Mesokinetics as a Tool Bridging the Microscopic-to-Macroscopic Transition to Rationalize Catalyst Design

Thermally Stable SiO2 from Coal Gangue-Supported CuOx and CeO2 Active Sites Ensemble as Catalysts for Efficient H2 Purification

Utilization of coal gangue holds immense significance in eliminating negative impacts on the environment. Mineral components in the coal gangue can be exploited as catalyst support to address the issues of reducing catalyst costs and enhancing catalytic performance. Here, we developed the CuCe/SiO2 catalysts (SiO2 derived from coal gangue) to achieve complete conversion of CO in the temperature range from 115 to 215 °C with long-term stable operation for 80 h in preferential CO oxidation. In situ/operando spectroscopy and density functional theory calculations reveal that the distribution of highly dispersed CuOx species on the surface of CeO2 with oxygen vacancies improves the adsorption of CO and O2 molecules, and the d-band center is relocated closer to the Fermi level as well as the CeO2 crystalline features are changed after CO and O2 adsorption. Furthermore, thermally stable SiO2 protects the active species, thus facilitating preferential CO oxidation. These findings will inspire the development of effective approaches for the reuse of coal gangue.

Unveiling pseudocapacitance: a kinetic treatment of the pseudocapacitive biosensor

A kinetic framework is introduced for a pseudocapacitive potentiometric biosensor. Mathematical derivation and kinetic modeling demonstrate that experimentally observed linearity in analyte-OCP response arises from a dynamic equilibrium between competing redox reactions on a single electrode. This system can be expanded to develop a new generation of biosensors.

Is Carbon Heteroatom Doping the Key to Active and Stable Carbon Supported Cobalt Fischer-Tropsch Catalysts?

Carbon supports are an interesting alternative to established oxidic catalyst supports for Co-based Fischer-Tropsch synthesis (FTS) catalysts as they allow high Co reducibility and do not suffer from the formation of Co/support compounds. To optimize Co-based carbon-supported FTS catalysts, significant research has focused on doping carbon supports with heteroatoms, aiming to enhance both catalytic activity and stability. While improvements in FTS performance have been reported for N-doped carbon supports, the exact effects of heteroatom doping are still poorly understood, largely due to difficulties in directly comparing Co FTS catalysts supported on doped versus nondoped carbon materials. In this study, we synthesized a series of highly comparable N-, S-, and P-doped carbon nanofiber (CNF) model supports, which were combined with size-controlled, colloidal Co nanoparticles to create well-defined model FTS catalysts. Comprehensive characterization of these catalysts using in situ X-ray absorption spectroscopy (XAS), in situ X-ray diffraction (XRD), and in situ magnetometry revealed that the presence of dopants significantly altered the structure and properties of the catalytically active Co0 phase, affecting Co coordination numbers, crystal phase composition, and magnetic behavior. Challenging optimistic literature reports, our findings demonstrate that all the studied heteroatoms negatively impact either FTS activity or catalyst stability. Co on N-doped CNFs experienced rapid deactivation due to increased sintering as well as Co phase transformations, which were not observed for Co on nondoped CNFs. Co on S-doped CNF suffered from instability of carbon-bound S species in a hydrogen atmosphere, contributing to low FTS performance by S-poisoning. Finally, Co on P-doped CNFs displayed strong metal-support interactions that improved sintering stability, but FTS activity was hampered by low Co reducibility and the loss of active Co0 due to a complex sequence of cobalt phosphide formation and its subsequent decomposition into phosphorus oxides and cobalt oxide species under FTS conditions.

Recyclable Hydrazine-Passivated NiBx/Ni Heterostructured Catalyst for Enhanced Hydrogenation of Polystyrene Pyrolysis Oil

Nickel boride (Ni2B) is known to be an excellent catalyst for hydrogenation of olefin structures under mild reaction conditions. Its susceptibility to oxidation in air environments, however, limits its practical applications. Here, a hydrazine-passivated nickel boride/nickel (NiBx/Ni) heterostructured catalyst is developed to address the oxidation problem while improving the conversion efficiency of styrene to ethylbenzene in a real polystyrene (PS) pyrolysis oil. The calculated turnover frequency for styrene to ethylbenzene conversion is 24.9 mmol/h·g, with 99.9% selectivity, representing a 38.3% improvement compared with the control Ni2B catalyst (18.0 mmol/h·g). This outstanding performance is attributed to the increased charge density on both Ni and B, induced by a strong hydrazine reductant, which surpasses other amine-structured ligands, such as ethanolamine and ethylamine. Additionally, the enhanced magnetic properties of NiBx/Ni, resulting from the Ni(111) nanocrystalline structure along the easy axis of magnetization, enable facile recovery after a neodymium magnet. The catalyst demonstrated excellent stability, retaining catalytic efficacy over five consecutive cycles with only a 4% loss in activity. This study highlights the potential of the NiBx/Ni catalyst for low-cost and efficient hydrogenation in industrial applications.

Asymmetric Co-Ru Heterostructure Catalyst for Surface-Plasmon-Enhanced Photothermocatalytic CO Hydrogenation to Fuels

Photothermal Fischer-Tropsch synthesis (FTS) aims to convert carbon monoxide (CO) into value-added long-chain hydrocarbons (C5+) under milder conditions, but the efficient C-C coupling of C1 intermediates remains challenging. Herein, a carbon-supported plasmonic CoRu5@C catalyst has been successfully constructed for promoting C-C coupling. Experimental results demonstrate that under ambient pressure and photothermal conditions at 250 °C, CoRu5@C exhibits a C5+ selectivity of 98.9% and FTS activity of 321.4 mmol gcat-1 h-1. Structural characterizations and finite element method simulations indicate that Ru-induced lattice strain in the Co-Ru heterogeneous catalyst boosts energetic charge carrier migration, promoting CO adsorption and activation. A series of in situ experiments reveal that electron-rich Co sites in the Co-Ru heterogeneous catalyst diminish C1 intermediate repulsion, boosting C-C coupling efficiency in the FTS process. This research not only provides an innovative approach to overcoming the challenges in CO hydrogenation selectivity and the synthesis of high-value fuels but also offers significant contributions to the development of sustainable energy technologies.

Proper aggregation of Pt is beneficial for the epoxidation of styrene by O2 over Ptx/γ-Al2O3 catalysts

The dispersion of metal catalysts has multiple effects on catalytic performance, and higher dispersions do not necessarily imply better performance. Herein, we report the epoxidation reaction of styrene over supported platinum catalysts as an example. Compared with the Pt1/γ-Al2O3 catalyst, the Ptn/γ-Al2O3 catalyst with a larger Pt cluster size showed a much better performance. Combining the results of various characterizations and density functional theory calculations, Ptn/γ-Al2O3 was found to be more favorable for oxygen adsorption and activation to generate singlet oxygen species, further promoting the styrene oxidation reaction to styrene oxide in terms of kinetics. In contrast the metallic center of Pt1 in Pt1/γ-Al2O3 was too small to efficiently activate the diatomic oxygen molecule. These insights provide valuable guidance for designing high-performance metal catalysts.

Effective Methane Suppression in Upcycling of Polyethylene into Fuels via Alloying Platinum with Ruthenium Supported on ZSM-5 Zeolite

Ruthenium (Ru)-based catalysts are active in catalyzing polyethylene (PE) upcycling, but their tendency for methanation devalues the process. Although previous works confirmed that the regulation of the Ru structure can inhibit methane yields, the mechanism is still unclear, and the catalytic performance remains higher upside potential. Herein, we synthesized M-Ru/H-ZSM-5 (M = Pt, Pd, Rh) catalysts for PE upcycling. Pt-Ru/H-ZSM-5 had better conversion (84.36%) and liquid fuel selectivity (78.38%) and extremely low methane selectivity (8.43%), which can be ascribed to its more electron-deficient Ruδ+ species and the synergistic catalytic effect induced by Pt doping. Through density functional theory calculations, the nature of methane inhibition was uncovered and the reaction pathway was proposed. Furthermore, the Pt-Ru/H-ZSM-5 catalyst demonstrated its stability and reusability, as well as its efficacy for upcycling various PEs. This work reveals the mechanism of Ru-based catalysts in PE upcycling reactions, promoting plastic recycling development.

Rules Describing CO2 Activation on Single-Atom Alloys from DFT-Meta-GGA Calculations and Artificial Intelligence

Single-atom alloys (SAAs) arise as a promising concept for the design of improved CO2 hydrogenation catalysts. However, from the immense number of possible SAA compositions and structures, only a few might display the properties required to be useful catalysts. Thus, the direct, high-throughput screening of materials is inefficient. Here, we use artificial intelligence to derive rules describing surface sites of SAAs that provide an effective CO2 activation, a crucial initial step to convert the molecule into valuable products. We start by modeling the CO2 interaction with 780 sites of flat and stepped surfaces of SAAs composed by Cu, Zn, and Pd hosts via high-quality DFT-mBEEF calculations. Then, we apply subgroup discovery to determine constraints on key physicochemical properties, out of 24 offered candidate descriptive parameters, characterizing subgroups (SGs) of surface sites where chemisorbed CO2 displays large elongations of its C-O bonds. The key identified parameters are free-atom properties of the elements constituting the surface sites, such as their electron affinity, electronegativity, and radii of the d-orbitals. Additionally, the generalized coordination number is selected as a key geometrical parameter. The SG rules are applied to identify promising surface sites from a candidate space of over 1500 possible ones in different single-atom and dual-atom alloys. Some of the promising alloys predicted by the SG rules were explicitly tested by additional DFT-mBEEF calculations and confirmed to provide a significant CO2 activation.

Employing Ammonia for the Synthesis of Primary Amines: Recent Achievements over Heterogeneous Catalysts

Primary amines represent highly privileged chemicals for synthesis of polymers, pharmaceuticals, agrochemicals, coatings, etc. Consequently, the development of efficient and green methodologies for the production of primary amines are of great importance in chemical industry. Owing to the advantages of low cost and ease in availability, ammonia is considered as a feasible nitrogen source for synthesis of N-containing compounds. Thus, the efficient transformation of ammonia into primary amines has received much attention. In this review, the commonly applied synthetic routes to produce primary amines from ammonia were summarized, including the reductive amination of carbonyl compounds, the hydrogen transfer amination of alcohols, the hydroamination of olefins and the arylation with ammonia, in which the catalytic performance of the recent heterogeneous catalysts is discussed. Additionally, various strategies to modulate the surface properties of catalysts are outlined in conjunction with the analysis of reaction mechanism. Particularly, the amination of the biomass-derived substrates is highlighted, which could provide competitive advantages in chemical industry and stimulate the development of sustainable catalysis in the future. Ultimately, perspectives into the challenges and opportunities for synthesis of primary amines with ammonia as N-resource are discussed.

Local Symmetry-Broken Single Pd Atoms Induced by Doping Ag Sites for Selective Electrocatalytic Semihydrogenation of Alkynes

Engineering the local coordination environment of single metal atoms is an effective strategy to improve their catalytic activity, selectivity, and stability. In this study, we develop an asymmetric Pd-Ag diatomic site on the surface of g-C3N4 for the selective electrocatalytic semihydrogenation of alkynes. The single Pd atom catalyst, which has a locally symmetric Pd coordination, was inactive for the semihydrogenation of phenylacetylene in a 1 M KOH and 1,4-dioxane solution at an applied potential of -1.3 V (vs RHE). In sharp contrast, doping Ag sites into single Pd atom catalyst to form paired Pd-Ag diatomic sites with asymmetric Pd coordination substantially enhanced the reaction, resulting in a high conversion (>98%) with exceptional time-independent selectivity to styrene under identical conditions. Characterization and theoretical calculations reveal that the introduction of a Ag site into single Pd atoms disrupts their symmetry coordination by forming Pd-Ag bonds with N2-Pd-Ag-N configuration, thereby modulating the electronic and geometric structures of Pd sites, which in turn benefits the adsorption and activation of substrate and lowers energy barrier for the rate-determining step of semihydrogenation, ultimately enhancing the electrocatalytic reaction. This work provides a facile and powerful strategy for the design of advanced catalysts by tuning the local coordination environment for selective catalysis.

f-p-d Orbital Hybridization Promotes Hydroxyl Intermediate Adsorption for Electrochemical Biomolecular Oxidation and Identification

The rational design of efficient hydroxyl intermediate (*OH) adsorption catalysts for dopamine electrooxidation still faces a major challenge. To address this challenge, a CeO2-loaded CuO catalyst inspired by the f-p-d orbital hybridization strategy is designed to achieve efficient *OH adsorption and improve dopamine oxidation. The experimental results and theoretical calculations demonstrate that the f-p-d orbital hybridization regulates the electron distribution at the Ce-O-Cu interface, which facilitates electron transfer and optimizes the adsorption of *OH, thereby promoting dopamine oxidation. The designed electrochemical sensor exhibits excellent catalytic activity and sensitivity, reaching a limit of detection of 3.22 nM. This work provides a promising approach for designing highly active electrocatalysts with orbital hybridization for dopamine oxidation.

Tuning the Selectivity in the Nonoxidative Alkane Dehydrogenation Reaction by Potassium-Promoted Zeolite-Encapsulated Pt Catalysts

The significance of the nonoxidative dehydrogenation of middle-chain alkanes into corresponding alkenes is increasing in the context of the world's declining demands on transportation fuels and the growing demand for chemicals and materials. The middle-chain alkenes derived from the dehydrogenation reaction can be transformed into value-added chemicals in downstream processes. Due to the presence of multiple potential reaction sites, the reaction mechanism of the dehydrogenation of middle-chain alkanes is more complicated than that in the dehydrogenation of light alkanes, and there are few prior studies on elucidating their detailed structure-reactivity relationship. In this work, we have employed Pt catalysts encapsulated in pure-silica MFI zeolite crystallites as model catalysts and studied how the catalytic performances for dehydrogenation of n-pentane can be modulated by the K+ promotor in the Pt-MFI catalyst. A combination of comprehensive structural characterizations by aberration-corrected electron microscopy, X-ray absorption spectroscopy, in situ CO-IR, X-ray photoelectron spectroscopy, and kinetic studies shows that K+ promoter can not only influence the particle size but also modify the electronic properties of Pt species, which further affect the activity and selectivity in the dehydrogenation of n-pentane.

Thermal Effect Management via Entropy Variation Strategy to Improve the Catalyst Stability in Acetylene Hydrogenation

The dynamic structure evolution of heterogeneous catalysts during reaction has gained great attention recently. However, controllably manipulating dynamic process and then feeding back catalyst design to extend the lifetime remains challenging. Herein, we proposed an entropy variation strategy to develop a dynamic CuZn-Co/HEOs catalyst, in which the non-active Co nano-islands play a crucial role in controlling thermal effect via timely capturing and utilizing reaction heat generated on the adjacent active CuZn alloys, thus solving the deactivation problem of Cu-based catalysts. Specifically, heat sensitive Co nano-islands experienced an entropy increasing process of slowly redispersion during the reaction. Under such heat dissipation effect, the CuZn-Co/HEOs catalyst exhibited 95.7 % ethylene selectivity and amazing long-term stability (>530 h) in the typical exothermic acetylene hydrogenation. Aiming at cultivating it as a catalyst with promising industrial potential, we proposed a simple regeneration approach via an entropy decreasing process.

Direct propylene epoxidation with molecular oxygen over titanosilicate zeolites

The direct epoxidation of propylene with molecular oxygen represents a desired route for propylene oxide (PO) production with 100% theoretical atomic economy. However, this aerobic epoxidation reaction suffers from the apparent trade-off between propylene conversion and PO selectivity, and remains a key challenge in catalysis. We report that Ti-Beta zeolites containing isolated framework Ti species can efficiently catalyze the aerobic epoxidation of propylene. Stable propylene conversion of 25% and PO selectivity of up to 90% are achieved at the same time, matching the levels of industrial ethylene aerobic epoxidation processes. H-terminated pentacoordinated Ti species in Beta zeolite frameworks are identified as the preferred active sites for propylene aerobic epoxidation and the reaction is initiated by the participation of lattice oxygen in Ti-OH. These results are expected to spark new technology for the industrial production of PO toward more sustainable chemistry and chemical engineering.

Restructuring the interfacial active sites to generalize the volcano curves for platinum-cobalt synergistic catalysis

Computationally derived volcano curve has become the gold standard in catalysis, whose practical application usually relies on empirical interpretations of composition or size effects by the identical active site assumption. Here, we present a proof-of-concept study on disclosing both the support- and adsorbate-induced restructuring of Pt-Co bimetallic catalysts, and the related interplays among different interfacial sites to propose the synergy-dependent volcano curves. Multiple characterizations, isotopic kinetic investigations, and multiscale simulations unravel that the progressive incorporation of Co into Pt catalysts, driven by strong Pt-C bonding (metal-support interfaces) and Co-O bonding (metal-adsorbate interfaces), initiates the formation of Pt-rich alloys accompanied by isolated Co species, then Co segregation to epitaxial CoOx overlayers and adjacent Co3O4 clusters, and ultimately structural collapse into amorphous alloys. Accordingly, three distinct synergies, involving lattice oxygen redox from Pt-Co alloy/Co3O4 clusters, dual-active sites engineering via Pt-rich alloy/CoOx overlayer, and electron coupling within exposed alloy, are identified and quantified for CO oxidation (gas-phase), ammonia borane hydrolysis (liquid-phase), and hydrogen evolution reaction (electrocatalysis), respectively. The resultant synergy-dependent volcano curves represent an advancement over traditional composition-/size-dependent ones, serving as a bridge between theoretical models and experimental observations in bimetallic catalysis.

Real-Time Simulation of the Reaction Kinetics of Supported Metal Nanoparticles

A common issue with supported metal catalysts is the sintering of metal nanoparticles, resulting in catalyst deactivation. In this study, we propose a theoretical framework for realizing a real-time simulation of the reactivity of supported metal nanoparticles during the sintering process, combining density functional theory calculations, microkinetic modeling, Wulff-Kaichew construction, and sintering kinetic simulations. To validate our approach, we demonstrate its feasibility on α-Al2O3(0001)-supported Ag nanoparticles, where the simulated sintering behavior and ethylene epoxidation reaction rate as a function of time show qualitative agreement with experimental observation. Our proposed theoretical approach can be employed to screen out the promising microstructure feature of α-Al2O3 for stable supported Ag NPs, including the surface orientation and promoter species modified on it. The outlined approach of this work may be applied to a range of different thermocatalytic reactions other than ethylene epoxidation and provide guidance for the development of supported metal catalysts with long-term stability.

Nickel-based perovskite-catalysed direct phenol-to-aniline liquid-phase transformations

Liquid phase direct amination of phenols to primary anilines with hydrazine was achieved using commercial NiLa-perovskite catalysts as bifunctional Lewis acid/redox-active catalysts without adding any external hydride sources. The amination strategy took place efficiently in the absence of any amount of reducing gasses (H2/NH3) and noble metals under mild conditions.

Hydrogen production by NH3 decomposition at low temperatures assisted by surface protonics

Ammonia, which can be decomposed on-site to produce CO2-free H2, is regarded as a promising hydrogen carrier because of its high hydrogen density, wide availability, and ease of transport. Unfortunately, ammonia decomposition requires high temperatures (>773 K) to achieve complete conversion, thereby hindering its practical applicability. Here, we demonstrate that high conversion can be achieved at markedly lower temperatures using an applied electric field along with a highly active and readily producible Ru/CeO2 catalyst. Applying an electric field lowers the apparent activation energies, promotes low-temperature conversion, and even surpasses equilibrium conversion at 398 K, thereby providing a feasible route to economically attractive hydrogen production. Experimentally obtained results and neural network potential studies revealed that this reaction proceeds via HN-NH intermediate formation by virtue of surface protonics.

Effect of Different N/C Coordination Electronic Structures on the Activity of Bifunctional Rare-Earth Ytterbium Electrocatalysts for Oxygen Electrodes

The research and development of bifunctional electrocatalysts for the oxygen electrode is of great significance to solve the problem of electrochemical energy. Herein, the effect of different structure-activity relationships on the performance of YbNxCy-gra catalysts was explored. The bifunctional activity of graphene with a vacancy defect supported by single-atom rare-earth ytterbium was studied by density functional theory (DFT) calculations. We systematically analyzed the stability, electronic properties, and catalytic performance of potential bifunctional catalysts. The results showed that all catalysts were thermodynamically and kinetically stable. Under acidic conditions, YbN2C2-oppo-gra and YbN2C2-pen-gra showed good ORR activity, and their overpotentials were 0.53 and 0.65 V, respectively. In an alkaline environment, most of the Yb(OH)NxCy-gra catalysts showed excellent ORR and OER bifunctional catalytic activity. Their overpotentials were all below 0.6 V. In particular, the ηORR and ηOER of the Yb(OH)N4C0-gra electrocatalyst were as low as 0.33 and 0.42 V. This verified the practicability and feasibility of hydroxyl-modified catalysts to enhance activity. This research provides theoretical insights into the further design and development of high-efficiency rare-earth-supported bifunctional catalysts.

Chemical and engineering bases for green H2O2 production and related oxidation and ammoximation of olefins and analogues

Plastics, fibers and rubber are three mainstream synthetic materials that are essential to our daily lives and contribute significantly to the quality of our lives. The production of the monomers of these synthetic polymers usually involves oxidation or ammoximation reactions of olefins and analogues. However, the utilization of C, O and N atoms in current industrial processes is <80%, which represents the most environmentally polluting processes for the production of basic chemicals. Through innovation and integration of catalytic materials, new reaction pathways, and reaction engineering, the Research Institute of Petroleum Processing, Sinopec Co., Ltd. (RIPP) and its collaborators have developed unique H2O2-centered oxidation/ammoximation technologies for olefins and analogues, which has resulted in a ¥500 billion emerging industry and driven trillions of ¥s' worth of downstream industries. The chemical and engineering bases of the production technologies mainly involve the integration of slurry-bed reactors and microsphere catalysts to enhance H2O2 production, H2O2 propylene/chloropropylene epoxidation for the production of propylene oxide/epichlorohydrin, and integration of H2O2 cyclohexanone ammoximation and membrane separation to innovate the caprolactam production process. This review briefly summarizes the whole process from the acquisition of scientific knowledge to the formation of an industrial production technology by RIPP. Moreover, the scientific frontiers of H2O2 production and related oxidation/ammoximation processes of olefins and analogues are reviewed, and new technological growth points are envisaged, with the aim of maintaining China's standing as a leader in the development of the science and technologies of H2O2 production and utilization.

Modulating Electron Transfer between Pt and MOF Support through Pd Doping Promotes Nanozyme Catalytic Efficiency

Electron transfer is considered to be a typical parameter that affects the catalytic activity of nanozymes. However, there is still controversy regarding whether higher or lower electron transfer numbers are beneficial for improving the catalytic activity of nanozymes. To address this issue, we propose the introduction of Pd doping as an important electron regulation strategy to tune electron transfer between Pt and ZIF-8 carriers (PtxPd1@ZIF-8). We observe a volcano-shaped relationship between the electron transfer number and catalytic activity, reaching its peak at Pt4Pd1@ZIF-8. Mechanism studies indicate that as the electron transfer number from Pt to ZIF-8 carriers increases, the d-band center of the active site Pt increases, reducing the occupancy of antibonding states and enhancing the adsorption capacity of the key intermediate (*O). However, a further increase in the adsorption of *O energy makes it difficult to desorb and participate in the next reaction, thus exhibiting volcanic activity. The optimized Pt4Pd1@ZIF-8 nanozyme is applied to develop an immunoassay for the detection of zearalenone, achieving a detection limit of 0.01 μg/L, which is 6 times higher than that of the traditional enzyme-linked immunosorbent assay. This work not only reveals the potential regulatory mechanism of electron transfer on the catalytic activity of nanozymes but also improves the performance of nanozyme-based biosensors.

Design Principle of Molybdenum-Based Metal Nitrides for Lattice Nitrogen-Mediated Ammonia Production

Chemical looping ammonia synthesis (CLAS) is a promising technology for reducing the high energy consumption of the conventional ammonia synthesis process. However, the comprehensive understanding of reaction mechanisms and rational design of novel nitrogen carriers has not been achieved due to the high complexity of catalyst structures and the unrevealed relationship between electronic structure and intrinsic activity. Herein, we propose a multistage strategy to establish the connection between catalyst intrinsic activity and microscopic electronic structure fingerprints using density functional theory computational energetics as bridges and apply it to the rational design of metal nitride catalysts for lattice nitrogen-mediated ammonia production. Molybdenum-based nitride catalysts with well-defined structures are employed as prototypes to elucidate the decoupled effects of electronic and geometrical features. The electron-transfer and spin polarization characteristics of the magnetic metals are constructed as descriptors to disclose the atomic-scale causes of intrinsic activity. Based on this design strategy, it is demonstrated that Ni3Mo3N catalysts possess the highest lattice nitrogen-mediated ammonia synthesis activity. This work reveals the structure-activity relationship of metal nitrides for CLAS and provides a multistage perspective on catalyst rational design.

Selective Cleavage of α-Olefins to Produce Acetylene and Hydrogen

Acetylene production from mixed α-olefins emerges as a potentially green and energy-efficient approach with significant scientific value in the selective cleavage of C-C bonds. On the Pd(100) surface, it is experimentally revealed that C2 to C4 α-olefins undergo selective thermal cleavage to form surface acetylene and hydrogen. The high selectivity toward acetylene is attributed to the 4-fold hollow sites which are adept at severing the terminal double bonds in α-olefins to produce acetylene. A challenge arises, however, because acetylene tends to stay at the Pd(100) surface. By using the surface alloying methodology with alien Au, the surface Pd d-band center has been successfully shifted away from the Fermi level to release surface-generated acetylene from α-olefins as a gaseous product. Our study actually provides a technological strategy to economically produce acetylene and hydrogen from α-olefins.

Layered Double Hydroxide Derivatives for Polyolefin Upcycling

While Ru-catalyzed hydrogenolysis holds significant promise in converting waste polyolefins into value-added alkane fuels, a major constraint is the high cost of noble metal catalysts. In this work, we propose, for the first time, that Co-based catalysts derived from CoAl-layered double hydroxide (LDH) are alternatives for efficient polyolefin hydrogenolysis. Leveraging the chemical flexibility of the LDH platform, we reveal that metallic Co species serve as highly efficient active sites for polyolefin hydrogenolysis. Furthermore, we introduced Ni into the Co framework to tackle the issue of restricted hydrogenation ability associated with contiguous Co-Co sites. In-situ analysis indicates that the integration of Ni induces electron transfer and facilitates hydrogen spillover. This dual effect synergistically enhances the hydrogenation/desorption of olefin intermediates, resulting in a significant reduction in the yield of low-value CH4 from 27.1 to 12.6%. Through leveraging the unique properties of LDH, we have developed efficient and cost-effective catalysts for the sustainable recycling and valorization of waste polyolefin materials.

Nanoparticles as an antidote for poisoned gold single-atom catalysts in sustainable propylene epoxidation

The development of sustainable and anti-poisoning single-atom catalysts (SACs) is essential for advancing their research from laboratory to industry. Here, we present a proof-of-concept study on the poisoning of Au SACs, and the antidote of Au nanoparticles (NPs), with trace addition shown to reinforce and sustain propylene epoxidation. Multiple characterizations, kinetics investigations, and multiscale simulations reveal that Au SACs display remarkable epoxidation activity at a low propylene coverage, but become poisoned at higher coverages. Interestingly, Au NPs can synergistically cooperate with Au SACs by providing distinct active sites required for H2/O2 and C3H6 activations, as well as hydroperoxyl radical to restore poisoned SACs. The difference in reaction order between C3H6 and H2 (nC3H6-nH2) is identified as the descriptor for establishing the volcano curves, which can be fine-tuned by the intimacy and composition of SACs and NPs to achieve a rate-matching scenario for the formation, transfer, and consumption of hydroperoxyl. Consequently, only trace addition of Au NPs antidote (0.3% ratio of SACs) stimulates significant improvements in propylene oxide formation rate, selectivity, and H2 efficiency compared to SACs alone, offering a 56-fold, 3-fold, and 22-fold increase, respectively, whose performances can be maintained for 150 h.

Leveraging the Proximity and Distribution of Cu-Cs Sites for Direct Conversion of Methanol to Esters/Aldehydes

Methanol serves as a versatile building-block for various commodity chemicals, and the development of industrially promising strategies for its conversion remains the ultimate goal in methanol chemistry. In this study, we design a dual Cu-Cs catalytic system that enables a one-step direct conversion of methanol and methyl acetate/ethanol into high value-added esters/aldehydes, with customized chain length and saturation by leveraging the proximity and distribution of Cu-Cs sites. Cu-Cs at a millimeter-scale intimacy triggers methanol dehydrogenation and condensation, involving proton transfer, aldol formation, and aldol condensation, to obtain unsaturated esters and aldehydes with selectivities of 76.3 % and 31.1 %, respectively. Cu-Cs at a micrometer-scale intimacy significantly promotes mass transfer of intermediates across catalyst interfaces and their subsequent hydrogenation to saturated esters and aldehydes with selectivities of 67.6 % and 93.1 %, respectively. Conversely, Cu-Cs at a nanometer-scale intimacy alters reaction pathway with a similar energy barrier for the rate-determining step, but blocks the acidic-basic sites and diverts the reaction to byproducts. More importantly, an unprecedented quadruple tandem catalytic production of methyl methacrylate (MMA) is achieved by further tailoring Cu and Cs distribution across the reaction bed in the configuration of Cu-Cs||Cs, outperforming the existing industrial processes and saving at least 15 % of production costs.