EES catalysis最新文献

Hydrogenolysis provides a promising pathway for converting polyolefin plastics into valuable liquid and wax fuels. This process involves dehydrogenation, C–C bond cleavage, and hydrogenation at the active metal sites of the catalyst. Controlling the nature of these metal sites is crucial to optimize overall reaction activity. In this study, Ru catalysts supported on nanosheet-assembled Al₂O₃ (NA-Al₂O₃) were used for the hydrogenolysis of polyethylene (PE). Unlike commercial Al₂O₃, NA-Al₂O₃ promotes Ru–Al bond formation, leading to stronger metal–support interactions. Under identical Ru loadings, these enhanced interactions resulted in higher Ru dispersion and smaller Ru species on the NA-Al₂O₃ surface. To investigate the effect of Ru loading, a series of catalysts (xRu/NA-Al₂O₃, x = 0.5, 1, 5, and 8 wt% Ru) was synthesized, revealing that Ru particle size and electronic properties varied with Ru loading. Among them, the 1Ru/NA-Al₂O₃ catalyst, featuring optimally sized Ru species (∼0.8 nm) and a tailored electronic structure, demonstrated the highest efficiency in PE hydrogenolysis by effectively suppressing successive C–C bond cleavage. This catalyst achieved an outstanding PE conversion rate of 1.15 × 10³ g_{converted PE} g_Ru⁻¹ h⁻¹ and a liquid/wax production rate of 9.23 x 10² g_liquid/wax g_Ru⁻¹ h⁻¹, highlighting its superior performance in catalytic PE hydrogenolysis.

Nb₂C MXene, obtained from Nb₂AlC by Al³⁺ etching and exfoliation, was characterized using XRD, HRTEM and AFM, with the data confirming the crystallinity of the sample and the 2D morphology of the sheets with an average layer thickness of 1.5 nm. Surface analysis using XPS revealed the presence of structural defects, and NH₃- and CO₂-TPD profiles confirmed the low density of acid and basic sites in the range of tens of μmol g_catalyst⁻¹ of weak and moderate strengths. The combination of acid and basic sites in close proximity on the solid surface was responsible for the remarkable catalytic activity of Nb₂C MXene in promoting aldolic condensation with high turnover frequencies of up to 855 h⁻¹, which was comparable to the values of benchmark catalysts, such as MgO or HZSM-5. Nb₂C MXene also catalyzed the aerobic oxidative aniline coupling to azo- and azoxy-benzene and hydrogenation of azoxybenzene to azobenzene.

Activation and catalytic transformation of dinitrogen (N₂) remains a grand challenge at the intersection of global food security, sustainable energy, and chemical manufacturing. The remarkable strength of the NN bond poses formidable thermodynamic and kinetic barriers, driving reliance on the century-old Haber–Bosch process-an energy-intensive route that consumes substantial fossil fuels. Recent advances underscore a growing shift toward alternative strategies, including biological and enzymatic pathways inspired by nitrogenase, homogeneous catalysis through transition-metal complexes, plasma-assisted reactions leveraging high-energy species, and diverse electrochemical or thermo-electrochemical methods integrating renewable power. Key breakthroughs in catalyst design, from metal nitrides and single-atom catalysts to next-generation perovskite oxides, highlight the importance of targeted bond weakening, electron back-donation, and multi-electron/proton transfer steps. Concurrently, mechanistic insights gleaned from in situ spectroscopy, density functional theory, and machine learning-guided screening are refining our understanding of molecular orbital interactions and reaction intermediates. Looking ahead, the N₂ activation field seeks to unite high efficiency with lower energy footprints by tailoring catalysts for mild conditions, exploring hydrogen sources beyond conventional H₂, and adopting process intensification strategies to curb carbon emissions. By bridging fundamental discoveries with scalable engineering, future research should aim to deliver cost-effective, low-carbon nitrogen fixation, reshaping the global nitrogen economy and paving the way toward sustainable ammonia production and novel nitrogen-based chemicals.

Development of suitable catalysts for light-driven CO₂ hydrogenation is an alluring goal in catalysis. In this study, plasmonic Ag nanoprisms were combined with Pt to make surface-alloyed nanoparticles for aqueous-phase CO₂ hydrogenation. The Pt loading favoured the product selectivity towards multi-electron C₁ products and promoted acetic acid production via C–C coupling. Increasing the reaction pressure further improved acetic acid production where the highest yield of 0.491 mmol g_cat⁻¹ was achieved at 20 bar. Within the visible-light region, the in-plane dipole resonance peak of Ag₉₁Pt₉ at 600 nm contributed the highest apparent quantum yield of 26.7%. These investigations demonstrated the significance of designer plasmonic catalysts and highlighted their photocatalytic enhancement towards CO₂ conversion.

Achieving high selectivity for carbon monoxide (CO) in the electrochemical reduction of carbon dioxide (CO₂) at industrially relevant current densities, particularly using dilute CO₂ feedstocks, remains a significant challenge. Herein, we demonstrate that combining elevated temperature and CO₂ pressure substantially enhances CO production in a membrane electrode assembly (MEA) electrolyzer using commercially available silver nanoparticles. Elevated CO₂ pressures increase CO₂ concentration and reduce the diffusion layer, counteracting the reduced CO₂ solubility in water and enhanced wetting of catalyst layer caused by high temperature. The synergy of high pressure and temperature ensures high CO₂ flux to the catalyst surface while leveraging elevated temperatures to accelerate reaction kinetics. Therefore, the pressurized and heated CO₂ electrolyzer achieves an FE_CO of 92% at a high current density of 2 A cm⁻² and a low cell voltage of 3.8 V under 10 bar and 80 °C when using 0.1 M KHCO₃ as the anolyte. Even when using pure water as the anolyte, the system maintains a FE_CO value of 90% at 300 mA cm⁻² and a cell voltage of 3.6 V. Furthermore, the system demonstrates exceptional performance with dilute 10 vol% CO₂ feedstocks, achieving a FE_CO of 96% at 100 mA cm⁻² and 2.4 V. These findings underscore the potential of combined temperature and pressure optimization to overcome mass transport limitations and enhance reaction kinetics, offering a viable pathway for scaling up CO₂ electrolyzers for industrial applications.

Vibrational excitation of reactants plays an important role in heterogeneous and plasma catalysis by increasing the reactivity of various rate-controlling steps. Therefore, state-of-the-art microkinetic models attempt to include this effect by modelling the change in reaction rate with the Fridman–Macheret α approach. Although this approach is ubiquitous in simulations of plasma catalysis, it is not well established how accurate it is. In this work, we evaluate the Fridman–Macheret α approach by comparing it to vibrational efficacies obtained with molecular dynamics simulations. Unfortunately, the agreement is extremely poor (R² = −0.35), raising questions about the suitability of using this method in describing vibrationally excited dissociative chemisorption on metal surfaces, as is currently the norm in plasma catalysis. Furthermore, the approach lacks vibrational mode specificity. Instead, we propose an alternative model at comparable computational cost, which is fitted to theoretical vibrational efficacies obtained with molecular dynamics. Our model uses (1) the barrier height to dissociative chemisorption, (2) an indication of how “late” the barrier is, and (3) the overlap of vibrational modes and the reaction coordinate at the barrier. These three features lead to a considerable qualitative and quantitative (R² = 0.52) improvement over the Fridman–Macheret α approach. Therefore, we advise to make use of our new model, since it can be readily plugged into existing microkinetic models for heterogeneous and plasma catalysis.

An anion exchange membrane water electrolyzer (AEMWE) is emerging as key technology for hydrogen production. However, its widespread application requires further reduction of cost and improvement of efficiencies. Here, we synthesize a four-in-one catalyst (V_SA-CoN_x) to achieve high-efficiency coupling hydrogen production by combining with the hydrazine oxidation reaction (HzOR) and the urea oxidation reaction (UOR). The as-synthesized V_SA-CoN_x exhibits excellent performance in all the four reactions of HzOR, UOR and hydrogen/oxygen evolution reactions (HER/OER). The HER–HzOR coupling system only requires an ultra-low voltage of 0.21 V to deliver an ampere-level current density (1 A cm⁻²), while the conventional HER–OER AEMWE needs nearly an input of 1.88 V. Remarkably, this HER–HzOR coupling system largely reduces the energy expenditure of the AEMWE by approximately 90%, which hits a record in the low energy cost for all water electrolysis systems known to date. Given the energy consumption of the traditional AEMWE of approximately 4.56 kW h Nm⁻³ of H₂ at a current density of 1 A cm⁻², the HER–HzOR AEM electrolyzer only requires 0.51 kW h Nm⁻³ of H₂. This HER–HzOR coupling system not only significantly lowers the energy expenditure of large-scale H₂ production but also addresses the hydrazine-associated environmental pollution.

Polymeric carbon nitride materials (CNs) show promising potential as photoanodes in water-splitting photoelectrochemical cells. However, poor catalytic activity at the electrode–water interface limits their performance and longevity, resulting in low photoactivity and unwanted self-oxidation. Here, we demonstrate a high-performance photoanode based on polymeric carbon nitride doped with yttrium clusters, achieving enhanced activity and stability with high faradaic efficiency for water oxidation. Incorporating yttrium clusters enhances light harvesting, electronic conductivity, charge separation, and hole extraction kinetics, enabling efficient water oxidation. Furthermore, the strong interaction between yttrium and the CN's nitrogen groups guides the formation of yttrium-rich one-dimensional tubular structures that interconnect two-dimensional CN sheets. The optimized photoanode delivers a photocurrent density of 275 ± 10 μA cm⁻² with 90% faradaic efficiency for oxygen evolution, demonstrates stable performance for up to 10 hours, and achieves external quantum efficiencies of up to 14% in an alkaline medium.

As fundamental chemicals and building blocks for the modern chemical industry, aromatics possess a huge market demand. The direct and atom-economic conversion of CO₂ to aromatics holds the potential to diminish the reliance on petroleum resources and provides a viable approach towards a net-zero chemical industry. The key lies in the implementation of the highly efficient coupling catalysis strategy and utilization of multi-functional catalysts. In this review, recent advances in the direct conversion of CO₂ to aromatics via the methanol-mediated pathway and the modified Fischer–Tropsch synthesis route are comprehensively discussed, including an in-depth analysis of the tandem reaction mechanism and bifunctional catalysts, which consist of metal-based materials (including metals, metal oxides, or metal carbides) and zeolites. Furthermore, several novel catalytic pathways, involving coupling CO₂ conversion with reactions such as CO hydrogenation, aromatic alkylation, or alkane aromatization, are also elaborated. Subsequently, the coupling effect of multi-functional catalysis, as well as the influence of the proximity between catalytic components, is explored. Moreover, the revealing and construction of the spatial pathway for tandem reactions, which enable the spatio-temporal coupling of multi-functional catalytic systems, are addressed. The challenges and potential directions for the further development of the direct CO₂-to-aromatics conversion technology are finally proposed.

Plasma catalysis is gaining increasing interest for the synthesis of chemicals and fuels, but the underlying mechanisms are still far from understood. This hampers plasma–catalyst synergy. Indeed, there is not enough insight into the optimal catalyst material tailored to the plasma environment, and vice versa, in the optimal plasma conditions for the catalyst needs. Furthermore, plasma catalysis suffers from energy losses via backward reactions, and probably most importantly, there is a clear need for improved plasma reactor design with better contact between plasma and catalyst. In this paper, we describe these critical limitations and suggest possible solutions. In addition, we stress the importance of correct measurements and consistent reporting, and finally we also propose other promising plasma–material combinations beyond the strict definition of catalysts. We hope this opinion paper can help to make progress in this booming research field.