Search Results (18)

The practical application of vanadium-based cathode materials in aqueous zinc-ion batteries (AZIBs) is severely hindered by vanadium dissolution, low electronic conductivity, and sluggish reaction kinetics in aqueous electrolytes. In this work, a three-dimensional confined V₂O₅@ nitrogen-doped carbon (V₂O₅@NC) composite was rationally designed and constructed through a dual-regulation strategy combining oxygen-vacancy engineering and conductive network enhancement. In this architecture, the nitrogen-doped carbon framework provides a highly conductive network and robust structural support, while in situ carbonization induces the generation of oxygen vacancies within V₂O₅. These oxygen vacancies cause lattice distortion and expand the interlayer spacing, thereby accelerating Zn²⁺ diffusion and improving reaction kinetics. Benefiting from this synergistic effect, the V₂O₅@NC electrode exhibits an excellent specific capacity of 437 mAh g⁻¹ at 0.1 A g⁻¹ and maintains a remarkable 89.3% capacity retention after 2000 cycles at 3 A g⁻¹, demonstrating outstanding rate performance and cycling stability. This study provides new insights and an effective design strategy for developing high-performance cathode materials for next-generation aqueous zinc-ion batteries. Full article

The role of metal additives in the synthesis of composite materials based on the silicon and carbon-containing materials to create the desired structural and adsorption properties is analyzed. A two-step procedure was applied to obtain a series of nanocomposites doped with metal oxides. Various techniques were used to characterize the phase composition and the textural, structural, morphological, and thermal properties of the synthesized materials: X-ray diffraction, scanning electron microscopy, Raman spectroscopy, nitrogen adsorption–desorption, and thermal analysis. The adsorption processes on the obtained nanocomposites were studied for aqueous solutions of aniline, benzoic acid, and phenol. The influence of the metal additives on the formation of carbonaceous structures, the adsorption efficiency, and the adsorption mechanism was determined. The synthesized composites show mesoporous and microporous structures, with varied proportions of both pore types. They are differentiated, taking into account the quality of the carbon material (defect density and degree of graphitization), which decreases in the Co > Ni > Cu > Zn > SiO line. The complex effect of the factors determining the adsorption mechanism and efficiency was investigated: textural, structural, and morphological characteristics and the role of the active metal centers. Generally, the results provide valuable insights into the adaptation of hybrid materials for various industrial applications and underline their versatility. Full article

Amorphous carbon and its heteroatom-doped derivatives often exhibit wrinkled, defective, porous structures, and find wide applications in the fields of energy storage and catalysis. To date, although many methods for preparing doped carbon materials have been reported, the preparation process is relatively complex, and there are still few simple methods available. Therefore, it is necessary to further develop simple and feasible preparation methods. In this study, we employed commercially available manganese disodium ethylenediaminetetraacetate (EDTA-Na₂Mn, serving as both carbon and nitrogen sources) as the precursor. Through thermal decomposition under a nitrogen atmosphere, a nitrogen-doped carbon composite embedded with manganese monoxide (MnO) was initially obtained. Subsequently, hydrochloric acid etching was applied to remove the MnO phases, yielding the final product: nitrogen-doped carbon, denoted as C-N-Mn. Notably, the carbonization and nitrogen-doping processes were simultaneously accomplished during pyrolysis, thereby streamlining the synthesis route for nitrogen-doped carbons. To demonstrate the versatility of this approach, we extended the methodology to two additional metal–organic salts (EDTA-Na₂Zn and EDTA-NaFe), successfully synthesizing nitrogen-doped carbon materials (C-N-Zn and C-M-Fe) in both cases. The phase composition, morphology, microstructure, specific surface area, and pore volume of the products were systematically characterized using X-ray diffraction (XRD), scanning/transmission electron microscopy (SEM/TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption/desorption analysis. These nitrogen-doped carbons exhibit high specific surface areas and tunable pore volumes, suggesting their potential applicability in energy storage systems. Full article

In this study, a V₂O₃/carbon (V₂O₃/C) composite was synthesized using zeolitic imidazolate framework 8 (ZIF-8) as both a sacrificial template and in situ carbon source. The composite was prepared by mixing ZIF-8 with NH₄VO₃, followed by annealing at 800 °C, resulting in nanoscale V₂O₃ embedded in a nitrogen-doped porous carbon matrix. Fabricated into a thin-film cathode via alternating current electrophoretic deposition (AC-EPD), the composite exhibited mixed capacitive–diffusion-controlled charge storage behavior with favorable Zn²⁺ transport kinetics, as confirmed by a b-value analysis (b = 0.72) and diffusion coefficient measurements (D_Zn = 6.2 × 10⁻¹¹ cm²/s). Notably, the cathode displayed photoresponsive redox behavior under 450 nm illumination, enhancing the Zn-ion kinetics. These findings demonstrate the potential of MOF-derived V₂O₃/C composites for high-performance, photo-enhanced zinc-ion energy storage applications. Full article

Eu₂SmSbO₇ and ZnBiEuO₄ were synthesized for the first time using the hydrothermal method. Eu₂SmSbO₇/ZnBiEuO₄ heterojunction photocatalyst (EZHP) was synthesized for the first time using the solvothermal method. The crystal cell parameter of Eu₂SmSbO₇ was 10.5547 Å. The band gap width of Eu₂SmSbO₇ was measured and found to be 2.881 eV. The band gap width of ZnBiEuO₄ was measured and found to be 2.571 eV. EZHP efficiently degraded the pesticide chlorpyrifos under visible light irradiation (VLID). After VLID of 160 min, the conversion rate of the chlorpyrifos concentration reached 100%, while the conversion rate of the total organic carbon (TOC) concentration was 98.02% using EZHP. After VLID of 160 min, the photocatalytic degradation conversion rates of chlorpyrifos using EZHP were 1.13 times, 1.19 times, and 2.84 times those using Eu₂SmSbO₇, ZnBiEuO₄, and nitrogen-doped titanium dioxide (N-doped TiO₂), respectively. The photocatalytic activity could be ranked as follows: EZHP > Eu₂SmSbO₇ > ZnBiEuO₄ > N-doped TiO₂. The conversion rates of chlorpyrifos were 98.16%, 97.03%, 96.03%, and 95.06% for four cycles of experiments after VLID of 160 min using EZHP. This indicated that EZHP was stable and could be reused. In addition, the experiments with the addition of capture agents demonstrated that the oxidation removal ability of three oxidation free radicals for degrading chlorpyrifos obeyed the following order: hydroxyl radical > superoxide anion > holes. This study examined the intermediates of chlorpyrifos during the photocatalytic degradation of chlorpyrifos, and a degradation path was proposed, at the same time, the degradation mechanism of chlorpyrifos was revealed. This study provides a scientific basis for the development of efficient heterojunction photocatalysts. Full article

A series of ZnO-doped nitrogen-carbon materials (xZnO-N-C) with ZnO contents of 5–40% are prepared by a vacuum curing–carbonization strategy using polyamide-imide as the N-C source and zinc nitrate as the metal source for propane dehydrogenation (PDH). 20ZnO-N-C exhibits outstanding initial activity (propane conversion of 35.2% and propene yield of 24.6%) and a relatively low deactivation rate (0.071 h⁻¹) at 600 °C. The results of detailed characterization show that small ZnO nanoparticles (5.5 nm) with high dispersion on the catalyst can be obtained by adjusting the ZnO loading. Moreover, more nitrogen-based species, especially ZnN_x species, are formed on 20ZnO-N-C in comparison with 20ZnO-N-C-air prepared via curing carbonization without vacuum, which may contribute to the higher product selectivity and catalytic stability of 20ZnO-N-C. The active sites for the PDH reaction on the catalyst system are proposed to be C=O species and Zn²⁺ species. Moreover, the carbon deposition and the aggregation of ZnO nanoparticles are the causes of activity loss on this catalyst system. Full article

Different concentrations (1, 3 and 5 wt%) of dysprosium (Dy³⁺)-doped ZnO/SnS (ZSD) nanophotocatalysts using the one-step facile hydrothermal method at 230 ℃ are presented. Their structure, morphological appearance, inclusion of constituent elements, bandgap engineering and luminescent nature are confirmed by the XRD, TEM, XPS, UV-DRS and PL techniques. The photocatalytic activity (PCA) of the prepared nano photocatalysts is studied in the presence of a model pollutant MB under solar light illumination. The degradation kinetics and charge separation mechanism of the ZSD photocatalysts are also presented. Our XRD analysis showed the mixed-phase occurrence of ZnO (hexagonal) and SnS (orthorhombic) from their JCPDS numbers with no additional traces of a doping element, which in turn indicates the purity, substantial crystal structure and high dispersion of the samples. TEM micrographs revealed the appearance of a flake structure and more agglomeration when increasing the dopant concentration. The XPS spectra confirmed the Zn²⁺, Sn²⁺, S²⁻, O²⁻ and Dy³⁺ oxidation states of the constituent elements along with carbon and nitrogen peaks. The Tauc plots showed a decreasing trend in the optical bandgap, i.e., a redshift due to the loading of Dy³⁺ ions into Sn²⁺ ions. The lower recombination rate of photoinduced e⁻-h⁺ pairs is noted when increasing the Dy³⁺ ion content; i.e., the luminescent intensity is suppressed when increasing the concentration of Dy³⁺ ions. The obtained degradation efficiency of the MB dye using the ZSD3 nano photocatalyst is around 98% for a duration of 120 min under solar light irradiation. The prepared ZSD photocatalyst follows pseudo first-order kinetics, and the evidence for attaining a robust Z-scheme PCA is presented in the form of the charge separation mechanism. Full article

This Special Issue includes 12 research papers on the development of various materials for adsorbing different contaminants in water, such as Sb, Cr(VI), Cu(II), Zn(II), fluorine, phenol, dyes (indigo carmine, Congo red, methylene blue, and crystal violet), and drugs (dlevofloxacin, captopril, and diclofenac, and paracetamol). The commercial, natural, and synthetic materials used as adsorbents comprise commercial activated carbon, natural clay and montmorillonite, biosorbent based on sugarcane bagasse or algal, graphene oxide, graphene oxide-based magnetic nanomaterial, mesoporous Zr-G-C₃N₄ nanomaterial, nitrogen-doped core–shell mesoporous carbonaceous nano-sphere, magnetic Fe-C-N composite, polyaniline-immobilized ZnO nanorod, and hydroxy-iron/acid–base-modified sepiolite composite. Various operational conditions are evaluated under batch adsorption experiments, such as pH, NaCl, solid/liquid ratio, stirring speed, contact time, solution temperature, initial adsorbate concentration. The re-usability of laden materials is evaluated through adsorption–desorption cycles. Adsorption kinetics, isotherm, thermodynamics, and mechanisms are studied and discussed. Machine learning processes and statistical physics models are also applied in the field of adsorption science and technology. Full article

The pyrolytic carbon of polymer adsorbent resin (SAP) is used as a waste carbon source, which can be used as a porous carbon network via pyrolysis to remove surface sodium carbonate and other substances. In this paper, a ZnFe₂O₄/nitrogen-doped porous carbon composite was prepared using the template method. Through the high-temperature carbonization of a polymer and crystallization of inorganic elements, the morphology of the composite showed uniform load characteristics. This well-defined structure and morphology facilitate the transport of Li⁺, enhance the effective contact area with the electrolyte, and provide a wealth of active sites. For the SAP-Fe/Zn anode, at a high current density of 0.1 A g⁻¹, the reversible capacity of the anode reached 753 mAh g⁻¹ after 200 cycles, showing excellent magnification performance. The final modified SAP-Fe/Zn&NC electrode had a reversible capacity of 205.6 mAh g⁻¹ after 1000 cycles at the high current density of 2 A g⁻¹, and the cycle retention rate was as high as 80.7%. The enhanced electrochemical performance can be attributed to the abundant active sites and shortened diffusion pathway of the composite. This ensures adequate conversion reactions during the Li-litization process between Zn, Fe, and Li⁺, alleviates volume expansion, and prevents comminution/aggregation during long cycles at high current densities. Full article

Metal/nitrogen-doped carbon single-atom catalysts (M−N−C SACs) show excellent catalytic performance with a maximum atom utilization and customizable tunable electronic structure. However, precisely modulating the M−N_x coordination in M−N−C SACs remains a grand challenge. Here, we used a N-rich nucleobase coordination self-assembly strategy to precisely regulate the dispersion of metal atoms by controlling the metal ratio. Meanwhile, the elimination of Zn during pyrolysis produced porous carbon microspheres with a specific surface area of up to 1151 m² g⁻¹, allowing maximum exposure of Co−N₄ sites and facilitating charge transport in the oxygen reduction reaction (ORR) process. Thereby, the monodispersed cobalt sites (Co−N₄) in N-rich (18.49 at%) porous carbon microspheres (CoSA/N−PCMS) displayed excellent ORR activity under alkaline conditions. Simultaneously, the Zn−air battery (ZAB) assembled with CoSA/N−PCMS outperformed Pt/C+RuO₂-based ZABs in terms of power density and capacity, proving that they have good prospects for practical application. Full article

Rational design of composite nanostructured photocatalytic systems with good sunlight absorption capacity and efficient charge separation and transfer ability is an urgent problem to be solved in photocatalysis research. Here, a ZnMn₂O₄ decorated three-dimensional carbon nitride with O, C co-doping, and nitrogen defect composite photocatalytic system was prepared using a simple hydrothermal method and subsequent calcination method. For the photocatalytic reactions, the presence of heterostructures, C, O co-doping, and nitrogen defects greatly promotes the separation and transfer of charges at the semiconductor/semiconductor interface under the local electric field, thereby extending its service life. The photocatalytic degradation efficiency of sulfamethoxazole in water is as high as 94.3% under the synergistic effects, which is also suitable for the complex water environment. In addition, the synthesized photocatalyst has good chemical stability and recyclability. This study provides a new opportunity to solve the problem of environmental pollution. Full article

Through high-temperature sintering and carbonization, two Co/ZnO nitrogen-doped porous carbon (NC) composites derived from ZIF-8 and ZIF-67 were manufactured for use as anodes for Li ion batteries: composite-type Co/ZnO-NC and core-shell-type Co@ZnO-NC. X-ray diffraction analysis, scanning electron microscopy, and the Brunauer–Emmett–Teller (BET) method were performed to identify the pore distribution and surface morphology of these composites. The findings of the BET method indicated that the specific surface area of Co/ZnO-NC was 350 m²/g, which was twice that of Co@ZnO-NC. Electrochemical measurements revealed that Co@ZnO-NC and Co/ZnO-NC had specific capacities of over 400 mAh g⁻¹ at a current density 0.2 A g⁻¹ after 50 cycles. After 100 cycles, Co/ZnO-NC exhibited a reversible capacity of 411 mAh g⁻¹ at a current density of 0.2 A g⁻¹ and Co@ZnO-NC had a reversible capacity of 246 mAh g⁻¹ at a current density of 0.2 A g⁻¹. The results indicated that Co/ZnO-NC exhibited superior electrochemical performance to Co@ZnO-NC as a potential anode for use in Li ion batteries. Full article

Originally, the new catalyst Bi₂SmSbO₇ was synthesized by the hydrothermal synthesis method or by the solid-phase sintering method at a lofty temperature. A solvothermal method was utilized to prepare a Bi₂SmSbO₇/ZnBiYO₄ heterojunction photocatalyst (BZHP). The crystal structure of Bi₂SmSbO₇ belonged to the pyrochlore structure and face-centered cubic crystal system by the space group of Fd3m. The cell parameter a was equivalent to 10.835(1) Å (Bi₂SmSbO₇). With Bi₂SmSbO₇/ZnBiYO₄ heterojunction (BZH) as the photocatalyst, the removal rate (RR) of direct orange (DO) and the total organic carbon were 99.10% and 96.21% after visible light irradiation of 160 min (VLI-160M). The kinetic constant k toward DO concentration and visible light irradiation time (VLI) with BZH as photocatalyst reached 2.167 min⁻¹. The kinetic constant k, which was concerned with total organic carbon, reached 0.047 min⁻¹. The kinetic curve that came from DO degradation with BZH as a catalyst under VLI conformed to the second-order reaction kinetics. After VLI-160M, the photocatalytic degradation (PD) removal percentage of DO with BZH as the photocatalyst was 1.200 times, 1.268 times or 3.019 times that with Bi₂SmSbO₇ as the photocatalyst, ZnBiYO₄ as the photocatalyst or with nitrogen-doped titanium dioxide as the photocatalyst. The photocatalytic activity (PA) was as following: BZH > Bi₂SmSbO₇ > ZnBiYO₄ > nitrogen-doped titanium dioxide. After VLI-160M for three cycles of experiments with BZH as the photocatalyst, the RR of DO reached 98.03%, 96.73% and 95.43%, respectively, which meant that BZHP possessed high stability. By using the experiment of adding a trapping agent, the oxidative purifying capability for degradation of direct orange, which was in gradual depressed order, was as following: hydroxyl radical > superoxide anion > holes. Finally, the possible degradation pathway and degradation mechanism of DO were discussed systematically. A new high active heterojunction catalyst BZHP, which could efficiently remove toxic organic pollutants such as DO from dye wastewater after VLI, was obtained. Our research was meant to improve the photocatalytic property of the single photocatalyst. Full article

Nitrogen-doped porous carbon (NPC) materials were successfully synthesized via a Zn-containing metal-organic framework (Zn-MOF). The resulting NPC materials are characterized using various physicochemical techniques which indicated that the NPC materials obtained at different carbonization temperatures exhibited different properties. Pristine MOF morphology and pore size are retained after carbonization at particular temperatures (600 °C-NPC₆₀₀ and 800 °C-NPC₈₀₀). NPC₈₀₀ material shows an excellent surface area 1192 m²/g, total pore volume 0.92 cm³/g and displays a higher CO₂ uptake 4.71 mmol/g at 273 k and 1 bar. Furthermore, NPC₆₀₀ material displays good electrochemical sensing towards H₂O₂. Under optimized conditions, our sensor exhibited a wide linearity range between 100 µM and 10 mM with a detection limit of 27.5 µM. Full article

As one of the most promising platinum group metal-free (PGM-free) catalysts for oxygen reduction reaction (ORR), Fe–N–C catalysts with a high density of FeN_x moieties integrated in a highly graphitic carbon matrix with a proper porous structure have attracted extensive attention to combine the high activity, high stability and high accessibility of active sites. Herein, we investigated a ZnCl₂/NaCl eutectic salts-assisted ionothermal carbonization method (ICM) to synthesize Fe–N–C catalysts with tailored porous structure, high specific surface area and a high degree of graphitization. However, it was found to be challenging to anchor a high density of FeN_x sites onto highly graphitized carbon. Iron precursors with preexisting Fe–N coordination were required to form FeN_x sites in the nitrogen-doped carbon with a high degree of graphitization, while individual Fe and N precursors led to a Fe–N–C catalyst with poor-ORR activity. This provides valuable insights into the synthesis-structure relationship. Moreover, the FeN_x moieties were identified as the major active sites in acidic conditions, while both FeN_x sites and Fe₂O₃ were found to be active in alkaline medium. Full article