Search Results (2,599)

Biochar was synthesized through high-temperature pyrolysis, and a biochar-supported nitrogen and sulfur co-doped BiOBr (BC/N,S-BiOBr) photocatalyst was successfully prepared via a one-step solvothermal method, which was applied for the degradation of tetracycline (TC), a widely detected representative antibiotic pollutant, in aqueous solution. This study systematically investigated the effects of catalyst type, initial solution pH, catalyst dosage and initial TC concentration on the photocatalytic degradation process. The experimental results showed that the as-prepared BC/N,S-BiOBr composite exhibited a flower-like nanosphere morphology, characterized by a more complete three-dimensional hierarchical structure, larger specific surface area and suitable optical absorption band, which endowed the composite with significantly improved visible-light absorption capability. Under the optimized reaction conditions (pH = 5, catalyst dosage of 0.7 g/L, initial TC concentration of 10 mg/L), the degradation efficiency of TC over BC/N,S-BiOBr reached 98% after 50 min of visible-light irradiation. In situ electron paramagnetic resonance (EPR) spectroscopy combined with radical quenching experiments confirmed that the modified composite contained abundant oxygen vacancies, and the main reactive species governing TC degradation were identified as photogenerated holes (h⁺), hydroxyl radicals (·OH) and superoxide radicals (·O₂⁻), with their contribution to TC degradation following the order of h⁺ > ·OH > ·O₂⁻. In summary, by converting municipal sludge into biochar-supported N,S-BiOBr photocatalyst, the modified BC/N,S-BiOBr composite exhibits faster photocatalytic reaction kinetics and higher tetracycline removal efficiency compared with pristine BiOBr, while simultaneously enabling waste resource recovery, solar energy exploitation, and water purification, thereby comprehensively promoting sustainable development in terms of environmental remediation, resource circulation, and low-carbon operation. Full article

Heterojunction construction is a key strategy for enhancing the photocatalytic efficiency of semiconductors. In this study, a composite of sulfur-doped CoAl layered double hydroxide and Fe-doped C₃N₅(S-CoAl-LDH/Fe-C₃N₅) was developed via a hydrothermal method for the synergistic oxidation-reduction degradation of the organic pollutant tetracycline (TC) and the detoxification of heavy-metal ions (Cr(VI)) in wastewater. After optimization, the CAF-4 heterojunction (the composite with 20 wt% Fe-C₃N₅ loading) exhibited TC degradation rates 5.51 and 3.97 times higher than those of pristine Fe-C₃N₅ and S-CoAl-LDH, respectively; under simulated sunlight, the Cr(VI) reduction rates were 11.75 and 4.22 times higher, respectively. The as-prepared catalyst demonstrated good stability across a wide pH range, in the presence of various cations and anions, and in different water matrices. Under coexisting pollutant conditions, the composite still achieved removal efficiencies of 82.1% for Cr(VI) and 64.7% for TC. After five cycling runs, the adsorption-photocatalytic efficiency of the composite for the removal of Cr(VI) and TC composite pollutants remained above 80%. Overall, CAF-4 shows great promise for application in the adsorption-photocatalytic treatment of wastewater containing combined Cr(VI) and TC pollution. Full article

The copper ferrite/nitrogen-doped biochar (CuFe₂O₄/N_x-BC) was synthesized by a one-step sol–gel pyrolysis method, and its efficiency in activating PS to degrade MB was evaluated. The influences of preparation conditions, degradation conditions, and common anions on the degradation efficiency of MB were investigated, and the mechanism of CuFe₂O₄/N_0.5-BC activating PS was inferred. The results showed the saturation magnetization of CuFe₂O₄/N_0.5-BC was 25.53 emu/g. Under the optimal degradation conditions, compared to PS alone, the degradation efficiency of MB in the CuFe₂O₄/N_0.5-BC + PS system increased from 26.2% to 94.1%, the reaction rate constant in the CuFe₂O₄/N_0.5-BC + PS system (0.02954 min⁻¹) was 9.12 times higher than that in the PS alone system (0.00324 min⁻¹); Compared to the CuFe₂O₄/BC system, the degradation efficiency of MB in the CuFe₂O₄/N_0.5-BC + PS system increased from 34% to 94.1%, while the reaction rate constant is 1.1 times that in the CuFe₂O₄/BC + PS system. After CuFe₂O₄/N_0.5-BC underwent five cycles of application, the degradation efficiency of MB in the CuFe₂O₄/N_0.5-BC + PS still reached 87.5%. SO₄^•− plays a major role, •OH played a certain role and O₂^•− was also responsible for the degradation of MB in the CuFe₂O₄/N_0.5-BC + PS system. CuFe₂O₄/N_0.5-BC is a green and effective catalyst for the PS-AOP method to treat MB-contaminated water. Full article

Industrial wastewater in Islamabad has led to serious environmental and human health impacts due to the release of endocrine-disrupting chemicals (EDCs) and volatile organic compounds (VOCs) in the water bodies. The advent of wastewater treatment technologies has led to the development of novel approaches like the use of an electrocatalyst for efficient and safe removal of toxic contaminants from the wastewater. In this study, an efficient tri-metallic NiCoFe₂-LDH electrocatalyst was prepared by optimizing the metal ratios in the synthesis process using a co-precipitation method. The catalyst was characterized by various tools such as UV-visible spectroscopy, SEM, EDX, and FTIR. A three-electrode electrochemical system (counter, reference, and working electrodes) was used for electrocatalytic activity and simultaneous removal of EDCs from the wastewater. Wastewater samples were collected from selected locations along the industrial discharge channel (Nullah Lai) in the industrial zone of Islamabad city. The physio-chemical analysis showed significant water pollution, including EDCs, VOC, and heavy metals. The electrochemical treatment using NiCoFe₂-LDH demonstrated high efficiency across different scan rates (5 to 50 mV/s) and voltages (−0.02 to 1.6 V); for instance, at 1.6 V, the current density rises from 10 mA/cm² in Scan 5 to 50 mA/cm² in Scan 50. Furthermore, COD levels were significantly reduced by 74.9%, from 665.6 mg/L to 166.4 mg/L, after electrochemical treatment with NiCoFe₂-LDH. GCMS analysis of organics revealed that the electrochemical process was effective in reducing several EDC- and VOC-related peak groups. Overall, this study highlights the potential of the electrochemical approach for treating EDC-contaminated wastewater and its applicability as a sustainable solution for industrial wastewater treatment. Full article

The development of materials capable of combining efficient CO₂ capture with catalytic conversion is an important objective in carbon utilization strategies. In this work, a series of Ni/ZSM-5 catalysts prepared by different methods and characterized by different nickel loadings and speciation was investigated by FTIR spectroscopy, complemented by structural characterization and catalytic CO₂ hydrogenation measurements, to establish the CO₂ coordination mode and the relationship between nickel speciation, molecular CO₂ adsorption, and catalytic performance. FTIR spectroscopy demonstrates that molecular CO₂ is preferentially adsorbed on Ni²⁺ cations. Detailed investigation of the low-loaded catalyst, in which nickel is predominantly present as highly dispersed, mainly exchanged Ni²⁺ cations, shows that adsorption initially proceeds through end-on Ni²⁺–CO₂ species, which progressively transform into geminal Ni²⁺(CO₂)₂ complexes with increasing coverage. The adsorption geometry was established by applying the isotopic linkage isomerism (ILI) approach using ¹³C¹⁶O₂–¹³C¹⁸O₂ isotopic mixtures. In contrast, CO₂ adsorption on Ni⁺ sites formed upon reduction with CO is negligible, whereas these sites strongly bind CO, a key intermediate in CO₂ hydrogenation. FTIR experiments performed under CO₂/H₂ mixtures reveal the formation of surface formate species at low temperatures, followed by the appearance of adsorbed and subsequently gaseous CO. For the catalysts containing larger amounts of nickel, in which less electrophilic and more readily reducible Ni species are additionally present, methane was also detected in the gas phase, and the onset of the reaction processes shifted to lower temperatures. The FTIR observations closely parallel the catalytic behaviour. Overall, the results demonstrate that isolated Ni²⁺ cations provide effective sites for molecular CO₂ adsorption, whereas its subsequent catalytic hydrogenation requires more readily reducible nickel species capable of generating metallic sites under reaction conditions. Full article

The development of highly efficient catalysts is important for the photothermal catalytic oxidation of volatile organic compounds (VOCs). Herein, MIL-100(Fe) was used as the sacrificial template to prepare MnFeO_x catalysts with different Mn contents through the impregnation–calcination method, and their performance in photothermal catalytic oxidation of toluene was investigated. The results show that the content of Mn significantly affects the crystal phase structure, pore properties, surface chemical state, and optical response of the catalyst. Among them, 30%MnFeO_x exhibits the best photothermal catalytic activity, with T₅₀ and T₉₀ being 211 and 237 °C, respectively, which are significantly lower than those of FeO_x (232 and 260 °C). Characterization results suggested that the introduction of Mn caused the bandgap of FeO_x to decrease from 1.96 to 1.67 eV. Meanwhile, the surface Fe²⁺, adsorbed oxygen (O_ads) species, and oxygen vacancies were increased, enhancing visible light absorption and gaseous oxygen species adsorption and activation, which promoted the photothermal catalytic oxidation of toluene. Additionally, the 30%MnFeO_x catalyst presented good thermal stability and water resistance. Furthermore, during the reaction process, the in situ activation of the catalyst’s surface induced the increase in surface Fe²⁺, Mn^3+, and O_ads species, which enhances the photothermal catalytic activity of the catalyst. Importantly, the in situ DRIFTS results further indicate that toluene is mainly oxidized along the path of toluene → benzyl alcohol → benzoate → maleic anhydride → CO₂ and H₂O. This work provides a theoretical basis for the construction of low-cost, non-precious-metal Mn–Fe-based photothermal catalysts. Full article

Low-temperature sintering flue gas contains both nitrogen oxides (NO_x) and carbon monoxide (CO), requiring bifunctional catalysts for concurrent pollutant abatement. Herein, CuSmTi composite oxides with an identical nominal composition were synthesized via impregnation, mechanical grinding, and sol–gel methods to examine the effects of preparation route on their structure, surface properties, and catalytic performance in coupled NH₃-SCR and CO oxidation. CuSmTi-SG exhibited the best performance, achieving >40% NO_x conversion at 125 °C, complete NO_x and CO conversion at 200 °C, and nearly 100% N₂ selectivity over 100–300 °C, with stable performance over 24 h. It possessed a higher surface area (131.4 m² g⁻¹), pore volume (0.230 cm³ g⁻¹), and smaller TiO₂ crystallite size (8.5 nm) than the other catalysts. Spectroscopic analyses showed that sol–gel synthesis altered the surface electronic states of Cu and Sm species, resulting in a higher Cu⁺ fraction and greater amounts of medium-to-strong Lewis acid sites and labile surface oxygen species. In situ DRIFTS indicated that CO oxidation proceeded predominantly via a Mars–van Krevelen mechanism over Cu⁺ sites, whereas NH₃-SCR mainly followed an Eley–Rideal pathway. CO and NH₃ preferentially interacted with different surface sites, resulting in limited mutual inhibition. These results demonstrate that the preparation route can modify the structure and surface chemistry of CuSmTi catalysts without changing their nominal composition, thereby affecting their performance in low-temperature NO_x and CO abatement. Full article

A series of Ni_xCo_3−xO₄ (x = 0.75, 1, 1.5, 2, 2.25) catalysts with different Ni/Co molar ratios was fabricated via the co-precipitation method. The catalytic performance for CO oxidation and SO₂ resistance of the prepared catalysts was systematically investigated, and their physicochemical properties were characterized by XRD, SEM, BET, H₂-TPR, CO-TPD and in situ DRIFTS. The experimental results reveal that the Ni_2.25Co_0.75O₄ catalyst exhibits the optimal CO oxidation activity, achieving a CO conversion of 93.25% at 120 °C. The superior catalytic performance can be attributed to its large specific surface area, low reduction temperature, and easily activated lattice oxygen species. When exposed to SO₂ at a concentration 10 times the industrial emission limit, all catalysts exhibited varying degrees of activity loss. Among them, NiCo₂O₄ exhibited the slowest deactivation rate and showed the greatest recovery in CO conversion after SO₂ was cut off, suggesting relatively better sulfur tolerance and recoverability among the investigated catalysts. In conclusion, tuning the Ni/Co molar ratio can effectively optimize the low-temperature CO oxidation activity and sulfur resistance of Ni-Co composite oxides. This work provides a useful reference for the structural composition design and practical application of such catalysts in flue gas purification. Full article

Biochar-supported rare earth oxides are herein assessed as heterogeneous catalysts for the UV-assisted Catalytic Wet Peroxide Oxidation (UV-CWPO) treatment of pharmaceuticals under mild conditions. Catalysts were synthesized by two different pyrolysis methods (activated carbon-assisted oxygen-limited pyrolysis in a muffle furnace, and inert-gas pyrolysis in a tubular furnace under nitrogen flow), and characterized by XRD, SEM, and N₂ adsorption–desorption isotherms. Their performance in assisting 385 nm UVA-LED CWPO treatment of acetaminophen (ACE), diclofenac (DCF), and metamizole (MTZ) was assessed under circumneutral pH conditions. The biochar-supported cerium-loaded catalyst prepared by oxygen-limited pyrolysis reported the highest activity, achieving 80% ACE and 70% DCF removals within 120 min of treatment, whereas MTZ was completely removed in less than 10 min, with only 16% of the removal attributable to adsorption. Superoxide radicals dominated the degradation mechanism, and photogenerated holes and hydroxyl radicals contributed moderately. Catalyst stability (minimal activity loss and negligible cerium leaching) was confirmed over five consecutive reuses. Degradation efficiency decreased ≈12–18% because of radical scavenging losses caused by the content of inorganic ions and organic matter in tap, river, and WWTP effluent waters. Treated effluents addressed lower toxicity than untreated solutions, reinforcing the environmental safety of this treatment strategy. Full article

Anode materials play a pivotal role in a wide range of electrochemical applications, including electrolysis, energy storage, corrosion protection, and industrial oxidation processes. This review provides a comprehensive analysis of recent advances in anode materials, with particular emphasis on their structural characteristics and major preparation methods, including thermal decomposition, electrochemical deposition, sol–gel processing, and magnetron sputtering. The degradation behaviour of anodes under electrochemical operating conditions is also critically discussed, together with strategies for improving their durability and overall performance. Particular attention is given to metal oxide-coated anodes, especially those based on ruthenium oxide (RuO₂) and iridium oxide (IrO₂), which remain the most representative systems in dimensionally stable anode (DSA) research and industrial applications. Emerging coating materials, including Co₃O₄- and carbon-based catalysts, are also reviewed as promising alternatives for reducing noble metal usage while maintaining acceptable electrochemical performance. In addition, the role of intermediate layers in titanium-based anodes is examined, with emphasis on their contribution to coating adhesion, conductivity, interfacial stability, and long-term electrode performance. This review further discusses the applications of anode materials in chlorine- and oxygen-related electrochemical industries and evaluates the performance of DSAs in relation to substrate selection, coating composition, and operational requirements. Alternative furnace technologies for anode baking are also reviewed, including conventional furnace heating, laser heating, and microwave heating, together with representative industrial furnace systems such as muffle, continuous, and vacuum furnaces. Overall, this review provides an integrated overview of the current progress in anode material research and development, while highlighting the key challenges and future directions for improving anode efficiency, durability, and sustainability in industrial electrochemical applications. Full article

CO₂ methanation is a promising power-to-gas technology that enables the conversion of carbon dioxide into methane. However, the development of efficient catalysts based on naturally abundant and inexpensive support remains an important challenge. In this work, metakaolin from natural kaolin was investigated as a novel support for high-loading (30 wt.%) Ni catalysts prepared using a melt infiltration method. The influence of CeO₂ and alkaline earth metal oxides (MgO, CaO) on the physicochemical properties and catalytic performance was systematically evaluated. It was evidenced that CeO₂ improved NiO reducibility, whereas MgO and CaO promoted Ni⁰ dispersion and modified textural and surface properties. In particular, Mg addition increased the S_BET from 23 to 39 m²/g and the total pore volume from 0.06 to 0.17 cm³/g compared with the Ni-MK sample. The promoted catalysts exhibited enhanced low-temperature activity and reached approximately 80% CO₂ conversion at 400 °C, close to thermodynamic equilibrium, maintaining CH₄ selectivity above 97%. Stable catalytic performance was preserved during 24 h time-on-stream tests. The results demonstrate that metakaolin is a promising sustainable support for Ni CO₂ methanation catalysts and that melt infiltration provides a simple and effective preparation route for obtaining high nickel loading. Full article

The performance of CO₂ hydrogenation to methanol strongly depends on catalyst structure, which can be effectively regulated through the synthesis method. Herein, different sugars (xylose, glucose, fructose, and sucrose) were utilized as complexing agents in the sol–gel method to prepare Cu/ZnO/ZrO₂ catalysts with varying physicochemical properties, thereby enabling the establishment of structure–activity relationships. The catalytic test results showed that the catalyst prepared with the assistance of glucose (CZZ-Glc) exhibited superior catalytic performance, with a STY of 316.87 mg ${\mathrm{g}}_{\mathrm{cat}}^{-1}$ h⁻¹, CO₂ conversion of 12.44%, and methanol selectivity of 59.36% at 240 °C, 3 MPa, and GHSV = 12,000 mL ${\mathrm{g}}_{\mathrm{cat}}^{-1}$ h⁻¹. Structural characterizations revealed that the CZZ-Glc catalyst had a smaller particle size and a higher Cu surface area, which strengthened the interactions between active phases. Additionally, XPS results revealed that more oxygenated carbon groups (C–O and C=O) were present on the CZZ-Glc catalyst. Both features could facilitate H₂ spillover, leading to an increased concentration of surface *H species. In situ DRIFTS experiments revealed that CO₂ hydrogenation to methanol over the obtained catalyst followed the formate pathway, and that hydrogenation of adsorbed CO₂ and intermediates was obviously promoted on the CZZ-Glc catalyst. These results highlight the importance of synthesis strategy in regulating catalyst structure and provide new insights into the development of high-performance catalysts for CO₂ hydrogenation to methanol. Full article

Transition metal phosphides (TMPs) have gained significant attention from researchers in the field of catalytic hydrogenation due to their excellent properties. However, existing studies have rarely explored the targeted regulation of the degree of crystal plane exposure of the Ni₁₂P₅ catalyst. It is difficult to significantly enhance the performance of this catalyst in the hydrogenation dechlorination (HDC) reaction of trichloroethylene by this strategy. This study proposes a regulatory approach: changing the ratio of ethylene glycol to water to precisely control the exposure ratio of the high-index (312) crystal plane of the Ni₁₂P₅ catalyst. Combined with the performance tests of trichloroethylene hydrogenation dechlorination at different reaction temperatures, the intrinsic relationship between the step atoms generated during the formation of the (312) crystal plane and the active sites of the catalyst was clarified. The study also utilized multiple characterization methods such as transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) to conduct a comprehensive property analysis of the prepared catalytic materials. Full article

Improving the separation efficiency between methyldichlorosilane (CH₃SiHCl₂) and trichlorosilane (SiHCl₃) is one of the key urgent problems to be solved for the quality improvement and consumption reduction in high-purity polysilicon. In this work, three types of porous supported catalysts were prepared via an in situ reaction method, taking aluminum chloride (AlCl₃) as the active component and activated carbon, silica gel and activated alumina as support; the catalytic reaction mechanisms of CH₃SiHCl₂ and silicon tetrachloride (SiCl₄) over the as-prepared porous supported catalysts were investigated, based on density functional theory (DFT). The results reveal that among the three supported catalysts, the activated carbon-supported aluminum chloride catalyst (C@AlCl₃) possesses the maximum binding energy (−3.20 eV) between the active component and support. CH₃SiHCl₂ and SiCl₄ possess the lowest co-adsorption energy (−1.8 eV) and the minimum reaction energy barrier (0.8 eV) on C@AlCl₃, accompanied by the maximum charge transfer to the catalyst surface (−2.65 e and −2.80 e), thus exhibiting the highest catalytic activity, with the maximum single-pass conversion of CH₃SiHCl₂ exceeding 90%. This work provides material basis and theoretical guidance for constructing a reactive distillation strategy for high-efficiency and low-energy separation of CH₃SiHCl₂ from SiHCl₃. Full article

Due to its abundant active sites, the bimetallic zeolite imidazole framework ZnCo-ZIF-67 exhibits excellent catalytic performance on the key oxidant ammonium perchlorate in composite solid propellants. In addition, carbon fiber has been proven to promote the combustion of propellants due to its high thermal conductivity efficiency. In order to integrate the advantages of both, this study designed and prepared a novel composite catalyst, ZnCo-ZIF-67/CF, by a co-precipitation method. The thermal decomposition test demonstrated that the ZnCo-ZIF-67/CF composite exhibited significant catalytic activity. When the addition amount was 5 wt%, the high-temperature decomposition peak temperature of AP decreased significantly from 424.3 °C to 337.2 °C, and the combustion process was also significantly accelerated. Furthermore, analysis of the products of thermal decomposition gases revealed a significant increase in the proportion of N₂O in the catalyzed products to 55.7%, whilst the proportion of high oxidation state nitrogen-containing oxides such as NO₂ and NOCl decreased. This finding suggests that the highly dispersed metal active sites in ZnCo-ZIF-67/CF synergistically promote the decomposition reaction pathway of AP, leading to enhanced N₂O generation. This study proposes a novel approach for the development of efficient and stable AP decomposition catalysts, which has positive significance for the regulation of the combustion performance of propellants. Full article