Topics in Catalysis最新文献

The exact determination of lactate concentration is very important in the fields of food quality and clinical diagnosis. A non-enzymatic amperometric sensor based on nanostructured porous Cu-Au electrocatalyst martial was designed and employed for lactate determination. For this purpose, the bimetallic surface was successfully coated on the glassy carbon electrode (GCE) using co-electrodeposition of copper and gold ions. The Cu-Au alloy proved to be an effective interface for the direct electrochemical oxidation of lactate. The Cu-Au modified GCE exhibits excellent lactate sensing capabilities thanks to the excellent conductivity of gold element in bimetallic material and high surface area of the porous Cu-Au alloy. In phosphate buffer solution, this novel electrochemical lactate sensor demonstrates a linear response to lactate within the concentration range of 20 to 2000 µM. The detection limit (based on S/N = 3) of the assay was estimated to be 5 µM. The established electrochemical sensing protocol is a highly selective device for the analysis of lactate in biological fluids. The lactate level in saliva samples was successfully quantified before and after exercise of athletes using the recommended strategy. The present non-enzymatic sensor offers a convenient, fast, cost-effective, and effective protocol for lactate measuring in clinical diagnosis applications.

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In this paper, the CoxMn1Cey composite oxide catalyst was synthesized by the co-precipitation method. The structure–activity relationship of the catalyst was analyzed by characterization methods such as XRD, Raman, H₂-TPR, NH₃/NO_x-TPD, XPS, and in situ DRIFTS. The results showed that the Co3Mn1Ce1 catalyst resisted high space velocity, water, and sulfur. In addition, Ce doping could effectively increase the specific surface area of the catalyst. In a sulfur-containing atmosphere, Ce could preferentially react with SO₂ and act as a sacrifice site to protect the active components from toxicity. Co-doping greatly enhanced the redox capacity of the catalyst and increased the chemisorbed oxygen (O_S) content on the surface of catalysts. Co-presence of Co and Ce increased the content of surface-active Mn species, which further effectively improved the adsorption capacity of the catalyst for NH₃ and NO reactants. In situ DRIFTS results showed that the reaction on the Co3Mn1Ce1 catalyst followed both the Langmuir–Hinshelwood and Eley–Rideal mechanisms.

Insufficient infrastructure for wastewater treatment stands as a critical global concern, profoundly impacting both the environment and public health. This issue is exacerbated by industrial effluents containing hazardous organic pollutants and dyes such as crystal violet (CV) and methyl orange (MO), posing significant environmental threats. This study introduces a novel approach utilizing chitosan microsphere-based iron–strontium–zinc oxide photocatalysts aimed at addressing the decontamination of these organic dyes. The synthesis of iron–strontium–zinc oxide was performed via co-precipitation method followed by its characterization using various techniques. The resulting CS-Fe₂SrZnO₄ microspheres exhibited a sleek morphology with an average diameter of 917 μm, featuring the confirmed presence of iron, strontium, and zinc oxide as ascertained by EDX analysis. With a bandgap of 1.24 eV, this material showcased remarkable efficacy in degrading CV and MO dyes under solar light irradiation. Optimized conditions were identified to attain maximum degradation efficiency for both dyes. The findings reveal that the maximum degradation achieved for MO and CV was 94% and 98%, respectively, at the optimized conditions (time; 60 min, catalyst dosage; 0.1 g, concentration 20 ppm, pH; 6 for MO and 8 for CV). The statistical analysis was also performed which supported the obtained results. The kinetics study showed that the degradation followed pseudo-first order kinetics with R² value of 0.96. The current study has a great environmental impact as the degradation of hazardous dyes reduces the health related risks. To our best knowledge, this is the first report on the combination of ternary metal oxides combined with chitosan for the degradation of hazardous dyes.

The conversion of reactants, reaction rate referred to catalyst mass, and turnover frequency (TOF) are values typically employed to compare the activity of different catalysts. However, experimental parameters have to be chosen carefully when systems of different complexity are compared. In order to characterize UHV-based model systems, we use a highly sensitive sniffer setup which allows us to investigate the catalytic activity by combining three different measurement modes: temperature-programmed desorption, continuous flow, and pulsed-reactivity experiments. In this article, we explore the caveats of quantifying catalytic activity in UHV on the well-studied and highly defined reference system of CO oxidation on Pt(111), which we later compare to the same reaction on Pt₁₉ clusters deposited on Fe₃O₄(001). We demonstrate that we can apply fast heating ramps for TOF quantification, thus inducing as little sintering as possible in the metastable clusters. By changing the reactant ratio, we find transient reactivity effects that influence the TOF, which should be kept in mind when comparing catalysts. In addition, the TOF also depends on the surface coverage that itself is a function of temperature and pressure. At a constant reactant ratio, in the absence of transient effects, however, the TOF scales linearly with total pressure over the entire measured temperature range from 200 to 700 K since the reaction rate is dependent on both reactant partial pressures with temperature-dependent reaction order. When comparing the maximum TOF at this particular reactant ratio, we find a 1.6 times higher maximum TOF for Pt₁₉/Fe₃O₄(001) than for Pt(111). In addition, pulsed-reactivity measurements help identify purely reaction-limited regimes and allow for a more detailed investigation of limiting reactants over the whole temperature range.

The potential of silica (SiO₂)-based materials in environmental remediation and energy production, particularly in the conversion of methane (CH₄) with carbon dioxide (CO₂) to fuels (synthesis gas, mixture of carbon monoxide and hydrogen) via dry reforming of methane (DRM), cannot be overemphasized. In this study, the significance of fibrous SiO₂ in minimizing waste and optimizing resource utilization through the exploration of CO₂ applications, its environmental consequences, the assessment of commercialization prospects, and the role of silica-based materials in environmental remediation are comprehensively presented. Analysis of research documents spanning from 1995 to 2022 is presented with an examination of 3122 Keywords Plus (ID) and 1211 Author's Keywords from these publications, which revealed trending themes, major funding institutions, prolific countries, notable authors, and leading journals. The findings underscore China’s dominance as the most productive country in terms of publications and citations (101, 2127), closely trailed by Iran (55, 688), India (47, 675), the USA (39, 864), Japan (26, 342), France (21, 425), Germany (18, 816), Spain (17, 309), South Korea (16, 239), and Malaysia (12, 282). The investigation inveils that implementing renewable energy-powered direct air capture demands a comprehensive strategy, addressing the potential negative impacts of SiO₂ nanoparticles and their interaction with biological components and environmental elements. This study elucidates the potential applications and commercialization prospects for fibrous SiO₂ materials, especially their incorporation into carbon capture and utilization technologies, thereby expanding the range of carbon–neutral solutions.