media. Herein, a novel ammonia ions-guided-nitrogenization-phosphorization strategy is developed to prepare N and P co-doped MoS2 with active basal plane for efficient catalyzing HER with a quite low overpotential of 116 and 78 mV in 0.5 M H2SO4 and 1.0 M KOH to achieve a current density of 10 mA cm−2, respectively. Experimental studies and theoretical calculations confirm Mo-N-P sites in the basal plane of MoS2 can not only accelerate HER kinetics, but also result in energetic favorability and structure stability. Furthermore, outstanding performances are also obtained under both sea and river water, vastly broadening the application prospects.

In Situ Fabrication of Ni2P Nanoparticles Embedded in Nitrogen and Phosphorus Codoped Carbon Nanofibers as a Superior Anode for Li-Ion Batteries

A facile and cost-effective method has been developed for the fabrication of Ni2P nanoparticles encapsulated in N,P-codoped carbon nanofibers (Ni2P@NPCNFs) using the commercialized products of melamine polyphosphate (MPP) and Ni foam. During the synthetic process, MPP serves as the solid phosphorus source for the phosphidation of Ni foam, and it simultaneously performs as a carbon source for the in situ growth of functionalized carbon nanofibers, resulting in a favorable architecture of an Ni2P well-integrated carbon matrix. With this unique structure, the resultant Ni2P@NPCNFs electrode shows remarkable Li-ion storage performance, in terms of high reversible capacity and long-cyclic lifespan (850 mAh g–1 at 200 mA g–1 after 450 cycles), as well as a good rate behavior (300 mAh g–1 at 3200 mA g–1). This work not only presents a new avenue to construct advanced Ni2P-based functional nanocomposites for Li-ion batteries but also paves the way to explore unique transition-metal phosphides toward diverse appli...

Nitrogen and Phosphorus Codoped Porous Carbon Framework as Anode Material for High Rate Lithium-Ion Batteries.

Slow kinetics and low specific capacity of graphite anode significantly limit its applications in the rapidly developing lithium-ion battery (LIB) markets. Herein, we report a carbon framework anode with ultrafast rate and cycling stability for LIBs by nitrogen and phosphorus doping. The electrode structure is constructed of a 3D framework built from 2D heteroatom-doped graphene layers via pyrolysis of self-assembled supramolecular aggregates. The synergistic effect from the nanostructured 3D framework and chemical doping (i.e., N- and P-doping) enables fast kinetics in charge storage and transport. A high reversible capacity of 946 mAh g-1 is delivered at a current rate of 0.5 A g-1, and excellent rate capability (e.g., a capacity of 595 mAh g-1 at 10 A g-1) of the electrode is shown. Moreover, a moderate surface area from the 3D porous structure contributes to a relatively high initial Coulombic efficiency of 74%, compared to other graphene-based anode materials. The electrode also demonstrates excellent cycling stability at a current rate of 2 A g-1 for 2000 cycles. The synthetic strategy proposed here is highly efficient and green, which can provide guidance for large-scale controllable fabrication of carbon-based anode materials.

Correction to “Phosphorus and Aluminum Codoped Porous NiO Nanosheets as Highly Efficient Electrocatalysts for Overall Water Splitting”

Correction to “Phosphorus and Aluminum Codoped Porous NiO Nanosheets as Highly Efficient Electrocatalysts for Overall Water Splitting”

Multiple active components synergistically driven heteroatom-doped porous carbon as high-performance counter electrode in dye-sensitized solar cells

Abstract A facile template-free in situ self-activation approach for the multiple active components synergistically driven porous carbon was presented via a feasible annealing process. The biomass-derived carbon without additional activation reagents was fabricated using K-rich pomelo peel (PP) as the carbon source, which possesses a high electric conductivity where abundant functional hetero-metal atoms are doped into the carbon framework that playing the role of catalytic graphitization. The K+ that exists within the biomass can induce self-activation during pyrolysis apart from the activating gases during the pyrolysis process. The resulting electrocatalyst of PP-850 (PP was pyrolyzed at 850 °C in an N2 atmosphere) with abundant heteroatoms possesses a higher power conversion efficiency (PCE) of 7.81% as the counter electrode (CE) of dye-sensitized solar cells (DSCs) compared with the CEs calcinated at other temperatures and a similar PCE with Pt counterpart (8.24%) based on the liquid I3−/I− electrolyte. The better electrocatalytic performance is attributed to the synergistic effect between self-activation and the co-doping of nitrogen, sulfur and phosphorus all together in a carbon matrix. Due to the feasibility of large-scale production, rich heteroatom doping, the PP-derived carbon, which simplifies the procedure and decreases the cost, has a potential application for an alternative electrocatalyst for high-performance photovoltaic devices.

Phosphorus and Aluminum Codoped Porous NiO Nanosheets as Highly Efficient Electrocatalysts for Overall Water Splitting

We present a facile way to fabricate phosphorus and aluminum codoped nickel oxide-based nanosheets by using layered double hydroxide (AlNi-LDH) as precursors, which showed an overall water-splitting performance in alkaline solution. The codoping of phosphorus and aluminum into nickel oxide nanosheets leads to an optimum balance among surface chemical state, electrochemically active surface area, and density of active sites. As a result, it can afford a current density of 100 mA cm–2 at the overpotential of 310 mV for oxygen evolution reaction (OER) and a current density of 10 mA cm–2 at the overpotential of 138 mV for hydrogen evolution reaction (HER) in 1 M KOH. When it was used as a bifunctional catalyst in a two-electrode water-splitting device, a potential of 1.56 V was achieved at the current density of 10 mA cm–2.

Origin of Radiation-Induced Darkening in Yb3+/Al3+/P5+-Doped Silica Glasses: Effect of the P/Al Ratio.

Yb3+/Al3+/P5+-co-doped silica glasses with different P/Al ratios were prepared using the sol-gel method combined with high-temperature sintering. The evolution of composition-dependent color centers caused by X-ray irradiation in these glasses was correlated with their structural changes, which are controlled by the P/Al ratio. Nuclear magnetic resonance (NMR) and Raman spectra have been used to characterize the glass network structure, and advanced pulse electron paramagnetic resonance (EPR) has been employed to study the local coordination atomic structures of Yb3+ ions in pristine glasses as a function of the P/Al ratio. Si- (Si-E'), Al- (Al-E', Al-ODC, AlOHC), P- (P1, P2, POHC), and Yb-related (Yb2+) color centers in irradiated glasses have been observed and explained by optical absorption and continuous wave-EPR spectroscopies. The formation mechanisms of these centers, the structural models of glasses, and the relationship between them were proposed. Direct evidence confirms that the formation of Yb2+ ions induced by radiation is highly dependent on the coordination environment of Yb3+ ions in glasses. In addition, the glass network structure significantly affects the generation of oxygen hole color centers (AlOHCs/POHCs) caused by radiation. These results are useful in understanding the microstructural origin and the suppression mechanism of the radiodarkening effect by phosphorus co-doping in Yb3+-doped silica fibers.

Phosphorus and Fluorine Co-Doping Induced Enhancement of Oxygen Evolution Reaction in Bimetallic Nitride Nanorods Arrays: Ionic Liquid-Driven and Mechanism Clarification.

Electrocatalytic splitting of water is becoming increasingly crucial for renewable energy and device technologies. As one of the most important half-reactions for water splitting reactions, the oxygen evolution reaction (OER) is a kinetically sluggish process that will greatly affect the energy conversion efficiency. Therefore, exploring a highly efficient and durable catalyst to boost the OER is of great urgency. In this work, we develop a facile strategy for the synthesis of well-defined phosphorus and fluorine co-doped Ni1.5 Co1.5 N hybrid nanorods (HNs) by using ionic liquids (ILs; 1-butyl-3-methylimidazolium hexafluorophosphate). In comparison to the IrO2 catalyst, the as-obtained PF/Ni1.5 Co1.5 N HNs manifests a low overpotential of 280 mV at 10 mA cm-2 , Tafel slope of 66.1 mV dec-1 , and excellent durability in 1.0 m KOH solution. Furthermore, the iR-corrected electrochemical results indicate it could achieve a current density of 100 mA cm-2 at an overpotential of 350 mV. The combination of cobalt and nickel elements, 1D mesoporous nanostructure, heteroatom incorporation, and ionic liquid-assisted nitridation, which result in faster charge transfer capability and more active surface sites, can facilitate the release of oxygen bubbles from the catalyst surface. Our findings confirm that surface heteroatom doping in bimetallic nitrides could serve as a new class of OER catalyst with excellent catalytic activity.

The phosphorus and boron co-doping behaviors at nanoscale in Si nanocrystals/SiO2 multilayers

Phosphorus (P) and Boron (B) co-doping effects at the nanoscale in Si nanocrystals/SiO2 multilayers have been studied in the present work. Several interesting experimental results are achieved which are in contrast to the case in bulk-Si and the previous observations on the doped Si nanocrystals. It is found that all the co-doping samples are n-type regardless of B doping ratios. The P doping efficiency in Si NCs is higher than B dopants, and it can be improved via B co-doping with suitable levels. Raman and ESR spectra indicate that the different occupation preferences of P and B in Si NCs are responsible for the interesting co-doping behaviors. It looks like that the electronic structures and the physical properties of Si NCs can be modulated via the impurities co-doping approach.

Interconnected Phosphorus and Nitrogen Codoped Porous Exfoliated Carbon Nanosheets for High-Rate Supercapacitors.

Carbon-based supercapacitors have high power density and long cycle life; however, they are known to suffer from problems related to low energy density and high inner resistance. Here, we report a novel hierarchically porous functional carbon that is made up of interconnected exfoliated carbon nanosheets with thickness of a few nanometers. Notably, these porous carbon nanosheets are doped with abundant nitrogen (N) dopants in the basal plane and phosphorus (P) functional groups at the edge of the graphene lattice. The specific surface chemistry and pore structure of the synthesized sample, combined with its large specific surface area, make it a high-performance active material for supercapacitor electrode. The obtained supercapacitor made with the optimized sample showed a high specific capacitance (265 F g-1 at 0.5 A g-1) as well as long-term stability (94% capacitance retention after 5000 cycles). Particularly, the enhanced electrochemical characteristics were maintained even at high electrode mass loading (time constant (τ0) is 1.10 s for an electrode mass loading of 12.38 mg cm-2 compared to 1.61 s for a mass loading of 4.17 mg cm-2 for commercial activated carbon), which is important for a high packing factor of the capacitor.

Nitrogen and Phosphorus Codoped Mesoporous Carbon Derived from Polypyrrole as Superior Metal-Free Electrocatalyst toward the Oxygen Reduction Reaction.

To replace high-cost platinum group metal (PGM) electrocatalysts for oxygen reduction reaction (ORR) that is the crucial cathode reaction in fuel cell technology and metal-air battery, the development of low-cost and high-efficiency non-PGM catalysts for ORR has attracted much attention during the past decades. As one of the promising candidates, N-doped carbon is highly desirable for its strong designability and outstanding catalytic activity and stability. In this work, a facile and rational strategy is demonstrated for preparation of N,P-codoped mesoporous carbon (N,P-MC) for ORR by the direct pyrolysis treatment of polypyrrole with phytic acid as P-dopant and polystyrene sphere as template. The resultant N,P-MC exhibits a mesoporous structure with the optimized ORR active sites originating from the N,P-codoping. Owing to these features, N,P-MC exhibits excellent ORR activity, remarkable electrochemical stability, and superior methanol tolerance, comparable or even better than that of commercial Pt/C catalyst. The origin of enhanced ORR performance can be attributed to both the increased active sites and the mesoporous structure, which is expected to guide the future preparation of more capable carbon-based electrocatalysts for oxygen reduction and other electrocatalytic application.

Trace-level phosphorus and sodium co-doping of g-C 3 N 4 for enhanced photocatalytic H 2 production

The conversion of solar energy into hydrogen fuels by semiconductor photocatalysts has been paid great attention in recent years. g-C3N4 has emerged as a rising star in this area for its numerous advantages. In this work, trace-amount phosphorus and sodium co-doped g-C3N4 is prepared by polymerizing the mixed precursors of melamine and sodium tripolyphosphate. The resultant photocatalyst exhibits remarkably enhanced photocatalytic performance in H2 production. Experimental analysis and theoretical calculation indicate that such performance enhancement is mainly due to the improved charge transfer and separation resulting from the interstitial doping of sodium and phosphorus, as well as the more porous structure with enlarged specific surface area.

N-type Conduction in Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films Prepared by Coaxial Arc Plasma Deposition Using Li3PO4-Blended Graphite Targets

Co-doping of lithium and phosphorus, which produce shallow donor levels in diamond, was examined for ultrananocrystalline diamond/hydrogenated amorphous carbon composite films prepared by coaxial arc plasma deposition. Semiconducting behaviors were electrically observed and the production of n-type conduction by doping was confirmed thermally. The electrical conductivity is on the order of 10−6 S/cm at room temperature, which suggests that the doping efficiency is extremely small. Totally considering the results of near-edge X-ray absorption fine structure and X-ray photoelectron spectra, Li2CO3 is supposed to be formed in the doped films, which might be a reason for the low doping efficiency.

Phosphorus and boron codoping into TiO2 nanoparticles; an avenue for enhancing the visible light photocatalytic activity

TiO2 nanoparticles codoped with phosphorus and boron (P,B-TiO2), having visible light activity were prepared by sol–gel method. As prepared samples were calcined at different temperatures and the obtained samples were characterized by different techniques. XRD analysis reveals that the codoping decreases the particle size and retards the phase transition by increasing the thermal stability. The absorption edge of the P,B co-doped samples exhibit redshift as evidenced by the UV–visible absorption spectra. From XPS measurements, it is clear that the doped boron and phosphorus substitutes the oxygen and titanium sites respectively. Visible light driven MB degradation by these phosphorus and boron codoped samples is much better than that of photocatalytic activity of only P doped TiO2, and commercially available Degussa P25. The P,B-TiO2 sample heated at different temperatures exhibits enhanced charge separation as evidenced by the low temperature EPR studies with in situ visible light irradiation (>400 nm) which inturn is responsible for the enhanced photocatalytic activity.

Size-Dependence of Acceptor and Donor Levels of Boron and Phosphorus Codoped Colloidal Silicon Nanocrystals.

Size dependence of the boron (B) acceptor and phosphorus (P) donor levels of silicon (Si) nanocrystals (NCs) measured from the vacuum level was obtained in a very wide size range from 1 to 9 nm in diameter by photoemission yield spectroscopy and photoluminescence spectroscopy for B and P codoped Si-NCs. In relatively large Si-NCs, both levels are within the bulk Si band gap. The levels exhibited much smaller size dependence compared to the valence band and conduction band edges. The Fermi level of B and P codoped Si-NCs was also studied. It was found that the Fermi level of relatively large codoped Si-NCs is close to the valence band and it approaches the middle of the band gap with decreasing the size. The results suggest that below a certain size perfectly compensated Si-NCs, that is, Si-NCs with exactly the same number of active B and P, are preferentially grown, irrespective of average B and P concentrations in samples.

Nitrogen, Phosphorus, and Sulfur Co-Doped Hollow Carbon Shell as Superior Metal-Free Catalyst for Selective Oxidation of Aromatic Alkanes.

Metal-free heteroatom-doped carbocatalysts with a high surface area are desirable for catalytic reactions. In this study, we found an efficient strategy to prepare nitrogen, phosphorus, and sulfur co-doped hollow carbon shells (denote as NPS-HCS) with a surface area of 1020 m(2) g(-1). Using a poly(cyclotriphosphazene-co-4,4'-sulfonyldiphenol) (PZS) shell as carbon source and N, P, S-doping source, and the ZIF-67 core as structural template as well as extra N-doping source, NPS-HCS were obtained with a high surface area and superhydrophilicity. All these features render the prepared NPS-HCS a superior metal-free carbocatalyst for the selective oxidation of aromatic alkanes in aqueous solution. This study provides a reliable and facile route to prepare doped carbocatalysts with enhanced catalytic properties.

Sulfur and phosphorus co-doping of hierarchically porous graphene aerogels for enhancing supercapacitor performance

The control in the heteroatom doping is critical for surface and electronic properties, but chemistry is more complicated when two or more heteratoms are incorporated. Herein, we have demonstrated the co-doping of sulfur (S) and phosphorus (P) atoms into the three-dimensional (3D) macroporous, activated graphene aerogel (SP-AG). The C–S and C–PO bondings as major functional groups are simultaneously incorporated into the surface of SP-AG. Despite the high loading of S and P of 5.8 and 4.6%, respectively, the 3D macroporous continuity is preserved. The specific capacitance of SP-AG is 438 F/g at 10 mV/s is much greater than 347, 313, and 240 F/g of S-AG, P-AG, and AG, respectively. Moreover, the SP-AG delivers a specific capacitance of 381 F/g as a scan rate is increased to 500 mV/s, indicating the capacitance retention of 87.2%. After 10000 charging/discharging cycles at current density of 1 A/g, the SP-AG shows a greater electrochemical stability than AG with the capacitance retention ratio of 93.4%, due to the synergistic effect of S and P co-doing and 3D architecture. This synergistic effect of composition and structure is further confirmed by the enhanced energy and power densities in organic and ionic liquid electrolytes.