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Layered iron/manganese-based oxides are a class of promising cathode materials for sustainable batteries due to their high energy densities and earth abundance. However, the stabilization of cationic and anionic redox reactions in these cathodes during cycling at high voltage remain elusive. Here, an electrochemically/thermally stable P2-Na0.67Fe0.3Mn0.5Mg0.1Ti0.1O2 cathode material with zero critical elements is designed for sodium-ion batteries (NIBs) to realize a highly reversible capacity of ≈210 mAh g-1 at 20 mA g-1 and good cycling stability with a capacity retention of 74% after 300 cycles at 200 mA g-1, even when operated with a high charge cut-off voltage of 4.5 V versus sodium metal. Combining a suite of cutting-edge characterizations and computational modeling, it is shown that Mg/Ti co-doping leads to stabilized surface/bulk structure at high voltage and high temperature, and more importantly, enhances cationic/anionic redox reaction reversibility over extended cycles with the suppression of other undesired oxygen activities. This work fundamentally deepens the failure mechanism of Fe/Mn-based layered cathodes and highlights the importance of dopant engineering to achieve high-energy and earth-abundant cathode material for sustainable and long-lasting NIBs.

The demand for gas-sensing operations with lower electrical power and guaranteed sensitivity has increased over the decades due to worsening indoor air pollution. In this report, we develop room-temperature operational NH3 gas-sensing materials, which are activated through electron doping and crystal structure distortion effect in Fe0.2Ni0.8WO4. The base material, synthesized through solid-state synthesis, involves Fe cations substitutionally located at the Ni sites of the NiWO4 crystal structure and shows no gas-sensing response at room temperature. However, doping Na into the interstitial sites of Fe0.2Ni0.8WO4 activates gas adsorption on the surface via electron donation to the cations. Additionally, the hydrothermal method used to achieve a more than 70-fold increase in the surface area of structure-distorted Na-doped Fe0.2Ni0.8WO4 powder significantly enhances gas sensitivity, resulting in a 4-times increase in NH3 gas response (Rg/Ra). Photoluminescence and XPS results indicate negligible oxygen vacancies, demonstrating that cation contributions are crucial for gas-sensing activities in Na-doped Fe0.2Ni0.8WO4. This suggests the potential for modulating gas sensitivity through carrier concentration and crystal structure distortion. These findings can be applied to the development of room-temperature operational gas-sensing materials based on the cations. [ABSTRACT FROM AUTHOR]

Multiphase composites of lithium ceramics have emerged as a prominent area of research in the development of advanced solid tritium breeding materials. In this study, Li 2 TiO 3 /Li 2 SiO 3 co-doped Li 4 SiO 4 ceramic pebbles were prepared through an in-situ reaction between Li 4 SiO 4 and TiO 2. The objective of this study is to enhance the thermal cycling stability of Li 4 SiO 4 by impeding the grain boundary migration of Li 4 SiO 4 under high temperature conditions. The effects of the in-situ generated Li 2 TiO 3 /Li 2 SiO 3 particles on the microstructure, crush load and thermal cycling stability of Li 4 SiO 4 ceramic pebbles were investigated. The in-situ formed Li 2 TiO 3 and Li 2 SiO 3 particles effectively hindered the grain growth and minimized the formation of large intracrystalline pores in Li 4 SiO 4. At a sintering temperature of 900 °C, the Li 2 TiO 3 /Li 2 SiO 3 particles are beneficial in increasing the crush load of Li 4 SiO 4 ceramic. However, at lower sintering temperatures, their impact was counterproductive. An increase in the volume fractions of the Li 2 TiO 3 /Li 2 SiO 3 had a positive effect on grain refinement but a negative effect on crush load. The Li 2 TiO 3 /Li 2 SiO 3 co-doped Li 4 SiO 4 ceramic pebbles exhibited excellent structural stability during thermal cycling. The optimum mechanical stability was achieved at a TiO 2 addition of y = 0.1. The in-situ generated fine second phase particles effectively impeded grain boundary migration at high temperatures, providing a viable strategy for improving the thermal stability of Li 4 SiO 4 tritium breeders. [ABSTRACT FROM AUTHOR]

Borophosphate-based glass materials have the potential to revolutionize optical technology because of their outstanding optical properties, long-lasting nature, and cost-effectiveness. The present research addresses the intricate functions of rare earth and metallic nanoparticles (NPs) in borophosphate glass, which have significant potential for optical photonic and medical applications by incorporating Dy3+ ions and Cu NPs. We developed novel hybrid glasses through the melt-quenching technique, which includes the creation of functional groups and the establishment of bonds between P2O5 and B2O3, as confirmed by FTIR and Raman spectroscopy. UV–visible absorption spectra were used to identify the presence of Cu⁺ and Cu (Saeed et al., 2021) [2]⁺ ions and Cu nanoparticles, with the absorption peaks indicating their respective states. Furthermore, the underlying mechanisms of energy transfer in a glass matrix that is co-doped with dysprosium ions (Dy3+) have been studied. The experimental findings of this research not only provide valuable information about the physical properties of borophosphate glass but also emphasize the collaborative relationship between the rare-earth ion and copper nano-powders. The Tauc plot analysis demonstrated a correlation between the concentration of Cu and Dy dopants and a decrease in the energy band gap of the glass. This suggests that these dopants influence the electronic structure of the glass. This study opens up possibilities for creating innovative photonic materials with customized optical attributes. [Display omitted] [ABSTRACT FROM AUTHOR]

The demand for gas-sensing operations with lower electrical power and guaranteed sensitivity has increased over the decades due to worsening indoor air pollution. In this report, we develop room-temperature operational NH3 gas-sensing materials, which are activated through electron doping and crystal structure distortion effect in Fe0.2Ni0.8WO4. The base material, synthesized through solid-state synthesis, involves Fe cations substitutionally located at the Ni sites of the NiWO4 crystal structure and shows no gas-sensing response at room temperature. However, doping Na into the interstitial sites of Fe0.2Ni0.8WO4 activates gas adsorption on the surface via electron donation to the cations. Additionally, the hydrothermal method used to achieve a more than 70-fold increase in the surface area of structure-distorted Na-doped Fe0.2Ni0.8WO4 powder significantly enhances gas sensitivity, resulting in a 4-times increase in NH3 gas response (Rg/Ra). Photoluminescence and XPS results indicate negligible oxygen vacancies, demonstrating that cation contributions are crucial for gas-sensing activities in Na-doped Fe0.2Ni0.8WO4. This suggests the potential for modulating gas sensitivity through carrier concentration and crystal structure distortion. These findings can be applied to the development of room-temperature operational gas-sensing materials based on the cations. [ABSTRACT FROM AUTHOR]

In this study, the WIEN2k code, utilizing the full potential linearized augmented plane wave (FPLAPW) approach within the framework of density functional theory (DFT), explicitly employing the PBEsol approximation, is employed to investigate the fundamental properties of W-doped and (Mo, W) co-doped cubic CeO2. Herein, lattice constants, bulk modulus and cell volumes were evaluated for structural properties. The total density of states (TDOS) for various doped and co-doped CeO2 systems was used to explain the origin of magnetic behavior. The band structure (BS) calculations show that the doped and co-doped materials exhibit semiconductor behavior with a direct bandgap in both spin channels. The calculated total spin magnetic moments of W/CeO2 and (Mo, W)/CeO2 alloys are 2.002 μ B and 4.007 μ B , respectively. Furthermore, the optical absorption shows absorption peaks in the visible range and a redshift. As a result, adding molybdenum and tungsten additives improves the electro-optical properties of previous materials. [ABSTRACT FROM AUTHOR]

Thin film thermoelectric technology has immense potential to become a next-generation power source for small-scale electronics. However, the rapid development of thin film thermoelectric still lacks a controllable structural design to improve the performance of thermoelectric devices for required temperature applications. This work presented a controlled thermoelectric design of ZnO-based thin films by Al and Mg co-doping using ALD. Herein, the Mg-doped ZnO sample exhibits the highest Seebeck coefficient of −311.83 μVK−1 at 500oC, while the maximum thermoelectric power factor of 3.68 μWcm−1K−2 is obtained at 300oC, which drops for higher temperatures. This decrease in power factor resulted from the reduction in electrical conductivity above 300oC. Similarly, the Al and Mg co-doped ZnO sample (Mg/Al ≈2 at%) exhibits a high thermoelectric power factor of 3.85 μWcm−1K−2 for ZnO based material due to its moderate electrical conductivity and Seebeck coefficient value at 325oC and behave monotonically for elevated temperatures. Scanning electron microscope (SEM) images show the formation of wedge-shaped structures for Al-incorporated samples, which helps to boost the overall thermoelectric performance. Additionally, we performed XRD, UV–Vis, Hall, and AFM analysis to get a deep insight into structural, optical, electrical, and surface features of the grown thin films and their linkage with the thermoelectric properties. [Display omitted] • Growth of Al and Mg co-doped ZnO thin films on quartz substrate using ALD. • SEM measurements reveal the formation of Wedge-shaped morphology for co-doped thin films. • Thermoelectric properties have been improved by tuning the Mg/Al concentration. • The highest thermoelectric power factor of 3.85 μWK−1cm−2 was obtained for the ZMA2 sample at 325oC. [ABSTRACT FROM AUTHOR]

Co‐free spinel LiNi0.5Mn1.5O4 (LNMO) is emerging as a promising contender for designing next generation high‐energy‐density and fast‐charging Li‐ion batteries, due to its high operating voltage and good Li+ diffusion rate. However, further improvement of the Li+ diffusion ability and simultaneous resolution of Mn dissolution still pose significant challenges for their practical application. To tackle these challenges, a simple co‐doping strategy is proposed. Compared to Pure‐LNMO, the extended lattice in resulting LNMO‐SbF sample provides wider Li+ migration channels, ensuring both enhanced Li+ transport kinetics, and lower energy barrier. Moreover, Sb creating structural pillar and stronger TM─F bond together provides a stabilized spinel structure, which stems from the suppression of detrimental irreversible phase transformation during cycling related to Mn dissolution. Benefiting from the synergistic effect, the LNMO‐SbF material exhibits a superior reversible capacity (111.4 mAh g−1 at 5C, and 70.2 mAh g−1 after 450 cycles at 10C) and excellent long‐term cycling stability at high current density (69.4% capacity retention at 5C after 1000 cycles). Furthermore, the LNMO‐SbF//graphite full cell delivers an exceptional retention rate of 96.9% after 300 cycles, and provides a high energy density at 3C even with a high loading. This work provides valuable insight into the design of fast‐charging cathode materials for future high energy density lithium‐ion batteries. [ABSTRACT FROM AUTHOR]

Y1-xNdxFe1-yNiyO3 (x = 0, y = 0; x = 0.05, y = 0.05; x = 0.05, y = 0.10; x = 0.05, y = 0.15) powders with different concentrations of Nd3+ and Ni2+ doped ions were synthesized by sol-gel method. The structure, morphology, and magnetic properties of the materials were characterized by powder X-ray diffraction (XRD), scanning electron microscope (SEM), and physical property measurement system (PPMS). X-Ray diffraction results show that all the prepared samples are in the single perovskite phase without any secondary phases. The measured doping content was basically consistent with the initial designed content. The remanent magnetization (Mr) and saturation magnetization (Ms) of the synthesized YFeO3 were 0.701 emu/g and 1.481 emu/g, respectively, and the coercivity (Hc) reached 19,000 Oe. The results also showed that the Mr and Ms values of YFeO3 increase, while the Hc values decrease with increasing Ni2+ ion content. When the doping concentrations are x = 0.05 and y = 0.15, the values of Mr and Ms are 0.787 emu/g and 1.782 emu/g, respectively, with Hc at 2100 Oe. From the research results, it can be observed that the introduction of doped ions enhances the super-exchange interactions. [ABSTRACT FROM AUTHOR]

Despite recent advances in growth and characterization of GaN:Be, reliable conductive p‐type GaN:Be remains elusive. In this work, GaN is co‐doped with Be and Mg to improve the incorporation and ionization efficiency of both Be and Mg. Be and Mg are found to interact in complex ways rendering GaN:Be,Mg semi‐insulating. Rather than improving Be and Mg incorporation efficiency, there is an apparent mutual inhibition of incorporation when Be and Mg are co‐dopants. Furthermore, photoluminescence measurements indicate that the BeGa acceptor is reduced in particular, relative to the total [Be]. The same effect is not observed for Mg. From this, it is concluded that Mg preferentially incorporates into Ga lattice sites over Be, and excess Be that cannot incorporate into substitutional sites instead occupies interstitial sites. The interstitial Be acts as donor defect, which compensate Mg acceptors. This provides an explanation for the observed reduction in BeGa‐related luminescence intensity (without an associated decrease in [Be]) in GaN:Be with significant [Mg] content. [ABSTRACT FROM AUTHOR]

Fluorinated sludge, as the main byproduct of refined production in the semiconductor industry, is a hazardous solid waste. In the process of co-treating fluorine-containing sludge in cement kilns, the fluorine, phosphate, and various heavy metal ions contained in the fluorinated sludge will inevitably be introduced into the cement raw material at the same time. These ions will significantly affect and change the calcination process and properties of cement raw material minerals. However, there are few studies on the impact of their coexistence on the properties of cement clinker. Therefore, this paper systematically studied the synergistic influence mechanism of fluorine, phosphate, and heavy metal ions co-doping on the calcination process, microstructure, and hydration characteristics of tricalcium silicate ( C3 S). The results show that compared with the single doping of phosphorus, the co-doping of phosphate and heavy metal ions is not conducive to the firing of C3 S, while the co-doping of fluorine, phosphate, and heavy metal ions has a significant synergistic promoting effect on the firing of C3 S, while significantly improving the symmetry of C3 S crystal structure, resulting in more defects of different types on the surface of C3 S minerals. Compared with the single doping of phosphorus, the co-doping of phosphate and heavy metal ions is beneficial for improving the initial and later hydration rates of C3 S, reducing the aspect ratio of rod- shaped hydrated calcium silicate (C-S-H). The effect of co-doping of fluorine, phosphate, and heavy metal ions on the hydration performance of C3 S depends on the doping ratio of each ion. However, as the doping amount of each ion increases, the acceleration period of C3 S hydration will be continuously delayed, and the co-doping of the three ions will promote the increase of the aspect ratio of rod-shaped C-S-H. [ABSTRACT FROM AUTHOR]

P-type dye-sensitized solar cells have been fabricated with the sensitizer derived from tender coconut husk and Rhodamine B incorporated with and without co-doped (Co and Ce) nickel oxide (NiO) nanoparticles. NiO nanoparticles are obtained via green synthesis using the mesocarp of tender coconut. Graphene-coated FTO and I−/I3− have been used as counter cathode and electrolyte, respectively, in the cells. The cubic structure was confirmed from XRD spectra, and Debye–Scherrer and Williamson-Hall equations were used for the evaluation of crystalline size (13.3 and 8.5 nm) and parameters of dislocation density, etc. Fingerprints of the samples by molecular vibrations were found using FTIR and UV–visible spectroscopy. SEM imaging has been recorded for both the NiO nanoparticles. The fabricated solar cells were subjected to JV characterization studies. Co-doped (Co and Ce) solar cell has shown better efficiency of 0.259% with short circuit current density and open circuit voltage of 1.382 mA/cm2 and 0.387 V, respectively. [ABSTRACT FROM AUTHOR]

Development of novel abrasive systems with functional activities and physicochemical properties are of great significance in the reactive oxygen species (ROS)-enhanced chemical mechanical polishing. In this work, Ce single-doped and Ce/Cu co-doped dendritic mesoporous silica nanoparticles (DMSNs), namely Ce−DMSNs and Ce/Cu−DMSNs, were produced via a simple impregnation and thermolysis procedure. The Ce and/or Cu species involved in DMSNs frameworks were characterized through X-ray diffractometry, infrared spectroscopy, scanning electron microscopy, energy dispersive spectrometry, transmission electron microscopy, X-ray photoelectron spectroscopy, and nitrogen adsorption/desorption techniques. We report the evolution of surface morphology and roughness, defects, peak-to-valley data, image surface area difference, and material removal efficiency during ROS-enhanced polishing experiments toward silica materials. All the pure, Ce single-doped, and Ce/Cu co-doped DMSNs abrasive systems offered nearly defect-free surfaces with close-to-atom scale roughness. It might be attributed to the "springlike effect" and "soft polishing/abrasion", possibly originating from the low-modulus DMSNs carriers. Among these abrasives, the Ce/Cu co-doped DMSNs systems achieved an evident improvement in removal efficiency, especially under ultraviolet irradiation-assisted polishing conditions. The coexisted Ce(Ⅲ)/Ce(Ⅳ) and Cu(Ⅰ)/Cu(Ⅱ) couples might be responsible for the effective production of ROS in photocatalysis and Fenton-like processes, thereby contributing to the Si–OH and Ce(Ⅲ)−O–Si bonding formations. The role of the developed Ce/Cu co-doped DMSNs abrasive systems in ROS-enhanced polishing processes was discussed. [ABSTRACT FROM AUTHOR]

Co-doping of phosphorus and boron elements into crystalline silicon quantum dot (c-Si QD) is an effective approach for enhancing the photoluminescence (PL) performance. In this paper, we report on the preparation of hydrogenated silicon nitride (SiNx:H) thin films embedded with phosphorus-boron co-doped c-Si QDs via plasma enhanced chemical vapor deposition route. Mixed dilution including hydrogen (H2) and argon (Ar) is applied in the in-situ deposition process for optimizing the deposition process. The P-B co-doped c-Si QD/SiNx:H thin films exhibit a wide range of PL spectra. The emission is greatly improved especially for the short-wavelength light when compared to the SiOx:H thin film containing P-B co-doped c-Si QDs. The effects of H2/Ar flow ratio on the structural and optical characteristics of thin films are systematically investigated through a series of characterizations. Experimental results show that various properties, such as crystallinity, QD size, optical band gap and doping concentrations, are effectively controlled by tuning H2/Ar flow ratio. Based on the red-shift of QCE-related PL peak, the successful P-B co-doping into Si QDs are verified. Finally, a comprehensive discussion has been made to analyze the influence of H2-Ar mixed dilution on the film growth and impurity doping in detail in this paper. [ABSTRACT FROM AUTHOR]

[Display omitted] We report on ultra-violet (UV) photodetectors based on BaO nanoparticles by the detailed investigation of band gap and photoluminescence properties. The BaO nanomaterials were fabricated by the modified sol–gel technique. The innovation of co-doping can modulate the photoluminescence or sensing properties by narrowing the band gap related to enhancing the high carrier concentration, higher electronic lifetime, and low carriers recombination. It is investigated that the BaO nanoparticles with co-doping reveals a highly reduced band gap and exceptional photoluminescence properties as compared to the pristine BaO nanoparticles due to hindering carrier,s recombination for Ultra-violet (UV) photodetectors. The optical studies revealed that the addition of co-dopants in BaO host material creates new energy sites, so the band gap declines up to 1.31 eV as compared to that of pristine BaO (1.36 eV). The photoluminescence properties recorded with photoluminescence (PL) spectroscopy were recorded which revealed the decrease in PL intensity due to the hindering of carriers recombination with the addition of co-dopant metal ions. Furthermore, the inclusion of co-dopant metals results in an improvement in electrical conductivity because of a decline in carrier recombination, according to an I-V characteristic study. This factor contributes to enhance the photoluminescence properties of BaO which, in turn, contributes to enhance the sensing capability of the photodetector device. These obtained features modify optoelectronic properties are far superior as compared to that of previously reported literature on BaO nanomaterials, and the synthesized BaO semiconductor material becomes a potential candidate for efficient use in the ultraviolet (UV) photodetectors device applications. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C3N4) is a promising material for photocatalytic applications. However, it suffers from poor visible-light absorption and a high recombination rate of photogenerated electron–hole pairs. Here, Co/La@g-C3N4 with enhanced photocatalytic activity was prepared by co-doping Co and La into g-C3N4 via a facile one-pot synthesis. Co/La@g-C3N4 displayed better performance, achieving 94% tetracycline (TC) removal within 40 min, as compared with g-C3N4 (BCN, 65%). It also demonstrated promising performance in degrading other pollutants, which was ~2–4-fold greater relative to BCN. The improved photocatalytic activity of Co/La@g-C3N4 was associated with improved photogenerated charge separation, reduced charge transfer resistance, a built-in electric field arising from the p-n-p heterojunction, and the synergistic effect of ternary components for the separation and transfer of the photogenerated charge carriers. Superoxide radicals are suggested to be the most notable reactive species responsible for the photocatalytic reaction. Environmental factors, including the pollutant concentration, catalyst dosage, solution pH, inorganic salts, water matrices, and mixture with dyes, were considered in the photocatalytic reactions. Co/La@g-C3N4 showed good reusability for five cycles of the photocatalytic degradation of TC. The facile one-pot co-doping of Co and La in g-C3N4 formed a p-n-p heterojunction with boosted photocatalytic activity for the highly efficient removal of TC from various water matrices. [ABSTRACT FROM AUTHOR]

Nanomaterials based on manganese oxides (MnOx) show considerable potential for large-scale electrochemical energy storage devices, driving significant research to explore their capabilities. One intriguing approach to enhance their performance involves the incorporation of other metals within their structure. Thus, we analyzed hierarchically obtained Cobalt (Co)-doped MnOx nanowires with different Co content, examining their storage properties. Notably, the initial impact of Co was observed in the structural characteristics of MnOx-based nanowires. As the Co content increased, there was a noticeable decrease in the cross-sectional widths of these nanowires. Also, we observed by XRD analysis that Co could effectively substitute manganese (Mn) within the crystal lattice. By XPS, the impact of Co doping on the Mn(IV)/Mn(III) ratio was of particular significance, as this ratio exhibited a direct correlation with the Co content (more Co, higher Mn(IV)/Mn(III) ratio), emphasizing the pivotal role of Co in modulating the oxidation states within these materials. Electrochemical studies revealed a remarkable dual behavior in the nanowires, combining pseudocapacitance and battery-like energy storage characteristics. Notably, our investigation uncovered a distinctive storage performance trend resembling a volcano, with the optimal energy storage material achieved using 1.4 wt.% Co-doped MnOx–Co nanowires. Applying the optimum material for a hybrid supercapacitor application, the energy and power density values were calculated as 48.08 Wh kg−1 and 2339.02 W kg−1, respectively. Thus, we believe that our comprehensive exploration of Co-doped MnOx nanowires provides valuable insights into understanding these materials' optimization for energy storage applications. [ABSTRACT FROM AUTHOR]

[Display omitted] Lithium cobalt phosphate (LiCoPO 4) 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 LiCoPO 4 : LiCo 0.9-x Fe 0.1 Zn x PO 4 /C is utilized to enhance the battery performance of LiCoPO 4. The electrochemical properties of LiCo 0.85 Fe 0.1 Zn 0.05 PO 4 /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 LiCoPO 4 , which showed that 10 % Fe and 5 % Zn co-doping enhanced the electrochemical performance of LiCoPO 4 as a cathode material in LIBs. [ABSTRACT FROM AUTHOR]

Facile template-free hydrothermal method was utilized for preparing CuO nanostructures (NSs) doped with Co element (Cu 1-x Co x O (x = 0.0, 0.02, 0.04, 0.06 and 0.08)). A single-phase monoclinic crystal with changing in morphology from rod-to sphere-like nanoparticles was observed. The temperature dependency of DC electrical conductivity revealed that the shallow and deep donor levels are responsible for the DC conduction in low and high temperature ranges, respectively. The Ac electrical conductivity, dielectric constant and dielectric loss were also measured as functions in frequency and temperature. The frequency dependence of the AC conductivity was well represented by the Jonscher's universal power law. The AC conduction was governed by the Correlated Barrier Hopping model where the inter-well and intra-well hopping mechanisms contribute to the electrical conduction in the low and high frequency ranges, respectively. The activation energies and the barrier height decreased while the dielectric constant and dielectric loss increased with increasing the Co content. The relaxation and deformational polarizations predominate and the overall behavior of dielectric constant fits well with the Koops' model. The Cole-Cole plots indicated a decrease in the sample resistance with increasing temperatures and Co concentrations. UV–vis absorption spectra exhibited two peaks at wavelengths 252 and 323 nm. The optical energy gap was calculated using Tauc's equation and decrease from 2.24 to 2.1 eV with increasing the Co concentrations. The effect of Co-doping on CuO was explored for oxygen evolution reaction (OER) and found a decrease in the overvoltage (μ) about 50 mV at 0.08 ratios, which declares that the doping of Co element enhances the electrical conductivity and feasibility for further electrocatalytic improvement. [ABSTRACT FROM AUTHOR]

Nanoparticles, considered building blocks of nanotechnology, are a topic of widespread research due to their extraordinary properties that are useful in diverse sectors. Among all nanoparticle types, TiO2 (anatase) has drawn the most attention, primarily because of its superhydrophilic properties and effective antibacterial actions. Its applications include self-cleaning of solid surfaces, treatment of water and air, production of clean energy, treatment of microbial infections, pesticide management, etc. making TiO2 a focal point of research in materials science. However, the lack of photosensitivity to visible light (>390 nm) reduces the scope for utilising TiO2 in photocatalytic processes. Therefore, most studies on TiO2 nanoparticles have focused on broadening their spectral sensitivity through band gap manipulation for effective photocatalysis under visible light. Researchers have doped/co-doped metals and non-metals, such as N, C, F, S, B, Cu, Fe, V, Pt, etc. to nano-TiO2 to shorten its band gap with varying degrees of success. This review paper mainly focuses on the mechanism and effectivity of N and Fe co-doped TiO2 nanoparticles. The progress of scientific research on TiO2 photocatalysis has introduced an array of new applications using TiO2 nanoparticles, and these applications have also been discussed in this article. [ABSTRACT FROM AUTHOR]

Bi2MoO6 (BMO) is a typical bismuth-based semiconductor material, and its unique Aurivillius structure provides a broad space for electron delocalization. In this study, a new type of bismuth molybdate Cd/Er-BMO photocatalytic material was prepared by co-doping Er3+ and Cd2+, and the performance of the photocatalytic degradation of sulfamethoxazole (SMZ) was systematically studied. The research results showed that the efficiency of SMZ degradation by Cd/Er-BMO was significantly improved after doping Er3+ and Cd2+ ions, reflecting the synergistic catalytic effect of Cd2+ and Er3+ co-doping. Cd/Er-BMO doped with 6% Cd had the highest degradation efficiency (93.89%) of SMZ under visible light irradiation. The material revealed excellent stability and reusability in repeated degradation experiments. In addition, 6% Cd/Er-BMO had a smaller particle size and a larger specific surface area, which is conducive to improving the generation efficiency of its photogenerated electron-hole pairs and reducing the recombination rate, significantly enhancing the photocatalysis of the material. This study not only provides an effective photocatalyst for degrading environmental pollutants such as SMZ, but also provides an important scientific basis and new ideas for the future development of efficient and stable photocatalytic materials. [ABSTRACT FROM AUTHOR]

Abstract Co-doping of phosphorus and boron elements into crystalline silicon quantum dot (c-Si QD) is an effective approach for enhancing the photoluminescence (PL) performance. In this paper, we report on the preparation of hydrogenated silicon nitride (SiNx:H) thin films embedded with phosphorus-boron co-doped c-Si QDs via plasma enhanced chemical vapor deposition route. Mixed dilution including hydrogen (H2) and argon (Ar) is applied in the in-situ deposition process for optimizing the deposition process. The P-B co-doped c-Si QD/SiNx:H thin films exhibit a wide range of PL spectra. The emission is greatly improved especially for the short-wavelength light when compared to the SiOx:H thin film containing P-B co-doped c-Si QDs. The effects of H2/Ar flow ratio on the structural and optical characteristics of thin films are systematically investigated through a series of characterizations. Experimental results show that various properties, such as crystallinity, QD size, optical band gap and doping concentrations, are effectively controlled by tuning H2/Ar flow ratio. Based on the red-shift of QCE-related PL peak, the successful P-B co-doping into Si QDs are verified. Finally, a comprehensive discussion has been made to analyze the influence of H2-Ar mixed dilution on the film growth and impurity doping in detail in this paper.

[Display omitted] The interfacial interaction of carbon nanotubes (CNTs) significantly enhances the output capability of piezoelectric nanogenerators (PENGs). However, overcoming the limitation of low specific surface area in one-dimensional materials remains a significant challenge. This paper introduces a hydrothermal method for composite MOF (C-M) using CNTs and MOF-5, demonstrating localized co-doping between them. Coaxial electrospun piezoelectric fiber membranes (C-MNF) were then prepared using PVDF/PAN as the matrix. Benefiting from C-M's excellent crystallinity and its synergistic interaction with the polymer matrix, the C-MNF-based PENG showed a 125 % increase in output voltage, reaching ∼25 V, compared to coaxial membranes simply mixing MOF-5 and CNTs. As a result, its short-circuit current was ∼1.8 μA, with a piezoelectric coefficient d 33 of ∼400 pC N−1. Consequently, this material exhibits superior piezoelectric output capabilities, paving the way for future functional material fabrication. [ABSTRACT FROM AUTHOR]

[Display omitted] • Successful preparation of cathode materials through doping and interface engineering has enhanced Li–S battery performance synergistically. • Nitrogen-nickel co-doped MXene nanosheets were employed as a conductive framework to successfully in-situ synthesize a TiO 2 homojunction structure containing both anatase and rutile phases. • Employing an in-situ transmission electron microscopy (TEM) technique allowed us to observe the growth process of the homojunction for the first time, revealing its temperature-dependent behavior. • The assembled ART@NNM cathode in the Li–S cell exhibits outstanding performance, effectively alleviating shuttle effects and promoting sulfur conversion reactions. The commercialization of lithium-sulfur (Li–S) batteries has faced challenges due to the shuttle effect of soluble intermediate polysulfides and the sluggish kinetics of sulfur redox reactions. In this study, a synergistic catalyst medium was developed as a high-performance sulfur cathode material for Li–S batteries. Termed A/R-TiO 2 @ Ni-N-MXene, this sulfur cathode material features an in-situ derived anatase–rutile homojunction of TiO 2 nanoparticles on Ni-N dual-atom-doped MXene nanosheets. Using in-situ transmission electron microscopy (TEM) technique, we observed the growth process of the homojunction for the first time confirming that homojunctions facilitated charge transfer, while dual-atom doping offered abundant active sites for anchoring and converting soluble polysulfides. Theoretical calculations and experiments showed that these synergistic effects effectively mitigated the shuttle effect, leading to improved cycling performance of Li–S batteries. After 500 cycles at a 1C rate, Li–S batteries using A/R-TiO 2 @Ni-N-MXene as cathode materials exhibited stable and highly reversible capacity with a capacity decay of only 0.056 % per cycle. Even after 150 cycles at a 0.1C rate, a high-capacity retention rate of 62.8 % was achieved. Additionally, efficient sulfur utilization was observed, with 1280.76 mA h/g at 0.1C, 694.24 mA h/g at 1C, alongside a sulfur loading of 1.5–2 mg/cm2. The effective strategy based on homojunctions showcases promise for designing high-performance Li–S batteries. [ABSTRACT FROM AUTHOR]

Abstract Herein, a hydrothermal etching approach was used to generate an innovative CuS/O,N-CNT composite. The hydrothermal etching of g-C3N4 led to the creation of O,N-CNT, with ethanol as the oxygen source. The SEM and TEM characterizations confirmed the formation of CNT, whereas the XPS analysis proved the doping of oxygen and nitrogen in the CNT matrix along with the incorporation of CuS. Under sun irradiation, the produced CuS/O,N-CNT showed outstanding photocatalytic efficiency, eliminating methyl orange and methylene blue dyes with 97.21% and 98.11% efficacy, respectively. Adding hydrothermally etched O,N-CNT increased light absorption and charge migration kinetics, as can be studied from the UV-DRS and PL analysis; hence, the observed improvements in light absorption and charge transfer pathways contributed to the CuS/O,N-CNT composite's enhanced photocatalytic activity, indicating its potential for efficient elimination of organic contaminants under solar irradiation. The catalyst demonstrated high reusability performance up to six cycles and significantly degraded other dyes. Scavenger analysis, along with VB-XPS and UV-DRS analysis, aid in developing a photocatalytic mechanism that confirms the participation of hydroxyl and superoxide radicals in the degradation process.

Over the past decade, there has been a pronounced research emphasis on leveraging the advantageous defect states inherent in metal dichalcogenide nanostructures to intricately modulate and tailor their optoelectronic characteristics. Here, we demonstrate how defects significantly impact the linear and nonlinear optical properties of pristine FeS2 nanomaterials (NMs), ionic liquids (DMII) passivated FeS2 NMs, and CoFeS2 NMs. These NMs were synthesized using a low-cost hot-injection process, and their structure was validated via X-ray diffraction analysis. The oval-like structure of the NMs is revealed by high-resolution transmission electron microscopy, and X-ray photoelectron spectra demonstrate the presence of the divalent oxidation state of iron (Fe) and cobalt (Co). After the treatment of DMII on the pristine NMs, a decrease in the Urbach energy (Eu) was found, with values reducing from 0.77 to 0.27 meV. This phenomenon may potentially be associated with the passivation of surface imperfections in pristine NMs. The treatment of DMII further enhances the lifetime of charge carriers (1.25 ns) and conductivity by one order compared to pristine FeS2 NMs. On the other hand, introducing Co in FeS2 alters the conductivity of pure FeS2 NMs, shifting them from p-type to n-type and significantly enhancing their electrical characteristics by 3 orders of magnitude. The open aperture z-scan study revealed that the CoFeS2 NMs have an effective nonlinear absorption coefficient (βeff) of 160 cm GW–1, which is superior to that of the pristine NMs with a βeff of 130 cm GW–1. The optical limiting threshold value (1.01 J cm–2) of CoFeS2 NMs is much higher than those of both pristine and DMII-treated FeS2 NMs, indicating superior optical limiting performance. The current work presents a comprehensive analysis of pristine, DMII-treated, and Co-alloyed FeS2 NMs, focusing on their potential for linear and nonlinear optoelectronic applications. [ABSTRACT FROM AUTHOR]

(Cu,Te) co-doped CoSb 3 -based thermoelectric compounds Cu 0.3 Co 4 Sb 12-x Te x were synthesized rapidly by solid-state reaction method with the sintering temperature∼923 K and holding time ∼20 min. XRD analysis showed that the prepared samples Cu 0.3 Co 4 Sb 12-x Te x were single-phase skutterudite structure in the range of x < 0.7 %. SEM and EDS analyses show that the sample grains are fine with an average diameter of micro-nanometer and the sample contains many micro-pores inside and the grains have a relatively uniform distribution of elements. The lattice thermal conductivity at high temperature of Cu 0.3 Co 4 Sb 12-x Te x (x = 0,0.3,0.5, 0.7,0.9) significantly reduced by ∼50 % when compared to the samples at room temperature due to enhanced scattering of fine grains, micro porosity and grain boundary. The maximum power factor ∼2824 μWm−1K−2 was obtained for Cu 0.3 Co 4 Sb 11.5 Te 0.5 at 769 K and a maximum ZT value of ∼0.83 at 623 K are obtained from (Cu,Te) co-doped CoSb 3 material. [ABSTRACT FROM AUTHOR]

Chemical modification via functional dopants in carbon materials holds great promise for elevating catalytic activity and stability. To gain comprehensive insights into the pivotal mechanisms and establish structure‐performance relationships, especially concerning the roles of dopants, remains a pressing need. Herein, we employ computational simulations to unravel the catalytic function of heteroatoms in the acidic oxygen evolution reaction (OER), focusing on a physical model of high‐electronegative F and N co‐doped carbon matrix. Theoretical and experimental findings elucidate that the enhanced activity originates from the F and pyridinic‐N (Py−N) species that achieve carbon activation. This activated carbon significantly lowers the conversion energy barrier from O* to OOH*, shifts the potential‐limiting step from OOH* formation to O* generation, and ultimately optimizes the energy barrier of the potential‐limiting step. This wok elucidates that the critical role of heteroatoms in catalyzing the reaction and unlocks the potential of carbon materials for acidic OER. [ABSTRACT FROM AUTHOR]

The design and construction of dual modifications on photocatalysts is a promising strategy to improve the photocatalytic properties. Herein, we fabricated the In 2 S 3 nano-foam blocks with dual modifications of Bi & Mo co-doping and structure construction via a simple hydrothermal method to achieve an enhanced photocatalytic hydrogen generation. The results reveal that Bi & Mo co-doped In 2 S 3 nano-foam blocks exhibit a high hydrogen generation rate of 5.45 mmol/g/h, which is 27 times that of bulk In 2 S 3. Owing to the structural advantages, the enhanced specific surface area of the as-prepared nano-foam blocks improve the light harvesting efficiency of photocatalytic system. More importantly, the doped Bi and Mo atoms boost the improvement in the transfer and separation of photogenerated electrons and holes by introducing the impurity energy level. This work provides a reliable strategy for the design and fabrication of high-efficiency photocatalytic reaction system. • A Bi & Mo co-doped In 2 S 3 nano-foam blocks was prepared. • The nano-foam blocks improve the light harvesting efficiency. • The Bi & Mo co-doping effect enhances the electron utilization efficiency. • The dual modifications endows an enhanced hydrogen evolution. [ABSTRACT FROM AUTHOR]

Herein, a hydrothermal etching approach was used to generate an innovative CuS/O,N-CNT composite. The hydrothermal etching of g-C3N4 led to the creation of O,N-CNT, with ethanol as the oxygen source. The SEM and TEM characterizations confirmed the formation of CNT, whereas the XPS analysis proved the doping of oxygen and nitrogen in the CNT matrix along with the incorporation of CuS. Under sun irradiation, the produced CuS/O,N-CNT showed outstanding photocatalytic efficiency, eliminating methyl orange and methylene blue dyes with 97.21% and 98.11% efficacy, respectively. Adding hydrothermally etched O,N-CNT increased light absorption and charge migration kinetics, as can be studied from the UV-DRS and PL analysis; hence, the observed improvements in light absorption and charge transfer pathways contributed to the CuS/O,N-CNT composite's enhanced photocatalytic activity, indicating its potential for efficient elimination of organic contaminants under solar irradiation. The catalyst demonstrated high reusability performance up to six cycles and significantly degraded other dyes. Scavenger analysis, along with VB-XPS and UV-DRS analysis, aid in developing a photocatalytic mechanism that confirms the participation of hydroxyl and superoxide radicals in the degradation process. [ABSTRACT FROM AUTHOR]

In this study, long-range van der Waals (vdW) and effective Coulomb interaction (Ueff) corrected density functional theory (DFT + vdW + Ueff) calculations were performed to explore the effect of co-doping (of Co and Sn) on the crystal structure, electronic, magnetic and chemical (H2 adsorption) properties of phosphorene. The stability of the doped structures was determined with formation energy (Ef) and molecular dynamics (MD) simulations. The dopants were found to form strong bonds with phosphorus (P) atoms. The introduction of Co/Sn-atoms slightly altered the local geometry of phosphorene, resulting in new electronic characteristics. For instance, unlike pristine phosphorene (P48), the co-doped phosphorene (P45CoxSny) can exhibit ferrimagnetic (FIM) or ferromagnetic (FM) coupling in the ground state. The doped structures exhibit integral magnetic moments, mainly contributed by the Co-atoms. The P45Co1Sn2 and P45Co2Sn1 structures show metallic band structure, while P45Co3 becomes a small band gap (Eg) semiconductor (Eg =0.2 eV). The adsorption of the H2 molecules was investigated at various sites on un-doped and co-doped phosphorene. It was found that H2 molecule is weakly adsorbed on un-doped phosphorene, whereas moderate adsorption was observed for co-doped systems. The adsorption energy (Ea) was found to be -0.03, -0.35, -0.48, and − 0.65 eV, respectively for P48, P45Co1Sn2, and P45Co2Sn1 and P45Co3. The DOS plots confirmed that the observed adsorption is due to the s-d interaction between H-atom and the doped Co-atom. The Bader charge and charge density difference (CDD) analysis showed that H2 molecule acts as a charge acceptor and doped phosphorene as a charge donor. In addition, the effect of strain on adsorption was also considered. The adsorption capacity of the doped systems decreased with the number of H2 molecules. These findings show that co-doped phosphorene can be used for spin-based nanodevices and hydrogen capture for energy storage applications. [ABSTRACT FROM AUTHOR]

In the dry reforming of methane (DRM), metal doping is used as one of the important methods to modulate the catalyst performance. In this paper, we synthesized two types of catalysts, Rh doped TiO2 (RTO) and Rh/Nb co-doped TiO2 (RNTO), and evaluated their performances in DRM. The CH4 and CO2 conversion of 79% and 95% in RTO were both higher than that in RNTO (the CH4 and CO2 conversion of 73% and 87%) as working for 80 h. The characterizations of XRD, TEM, XPS, EPR, BET, and TPR were carried out to determine the structure of catalysts. We found that the creation of the oxygen vacancies is favorable in Rh solely doped TiO2 but restricted by Rh/Nb co-doping. The XPS results verified that Rh4+ and Rh3+ were presented in RTO, while only Rh3+ can be observed in RNTO. Due to the co-doping of Nb, the Rh induced charge perturbation was balanced by Nb5+ rather than the deprivation of electrons from O2−, therefore the state of Rh3+ was stabilized and the content of oxygen vacancies were decreased which resulted in attenuated activity in the DRM reaction. [ABSTRACT FROM AUTHOR]

Rising energy demand has forced to look for new ways to convert energy. Graphene quantum dots (GQD) has received extensive attention in many fields due to their low toxicity, abundant active sites, sound water solubility and photoluminescence stability. Here, a fluorine-nitrogen co-doped GQD (C-GQD) is synthesized for efficient oxygen reduction reaction (ORR) catalysts. The incorporation of fluorine and nitrogen atoms changed the electronic structure of the carbon atom, resulting into synergistic enhancement of catalytic performance toward ORR. Electrochemical studies of the ORR showed that the initial potentials of C-GQD were positively shifted by 200 mV and 170 mV compared with those of GQD and N-GQD, respectively, and the half-wave potentials were positively shifted by 200 mV and 180 mV, which were comparable to that of 20% Pt/C. The CV curves underwent only slight fluctuations after 10,000 cycle tests. The obtained results provide important insights into the use of metal-free catalysts with GQDs as carriers as promising electrocatalysts for proton exchange membrane fuel cells with low cost and easy preparation procedures. [ABSTRACT FROM AUTHOR]

Attributed to the enriched adsorption of urea, tailored adsorption of OH−, and high exposure of active sites, the defect-rich PMo-NiCo exhibits satisfied catalytic performance for UOR (η 10/2000 = 1.27/1.51 V) and HER (η −10/−500 = −57/256 mV). [Display omitted] • NiCo compressive strain inhibits OH− adsorption, while enriching the urea adsorption. • OH− is preferentially adsorbed on oxygenophilic P/Mo, releasing the Ni/Co active site. • PMo-NiCo catalyst could avoid the competition of OER and realize highly efficient UOR. Alloys with bimetallic electron modulation effect are promising catalysts for the electrooxidation of urea. However, the side reaction oxygen evolution reaction (OER) originating from the competitive adsorption of OH− and urea severely limited the urea oxidation reaction (UOR) activity on the alloy catalysts. This work successfully constructs the defect-rich NiCo alloy with lattice strain (PMo-NiCo/NF) by rapid pyrolysis and co-doping. By taking advantage of the compressive strain, the d-band center of NiCo is shifted downward, inhibiting OH− from adsorbing on the NiCo site and avoiding the detrimental OER. Meanwhile, the oxygenophilic P/Mo tailored specific adsorption sites to adsorb OH− preferentially, which further released the NiCo sites to ensure the enriched adsorption of urea, thus improving the UOR efficiency. As a result, PMo-NiCo/NF only requires 1.27 V and −57 mV to drive a current density of ±10 mA cm−2 for UOR and hydrogen evolution reaction (HER), respectively. With the guidance of this work, reactant competing adsorption sites could be tailored for effective electrocatalytic performance. [ABSTRACT FROM AUTHOR]

The primary goal for the development of energy-storage devices is to find affordable ways to increase their efficiency, activity, and stability. In this regard, transition metal oxide mainly MoO 3 enhances the electrochemical properties of the material due to various oxidation states. On the other hand, carbonaceous materials, such as reduced graphene oxide, provide a large surface area that increases the conductivity of nanomaterials. In this work, we have synthesized pristine and codoped MoO 3 material using the co-precipitation route. While the r-GO based composite was prepared by a simple sonication approach. The prepared composite material showed a higher specific capacitance of 987 F/g than the pristine and codoped material. The BAMO@r-GO discharges after 346 s which was the higher time of discharge than that of pure and codoped material. Moreover, the obtained results from EIS measurement confirmed that the composite material showed less resistance than all other synthesized materials. The synergistic effect between the r-GO and BAMO materials is the reason for the higher supercapacitor performances of BAMO@r-GO. Based on these results, the fabricated BAMO@r-GO material can be effectively utilized as an electrode material in electrochemically powered energy storage devices. [ABSTRACT FROM AUTHOR]

Re3+ ions (Re = Y, La, Gd)-doped MSi2O2N2:Eu2+ (M = Ca, Sr) phosphors were prepared by the solid-state reaction method. The effects of co-dopants (Y3+, La3+, Gd3+) and Eu2+ doping concentration on the luminescent performance of MSi2O2N2:Eu2+ have been investigated. The co-doping with Re3+ (Re = Y, La, Gd) significantly improved the luminescent performance of MSi2O2N2:Eu2+ (M = Ca, Sr) overall. Re3+ co-doping had a greater enhancing effect on higher Eu2+ concentration samples and the Re3+-doped CaSi2O2N2:Eu2+ phosphors exhibited better luminescence properties than Re3+-doped SrSi2O2N2:Eu2+ ones. In addition, incorporation of Y3+ ions to SrSi2O2N2:Eu2+ showed the strongest emission among the three dopants (Y3+, La3+, and Gd3+), while the Gd3+ doping ions in CaSi2O2N2:Eu2+ exhibited superior luminescence properties compared to Y3+ and La3+. [ABSTRACT FROM AUTHOR]

Recently, there has been a growing interest in skutterudite (SKD) compounds containing electronegative elements such as Br, Cl, S, Se, and Te, owing to their increased diversity and the versatility of filler atoms. This study focused on the thermoelectric performance of a series of (Ni, Te) co-doped SKDs filled with the electronegative element S, denoted as SxNi0.4Co3.6Sb11.2Te0.8 (x = 0, 0.1, 0.2, and 0.3). These compounds were prepared using a combination of a solid-state reaction and spark plasma sintering techniques. The results showed that (Ni, Te) co-doping introduced excess electrons in the SKD lattice, while the incorporation of the element S into the SKD voids optimized carrier concentration. This led to a considerable increase in the absolute Seebeck coefficient to 110.6 μV K−1 at ambient temperatures. The presence of S fillers induced phonon resonance scattering and point scattering, which reduced lattice thermal conductivity and ultimately improved the thermoelectric figure of merit zT, which reached 0.93 for S0.3Ni0.4Co3.6Sb11.2Te0.8 at 823 K. [ABSTRACT FROM AUTHOR]

Circularly polarized luminescence (CPL) materials offer exciting potential due to their unique light properties. However, controlling the color of afterglow emission, a key feature for many applications remains a challenge. Here, a co‐doping strategy is presented for precise control of multicolor CPL afterglow in films. This approach utilizes chiral naphthylphosphoric acid derivatives as energy and chirality transfer donors, commonly used fluorescent dye rhodamine B (RB) and PVA are selected as the acceptor and the polymeric matrix, respectively. Remarkably, the co‐doped films exhibit ultra‐long green circular polarization phosphorescence lasting several seconds with high efficiency (14.23%), lifetime (1025.5 ms), and dissymmetry factor (8.44 × 10−3). Crucially, by adjusting the acceptor content, it can precisely tune the phosphorescence‐to‐fluorescence ratio and achieve multicolor afterglow. This control stems from a combination of Förster resonance energy transfer, chirality transfer, and color‐mixing effects. Furthermore, this approach significantly improves the asymmetry factor of the CPL afterglow by an order of magnitude (5.17 × 10−2). It is anticipated that this straightforward approach to precisely regulating the afterglow color of CPL will provide invaluable insights for the future design of highly efficient and innovative CPL materials. [ABSTRACT FROM AUTHOR]

Due to a wide band gap and large exciton binding energy, zinc oxide (ZnO) is currently receiving much attention in various areas, and can be prepared in various forms including nanorods, nanowires, nanoflowers, and so on. The reliability of ZnO produced by a single dopant is unstable, which in turn promotes the development of co-doping techniques. Co-doping is a very promising technique to effectively modulate the optical, electrical, magnetic, and photocatalytic properties of ZnO, as well as the ability to form various structures. In this paper, the important advances in co-doped ZnO nanomaterials are summarized, as well as the preparation of co-doped ZnO nanomaterials by using different methods, including hydrothermal, solvothermal, sol-gel, and acoustic chemistry. In addition, the wide range of applications of co-doped ZnO nanomaterials in photocatalysis, solar cells, gas sensors, and biomedicine are discussed. Finally, the challenges and future prospects in the field of co-doped ZnO nanomaterials are also elucidated. [ABSTRACT FROM AUTHOR]

The increasing oil scarcity and environmental awareness have accelerated the rise of the new energy vehicle industry, but range and cost issues have hindered the rapid popularization of new energy vehicles. The Co-free Ni-rich layered cathode materials have received a wide attention due to their high energy density, low cost, and stable raw material supply. However, its structure and electrochemical stability still need to be further improved. In this study, the electrochemical properties of LiNi 0·94 Mn 0·04 Al 0·02 O 2 (NMA), a Co-free Ni-rich layered cathode material, have been improved by co-doping of Mg, Nb, and Zr. Also, the effects of co-doping on the crystal structure, morphology and electrochemical properties of NMA cathode materials were investigated, too. The results show that the NMA material (NMA-333) with 0.9 mol% doping amount has the best electrochemical performance. The discharge-specific capacity in the first cycle at 1 C was 199.6 mAh g−1, and the capacity retention after 200 cycles reached 73.94 %, which is nearly 24 % higher than that of the original material (NMA-1.03). Meanwhile, the NMA-333 material has a relatively better rate performance, with a discharge-specific capacity of 125.2 mAh g−1 at 10 C. Moreover, the structure and morphology of the modified material were represented by SEM, TEM, XRD, and XPS. And the results showed that the co-doping modification could refine the primary particles of the NMA material, reduce the lithium-nickel mixing, and increase the lattice spacing. The XPS, SEM, and XRD of the post-cycle electrodes further showed that co-doping had stabilized the crystal structure, inhibited the generation and expansion of microcracks, and reduced the occurrence of harmful side reactions, thus improving the cycling performance of the NMA materials at high voltage. The method could be a feasible way to improve the electrochemical performance of layered high-nickel cobalt-free cathode materials. [ABSTRACT FROM AUTHOR]

Elemental doping is a promising way for enhancing the electrocatalytic activity of metal oxides. Herein, we fabricate Ti/ Ti4O7-CB-Ce anode materials by the modification means of carbon black and cerium co-doped Ti4O7, and this shift effectively improves the interfacial charge transfer rate of Ti4O7 and •OH yield in the electrocatalytic process. Remarkably, the Ti4O7-CB-Ce anode exhibits excellent efficiency of minocycline (MNC) wastewater treatment (100% removal within 20 min), and the removal rate reduces from 100 to 98.5% after five cycles, which is comparable to BDD electrode. •OH and 1O2 are identified as the active species in the reaction. Meanwhile, it is discovered that Ti/ Ti4O7-CB-Ce anodes can effectively improve the biochemical properties of the non-biodegradable pharmaceutical wastewater (B/C values from 0.25 to 0.44) and significantly reduce the toxicity of the wastewater (luminescent bacteria inhibition rate from 100 to 26.6%). This work paves an effective strategy for designing superior metal oxides electrocatalysts. [ABSTRACT FROM AUTHOR]

An investigation examined the impact of co-doping BaTiO3 ceramics with La3+ and Nd3+ on their microstructural, dielectric, and phase transition properties. The synthesis of BaTiO3 with co-doping of La3+ and Nd3+, using the general formula Ba1-x(La1/3, Nd1/3)xTiO3 (BLNdTx) with varying concentrations of x (0%, 2%, 4%, and 8%), is achieved by the solid-state reaction technique. A temperature-dependent dielectric permittivity investigation was conducted at four distinct frequencies (1 kHz, 10 kHz, 100 kHz, 500 kHz, and 1 MHz) within the 30-200 °C temperature range. The findings indicate that the samples show a diffuse phase transition and a noticeable divergence from the typical Curie-Weiss equation. The diffuseness parameters γ for phase transition rose from 1.15 to 1.75 as x grew from 0 to 8%, respectively. The concurrent impact of surface phenomena, mechanical stress phenomena, and the external effect of grain boundaries might explain the substantial size reduction. An in-depth understanding of the grain size effect and its underlying mechanism would be advantageous for advancing and practically using BaTiO3-based ceramics and other ferroelectrics. [ABSTRACT FROM AUTHOR]

The physical parameters of solid-state produced tin and tellurium co-doped bismuth selenide polycrystalline crystals were described. Powder X-ray diffraction revealed the hexagonal structure in the samples' phase domination. A field emission scanning electron microscope was used to analyze the surface microstructure. Thermoelectric properties such as Seebeck coefficient, electrical resistivity, and thermal conductivity were analyzed in the temperature range 10–350 K. The electrical resistivity of (Bi0.96Sn0.04)2Se2.7Te0.3 was found to be four times lower than that of pure Bi2Se3. Due to donor-like effects and antisite defects, the Seebeck coefficient demonstrates a p- to n-type semiconducting transition. When compared to pure Bi2Se3, power factor and thermoelectric figure of merit of (Bi0.96Sn0.04)2Se2.7Te0.3 is found to increase by 15 and 9 times respectively. Tellurium excess boosts tin vacancies, promoting the p to n-type transition in (Bi0.96Sn0.04)2Se2.7Te0.3, making it a good option for low temperature thermoelectric and sensor applications. [ABSTRACT FROM AUTHOR]

Multi-element co-doping and its impact on the stability of the ultrahigh-Ni cathodes during extended cell cycling have not yet been fully established. Synergistic mechanisms still need to be thoroughly understood, and there is potential for further enhancing the structural stability and electrochemical performance of layered cathode materials. In this work, an Nb and Mg co-doped ultrahigh-Ni cathodes (LiNi 0. 92 Co 0. 06 Mn 0. 02 O 2) is prepared by solid-state synthesis methods. The effect of Nb and Mg dopants on the microstructure and electrochemical properties are systematically investigated. It is found that the Nb dopant can overcome the main shortcomings provided by Mg doping, including increasing the unit cell volume, suppress harmful phase transformation and enhancing lithium-ion diffusion kinetics. The cathode materials with optimized amounts of Nb and Mg dopants are demonstrated with excellent electrochemical performances. They reveal a specific capacity of 191 mAh g−1 at 1C with a good capacity retention of 92.8% after 500 cycles and a rated capacity of 141 mAh g−1 at 10C. It is also found that excessive Nb doping could lead to a decrease in rhombohedral ordering for crystal lattices, resulting in reduced structural stability and cyclability. This work investigates the strategy of Nb and Mg co-doping for enhancing electrochemical performances of ultrahigh-Ni cathodes, and the results obtained from this work can provide insights into improve the cyclability of these materials. [ABSTRACT FROM AUTHOR]

A fluorine-free route has been developed to fabricate V/Pr co-doped zircon (ZrSiO 4) ceramic pigments with Na 3 VO 4 and Pr(NO 3) 3 ·6H 2 O as colourants. The as-prepared pigments were characterized by XRD, Raman, XPS, UV–vis, FE-SEM, TEM and automatic colourimeters. The results show that Na 3 VO 4 can not only act as colourant to produce blue hue, but as mineralizer to accelerate the formation of V/Pr co-doped ZrSiO 4 pigment. A colour tuning between blue, green and yellow can be achieved by increasing the mole ratio of Pr/V, and the most intense yellow hue (L* = 74.55, a* = −0.38, b* = 46.82) is obtained at a mole ratio of Pr/V = 0.5. Both Pr4+ and Pr3+ cations are co-existed in the pigments, where Pr4+ contributes to the generation of yellow hue while Pr3+ undermines the yellow hue. The good chromatic ability in glaze at high temperature suggest its potential application in ceramic decoration. [ABSTRACT FROM AUTHOR]

Persistent emission is a well-known property of cadmium metasilicate (CdSiO 3) doped and co-doped with rare earth ions due to the ease of choosing the desired luminescence colour, as well as the possibility of adjusting the emission colour and the luminescence duration. Experimental work has demonstrated that combinations of different rare earth ions can produce different emission spectra colours as well as modify the lifetime of emissions. Theoretical work demonstrated a preference of single dopants to substitute cadmium sites with a Cd-vacancy as a compensation mechanism. To help elucidate the luminescent mechanisms through structural modification and consequently modification of the crystal field generated in the material by the defective region, in this work, several configurations for combined defects were tested considering the distance and preferential configuration of all the defects that comprise the system, as well as the possibility of a high concentration of these defects. Results showed a preferential arrangement for the incorporation of a Cd-vacancy as a form of charge compensation. The arrangement forms an angle closer to 180° considering the Cd-vacancy as vertex and presents a distance of around 7 Å between rare earth ions. It was also identified that the formation of a single pair with two different RE3+ ions close to a cadmium vacancy are minimally energetically more favourable to be formed in relation to clusters of dopants and co-dopants. This indicates that at low doping concentrations, RE3+ dopant pairs will form separately, but by increasing the concentration it is possible to form a cluster of defects involving RE3+. This may explain the low concentrations of dopants in this matrix. The distortion caused in the local lattice by the presence of a RE3+ pair of different dopants is bigger than the distortion caused by a RE3+ pair of dopants of the same chemical species. Therefore, CdSiO 3 : RE13+, RE23+ has a crystal field that is different from the crystal field experienced by RE3+ as a single dopant and the presence of the co-dopant ion will modify the luminescence of the system even though the generating defect of the luminescent centre remains the same. [ABSTRACT FROM AUTHOR]

An electrochemical sensor was developed using N, P-codoped biocarbon modified glassy carbon electrode for ultrasensitive nitrite detection. The biocarbon was derived from sustainable chitosan biopolymer integrated with phosphorus functionality via triphenylphosphine. Controlled hydrothermal treatment and pyrolysis yielded a hierarchically porous structure with high surface area of 152 m2/g favorable for electrocatalysis. X-ray photoelectron spectroscopy confirmed uniform N, P-doping within the carbon lattice. Using ferro/ferricyanide redox probe, an excellent electron transfer rate constant of 18.7 s− 1 was obtained. Amperometric method displayed two wide linear ranges of 0.1–500 µM and 500–2000 µM nitrite with a remarkably low limit of detection down to 90 nM. This sensor showed negligible interference from common metal ions and relative standard deviation below 5%. Over 95% initial current response was retained following continuous usage for 25 days, highlighting satisfactory stability. Successful practical analysis of various food products further proves the superiority over previous carbon nanomaterial based electrochemical nitrite sensors in terms of tunability, cost-effectiveness and scalability for real sample assays. [ABSTRACT FROM AUTHOR]

(KMg)3+ co-doped Sc 2 W 3 O 12 ceramics have been prepared via co-precipitation method. Effects of (KMg)3+ co-doping amount and sintering temperature on the phase constitution, microstructure, morphology, and negative thermal expansion (NTE) performance of K x Mg x Sc 2- x W 3 O 12 (0 ≤ x ≤ 1.25) ceramics were studied. Results indicate that: Sc3+ cations can be substituted by (KMg)3+ dual-cations and a composition-induced structural phase transition was observed in K x Mg x Sc 2- x W 3 O 12. For x ≤ 0.25, orthorhombic Sc 2 W 3 O 12 gradually changed into hexagonal K x Mg x Sc 2- x W 3 O 12 and coexisted. Single phase K x Mg x Sc 2- x W 3 O 12 with hexagonal symmetry can be prepared for 0.25 < x ≤ 1. When x ≥ 1.25, (KMg)3+ substitution reaches its solid solution limit in Sc 2 W 3 O 12 , and impurity MgWO 4 formed in the samples. As co-doping amount x increased, the NTE performance of the K x Mg x Sc 2- x W 3 O 12 (0 ≤ x ≤ 1) ceramics gradually enhanced. The coefficient of thermal expansion (CTE) of K x Mg x Sc 2- x W 3 O 12 (0 ≤ x ≤ 1) ceramics enhanced from −2.14 × 10−6 °C−1 to −19.68 × 10−6 °C−1 in 30–700 °C. With the increase of sintering temperature from 800 to 1100 °C, the grains grew up and the density of the K 0.75 Mg 0.75 Sc 1.25 W 3 O 12 ceramics increased as well, and the NTE performance was also improved. The linear CTE of K 0.75 Mg 0.75 Sc 1.25 W 3 O 12 ceramics enhances from −2.15 × 10−6 °C−1 to −14.70 × 10−6 °C−1 in 30–700 °C. [ABSTRACT FROM AUTHOR]

Compressed leachate is a contaminated liquid containing various organic and inorganic pollutants produced in municipal refuse transfer stations, which pollute soil and groundwater, posing serious risks to the environment and human health. The Environmental Technology Co., Ltd. (Shenzhen, Guangdong Province, South China) treated compressed leachate obtained from a refuse transfer station. The chemical oxygen demand (COD) (641.2 mg/L) of treated compressed leachate did not meet the wastewater quality standards in China for discharge into municipal sewers (COD ≤ 500 mg/L) and the company's design discharge requirements (COD ≤ 400 mg/L). Therefore, their further in-depth treatment is necessary. To this end, waste tobacco leaves were used as the biotemplate herein, and Fe/La-co-doped TiO2 (xFe,yLa)-TTiO2(g) was synthesized using a solvothermal-assisted biotemplating method. The photocatalytic depth treatment of compressed leachate was performed under simulated solar light using the prepared catalysts. After (3Fe,3La)-TTiO2(g) treatment, the COD of the leachate decreased from 641.2 to 280.1 mg/L, and the COD removal rate was 1.2, 1.1, and 1.6 times higher than that of pure Fe-doped, La-doped and non-biological template TiO2, respectively. Characterization confirmed that the biological template endowed the catalyst with a unique morphology and high specific surface area. Its rich activity sites are conducive to enhancing the adsorption capacity of pollutants and providing an ideal place for photocatalytic reactions. Co-doping with iron and lanthanum ions altered the band structure of TiO2 and promoted the interconversion of Fe3+/Fe2+ and La3+/La2+ during photocatalysis. First-principles density functional theory simulations demonstrated that co-doping Fe and La in TiO2 created impurity levels that facilitated the transfer of photogenerated electrons. This study provides a new purification pathway for the depth treatment of compressed leachate. [ABSTRACT FROM AUTHOR]