Search Results (349)

The development of highly selective and sensitive gas sensors is essential for detecting toxic pollutants, such as carbon monoxide (CO), which pose severe health and environmental risks. In this work, the adsorption of CO molecules on Ni_6−xCu_x (x = 0–6) clusters supported on hexagonal boron nitride quantum dots with nitrogen vacancies (h-BN_VQDs) is explored through density functional theory (DFT) calculations. For this purpose, the stability of the metallic clusters supported on the boron nitride sheet was calculated, and the adsorption properties of the CO molecule on the Ni_6−xCu_x (x = 0–6)/h-BN_VQDs composite were determined. The results demonstrated a high binding energy between Ni_6−xCu_x (x = 0–6) clusters and the h-BN_VQDs sheets, suggesting that Ni-Cu clusters are highly stable on h-BN_VQDs sheets. For CO adsorption, adsorption energy and charge transfer calculations indicated that the Ni₆ and Ni_6−xCu_x (x = 2 and 3) clusters exhibit the strongest CO binding and highest charge transfer, suggesting them as good candidates for CO gas sensing. These findings provide theoretical insights into the rational design of bimetallic catalysts for gas-sensing applications. Full article

The catalytic performance of metal oxide materials is profoundly influenced by both chemical composition and surface morphology, particularly at high dopant loadings where metallic clusters can form. Here, we use density functional theory (DFT) to elucidate how copper incorporation—either as isolated dopants or as surface clusters—modulates the mechanism and activity of ZrO₂ catalysts in the direct carboxylation of phenol to para-hydroxybenzoic acid. Our results reveal that while Cu doping inhibits C–H bond activation, the presence of Cu clusters at the ZrO₂ surface dramatically lowers the barrier for C–C coupling with CO₂, owing to unique interfacial sites that facilitate substrate activation and CO₂ bending. We show that the reaction mechanism shifts from an Eley–Rideal pathway on pure ZrO₂ to a Langmuir–Hinshelwood mechanism on Cu-modified surfaces, with the rate-determining step depending on the Cu morphology. These findings demonstrate that even small amounts of metallic clusters can fundamentally alter catalytic pathways, providing actionable insights for the rational design of heterogeneous catalysts for selective aromatic carboxylation. Full article

Transition metal dichalcogenides (TMSs), exemplified by molybdenum disulfide (MoS₂), exhibit significant potential as alternatives to noble metals (e.g., Pt) for the hydrogen evolution reaction (HER). However, conventional synthesis methods of MoS_x often suffer from active site loss, harsh reaction conditions, or undesirable oxidation, limiting their practical applicability. The development of MoS_x with high-density active sites remains a formidable challenge. Herein, we propose a novel strategy employing [Mo₃S₁₃]²⁻ clusters as precursors to construct three-dimensional amorphous MoS_x nanosheets through optimized hydrothermal and solvent evaporation-induced self-assembly approaches. Comprehensive characterization confirms the material’s unique amorphous lamellar structure, featuring preserved [Mo₃S₁₃]²⁻ units and engineered interlayer dislocations that facilitate enhanced electron transfer and active site exposure. This work not only establishes [Mo₃S₁₃]²⁻ clusters as effective building blocks for high-performance MoS_x catalysts, but also provides a scalable and environmentally benign synthesis route for the large-scale production of such nanostructured a-MoS_x. Our findings facilitate the rational design of non-noble HER catalysts via structural engineering, with broad implications for energy conversion technologies. Full article

Developing efficient and recyclable periodate (PI)-based advanced oxidation processes (AOPs) for the removal of emerging organic pollutants (EOPs) has attracted considerable attention. However, the structure–activity relationship of single-atom catalyst in PI-AOP systems remains poorly understood. In this study, a hollow carbon-supported single-Fe atom catalyst (HCFe800) was synthesized and applied for PI activation toward bisphenol A (BPA) degradation. Under neutral pH and ambient temperature, HCFe800 enabled complete removal of BPA within 1 min, achieving a degradation rate constant (k) of 5.094 min⁻¹—approximately 3 and 10 times higher than that of Fe-free and solid control catalysts, respectively. After normalization, the apparent degradation rate constant was 1–3 orders of magnitude greater than those of previously reported catalysts. The optimized Fe doping amount and pyrolysis temperature facilitated the formation of atomically dispersed FeN₄ sites, which outperformed Fe clusters and iron oxides in catalytic activity. The hollow porous structure further enhanced the exposure of active sites, contributing to the exceptional performance. The HCFe800/PI system remained highly effective across broad pH (3–7) and temperature (5–35 °C) ranges and in the presence of 100-fold concentrations of common inorganic ions. Mechanistic studies revealed that the main reactive species were ¹O₂, O₂^•−, and IO₃^•, with negligible involvement of high-valent Fe species. Eight less-toxic BPA degradation products were identified. Moreover, the system was extendable to various other EOPs and exhibited excellent recyclability via thermal regeneration. This work provided fundamental insights into designing and applying single-atom catalysts for PI-based advanced treatment of EOPs. Full article

This empirical investigation explores the complex interdependencies between the concept of the Smart University Campus and the broader ecosystem of Smart City policies, with a particular focus on the New European Bauhaus initiative as a catalyst for educational transformation. The study examines how university campuses can evolve into paradigmatic models of innovation, sustainability, and inclusion through the strategic integration of emerging technologies, circular bioeconomy principles, and holistic ecological strategies. A comprehensive case study, grounded in rigorous quantitative analysis, including Principal Component Analysis (PCA), Importance-Performance Analysis (IPA), and Cluster Analysis (CA), based on questionnaires administered to a sample of 245 high school and university students—primarily from the academic community of the “King Mihai I” University of Life Sciences in Timișoara (USVT)—provides empirical insights into perceptions and expectations regarding the Smart Campus ecosystem and its core components: Smart Learning, Smart Living, Smart Safety and Security, Smart Socialization and Smart Health. The distinctive contribution of this research lies in its empirical demonstration that the strategic alignment between university campuses and Smart City initiatives, guided by the principles of the New European Bauhaus, can enhance educational efficiency by creating integrated learning ecosystems that simultaneously address academic needs, sustainability imperatives, and goals of sustainable urban development. Full article

Supported metal catalysts are extensively applied in the heterogeneous catalysis field. However, metal species are prone to migration and aggregation during catalytic reactions due to their high surface energy, which leads to deactivation. In recent years, the use of porous materials, particularly zeolites, to anchor metal species has gained significant attention. By confining metal single atoms, subnanometer metal clusters, and nanoparticles within the pores or nanocavities of these materials, the dispersion and stability of the metal species can be greatly enhanced, thereby improving the catalytic performance. This review systematically discussed the synthesis principles and diverse methodologies to fabricate zeolite-encapsulated metal catalysts. It further outlined their catalytic applications across various catalysis fields, emphasizing enhanced stability and selectivity enabled by confinement effects. Finally, the review provided critical perspectives on future developments, addressing challenges in precise structural control and scalability for industrial implementation. Full article

Zeolites are promising materials for volatile organic compound (VOC) adsorption and catalytic oxidation, where tuning their structure via defect engineering can enhance adsorption capacity and active metal dispersion. In this study, a concentration-sensitive chelation strategy using diethylenetriaminepentaacetic acid (DTPA) was developed to achieve moderate dealumination for Beta and Y zeolites. For Y zeolite, 0.1 M DTPA treatment increased the toluene adsorption capacity from 59 to 110 mg/g. After platinum (Pt) loading, both DTPA-modified Beta- and Y-based catalysts showed improved toluene oxidation efficiency compared to their unmodified counterparts. Remarkably, the Y-DTPA-0.01-Pt catalyst achieved 90% toluene conversion at 150 °C with CO₂ selectivity above 90%. DRIFTS and H₂-TPR results confirmed that moderate dealumination by DTPA generated silanol defects in zeolite Y that strongly anchored Pt²⁺ in a highly dispersed form and suppressed PtO formation. Severe dealumination using 0.1 M DTPA created larger defects that favored the aggregation of Pt⁰ clusters whilst causing significant loss in the micropores, thus reducing the Pt loading content and catalytic activity. This work demonstrates a simple and effective approach to optimize zeolite-based catalysts by controlling defect formation through controllable chelation, offering new insights into VOC abatement via tailored support design. Full article

Surface and sub-surface atomic configurations are critical for catalysis as they host the active sites governing electrochemical processes. This study employs density functional theory (DFT) calculations and Monte Carlo simulations combined with the cluster-expansion approach to investigate atom distribution and Pt segregation in Pt-Fe alloys across varying Pt/Fe ratios. Our simulations reveal a strong tendency for Pt atoms to segregate to the surface layer while Fe atoms enrich the sub-surface region. Crucially, the calculations predict the stability of a periodic Pt₂Fe alloy surface model, characterized by specific defect structures, at low platinum content and low annealing temperatures. Electronic structure analysis indicates that forming this Pt₂Fe surface alloy lowers the d-band center of Pt atoms, weakening CO adsorption and thereby enhancing resistance to CO poisoning. Although defect-induced strains can modulate the d-band center, crystal orbital Hamilton population (COHP) analysis confirms that such strains generally strengthen Pt-CO interactions. Therefore, the theoretical design of Pt₂Fe alloy surfaces and controlling defect density are predicted to be effective strategies for enhancing catalyst resistance to CO poisoning. This work highlights the advantages of periodic Pt₂Fe surface models for anti-CO poisoning and provides computational guidance for designing efficient Pt-based electrocatalysts. Full article

Inspired by the active site of methane monooxygenase, we designed a Cu₂O cluster anchored in the six-membered nitrogen cavity of a C₂N monolayer (Cu₂O@C₂N) as a stable and efficient enzyme-like catalyst. Density functional theory (DFT) calculations reveal that the bridged Cu-O-Cu structure within C₂N exhibits strong electronic coupling, which is favorable for methanol formation. Two competing mechanisms—the concerted and radical-rebound pathways—were systematically investigated, with the former being energetically preferred due to lower energy barriers and more stable intermediate states. Furthermore, strain engineering was employed to tune the geometric and electronic structure of the Cu-O-Cu site. Biaxial strain modulates the Cu-O-Cu bond angle, adsorption properties, and d-band center alignment, thereby selectively enhancing the concerted pathway. A volcano-like trend was observed between the applied strain and the methanol formation barrier, with 1% tensile strain yielding the overall energy barrier to methanol formation (ΔG_overall) as low as 1.31 eV. N₂O effectively regenerated the active site and demonstrated strain-responsive kinetics. The electronic descriptor Δε (ε_d − ε_p) captured the structure–activity relationship, confirming the role of strain in regulating catalytic performance. This work highlights the synergy between geometric confinement and mechanical modulation, offering a rational design strategy for advanced C1 activation catalysts. Full article

As diversity, equity, and inclusion (DEI) efforts in higher education face increasing political resistance, it is critical to understand how equity-centered institutional change is fostered, and who is transformed in the process. This study examines the intended and emergent outcomes of faculty professional development initiatives implemented through the Howard Hughes Medical Institute’s Inclusive Excellence (HHMI IE) program. We analyzed annual institutional reports and anonymous reflections from four public universities in a regional Peer Implementation Cluster (PIC), focusing on how change occurred at individual, community, and institutional levels. Guided by Kezar’s Shared Equity Leadership (SEL) framework, our thematic analysis revealed that while initiatives were designed to improve student outcomes through inclusive pedagogy, the most profound outcome was the development of equity consciousness among faculty. Defined as a growing awareness of systemic inequities and a sustained commitment to address them, equity consciousness emerged as the most frequently coded theme across all levels of change. These findings suggest that equity-centered faculty development can serve as a catalyst for institutional transformation, not only by shifting teaching practices but also by building distributed leadership and deeper organizational engagement with equity. This effort also emphasizes that documenting emergent outcomes is essential for recognizing the holistic impact of sustained institutional change. Full article

In this study, density functional theory (DFT) was used to analyze the processes that govern the interactions among triethylaluminum (TEAL), the Ziegler–Natta (ZN) catalyst, and the inhibitory compounds dimethylamine (DMA) and diethylamine (DEA) during olefin polymerization. The structural and charge characteristics of these inhibitors were examined through steric maps and DFT calculations. Combined DFT calculations (D3-B3LYP/6-311++G(d,p)) and IR spectroscopic analysis show that the most efficient way to deactivate the ZN catalyst is via the initial formation of the TEAL·DMA complex. This step has a kinetic barrier of only 27 kcal mol⁻¹ and a negative ΔG, in stark contrast to the >120 kcal mol⁻¹ required to form TEAL·DEA. Once generated, TEAL·DMA adsorbs onto the TiCl₄/MgCl₂ cluster with adsorption energies of −22.9 kcal mol⁻¹ in the gas phase and −25.4 kcal mol⁻¹ in n-hexane (SMD model), values 5–10 kcal mol⁻¹ more favorable than those for TEAL·DEA. This explains why, although dimethylamine is present at only 140 ppm, its impact on productivity (−19.6%) is practically identical to that produced by 170 ppm of diethylamine (−20%). The persistence of the ν(Al–N) band at ~615 cm⁻¹, along with a >30% decrease in the Al–C/Ti–C bands between 500 and 900 cm⁻¹, the downward shift of the N–H stretch from ~3300 to 3200 cm⁻¹, and the +15 cm⁻¹ increase in ν(C–N) confirm Al←N coordination and blockage of alkyl transfer, establishing the TEAL·DMA → ZN pathway as the dominant catalytic poisoning mechanism. Full article

The fundamental chemistries and electronic structures of platinum catalysts over nitrogen-doped carbon supports were examined to determine the subtle yet important roles graphitic defect-based and pyridinic defect-based nitrogen defects have in stabilizing platinum. These roles address and extend previously gathered incomplete knowledge of how combinations of graphitic defect and pyridinic defect affect the local electronic structure, leading to a greater unified understanding of platinum stability. A theoretical study was designed where different atomically sized platinum clusters were investigated over seven different nitrogen defect combinations on graphene carbon support. Differently sized platinum clusters offered parametric insights into the differences in metal–support interactions. Full article

Cocktail-type catalysis represents a significant shift in the understanding of catalytic processes, recognizing that multiple interconverting species—such as metal complexes, clusters, and nanoparticles—can coexist and cooperate within a single reaction environment. Originating from mechanistic studies on palladium-catalyzed systems, this concept challenges the classical division between homogeneous and heterogeneous catalysis. Instead, it introduces a dynamic framework where catalysts adapt and evolve under reaction conditions, often enhancing efficiency, selectivity, and durability. Using advanced spectroscopic, microscopic, and computational techniques, researchers have visualized the formation and transformation of catalytic species in real time. The cocktail-type approach has since been extended to platinum, nickel, copper, and other transition metals, revealing a general principle in catalysis. This approach not only resolves long-standing mechanistic inconsistencies, but also opens new directions for catalyst design, green chemistry, and sustainable industrial applications. Embracing the complexity of catalytic systems may redefine future strategies in both fundamental research and applied catalysis. Full article

Asymmetric-atomic-structure catalysts can modulate the interactions between active sites and intermediates through their unique electronic filling states and asymmetric charge distribution, breaking the linear relationship between adsorption energy and activity, thereby enhancing the catalytic performance of the oxygen reduction reaction (ORR). By introducing heteroelements, vacancies, or clusters into symmetric-atomic-structure catalysts (e.g., M-N₄), asymmetric configurations (such as M-N_x, M-N_x-S/B/O, etc.) can be formed. These modifications substantially alter their internal structure, trigger charge redistribution, and create asymmetric sites to reduce reaction energy barriers, effectively regulating the adsorption strength of oxygen intermediates and significantly improving ORR performance. This review systematically summarizes recent advancements in asymmetric-atomic-structure catalysts for ORR, elucidating the intrinsic “structure–performance–application” relationships to provide theoretical guidance for developing high-performance asymmetric atomic catalysts. First, the ORR mechanisms, including the two-electron and four-electron pathways, are introduced. Furthermore, strategies to modulate catalyst selectivity and activity through doping with metallic/nonmetallic elements or introducing defects are discussed. Finally, prospects for asymmetric-atomic-structure catalysts in next-generation energy storage and conversion technologies are outlined, offering novel insights to overcome current ORR performance bottlenecks. Full article

As urbanization accelerates globally, higher education agglomeration (HEA) emerges as a critical mechanism for integrating regional economic theories with practical strategies, driving innovation and sustainable development. This paper examines how HEA promotes innovation, human capital accumulation, industrial restructuring, and equitable income distribution across 193 cities in the “Two Transverse and Three Lengthways” urban clusters from 2006 to 2020. Using dynamic panel regression and spatial econometric models, the results show that HEA yields significant local and spatial spillover benefits, particularly in core cities that facilitate knowledge diffusion and resource sharing. Heterogeneity analysis reveals that these positive spillovers are strongest in first-tier, highly developed clusters and third-tier, early-stage clusters but weaker or even negative in second-tier, rapidly expanding regions. These spatial effects grow over time, reflecting the evolving patterns of regional integration. Theoretically, the paper advances the understanding of spatial synergy and spillover mechanisms in HEA in urban clusters. Practically, the findings highlight the need to tailor higher education strategies to the developmental stage of each urban cluster to optimize resource allocation and foster inclusive growth. This paper provides policy insights for using HEA as a catalyst for coordinated urban development. Full article