Anion Doping Research Articles

Customized poly (aniline-co-o-aminobenzoic acid) by functionalizing with n/p dopants and its application in symmetrical redox supercapacitor

The chemically synthesized poly (aniline-co-o-aminobenzoic acid) copolymer was functionalized electrochemically by cationic and anionic doping and tailored its property for suitable redox behavior. The mechanism during this process has been proposed using cyclic voltammetry studies, and the doping was confirmed in FTIR and UV studies. In the electrochemical impedance spectroscopy, undoped and doped behavior revealed the possibility of fine-tuning of conditions that are required for redox supercapacitor. A symmetrical supercapacitor was fabricated with an optimized doped co-polymer-based electrode and the specific capacitance values were 107 Fg−1 for n-doped polymer and 140 Fg−1 for p-doped polymer. The electrochemical characterization of n/p 1 cm2 cells in terms of specific power, specific energy, specific capacitance, columbic efficiency, IR drop, and ESR was calculated from charge/discharge studies. Data were analyzed in terms of complex power versus complex capacitance, and hence, active region of n/p supercapacitor was obtained. This concept paves way for future tailoring of dopants during the synthesis of conducting polymer and its copolymers.Graphical abstract

Co-regulation of anion-cation in transition metal high entropy oxide for outstanding OER electrocatalytic performance

Transition metal oxides (TMO) are promising non-noble-metal electrocatalysts for OER due to their high activities and abundant crustal reserves. Introducing multiple cations and anions simultaneously into TMO is an effective route to ameliorate the catalytic property. Herein, a series of S-doped high entropy oxide (HEO) electrocatalysts consisting of five transition metals (including Cr, Mn, Fe, Co, and Ni) have been synthesized by microwave-assisted hydrothermal method. Compare with the low-component counterparts and the HEO without anion-doping, MS0.3 with the optimized S content exhibits superior performance, in terms of a low overpotential of 243 mV at a current density of 10 mA cm−2 and excellent stability. The synergistic effect of multiple cations and anion doping not only regulates the morphology and crystallinity of the catalyst significantly, but also effectively adjusts the electronic structure of the catalyst, improves conductivity, and provides suitable covalent bonds. In addition, the quasi-amorphous structure derived from the low-temperature microwave-hydrothermal effects and S doping introduces more defects and increases the active sites. The intrinsic entropy stabilization mechanism of HEO improves the durability of the catalyst. This work provides a guide for the design of electrocatalyst with controllable morphology, composition, and structure to achieve remarkable catalytic performance.

Band-gap engineering of zirconia by nitrogen doping in reactive HiPIMS: a step forward in developing innovative technologies for photocatalysts synthesis.

In the global context of climate change and carbon neutrality, this work proposes a strategy to improve the light absorption of photocatalytic water-splitting materials into the visible spectrum by anion doping. In this framework, reactive high power impulse magnetron sputtering (HiPIMS) of a pure Zr target in Ar/N2/O2 gas mixture was used for the deposition of crystalline zirconium oxynitride (ZrO2-xNx) thin films with variable nitrogen doping concentration and energy band-gap. The nitrogen content into these films was controlled by the discharge pulsing frequency, which controls the target surface poisoning and peak discharge current. The role of the nitrogen doping on the optical, structural, and photocatalytic properties of ZrO2-xNx films was investigated. UV-Vis-NIR spectroscopy was employed to investigate the optical properties and to assess the energy band-gap. Surface chemical analysis was performed using X-ray photoelectron spectroscopy, while structural analysis was carried out by X-ray diffraction. The increase in the pulse repetition frequency determined a build-up in the nitrogen content of the deposited ZrO2-xNx thin films from ∼10 to ∼25at.%. This leads to a narrowing of the optical band-gap energy from 3.43 to 2.20eV and endorses efficient absorption of visible light. Owing to its narrow bandgap, ZrO2-xNx thin films obtained by reactive HiPIMS can be used as visible light-driven photocatalyst. For the selected processing conditions (pulsing configuration and gas composition), it was found that reactive HiPIMS can suppress the hysteresis effect for a wide range of frequencies, leading to a stable deposition process with a smooth transition from compound to metal-sputtering mode.

How Anionic Dopants Impact the Electrochemical Additive Manufacturing of Polypyrrole

How Anionic Dopants Impact the Electrochemical Additive Manufacturing of Polypyrrole

Synergistic effects of A-site deficiency and anion doping on Pr0.4Sr0.6Ni0.2Fe0.7Mo0.1O3 cathode for H2O electrolysis and CO2 electrolysis

In this work, a strategy of A-site deficiency and F-doping was proposed to prepare Pr0.4Sr0.55Ni0.2Fe0.7Mo0.1F0.1O2.9 (PSNFMF) cathode. Compared with the reduced Pr0.4Sr0.6Ni0.2Fe0.7Mo0.1O3 (R-PSNFM), the reduced PSNFMF facilitate the exsolution reaction and generate more oxygen vacancies. Moreover, at 800 °C, the chemical oxygen surface exchange coefficient (kchem) of R-PSNFMF is 4.31 × 10−4 cm s−1, 21.8% higher than the value of 3.54 × 10−4 cm s−1 for R-PSNFM, and the oxygen chemical bulk diffusion coefficient (Dchem) of R-PSNFMF is 34.21 × 10−5 cm2 s−1, 24.3% higher than the value of 27.53 × 10−5 cm2 s−1 for R-PSNFM, suggesting faster oxygen transport kinetics are obtained for R-PSNFMF. Meanwhile, the synergistic effect of A-site deficiency and anion doping can also promote the electrolysis of H2O and CO2. For H2O electrolysis, the current density of R-PSNFMF based cell at 0.4 V (vs. OCV) is −0.75 A cm−2, 31.6% higher than the value of −0.56 A cm−2 for R-PSNFM based cell. And for CO2 electrolysis in harsh condition at 800 °C, the current density of R-PSNFMF based cell at 0.4 V (vs. OCV) is −0.43 A cm−2, 38.7% higher than the value of −0.31 A cm−2 for R-PSNFM based cell.

Super Ionic Li3–2xMx(OH)1-yNyCl (M=Ca, W, N=F) Halide Hydroxide as an Anti-Perovskite Electrolyte for Solid-State Batteries

Lithium halide hydroxide (Li2OHX) as a new class of low-cost, lightweight solid electrolyte (SSE) shows promising lithium-ion conductivity for advanced solid-state batteries. Here, using solid-state synthesis and extensive materials characterization, the impurity-free Li3–2xMx(OH)1-yNyCl (M=Ca, W, N=F) are reported, having mS cm−1 and mS cm−1 at 140 °C for Substituted smaller anionic dopants, such as facilitate the movement of Li ions within the anti-perovskite framework through rotational disordering in local coordination, resulting in the highest ion conductivity of 0.28 mS cm−1 at 25 °C. Using a strong combination of XRD, FTIR, pH, elemental EDS analysis, and calculated activation energies, it is demonstrated that the presence of H in these SSEs yields significantly higher Li+-ionic conductivity. Rotation of an OH-group in enlarged Cl-O-Cl triangular in the synthesized SSEs and their fully defected/ disordered structures enhance Li-ion conductivity.

Enhanced electrochemical performance of Li1.3Al0.3Ti1.7(PO4)3 solid electrolyte by anion doping

Enhanced electrochemical performance of Li1.3Al0.3Ti1.7(PO4)3 solid electrolyte by anion doping

Synergistic Mo and S co-doping on NiSe2 electrodes for reduced kinetic barrier of water electrolysis

Hydrogen is an ideal energy carrier that can replace non-renewable fossil fuels in the future, and its production using electrochemical water splitting is one of the cleanest and best effective approaches. However, the commercialization of large-scale H2 production technologies requires earth-abundant electrocatalysts that exhibit Pt-like activity. This study reports, the dual doping of cations (Mo) and anions (S) into metallic NiSe2 using a green electrodeposition method to upgrade the H evolution reaction (HER) activity and durability of NiSe2, at the same time. Sulfur doping into NiSe2 provides an additional active site, whereas dual doping of Mo/S into NiSe2 boosts the HER kinetics and durability. Additionally, a NiSe2 matrix is doped with different concentrations of Mo/S and their HER performance is studied. A 5% Mo/S–NiSe2 has an optimized H∗ absorption energy, which is favorable for high HER performance. To drive the current densities of −10 and −100 mA cm−2, 5% Mo/S–NiSe2 electrode requires a small overpotentials of 89 and 222 mV, respectively, and the corresponding Tafel slope is 57 mV dec−1. The enhanced HER activity of Mo/S–NiSe2 is credited to the electronic structure adjustment, generation of a porous structure, and ample electrochemically active surface area owing to Mo/S dual doping. This strategy is promising for exploring new functional electrocatalysts for clean H2 production.

Resent Progress of LiNi1-x-yCoxMnyO2 for Lithium-ion batteries

The increased use of lithium-ion batteries in larger devices such as electric vehicles and energy storage devices has led to a need for improved battery performance. Researchers are developing cathode active materials with higher energy density, such as lithium phosphate and lithium transition metal compounds. Ternary cathode active materials with high capacity have also been developed, but there are issues with cation mixing and side reactions that can lead to reduced capacity, voltage drop, and even explosions. To address these issues, researchers are focusing on stabilizing and optimizing the cathode-electrolyte interface through methods such as coating with protective layers, cation or anion doping and changing of active materials structure. Herein, we briefly introduce and discuss the recent research with development trend of cathode material’s degradation solution for Li-ion batteries.

Anionic Fluorine and Cationic Niobium Codoped Tin Oxide Thin Films as Transparent Conducting Electrodes for Optoelectronic Applications

Exploration of alternatives for supplementing indium tin oxide electrode is currently trending due to scarcity of indium, leading to a steep increase in the cost of related optoelectronic components. Codoping of niobium (Nb) and fluorine (F) into SnO2 lattice as cationic and anionic dopants, respectively, is explored by spray deposition technique. A fixed 10 wt% F and varying Nb concentration from 0 to 5 wt% is incorporated into the SnO2 lattice. X‐ray diffraction reveals substitution of Nb and F into the SnO2 lattice without altering the structure. Optical transmittance is found to increase with Nb content up to 4% of Nb (77.59%), and it decreases thereafter. Scanning electron microscope and optical profiler imply a relatively smooth surface with sharp‐tipped particles which vary with Nb concentration. Sheet resistance decreases up to 3 wt% of Nb doping and increases thereafter. Contact angle measurement indicates that upon doping with Nb, the films turn hydrophilic. Among the deposited films, 4 wt% of Nb‐doped film shows the highest figure of merit of 5.01 × 10−3 Ω−1. The surface work function of the 4 wt% Nb‐doped SnO2 film is 4,687.85 meV. The optimal films are tested as electrodes in dye‐sensitized solar cells and are discussed in detail.

Fluorinated Ni‐O‐C Heterogeneous Catalyst for Efficient Urea‐Assisted Hydrogen Production

AbstractConstructing multiple heterogeneous structures allows for improving the electrocatalytic activity of NiO by incorporating multiple active sites. Unfortunately, the poor conductivity of NiO makes efficient charge transfer within the heterogeneous structures difficult, thereby inhibiting the improvement of its intrinsic activity. Herein, F‐doped NiO/Ni@C heterogeneous catalyst (F‐NiO/Ni@C) is fabricated via a new organic‐inorganic hybrid approach, showing both advanced hydrogen evolution reaction (HER) and urea oxidation reaction (UOR) activity. The targeted F‐doping increases electron delocalization, and facilitates electron transfer from Ni to NiO at the nano‐interfaces. This interphase synergy provides ready‐to‐use F‐NiO active sites, allowing F‐NiO/Ni@C to achieve optimum H* adsorption Gibbs free energy for HER and a lower energy barrier for UOR. As a result, the as‐configured F‐NiO/Ni@C || F‐NiO/Ni@C cell requires an ultra‐low cell voltage of 1.37 V to achieve 10 mA cm−2 in alkaline media (with 0.3 M urea), outperforming the state‐of‐the‐art benchmark Pt/C|| RuO2 cell (1.45 V). This study reveals the positive impact of anion doping on interphase synergy and provides useful guidelines for designing monometallic catalysts for UOR as well as hydrogen generation.

Template-assisted Fabrication of O-doped CoP Microflowers with Optimal Electronic Modulation for Electrochemical Hydrogen Evolution.

Exploring efficient, affordable and stable electrocatalyst toward hydrogen evolution reaction (HER) is of great scientific significance for the practical implementation of the water splitting. The heteroatom doping represents a serviceable strategy to further elevate the catalytic performance for a transition metal-based electrocatalyst because of the electronic regulation effect. Herein, a reliable self-sacrificial template-engaged approach is proposed to synthesize O-doped CoP (denoted as O-CoP) microflowers, which simultaneously considers the regualtion of electronic configuration via anion doping and sufficient exposure of active sites via nanostructure engineering. The suitable O incorporation content in CoP matrix could tremendously modify the electronic configuration, accelerate the charge transfer, promote the exposure of active sites, strengthen the electrical conductivity, and adjust the adsorption state of H*. Consequently, the optimized O-CoP microflowers with optimal O concentration display a remarkable HER property with a small overpotential of 125 mV to afford a current density of 10 mA cm-2 , a low Tafel slope of 68 mV dec-1 and long-term durability for 32 h under alkaline electrolyte, manifesting a considerable potential application for hydrogen production at large scale. The integration of anion incorporation and architecture engineering in this work will bring in a depth insight for the design of low-cost and effective electrocatalysts in energy conversion and storage systems.

Effects of Secondary Dopant Anions on Emissivity and Related Properties of Poly(3,4-ethylenedioxythiophene).

Smart materials that are energy efficient and take up less space are crucial in the development of new technologies. Electrochromic polymers (ECPs) are one such class of materials that actively change their optical behavior in both visible and infrared parts of the electromagnetic spectrum. They show promise in a wide range of applications, from active camouflage to smart displays/windows. The full capabilities of ECPs are still yet to be explored, for while their electrochromic properties are well established, their IR modulation is less reported on. This study addresses the potential of ECPs in active IR modulating devices by optimization of Vapor Phase Polymerized poly(3,4-ethylenedioxythiophene) (PEDOT) thin films via the substitution of its dopant anion. Dynamic ranges denoting emissivity changes between reduced and oxidized states of PEDOT were found across dopants of tosylate, bromide, sulfate, chloride, perchlorate and nitrate. Relative to the emissivity of reduced (neutral) PEDOT, a range of ±15% was achieved from the doped PEDOT films, and a maximum dynamic range of 0.11 across a 34% change was recorded for PEDOT doped with perchlorate. This article is protected by copyright. All rights reserved.

Research Progress on Photocatalytic CO2 Reduction Based on Perovskite Oxides.

Photocatalytic CO2 reduction to valuable fuels is a promising way to alleviate anthropogenic CO2 emissions and energy crises. Perovskite oxides have attracted widespread attention as photocatalysts for CO2 reduction by virtue of their high catalytic activity, compositional flexibility, bandgap adjustability, and good stability. In this review, the basic theory of photocatalysis and the mechanism of CO2 reduction over perovskite oxide are first introduced. Then, perovskite oxides' structures, properties, and preparations are presented. In detail, the research progress on perovskite oxides for photocatalytic CO2 reduction is discussed from five aspects: as a photocatalyst in its own right, metal cation doping at A and B sites of perovskite oxides, anion doping at O sites of perovskite oxides and oxygen vacancies, loading cocatalyst on perovskite oxides, and constructing heterojunction with other semiconductors. Finally, the development prospects of perovskite oxides for photocatalytic CO2 reduction are put forward. This article should serve as a useful guide for creating perovskite oxide-based photocatalysts that are more effective and reasonable.

Structural stabilizing action of terbium cation and phosphate anion to layered transition-metal oxide cathodes

The capacity decay and safety issues of layered cathodes caused by structural deterioration upon deeply delithiated state, have impeded the further large-scale commercial-used of layered transition-metal cathodes in advanced lithium-ion batteries. In this work, the terbium cation and phosphate anion are doped homogeneously into LiCoO2 and LiNi0.83Co0.11Mn0.06O2 cathodes via the facile solid phase reaction method. We found that the lattice oxygen can be stabilized by the introduction of the Tb element, leading to the mitigation of structural degradation. More impressively, the PO43− polyanion possesses a benign binding affinity for Li-ions, further accelerating Li-ion transportation. Theoretically, the incorporation of the Tb element into the crystal lattice can alleviate oxygen redox activity in the high delithiation state. Thus, the introduction of an appropriate content of anion and cation dopants synergistically modulates the robust layered structure to suppress structural collapse during cycling. Consequently, the Tb element and PO43− polyanion co-doped LiNi0.83Co0.11Mn0.06O2 (a capacity of 179.3 mAh g−1 after 100 cycles with capacity retention of 96%) and LiCoO2 (169.4 mAh g−1 after 400 cycles and with capacity retention of 95%) illustrate prominent cycling stability. This study proposes a feasible and powerful strategy for enhancing the structural stability and cycling durability of high-voltage LiCoO2 and nickel-rich ternary layered cathode materials.

PROPERTIES OF NANOSTRUCTURED COMPOSITES OF POLY(VINYLIDENE FLUORIDE) WITH DOPED POLY(3-METHYLTHIOPHENE)

The combination of properties of intrinsically conducting polymers (ICPs) and functional nanostructured template materials opens up prospects for their use in various fields, ranging from bioelectronics to sensors and energy conversion. Successful combinations solve one of the important drawbacks of many ICPs, created by their insolubility and infusibility, and help to achieve their full potential in thermally processable materials. When developing such hybrid materials, it is necessary to take into account the sensitivity of ICP properties to interphase interactions due to extended π-conjugation in these polymers. However, this aspect of ICP-based nanocomposites has not been sufficiently studied yet. In this paper we investigate the effect of template submicron poly(vinylidene fluoride) (PVDF) particles and the nature of the dopant on properties of poly(3-methylthiophene) (P3MT) precipitated as the shell at the PVDF core surface in the course of the 3MT oxidative polymerization. For this purpose, we compare the properties of P3MT phase of the composites with the properties of the neat P3MT doped with dodecylbenzenesulfonate (DBS), perfluorooctanoate (PFO) and chloride anions. In the formed composite core-shell particles the P3MT is in the form of asymmetric nanoparticles which are localized almost exclusively at the surface of PVDF particles. According to the conjugation length, neat polymers form the following series: P3MT-Cl > P3MT-DBS > P3MT-PFO as evidenced by the IR spectral analysis. In their composites the conjugation length of P3MT doped with Cl- does not change noticeably, while for the DBS and PFO anions cases it increases and for the DBS case it exceeds that of Cl- case. X-ray phase analysis showed an increase in the degree of crystallinity of P3MT-Cl and P3MT-DBS phases in the composition of composites by 1.4 and 1.3 times relative to the corresponding values for the neat doped P3MTs. Such an increase can be caused by the influence of the local electric field of the dipoles of the electroactive part of the crystalline phase of PVDF (β- and γ-phase) on the spatial arrangement of charged P3MT macromolecules formed on the surface of PVDF. Thermogravimetric studies show an increase in the thermal stability of the doped P3MT phase of nanocomposites while conductivity measurements reveal a significant effect of the nature of the dopant anion.

Anion-Dependent Redox Chemistry of p-Type Poly(vinyldimethylphenazine) Cathode Materials.

Metal-free organic electrode materials have attracted vast research attention owing to their designable structures and tunable electrochemical properties. Although n-type cathode materials could be used in various metal-ion batteries, p-type ones with high potential can deliver high energy density. Herein, we report a new p-type polymeric cathode material, poly(2-vinyl-5,10-dimethyl-dihydro-phenazine) (PVDMP), with a theoretical capacity of 227 mAh g-1. PVDMP featuring two-step redox reaction will be doped by two anions to maintain electroneutrality during oxidation, which resulted in an anion-dependent electrochemical behavior of PVDMP-based cathode. The suitable dopant anion for PVDMP was selected and the doping mechanism was confirmed. Under the optimized condition, PVDMP cathode can deliver a high initial capacity of 220 mAh g-1 at 5 C and even remains 150 mAh g-1 after 3900 cycles. This work not only provides a new kind of p-type organic cathode materials but also deepens the understanding of its anion-dependent redox chemistry.

Anion‐Dependent Redox Chemistry of p‐Type Poly(vinyldimethylphenazine) Cathode Materials

AbstractMetal‐free organic electrode materials have attracted vast research attention owing to their designable structures and tunable electrochemical properties. Although n‐type cathode materials could be used in various metal‐ion batteries, p‐type ones with high potential can deliver high energy density. Herein, we report a new p‐type polymeric cathode material, poly(2‐vinyl‐5,10‐dimethyl‐dihydrophenazine) (PVDMP), with a theoretical capacity of 227 mAh g−1. PVDMP featuring two‐step redox reaction will be doped by two anions to maintain electroneutrality during oxidation, which resulted in an anion‐dependent electrochemical behavior of PVDMP‐based cathode. The suitable dopant anion for PVDMP was selected and the doping mechanism was confirmed. Under the optimized condition, PVDMP cathode can deliver a high initial capacity of 220 mAh g−1 at 5 C and even remains 150 mAh g−1 after 3900 cycles. This work not only provides a new kind of p‐type organic cathode materials but also deepens the understanding of its anion‐dependent redox chemistry.

Controlling the electrocatalytic activities of conducting polymer thin films toward suitability as cost-effective counter electrodes of dye-sensitized solar cells

Role dopant anions and solvents in electropolymerized conducting polymers (CPs) on controlling the morphology of thin films and electrocatalytic activities to judge their suitability as low-cost counter electrodes (CE) of dye-sensitized solar cells ( DSSCs) was systematically investigated. Amongst various CPs such as polyaniline (PANI), polypyrrole (PPy), and PEDOT with sodium dodecyl sulfate (SDS) as a dopant, PEDOT was found to exhibit the best photovoltaic performance with a photoconversion efficiency (PCE) of 6.99 %. This was attributed to the best electrocatalytic activity due to the smallest ΔEp, most minor R1, and nano-morphology-assisted high surface area, as confirmed by CV, EIS, and FE-SEM investigations. Using PEDOT as CP, the nature of dopants such as SDS, TFSI, and ClO4 has also been found to control the electrocatalytic activities and the morphology of the fabricated thin films affecting overall photovoltaic performance DSSCs. Amongst the various CP-based CE fabricated using different dopants and solvents, PEDOT:TFSI thin films prepared in acetonitrile solvent and used as CE exhibited not only the best electrocatalytic activity as CE but also demonstrated the best photovoltaic performance with PCE of 7.0 %, which almost similar to that of DSSC utilizing Pt as CE with PCE of 7.1 %. Therefore, it was concluded that the nature of CP and dopant ions were vital factors in governing the electrocatalytic activities of the thin films to ensure their suitability as CE for optimal functioning and controlling the DSSC performance.

Tubular Polypyrrole with Chloride Ion Dopants as an Ultrafast Organic Anode for High-Power Lithium-Ion Batteries.

Polypyrrole (PPy), as a representative p-type conductive polymer, attracts wide attention for energy storage materials. However, the sluggish reaction kinetics and low specific capacity of PPy impede its application in high-power lithium-ion batteries (LIBs). Herein, tubular PPy with chloride and methyl orange (MO) anionic dopants is synthesized and investigated as an anode for LIBs. The Cl- and MO anionic dopants can increase the ordered aggregation and the conjugation length of pyrrolic chains, forming plentiful conductive domains and affecting the conduction channel inside the pyrrolic matrix, thereby achieving fast charge transfer and Li+ ion diffusion, low ion transfer energy barriers, and rapid reaction kinetics. On account of the above synergistic effect, PPy electrodes deliver a high specific capacity of 2067.8 mAh g-1 at 200 mA g-1 and a remarkable rate capacity of 1026 mAh g-1 at 10 A g-1 , realizing high energy density (724 Wh kg-1 ) and power density (7237 W kg-1 ) simultaneously.