Zn Co-doping Research Articles

Achieving Stable Cycling Performance in a P2-Type Layered Oxide Cathode through a Synergic Li/Zn Doping for Sodium-Ion Batteries.

It has been suggested that sodium layered transition metal oxides could potentially serve as excellent cathodes for sodium-ion batteries (SIBs) because of their appropriate operating potentials and high capacities. However, the growing reliance on energy requirements has necessitated a higher energy density of SIBs. It has been demonstrated that activating oxygen-related activities for SIBs is a viable method to improve energy density. Herein, we suggest applying the synergy of Li and Zn codoping to activate the anionic redox reactions (ARRs) and improve their reversibility in Na0.75Ni0.3Mn0.7O2. The dual ion doping alleviates the phase transition and inhibits the Na+/vacancy arrangements, consequently improving the rate capacity and cyclic stability. The Na0.75Li0.15Ni0.1Zn0.05Mn0.7O2 delivers a discharge capacity of 134 mA h g-1 and no significant capacity loss at 100 mA g-1 between 2 and 4.5 V after 200 cycles. More importantly, the density functional theory (DFT) calculation proves that the codoping strategy triggers more ARRs compared to single-element doping, thereby providing enhanced capacity. The codoping induced oxygen redox strategies will create a new path for rational design of cathodes to enhance the energy density for SIBs.

ZnO thin films co-doped with III-valence metals and halogens: theory and experiment

The efficiency of metal-halogen co-doping of ZnO thin films deposited by DC magnetron sputtering of ceramic targets has been studied theoretically and experimentally. The influence of deposition temperature (300 − 900 K range), ZnX2 pressure (10−10−1 atm), Me2O3 dopant concentration (10−3 − 10 mol %), and Zn pressure (10−14 − 10−6 atm) on the composition of ZnO − Me2O3 − ZnX2 − Zn (Me = Al, Ga, In; X = F, Cl, Br, I) systems has been analyzed theoretically. The surface migration velocity of oxides and halides is also estimated for a wide temperature range. According to the calculation results, the optimal deposition conditions have been recommended. ZnO thin films co-doped with Al+Cl, Ga+Cl, Ga+Br, Ga+I, and In+Cl were deposited using ZnO:Me:X ceramic targets sintered by chemical vapor transport based on halides. The influence of the stoichiometric deviation of ceramic targets, the concentration of halogens, and metal impurities on thin films’ electrical, structural, compositional, and optical properties has been investigated. It is shown that Ga+Cl+Zn co-doping is the most promising. This co-doping increases both the structural perfection of films (electron mobility) and doping efficiency by Ga (charge carrier concentration), reducing the resistivity of thin films by two times compared to the use of classical ZnO:Ga ceramic targets. The optimal stoichiometric deviation of ZnO:Me:X ceramics targets, corresponding to the highest electron mobility and figure of merit of thin films, has been recommended.

The MOFs derived Co, Zn co-doping porous carbon framework as the collector for stable Li metal anodes

The Li metal anode is regarded as the most potential electrode material in the next-generation energy storage system, because of the high energy density and specific capacity. However, the advancement of Li metal anode is restricted by the volume changing and dendrite growth. In this paper, the Co and Zn co-doped porous carbon framework (CF-CZ) derived from MOF structure was designed and produced to realize the dendrite-free Li metal anode. The porous structure could accommodate the deposited Li metal, which relaxes the pressure of electrode structure and relieves the volume changes. Meanwhile, the Co, Zn co-doping effectively improves the lithiophilicity of framework, which attracts Li+ and decreases the nucleation barrier. Besides, numerous micropores of MOF structure could divide the Li+ flux to reduce the local current density for dense sedimentation. With the synergies of co-doping and porous structure, the symmetric cell of CF-CZ shows better electrochemical performance (the overvoltage can be stable at 14 mV after 1200 cycles) than pure Cu foil, and the LFP cells deliver 116.4 mAh g−1 at 1 C after 200 cycles. As a consequence, the CF-CZ possesses the potential to be applied in Li metal anodes.

A high-entropy cathode for sodium-ion batteries: Cu/Zn-doping O3-Type Ni/Fe/Mn layer oxides

The O3 layered oxides have been extensively investigated as cathode materials for sodium-ion batteries due to their remarkable theoretical capacity. However, the large radius of Na+ lead to complex phase transitions and tortuous diffusion channels during extraction/insertion, which ultimately restricts the Na+ diffusion kinetics and cyclic stability. In this study, we report a Zn and Cu co-doping strategy to the high entropy layer oxide Na [Ni0·2Fe0·2Mn0·4Cu0·15Zn0.05]O2 (HEO-CuZn) using the sol-gel method to prepare the oxides. Here, Zn is used to stabilize the structure of layer between the transition metal and O atoms, which slows down the adverse phase transition. In the fabricated sample, the element Cu provides additional capacity and inhibits excessive oxidation. The prepared HEO-CuZn used as cathode for Na+ ion battery exhibits better electrochemical performance, delivering a high specific capacity of 148 mA h g−1, and 84 % capacity retention after 100 cycles, which is attributed to the expanded Na+ transfer channels, reduced activation energy and interface side reactions, thus enhancing the Na+ diffusion kinetics. Meanwhile, the high entropy strategy stabilizes the overall structure by reducing the John-Teller distortion and suppressing the Na+/vacancy order, and effectively avoids adverse phase transitions such as O′3 and P′3. This study provides a new insight for the advance of the next generation high specific energy sodium-ion battery.

Effect of Fe and Zn co-doping on LiCoPO4 cathode materials for High-Voltage Lithium-Ion batteries

Lithium cobalt phosphate (LiCoPO4) has great potential to be developed as a cathode material for lithium-ion batteries (LIBs) due to its structural stability and higher voltage platform with a high theoretical energy density. However, the relatively low diffusion of lithium ions still needs to be improved. In this work, Fe and Zn co-doped LiCoPO4: LiCo0.9-xFe0.1ZnxPO4/C is utilized to enhance the battery performance of LiCoPO4. The electrochemical properties of LiCo0.85Fe0.1Zn0.05PO4/C demonstrated an initial capacity of 118 mAh/g, with 93.4 % capacity retention at 1C after 100 cycles, and a good capacity of 87 mAh/g remained under a high current density of 10C. In addition, the diffusion rate of Li ions was investigated, proving the improvement of the materials with doping. The impedance results also showed a smaller resistance of the doped materials. Furthermore, operando X-ray diffraction displayed a good reversibility of the structural transformation, corresponding to cycling stability. This work provided studies of both the electrochemical properties and structural transformation of Fe and Zn co-doped LiCoPO4, which showed that 10 % Fe and 5 % Zn co-doping enhanced the electrochemical performance of LiCoPO4 as a cathode material in LIBs.

The effects of Zn and Yb co-dopants on the electronic, radiation shielding, structural, thermal and spectroscopic properties of hydroxyapatite

This work presents a comprehensive investigation of the electronic properties of hydroxyapatite (HA) doped with zinc (Zn) and ytterbium (Yb). Four different compositions, namely 0.33Zn-0.33Yb-HA, 0.33Zn-0.66Yb-HA, 0.66Zn-0.33Yb-HA, and 0.66Zn-0.66Yb-HA, were studied using Density of States (DOS) and band structure calculations. The computed band gap values for each composition were determined to be 4.3097 eV, 4.1324 eV, 4.2527 eV, and 4.2088 eV, respectively. The observed decrease in the band gap energy from 0.33Zn-0.33Yb-HA to 0.66Zn-0.66Yb-HA signifies a significant impact of the dopant composition on the electronic properties of the material. Furthermore, the inclusion of ytterbium in the HA matrix resulted in the formation of a distinct band and peak in the density of states. This indicates the emergence of specific energy levels associated with Yb, suggesting a distinct influence on the electronic structure of the material. These findings provide valuable insights into the tunability of the electronic properties of HA through controlled doping with Zn and Yb. Such knowledge is crucial for tailoring materials with desired electronic characteristics, thus holding promise for various applications in electronic devices and biocompatible coatings. The as-modeled structures were synthesized via a wet chemical route. Fourier transform infrared (FTIR), Raman, and X-ray diffraction (XRD) analyses verified the formation of the HA structure for each sample. Differential thermal analysis (DTA) results showed that all the as-prepared samples were thermally stable. The negligible mass losses were detected for all the samples in the thermogravimetric analysis (TGA) measurements. The addition of both co-dopants affected crystal structure related parameters and decreased the crystallinity and cell viability.

Zinc and sulfur functionalized biochar as a peroxydisulfate activator via deferred ultraviolet irradiation for tetracycline removal.

To enhance the degradation of tetracycline class (TC) residuals of high-concentration from pharmaceutical wastewater, a novel zinc (Zn) and sulfur (S) functionalized biochar (SC-Zn), as a peroxydisulfate (PDS) activator, was prepared by two-step pyrolysis using ZnSO4 accumulated water-hyacinth. Results showed that the removal rate of 50, 150, and 250 mg per L TC reached 100%, 99.22% and 94.83% respectively, by the SC-Zn/PDS system at a dosage of 0.3 g per L SC-Zn and 1.2 mM PDS, via the deferred ultraviolet (UV) irradiation design. Such excellent performance for TC removal was due to the synergetic activation of PDS by the biochar activator and UV-irradiation with biochar as a responsive photocatalyst. The functionalization of the co-doped Zn and S endowed the biochar SC-Zn with a significantly enhanced catalytic performance, since Zn was inferred to be the dominant catalytic site for SO4˙- generation, while S played a key role in the synergism with Zn by acting as the primary adsorption site for the reaction substrates. The employed SC-Zn/PDS/UV system had excellent anti-interference under different environmental backgrounds, and compared with the removal rate of TC by adsorption of SC-Zn, the increasing rate in the SC-Zn/PDS/UV system (18.75%) was higher than the sum of the increases in the SC-Zn/PDS (9.87%) and SC-Zn/UV systems (3.34%), furtherly verifying the systematic superiority of this synergy effect. This study aimed to prepare a high-performance functionalized biochar activator and elucidate the rational design of deferred UV-irradiation of PDS activation to efficiently remove high-concentration antibiotic pollutants.

Synthesis of Binary Metal Doped CuO Nanoarchitecture for Congo red dye Removal: Synergistic Effects of Adsorption and Mineralization Techniques

Herein, a microwave-assisted fabrication technique has been practiced for the generation of pristine CuO and Cd/Zn co-doped CuO (Cu0.94Cd0.03Zn0.03O) nanopowders with the identical weight ratio of cadmium and zinc metals. The structure, chemical nature, shape, and optical response of CuO and Cu0.94Cd0.03Zn0.03O were assessed by PXRD, FESEM, FTIR, and UV–vis analytical techniques. PXRD results affirmed that CuO and Cu0.94Cd0.03Zn0.03O have developed in a single monoclinic phase; other extra phases are absent. The crystallite sizes of CuO and Cu0.94Cd0.03Zn0.03O were identified as 18.5 nm and 14.39 nm. The FESEM image of the Cu0.94Cd0.03Zn0.03O sample demonstrated a nanosheet-like morphology that was developed after the co-doping of Zn and Cd metal ions. FTIR graphs established the occurrence of Cu–O main bonds in both fabricated nanopowders. The UV–vis examination demonstrated that Cd and Zn co-doping has substantially reduced the energy gap of pristine CuO from 2.0 eV to 1.54 eV. This massive reduction in CuO bandgap assists it in catching extra photons to stimulate valence-band electrons and hence boosts the activity of the catalyst under sunlight irradiations. Moreover, including Cd and Zn has also effectively hindered the e−/h+ recombination in CuO throughout the photocatalysis process. The photocatalytic activities of pristine CuO and Cu0.94Cd0.03Zn0.03O nanosheets were probed against Congo-red (CR) pollutants under sunlight irradiations. The mineralization efficiency was detected as maximum (∼87.88%) for Cu0.94Cd0.03Zn0.03O nanosheets in contrast to pristine CuO nanostructures. Cu0.94Cd0.03Zn0.03O nanosheets, due to their astonishing properties, could be an economical alternative in creating intelligent strategies for mineralizing organic pollutants in industrial effluents.

Hard template synthesis of Zn, Co co-doping hierarchical porous carbon framework for stable Li metal anodes

Li metal is regarded as the most potential anode material due to the high energy density, low redox potential and high theoretical specific capacity. However, the development of the Li metal battery is seriously restricted by dendrite and huge volume change. In this paper, a hierarchical porous carbon framework with Zn/Co co-doping (PACF-ZC) is prepared by hard template method. Due to the combined action of different porous structures, the interior space provides sufficient reduction place for Li+ plating, when the Li+ flux uniformly disperses on the surface of PACF-ZC. So, the huge volume and growth of dendritic Li can be repressed by the distinctive hierarchical porous structure, effectively. In addition, the co-doping of Zn and Co reduces the nucleation barrier and promotes the Li affinity of PACF-ZC. The pyridine N and pyrrolidine N in precursor can optimize the behavior of Li+ plating. Benefit from the synergistic effect of hierarchical porous structure and Zn, Co co-doping, the symmetrical battery with Li@PACF-ZC obtains an ultra-long cycle life (1800 h) at 1 mA cm−2 with a capacity of 1 mAh cm−2. Meanwhile, the full cell of Li@PACF-ZC||LiFePO4 yields a high specific capacity of 128.8 mAh/g under 1C after 100 cycles.

Raising n-Type Thermoelectric Performance in (Te, Zn)-Codoped CuAgSe

We have successfully fabricated undoped and (Te, Zn)-codoped n-type CuAgSe polycrystals. For doping studies, we kept 5% Te over Se and changed from 0 to 10% Zn over Cu. (Te, Zn) codoping on CuAgSe reduces the lattice thermal conductivity to about 0.3 W m–1 K–1 at 673 K and increases the electrical conductivity. In particular, a ZT value of 0.91 was achieved at 623 K, which is the highest ZT value in n-type CuAgSe. Our results thus indicate that Te and Zn codoping is a potential way to improve the thermoelectric performance of n-type CuAgSe.

Obtaining of Mg-Zn Co-Doped GaN Powders via Nitridation of the Ga-Mg-Zn Metallic Solution and Their Structural and Optical Properties.

Mg-Zn co-dopedGaN powders via the nitridation of a Ga-Mg-Zn metallic solution at 1000 °C for 2 h in ammonia flow were obtained. XRD patterns for the Mg-Zn co-dopedGaN powders showed a crystal size average of 46.88 nm. Scanning electron microscopy micrographs had an irregular shape, with a ribbon-like structure and a length of 8.63 µm. Energy-dispersive spectroscopy showed the incorporation of Zn (Lα 1.012 eV) and Mg (Kα 1.253 eV), while XPS measurements showed the elemental contributions of magnesium and zinc as co-dopant elements quantified in 49.31 eV and 1019.49 eV, respectively. The photoluminescence spectrum showed a fundamental emission located at 3.40 eV(364.70 nm), which was related to band-to-band transition, besides a second emission found in a range from 2.80 eV to 2.90 eV (442.85-427.58 nm), which was related to a characteristic of Mg-doped GaN and Zn-doped GaN powders. Furthermore, Raman scattering demonstrated a shoulder at 648.05 cm-1, which could indicate the incorporation of the Mg and Zn co-dopants atoms into the GaN structure. It is expected that one of the main applications of Mg-Zn co-doped GaN powders is in obtaining thin films for SARS-CoV-2 biosensors.

Preparation of Ni–Zn dual-doped polyhedral LiMn2O4 for endurable cycling lithium ion batteries at high rate

Jahn-Teller distortion and manganese dissolution are always the dominant problem of attenuating long cyclic performance and rate capacity of spinel LiMn2O4 cathode materials. Herein, a Ni–Zn dual-doping strategy is proposed to synthesize various LiNi0.05ZnxMn1.95-xO4 (x = 0–0.05) materials via a solid phase combustion method. All the as-prepared Ni–Zn co-doping materials have a good spinel structure with Fd3m space group and present unique polyhedron morphology with exposed (111) facets, which is conductive to relieving the manganese dissolution and Jahn-Teller effect. Moreover, the Ni–Zn co-doping gives rise to the extended Li–O bond and increased cell volume, hence boosting the favorable intercalation and deintercalation kinetics of Li+ ions. Consequently, the optimized LiNi0·05Zn0·02Mn1·93O4 cathode exhibits good electrochemical performance with the initial discharge capacity of 127.30 mAh g−1 and capacity retention of 70% after 1000 cycles at 1 C. At 5 C, an ultra-long cycle stability with a capacity retention of 61% is obtained up to 1800 cycles. Even at the high current rates of 10 C and 20 C, the relatively high first discharge capacities of 106.50 mAh g−1 and 99.40 mAh g−1 are also delivered, respectively. The Ni–Zn co-doping polyhedral LiMn2O4 will provide a solution for developing high-performance cathode materials in lithium ion battery.

Effect of codoping of Zn and Ag on the spatial, optical and photocatalytic properties of cadmium oxide nanoparticles

The present article outlines the characterization of pure as well as Zn and Ag codoped cadmium oxide (CdO) nanoparticles prepared via co-precipitation method. To characterize prepared samples, X-Ray Diffraction (XRD), Diffused Reflectance Spectroscopy (DRS), Field Emission Scanning Electron Microscopy (FESEM), X-ray photoelectron spectroscopy (XPS) studies have been carried out. From XRD spectra, it has been observed that prepared samples are crystalline in nature due to presence of sharp diffraction peaks and their crystallite size lies in the range of 20–31 nm. From DRS technique, optical bandgap has been calculated and found that incorporation of Zn and Ag decrease bandgap of prepared samples from 2.45 eV to 2.23 eV as concentration of dopants are increasing. The examination of FESEM micrographs revealed the typical shape and particle size of prepared samples. The studies of XPS spectra allow identification of elements present and their respective chemical states. To study photocatalytic property of prepared samples, Crystal Violet (CV) dye has been used with sunlight as a source of radiation. It has been observed that degradation increases as we go from pure to codoped CdO and maximum of 98% degradation was obtained after 120 min of exposure to sunlight in case of codoped CdO. The enhanced photocatalytic efficiency in case of codoped CdO suggests that prepared sample can be excellently used for water treatment applications. Scavenger test using Isopropyl alcohol (IPA) has been carried out for hydroxyl radical (•OH) and breakdown of dye molecules suggested that •OH play an important part in degradation.

Simultaneous Enhancement of Magnetothermal and Photothermal Responses by Zn, Co Co-Doped Ferrite Nanoparticles.

Reducing nanoparticle (NP) dosage for hyperthermia therapy has remained a great challenge. In this work, efficiencies of alternating current (AC) magnetic field and near-infrared (NIR) heating are simultaneously enhanced by Zn and Co co-doping of magnetite NPs. The optimum magnetic anisotropy for maximized loss power under each magnetic field is achieved by tuning the doping concentration. The specific loss power of Zn0.3 Co0.08 Fe2.62 O4 @SiO2 NPs reaches 2428 W g-1 under an AC field of 27 kA m-1 at 430 kHz; 12296 W g-1 under NIR laser irradiation at 808 nm and 2.5 W cm-2 ; and an unprecedented value of 14724 W g-1 under dual mode. These values far exceed what has been achieved previously in iron oxide NPs. Ex vivo experiments on sacrificial mice show that while the NP dosage is substantially reduced to that used for magnetic resonance imaging, the surface body temperature of the mice reaches 50 °C after exposure to both AC field and laser irradiation under field parameters and laser intensity below safety limits. This nanoplatform is thus promising for multi-modal local hyperthermia therapy.

Facile Zn and Ni Co-Doped Hematite Nanorods for Efficient Photocatalytic Water Oxidation.

In this work, we report the effect of zinc (Zn) and nickel (Ni) co-doping of hydrothermally synthesized hematite nanorods prepared on fluorine-doped tin oxide (FTO) substrates for enhanced photoelectrochemical (PEC) water splitting. Seeded hematite nanorods (NRs) were facilely doped with a fixed concentration of 3 mM Zn and varied concentrations of 0, 3, 5, 7, and 9 mM Ni. The samples were observed to have a largely uniform morphology of vertically aligned NRs with slight inclinations. The samples showed high photon absorption within the visible spectrum due to their bandgaps, which ranged between 1.9–2.2 eV. The highest photocurrent density of 0.072 mA/cm2 at 1.5 V vs. a reversible hydrogen electrode (RHE) was realized for the 3 mM Zn/7 mM Ni NRs sample. This photocurrent was 279% higher compared to the value observed for pristine hematite NRs. The Mott–Schottky results reveal an increase in donor density values with increasing Ni dopant concentration. The 3 mM Zn/7 mM Ni NRs sample produced the highest donor concentration of 2.89 × 1019 (cm−3), which was 2.1 times higher than that of pristine hematite. This work demonstrates the role of Zn and Ni co-dopants in enhancing the photocatalytic water oxidation of hematite nanorods for the generation of hydrogen.

Tailoring of structural, opto-nonlinear and electrical properties of CdO thin films via Zn and Ag co-doping for optoelectronics applications

Sol-gel spin coating technique was used to develop Zn and Ag co-doped CdO thin films with 3.0 wt% Zn and various Ag doping concentrations. A cubic structure and a preferred orientation along (111) growth plane of samples was confirmed from films diffractograms analysis. The crystallites sizes of the samples were calculated and found about ∼33–44 nm. A further investigation of the structural phase of the films was carried out using Raman spectroscopy. The elemental composition of the films was examined using EDX technique which confirmed the presence of all elements. The collected EDX mapping spectra revealed a successful Zn and Ag co-doping of CdO films with a uniform elemental distribution. A controlled tailoring of the optical band gap of the film was achieved via Zn and Ag co-doping of CdO films. The band gaps of films were obtained from the Uv–vis absorbance spectra and were found to be in the order ∼1.87–2.32 eV. A significant improvement in nonlinear optical parameters was observed for the Zn doped CdO matrix with high Ag doping concentrations where χ(3) was estimated to be about 5.52 × 10−12-4.16 × 10−12 esu and (n2) ∼1.84 × 10−11-1.51 × 10−10 esu; respectively. On the other hand, Hall measurements of the grown films revealed interesting improvements in the carrier concentrations and conductivity. Films I–V characteristics show an ohmic contact with enhanced conducting behavior which suggests that the developed co-doped CdO films are promising for optoelectronics applications.

Sol-gel extended hydrothermal pathway for novel Cd-Zn co-doped Mg-ferrite nano-structures and a systematic study of structural, optical and magnetic properties

The novel study of Cd-Zn co-doped Magnesium ferrites CdxZn1-xMg0.25Fe1.75O4 (where x = 0, 0.25, 0.75, 0.50, and 1.00) has been made successfully by adopting a facile sol-gel extended hydrothermal pathway. Structural, optical, and magnetic behavior of the Cd-Zn co-doped Magnesium ferrites were systematically analyzed. From the X-ray Diffraction (XRD) patterns it was confirmed that the prepared samples have a cubic spinel structure. Scanning electron microscopic (SEM) study revealed the agglomerated and irregular shape of Cd-Zn co-doped Magnesium ferrites nanoparticles. Fourier transforms infrared (FTIR) spectroscopy has been studied for the confirmation of the presence of (M-O) bonding in the synthesized samples. Furthermore, the synthesized samples showed two frequency bands related to phonon vibrational stretching in both octahedral and tetrahedral lattice positions. The PL spectrum revealed the strong emission peaks in the ultraviolet to the visible region of all the synthesized samples. Raman spectroscopy showed the formation of four active modes due to the cubic spinel structure of all samples.Finally, the magnetic characteristics are calculated by using a vibrating sample magnetometer (VSM) showing ferrimagnetic and soft magnetic behavior of all the Magnesium ferrite samples. As the Cd and Zn co-doping in Mg ferrites was increased, the Hc was decreased. The magnetic studies revealed that the maximum Hc of 576 Oe and maximum saturation magnetization (Ms) appeared for the sample Cd0.50Zn0.50Mg0.25Fe1.75O4, carrying Cd/Zn in 50/50 ratio. It is envisaged that the novel preparation of Cd-Zn co-doped Magnesium ferrite would be suitable for several applications, for example, magnetic recording devices, actuators, high-density data storage devices sensors, and biomedical equipments.

Composition-controlled high entropy metal glycerate as high-performance electrocatalyst for oxygen evolution reaction

Direct growth of novel high entropy glycerate (HEG) on Ni foam using a facile microwave-assisted solvothermal method is demonstrated. The effect of adding Ti, V, Cu, Zn, and/or Mo into a baseline quinary-metal HEG, consisting of Cr, Mn, Fe, Co, and Ni, on the electrocatalytic performance is investigated. The quinary-metal HEG shows an overpotential of 307 mV at 50 mA cm−2 (η50). We demonstrate that the catalytic activity can only be enhanced via doping with desired metals. The additions of Ti, V, and Zn lead to enhanced electrocatalytic performances, exhibiting η50 of 254, 283, and 289 mV, respectively. The co-doping of Ti and Zn into the quinary-metal HEG results in a synergistic effect, giving robust catalytic activity with an ultra-low overpotential of 251 mV at 50 mA cm−2 and a low Tafel slope of 42.3 mV dec−1, and durable stability in 1 M KOH electrolyte for 60 h at different current densities of 10 and 100 mA cm−2. Also, phase transformation of the metal glycerate into metal (oxy)hydroxide during OER is investigated using various in situ and ex-situ analyses. Density functional theory (DFT) calculation validates the synergistic effect of addition of Ti and Zn in HEG system.

Realizing High Thermoelectric Performance in p-Type SnSe Crystals via Convergence of Multiple Electronic Valence Bands.

SnSe crystals have gained considerable interest for their outstanding thermoelectric performance. Here, we achieve excellent thermoelectric properties in Sn0.99-xPbxZn0.01Se crystals via valence band convergence and point-defect engineering strategies. We demonstrate that Pb and Zn codoping converges the energy offset between multiple valence bands by significantly modifying the band structure, contributing to the enhancement of the Seebeck coefficient. The carrier concentration and electrical conductivity can be optimized, leading to an enhanced power factor. The dual-atom point-defect effect created by the substitution of Pb and Zn in the SnSe lattice introduces strong phonon scattering, significantly reducing the lattice thermal conductivity to as low as 0.284 W m-1 K-1. As a result, a maximum ZT value of 1.9 at 773 K is achieved in Sn0.93Pb0.06Zn0.01Se crystals along the bc-plane direction. This study highlights the crucial role of manipulating multiple electronic valence bands in further improving SnSe thermoelectrics.

A case of perfect convergence of light and heavy hole valence bands in SnTe: the role of Ge and Zn co-dopants

Remarkable engineering of the electronic structure of SnTe by co-doping Ge and Zn. The synergistic effect of the resonance level, increase in the band gap and perfect convergence of valence sub-bands with reduced thermal conductivity leads to enhanced TE performance.