Construction of phosphorus-doping with spontaneously developed selenium vacancies: Inducing superior ion-diffusion kinetics in hollow Cu_(2)Se@C nanospheres for efficient sodium storage

Achieving high-efficiency sodium storage in metal selenides is still severely constrained in consideration of their inferior electronic conductivity and inadequate Na^(+)insertion pathways and active sites.Heteroatom doping accompanied by spontaneously developed lattice defects can effectively tune electronic structure of metal selenides,which give a strong effect to motivate fast charge transfer and Na^(+)accessibility.Herein,we finely designed and successfully constructed a fascinating phosphorus-doped Cu_(2)Se@C hollow nanosphere with abundant vacancy defects(Cu_(2)P_(x)Se_(1-x)@C)through a combination strategy of selenization of Cu_(2)O nanosphere template,self-polymerization of dopamine,and subsequent phosphorization treatment.Such exquisite composite possesses enriched active sites,superior conductivity,and sufficient Na^(+)insertion channel,which enable much faster Na^(+)diffusion rates and more remarkable pseudocapacitive features,Satisfyingly,the Cu_(2)P_(x)Se_(1-x)@C composites manifest the supernormal sodium-storage capabilities,that is,a reversible capacity of 403.7 mA h g^(-1) at 1.0 A g^(-1) over 100 cycles,and an ultrastable cyclic lifespan over 1000 cycles at 20.0 A g^(-1) with a high capacity-retention of about249.7 mA h g^(-1).The phase transformation of the Cu_(2)P_(x)Se_(1-x)@C involving the intercalation of Na^(+)into Cu_(2)Se and the following conversion of NaCuSe to Cu and Na2Se were further demonstrated through a series of ex-situ characterization methods.DFT results demonstrate that the coexistence of phosphorusdoping and vacancy defects within Cu_(2)Se results in the reduction of Na^(+)adsorption energy from-1.47to-1.56 eV improving the conductivity of Cu_(2)Se to further accelerate fast Na^(+)mobility.

Electrochemical Surface Restructuring of Phosphorus-Doped Carbon@MoP Electrocatalysts for Hydrogen Evolution

The hydrogen evolution reaction(HER) through electrocatalysis is promising for the production of clean hydrogen fuel. However,designing the structure of catalysts,controlling their electronic properties,and manipulating their catalytic sites are a significant challenge in this field. Here,we propose an electrochemical surface restructuring strategy to design synergistically interactive phosphorus-doped carbon@MoP electrocatalysts for the HER. A simple electrochemical cycling method is developed to tune the thickness of the carbon layers that cover on MoP core,which significantly influences HER performance. Experimental investigations and theoretical calculations indicate that the inactive surface carbon layers can be removed through electrochemical cycling,leading to a close bond between the MoP and a few layers of coated graphene. The electronsdonated by the MoP core enhance the adhesion and electronegativity of the carbon layers;the negatively charged carbon layers act as an active surface. The electrochemically induced optimization of the surface/interface electronic structures in the electrocatalysts significantly promotes the HER. Using this strategy endows the catalyst with excellent activity in terms of the HER in both acidic and alkaline environments(current density of 10 mA cm^(-2) at low overpotentials,of 68 mV in 0.5 M H_(2)SO_(4) and 67 mV in 1.0 M KOH).

Phosphorus-doped Ni–Co sulfides connected by carbon nanotubes for flexible hybrid supercapacitor

As promising electrode materials for supercapacitors,nickel-cobalt bimetallic sulfides render the advantages of abundant redox reactions and inherently high conductivity.However,in general,unsatisfactory performance of low specific capacity,low rate capability,and fast capacity loss exist in Ni–Co sulfide electrodes.Herein,we rationally regulate phosphorus-doped nickel–cobalt sulfides(P-NCS)to enhance the electrochemical performance by gas–solid phosphorization.Moreover,carbon nanotubes(CNTs)as conductive additives are added to improve the cycle stability and conductivity and form the composite P-NCS/C/CNT.According to density functional theory,more electrons near the Fermi surface of P-NCS are demonstrated notionally than those of simple CoNi2S4.Electrochemical results manifest that P-NCS/C/CNT exhibits superior electrochemical performance,e.g.,high specific capacity(932.0 C·g^(-1)at 1 A·g^(-1)),remarkable rate capability(capacity retention ratio of 69.1%at 20 A·g^(-1)),and lower charge transfer resistance.More importantly,the flexible hybrid asymmetric supercapacitor is assembled using P-NCS/C/CNT and activated carbon,which renders an energy density of 34.875 W·h∙kg^(-1)at a power density of 375 W∙kg^(-1).These results show that as-prepared P-NCS/C/CNT demonstrates incredible possibility as a battery-type electrode for high-performance supercapacitors.

P-Doped Titania Xerogels as Efficient UV-Visible Photocatalysts

In the present study, sol-gel process is used to synthesize P-doped TiO2 xerogels by the cogelation method of a functionalized P alkoxide, (NH2-(CH2)2-NH-(CH2)2-P(O)-(OC2H5)2) with Ti(OC3H7)4 in either 2-methoxyethanol or isopropanol. The phosphorus-doping improved the thermal stability of titania and decreased the phase transformation of anatase into rutile. This modification by phosphorus shifted the absorption edge of titania to the visible region as proved by Diffuse reflectance measurements, and thus offers the possibility to produce visible light effective TiO2 photocatalyst. The excellent photocatalytic activity of P-doped TiO2 xerogels compared to pure TiO2 could be explained by its high surface area and small TiO2-anatase crystallite size. From these results, it was proved by using three different models that phosphorus intrinsically influences the photocatalytic activity.

Electronic structures of phosphorus-doped diamond films and impacts of their vacancies

In order to better understand the bonding mechanisms of the phosphorus-doped diamond films and the influences of the phosphorus-doped concentration on the diamond lattice integrity and conductivity,we calculate the electronic structures of the phosphorus-doped diamond with different phosphorus concentrations and the density of states in the phosphorus--doped diamond films with a vacant lattice site by the first principle method.The calculation results show the phosphorus atom only affects the bonds of a few atoms in its vicinity,and the conductivity increases as the doped concentration increases.Also in the diamond lattice with a total number of 64 atoms and introducing a vacancy into the non-nearest neighbor lattice site of a phosphorus atom,we have found that both the injuries of the phosphorus-doped diamond films and the N-type electron conductivity of diamond films could be improved.

Cladding-pumped Raman fiber laser with 0.78%quantum defect enabled by phosphorus-doped fiber

The quantum defect(QD)is an important issue that demands prompt attention in high-power fiber lasers.A large QD may aggravate the thermal load in the laser,which would impact the frequency,amplitude noise and mode stability,and threaten the security of the high-power laser system.Here,we propose and demonstrate a cladding-pumped Raman fiber laser(RFL)with QD of less than 1%.Using the Raman gain of the boson peak in a phosphorus-doped fiber to enable the cladding pump,the QD is reduced to as low as 0.78%with a 23.7 W output power.To our knowledge,this is the lowest QD ever reported in a cladding-pumped RFL.Furthermore,the output power can be scaled to 47.7 W with a QD of 1.29%.This work not only offers a preliminary platform for the realization of high-power low-QD fiber lasers,but also proves the great potential of low-QD fiber lasers in power scaling.

Electrocatalytic reduction of NO to NH_(3) in ionic liquids by P-doped TiO_(2) nanotubes

Designing advanced and cost-effective electrocatalytic system for nitric oxide(NO)reduction reaction(NORR)is vital for sustainable NH_(3) production and NO removal,yet it is a challenging task.Herein,it is shown that phosphorus(P)-doped titania(TiO_(2))nanotubes can be adopted as highly efficient catalyst for NORR.The catalyst demonstrates impressive performance in ionic liquid(IL)-based electrolyte with a remarkable high Faradaic efficiency of 89%and NH3 yield rate of 425μg·h^(−1)·mg_(cat).^(−1),being close to the best-reported results.Noteworthy,the obtained performance metrics are significantly larger than those for N_(2) reduction reaction.It also shows good durability with negligible activity decay even after 10 cycles.Theoretical simulations reveal that the introduction of P dopants tunes the electronic structure of Ti active sites,thereby enhancing the NO adsorption and facilitating the desorption of ^(*)NH_(3).Moreover,the utilization of IL further suppresses the competitive hydrogen evolution reaction.This study highlights the advantage of the catalyst−electrolyte engineering strategy for producing NH_(3) at a high efficiency and rate.

The synergistic effect of P-doping and carbon coating for boosting electrochemical performance of TiO_(2) nanospheres for sodium-ion batteries

P-doping is an effective way to modulate the electronic structure and improve the Na+diffusion kinetics of TiO_(2), enabling enhanced electrochemical performance. However, it is a challenge to prepare TiO;with a high P-doping concentration starting from TiO_(2)in a crystalline state. In this work, we design a novel two-step route for constructing a carbon-coated anatase P-doping TiO_(2)nanospheres(denote as(PAn TSS)@NC) with high P-doping concentration, by utilizing amorphous TiO;nanospheres with the ultrahigh specific area as P-doping precursor firstly, and followed by carbon coating treatment. Experimental results demonstrate that P is successfully doped into the crystal lattice and carbon layer is well coated on the surface of TiO_(2), with P-doping and carbon-coating contents of ~13.5 wt% and 10.4 wt%, respectively,which results in the enhanced pseudocapacitive behavior as well as favorable Na+and electron transferring kinetics. The(P-AnTSS)@NC sample shows excellent rate and cycle performance, exhibiting specific capacities of 177 and 115 m Ah/g at 0.1 and 1.0 A/g after 150 and 2000 cycles, respectively.