Low-Temperature Synthesis of Single Palladium Atoms Supported on Defective Hexagonal Boron Nitride Nanosheet for Chemoselective Hydrogenation of Cinnamaldehyde

Graphene Chainmail Shelled Dilute Ni─Cu Alloy for Selective and Robust Aqueous Phase Catalytic Hydrogenation

Cost-effective non-noble metal-based catalysts for selective hydrogenation with excellent activity, selectivity, and durability are still the holy grail. Herein, an oxygen-doped carbon (OC) chainmail encapsulated dilute Cu-Ni alloy is developed by simple pyrolysis of Cu/Ni-metal-organic framework. The CuNi0.05@OC catalyst displays superior performance for atmospheric pressure transfer hydrogenation of p-chloronitrobenzene and p-nitrophenol, and for hydrogenation of furfural, all in water and with exceptional durability. Comprehensive characterizations confirm the close interactions between the diluted Ni sites, the base Cu, and optimized three-layered graphene chainmail. Theoretical calculations demonstrate that the properly tuned lattice strain and Schottky junction can adjust electron density to facilitate specific adsorption on the active centers, thus enhancing the catalytic activity and selectivity, while the OC shell also offers robust protection. This work provides a simple and environmentally friendly strategy for developing practical heterogeneous catalysts that bring the synergistic effect into play between dilute alloy and functional carbon wrapping.

The single metal atom (Ni, Pd, Pt) anchored on defective hexagonal boron nitride for oxidative desulfurization

Single-atom catalysts (SACs) have attracted great attention for various chemical reactions because of their strong activity, high metal utilization ratio, and low cost. Here, by using the density functional theory (DFT) method, the stability of a single VIII-group metal atom (M = Ni, Pd, Pt) anchored on the defective hexagonal boron nitride (h-BN) sheet and its possible application in oxidative desulfurization (ODS) are investigated. Calculations show that the stability of the single M atom embedded in the h-BN surface with B and N vacancies is strikingly enhanced compared to that on the perfect h-BN surface. The catalytic activities of the defective h-BN-supported single metal atom are further studied by the activation of molecular oxygen and subsequent oxidation of dibenzothiophene (DBT). O2 is activated to the super-oxo state with large interaction energies on three M/VN surfaces. However, among the three M/VB surfaces, only Pt/VB performs efficient activation of O2. The oxidation of DBT proceeds in two steps; the rate-determining step is the initial step, in which activated O2 oxidizes DBT to produce sulfoxide. By comparing the energy barrier in the first reaction step, both Ni/VN and Pt/VB are revealed as promising candidates for the ODS reaction.

Enhanced Selective Hydrogenation of Cinnamaldehyde to Cinnamyl Alcohol over Silica-Coated Pt-CoxOy Hybrid Nanoparticles

Selective hydrogenation of cinnamaldehyde (CAL) to cinnamyl alcohol (COL) is difficult due to the intrinsic difficulty with thermodynamically easier hydrogenation of C═C bonds. In this work, Pt-CoxOy hybrid nanoparticles encapsulated in mesoporous silica nanospheres (Pt-CoxOy@mSiO2) were synthesized by a sol-gel method, which showed greatly improved COL selectivity for hydrogenation of CAL. At 80 °C and 1.0 MPa of H2, Pt-CoxOy@mSiO2 achieved a CAL conversion of 98.7% with a COL selectivity of 93.5%. In contrast, Pt@mSiO2 yields 3-phenylpropanol (HCOL) as the major product with HCOL selectivity of 67.2%, while PtCo@mSiO2 yields 3-phenylpropionaldehyde with selectivity of 51.8% under the same conditions. The enhanced catalytic performance of Pt-CoxOy@mSiO2 for hydrogenation of CAL to COL is ascribed to the Pt surface electron deficiency induced by metal-oxide interaction, and the protection of active NPs by silica shells results in good catalytic stability.

Atomically dispersed Pd on defective BN nanosheets for nitrite electroreduction to ammonia

Electrocatalytic NO2- reduction to NH3 (NO2RR) offers a prospective strategy to concurrently achieve polluted NO2- removal and effective NH3 electrosynthesis. In this work, we report atomically dispersed Pd on defective BN nanosheets (Pd1/BN) as an efficient catalyst for the NO2RR, achieving the highest NH3-Faradaic efficiency of 91.7% with an NH3 yield rate of 347.1 μmol h-1 cm-2 at -0.6 V vs. RHE, superior to those of most previously reported electrocatalysts. Theoretical computations reveal the isolated Pd sites as catalytic centers to selectively adsorb NO2- and accelerate NO2--to-NH3 hydrogenation process with a minimized reaction barrier, eventually contributing to the considerably enhanced NO2RR selectivity and activity of Pd1/BN.

Few-layered boron nitride nanosheet as a non-metallic phosphatase nanozyme and its application in human urine phosphorus detection

Human urine phosphorus (existing in the form of phosphate) is a biomarker for the diagnosis of several diseases such as kidney disease, hyperthyroidism, and rickets. Therefore, the selective detection of phosphate in urine samples is crucial in the field of clinical diagnosis. Herein, we reported the phosphatase-like catalytic activity of few-layered h-BNNS for the first time. As the phosphatase-like activity of few-layered h-BNNS could be effectively inhibited by phosphate, a selective fluorescent method for the detection of phosphate was proposed. The linear range for phosphate detection is 0.5-10 µM with a detection limit of 0.33 µM. The fluorescent method was then explored for the detection of human urine phosphorus in real samples. The results obtained by the proposed method were consistent with those of the traditional method, indicating that the present method has potential application for urine phosphorus detection in clinical disease diagnosis.

Dual-Site Metal Catalysts for Electrocatalytic CO2 Reduction Reaction

Electrocatalytic CO2 reduction reaction (CO2 RR) is a promising and green approach for reducing atmospheric CO2 concentration and achieving high-valued conversion of CO2 under the carbon-neutral policy. In CO2 RR, the dual-site metal catalysts (DSMCs) have received wide attention for their ingenious design strategies, abundant active sites, and excellent catalytic performance attributed to the synergistic effect between dual-site in terms of activity, selectivity and stability, which plays a key role in catalytic reactions. This review provides a systematic summary and detailed classification of DSMCs for CO2 RR, describes the mechanism of synergistic effects in catalytic reactions, and also introduces in situ characterization techniques commonly used in CO2 RR. Finally, the main challenges and prospects of dual-site metal catalysts and even multi-site catalysts for CO2 recycling are analyzed. It is believed that based on the understanding of bimetallic site catalysts and synergistic effects in CO2 RR, well-designed high-performance, low-cost electrocatalysts are promising for achieving CO2 conversion, electrochemical energy conversion and storage in the future.

Constructing multiple active sites in iron oxide catalysts for improving carbonylation reactions

Surface engineering is a promising strategy to improve the catalytic activities of heterogeneous catalysts. Nevertheless, few studies have been devoted to investigate the catalytic behavior differences of the multiple metal active sites triggered by the surface imperfections on catalysis. Herein, oxygen vacancies induced Fe2O3 catalyst are demonstrated with different Fe sites around one oxygen vacancy and exhibited significant catalytic performance for the carbonylation of various aryl halides and amines/alcohols with CO. The developed catalytic system displays excellent activity, selectivity, and reusability for the synthesis of carbonylated chemicals, including drugs and chiral molecules, via aminocarbonylation and alkoxycarbonylation. Combined characterizations disclose the formation of oxygen vacancies. Control experiments and density functional theory calculations demonstrate the selective combination of the three Fe sites is vital to improve the catalytic performance by catalyzing the elemental steps of PhI activation, CO insertion and C-N/C-O coupling respectively, endowing combinatorial sites catalyst for multistep reactions.

VSe2-x O x @Pd Sensor for Operando Self-Monitoring of Palladium-Catalyzed Reactions

Operando monitoring of catalytic reaction kinetics plays a key role in investigating the reaction pathways and revealing the reaction mechanisms. Surface-enhanced Raman scattering (SERS) has been demonstrated as an innovative tool in tracking molecular dynamics in heterogeneous reactions. However, the SERS performance of most catalytic metals is inadequate. In this work, we propose hybridized VSe_2-x O _x @Pd sensors to track the molecular dynamics in Pd-catalyzed reactions. Benefiting from metal-support interactions (MSI), the VSe_2-x O _x @Pd realizes strong charge transfer and enriched density of states near the Fermi level, thereby strongly intensifying the photoinduced charge transfer (PICT) to the adsorbed molecules and consequently enhancing the SERS signals. The excellent SERS performance of the VSe_2-x O _x @Pd offers the possibility for self-monitoring the Pd-catalyzed reaction. Taking the Suzuki-Miyaura coupling reaction as an example, operando investigations of Pd-catalyzed reactions were demonstrated on the VSe_2-x O _x @Pd, and the contributions from PICT resonance were illustrated by wavelength-dependent studies. Our work demonstrates the feasibility of improved SERS performance of catalytic metals by modulating the MSI and offers a valid means to investigate the mechanisms of Pd-catalyzed reactions based on VSe_2-x O _x @Pd sensors.

Heterogeneous Hydrogenation with Hydrogen Spillover Enabled by Nitrogen Vacancies on Boron Nitride-Supported Pd Nanoparticles

Heterogeneous hydrogenation with hydrogen spillover has been demonstrated as an effective route to achieve high selectivity towards target products. More effort should be paid to understand the complicated correlation between the nature of supports and hydrogenation involving hydrogen spillover. Herein, we report the development of the hydrogenation system of hexagonal boron nitride (h-BN)-supported Pd nanoparticles for the hydrogenation of aldehydes/ketones to alcohols with hydrogen spillover. Nitrogen vacancies in h-BN determine the feasibility of hydrogen spillover from Pd to h-BN. The hydrogenation of aldehydes/ketones with hydrogen spillover from Pd proceeds on nitrogen vacancies on h-BN. The weak adsorption of alcohols to h-BN inhibits the deep hydrogenation of aldehydes/ketones, thus leading to high catalytic selectivity to alcohols. Moreover, the hydrogen spillover-based hydrogenation mechanism makes the catalyst system exhibit a high tolerance to CO poisoning.

A One-Pot Hydrothermal Preparation of High Loading Ni/La2O3 Catalyst for Efficient Hydrogenation of Cinnamaldehyde

It is a challenging task for selective hydrogenation of cinnamaldehyde (CAL) to hydrocinnamaldehyde (HCAL) without additional by-product formation. In this work, a La2O3 supported high Ni content nanoparticle catalyst was prepared for CAL selective hydrogenation. Meanwhile, Co-La2O3 catalysts were used as a reference catalyst. XRD, TEM, STEM-HAADF, XPS, and H2-TPR measurements were used to investigate the physicochemical properties of Ni-La2O3 catalysts. The experimental results confirmed that the CAL conversion and HCAL selectivity were effectively promoted with the increase of Ni loading amounts. At a Ni/La molar ratio of four, a high HCAL selectivity of 87.4% was obtained at a CAL conversion of 88.1% under mild reaction conditions. The catalyst was recycled five times without activity loss. Combined with various characterizations, it could be inferred that the good hydrogen adsorption and dissociation capacity of Ni and the presence of a certain amount of oxygen vacancies on the La2O3 support have a positive effect on the improvement of HCAL selectivity. This work provided an effective path to design transition-metal-based supported oxide catalyst for the cinnamaldehyde hydrogenation to hydrocinnamaldehyde.

Sequential hydrogenation of nitroaromatics to alicyclic amines via highly-dispersed Ru-Pd nanoparticles anchored on air-exfoliated C3N4 nanosheets

Developing efficient and green catalytic systems is highly desired in the syntheses of alicyclic amines via hydrogenation of nitroaromatics. Herein, we developed Ru-Pd dual active site catalysts in which Ru and Pd species were anchored and highly dispersed on air-exfoliated carbon nitride (Ru-Pd/C₃N₄-air). As-prepared catalysts were employed in the hydrogenation of nitrobenzene (NB) to cyclohexylamine (CHA). Compared with single Ru or Pd based catalysts, Ru-Pd dual active site catalysts obtained a higher CHA production rate of 26.7 mol CHA mol^-1 Ru·Pd h^-1 at 80 °C and 3 MPa H₂. The activation energy for the hydrogenation of the nitro group and benzene ring was calculated as 26.26 kJ mol^-1 and 66.30 kJ mol^-1, respectively. Intrinsic kinetic studies demonstrated that Pd was the dominant metal for hydrogenation of nitro group, while Ru was dominant for benzene ring. Thereinto, the corresponding non-dominant metals enhanced activation and dissociation of H₂, thereby improving catalytic activity significantly. This excellent performance of Ru-Pd catalysts could be attributed to highly dispersed Ru-N _x and Pd-N _x at a nanoscale distance, which was conducive to metal-assisted hydrogenation. Stability investigation showed that the performance of Ru-Pd catalysts could be essentially maintained at a high level. Additionally, the substrate scope could be successfully extended to hydrogenation of other nitroaromatics with different substituents.

Defective hBN-Supported Fe2N Single Cluster Catalyst for Active and Selective Electro-Reduction of Multiple CO to Propane: Theoretical Elucidation of Metal-Nonmetal Synergic Effects

The present work introduces the multiple CO reduction toward C₃ products promoted by a newly designed single cluster catalyst consisting of defective hBN and embedded dimerized Fe, by means of density functional theory calculations. We find the strong metal-support interactions give rise to the local strain and electron accumulation of the N coordinated with two metals and resultantly form a Fe₂N active center. The metal-nonmetal synergic effect facilitates the coadsorption and C-C coupling of triple CO molecules and finally generates propane in a highly active and selective way.

General Strategy toward Hydrophilic Single Atom Catalysts for Efficient Selective Hydrogenation

Well dispersible and stable single atom catalysts (SACs) with hydrophilic features are highly desirable for selective hydrogenation reactions in hydrophilic solvents towards important chemicals and pharmaceutical intermediates. A general strategy is reported for the fabrication of hydrophilic SACs by cation-exchange approach. The cation-exchange between metal ions (M = Ni, Fe, Co, Cu) and Na⁺ ions introduced in the skeleton of metal oxide (TiO₂ or ZrO₂ ) nanoshells plays the key role in forming M₁ /TiO₂ and M₁ /ZrO₂ SACs, which efficiently prevents the aggregation of the exchanged metal ions. The as-obtained SACs are highly dispersible and stable in hydrophilic solvents including alcohol and water, which greatly facilitates the catalysis reaction in alcohol. The Ni₁ /TiO₂ SACs have been successfully utilized as catalysts for the selective C=C hydrogenation of cinnamaldehyde to produce phenylpropanal with 98% conversion, over 90% selectivity, good recyclability, and a turnover frequency (TOF) of 102 h^-1 , overwhelming most reported catalysts including noble metal catalysts.

Recent Progress in Fabrication and Application of BN Nanostructures and BN-Based Nanohybrids

Due to its unique physical, chemical, and mechanical properties, such as a low specific density, large specific surface area, excellent thermal stability, oxidation resistance, low friction, good dispersion stability, enhanced adsorbing capacity, large interlayer shear force, and wide bandgap, hexagonal boron nitride (h-BN) nanostructures are of great interest in many fields. These include, but are not limited to, (i) heterogeneous catalysts, (ii) promising nanocarriers for targeted drug delivery to tumor cells and nanoparticles containing therapeutic agents to fight bacterial and fungal infections, (iii) reinforcing phases in metal, ceramics, and polymer matrix composites, (iv) additives to liquid lubricants, (v) substrates for surface enhanced Raman spectroscopy, (vi) agents for boron neutron capture therapy, (vii) water purifiers, (viii) gas and biological sensors, and (ix) quantum dots, single photon emitters, and heterostructures for electronic, plasmonic, optical, optoelectronic, semiconductor, and magnetic devices. All of these areas are developing rapidly. Thus, the goal of this review is to analyze the critical mass of knowledge and the current state-of-the-art in the field of BN-based nanomaterial fabrication and application based on their amazing properties.

Homogeneity of Supported Single-Atom Active Sites Boosting the Selective Catalytic Transformations

Selective conversion of specific functional groups to desired products is highly important but still challenging in industrial catalytic processes. The adsorption state of surface species is the key factor in modulating the conversion of functional groups, which is correspondingly determined by the uniformity of active sites. However, the non-identical number of metal atoms, geometric shape, and morphology of conventional nanometer-sized metal particles/clusters normally lead to the non-uniform active sites with diverse geometric configurations and local coordination environments, which causes the distinct adsorption states of surface species. Hence, it is highly desired to modulate the homogeneity of the active sites so that the catalytic transformations can be better confined to the desired direction. In this review, the construction strategies and characterization techniques of the uniform active sites that are atomically dispersed on various supports are examined. In particular, their unique behavior in boosting the catalytic performance in various chemical transformations is discussed, including selective hydrogenation, selective oxidation, Suzuki coupling, and other catalytic reactions. In addition, the dynamic evolution of the active sites under reaction conditions and the industrial utilization of the single-atom catalysts are highlighted. Finally, the current challenges and frontiers are identified, and the perspectives on this flourishing field is provided.

Photothermal-Driven High-Performance Selective Hydrogenation System Enabled by Delicately Designed IrCo Nanocages

The incorporation of a transition metal into a noble metal for the formation of nanoalloys paves a potential way to modulate the electronic structures and spatial arrangement modes, thereby manipulating the target catalysis under the desired reaction pathways. Herein, a top-down synthetic route to fabricate IrCo nanoalloys with delicately designed compositions and morphologies at an extremely low calcination temperature of 200 °C is reported, which efficiently breaks through the thermodynamic limitations caused by the large atomic radii and electronegativity discrepancies between Co and Ir. A high-performance selective hydrogenation system enabled by the synthesized IrCo nanoalloys and the light irradiation is further established. Significantly, the unique properties of IrCo alloy, involving the special capability of generating local heating rather than hot electrons under light irradiation (the hot-electron effect was considered detrimental to hydrogenation reactions), as well as the highly polarized surface which aids in the hydrogen transfer from borane-ammonia complex (AB) to 4-nitrostyrene (4-NS) are discovered.

Mechanistic Insight into the Photo-Oxidation of Perfluorocarboxylic Acid over Boron Nitride

Hexagonal boron nitride (hBN) can photocatalytically oxidize and degrade perfluorocarboxylic acids (PFCA), a common member of the per/polyfluoroalkyl substance (PFAS) family of water contaminants. However, the reaction mechanism governing PFCA activation on hBN is not yet understood. Here, we apply electronic grand canonical density functional theory (GC-DFT) to assess the thermodynamic and kinetic favorability of PFCA photo-oxidative activation on hBN: C_nF_2n+1COO^- + h⁺ → C_nF_2n+1^· + CO₂. The oxidation of all PFCA chains is exothermic under illumination with a moderate barrier. However, the longer-chain PFCAs are degraded more effectively because they adsorb on the surface more strongly as a result of increased van der Waals interactions with the hBN surface. The ability of hBN to act as a photocatalyst is unexpected because of its wide band gap. Therefore, we apply both theoretical and experimental analyses to examine possible defects on hBN that could account for its activity. We find that a nitrogen-boron substitutional defect (N_B), which generates a mid-gap state, can enhance UVC (ultraviolet C) absorption and PFCA oxidation. This work provides insight into the PFCA oxidation mechanism and reveals engineering strategies to design better photocatalysts for PFCA degradation.

Platinum clusters anchored on sulfur-doped ordered mesoporous carbon for chemoselective hydrogenation of halogenated nitroarenes

Chemoselective hydrogenation of unsaturated organic compounds is a significant research topic in the catalysis field. Herein, a sulfur-doped ordered mesoporous carbon (SMC) material was prepared to anchor ultrafine platinum (Pt) clusters for the chemoselective hydrogenation of halogenated nitroarenes. The confinement effect of the ordered pores and the strong metal-support interaction caused by Pt clusters and sulfur atoms, efficiently suppress the aggregation and regulate the electronic states of the ultrafine Pt clusters. Thus, the hydrogenation of parachloronitrobenzene (p-CNB) shows high selectivity catalyzed by the ultrafine Pt clusters with electron-rich states. Meanwhile, the catalytic performance of the hydrogenation reaction catalyzed by Pt/SMC is capable of being maintained after at least 5 cycles, and the catalytic universality can also be applied to different halogenated nitroarenes hydrogenation. Therefore, this study may promote the research into the construction of noble metal-based catalysts for chemoselective hydrogenation reactions in green and sustainable chemical processes.

Coadsorption Interfered CO Oxidation over Atomically Dispersed Au on h-BN

Similar to the metal centers in biocatalysis and homogeneous catalysis, the metal species in single atom catalysts (SACs) are charged, atomically dispersed and stabilized by support and substrate. The reaction condition dependent catalytic performance of SACs has long been realized, but seldom investigated before. We investigated CO oxidation pathways over SACs in reaction conditions using atomically dispersed Au on h-BN (AuBN) as a model with extensive first-principles-based calculations. We demonstrated that the adsorption of reactants, namely CO, O₂ and CO₂, and their coadsorption with reaction species on AuBN would be condition dependent, leading to various reaction species with different reactivity and impact the CO conversion. Specifically, the revised Langmuir–Hinshelwood pathway with the CO-mediated activation of O₂ and dissociation of cyclic peroxide intermediate followed by the Eley–Rideal type reduction is dominant at high temperatures, while the coadsorbed CO-mediated dissociation of peroxide intermediate becomes plausible at low temperatures and high CO partial pressures. Carbonate species would also form in existence of CO₂, react with coadsorbed CO and benefit the conversion. The findings highlight the origin of the condition-dependent CO oxidation performance of SACs in detailed conditions and may help to rationalize the current understanding of the superior catalytic performance of SACs.

NP monolayer supported transition-metal single atoms for electrochemical water splitting: a theoretical study

The development of cost-effective and highly efficient electrocatalysts for water splitting is highly desirable but remains an ongoing challenge. Numerous single-atom catalysts (SACs) have achieved satisfactory performances in this area; however, non-carbon metal-free substrates have been rarely explored. Herein, we report a series of single-metal atoms supported on a novel two-dimensional NP monolayer as promising electrocatalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) by theoretical calculations. Our results disclose that Ti@NP, V@NP and Ir@NP exhibit desirable catalytic activity for the HER with extremely low of -0.004, -0.051, and 0.017 eV, respectively. More importantly, the calculated activation barriers for the Tafel reactions of these SACs are much lower than those for the benchmark Pt catalysts. In addition, Pt@NP shows the lowest η^OER of 0.495 V, followed by Rh@NP (η^OER = 0.548 V), which are even superior to that of state-of-the-art IrO₂. This work highlights the potential application of metal-free supports in SACs, which also further enriches the application of a NP monolayer in other related electrochemical processes.

Modulating the Local Coordination Environment of Single-Atom Catalysts for Enhanced Catalytic Performance in Hydrogen/Oxygen Evolution Reaction

Single-atom catalysts (SACs) hold the promise of utilizing 100% of the participating atoms in a reaction as active catalytic sites, achieving a remarkable boost in catalytic efficiency. Thus, they present great potential for noble metal-based electrochemical application systems, such as water electrolyzers and fuel cells. However, their practical applications are severely hindered by intrinsic complications, namely atom agglomeration and relocation, originating from the uncontrollably high surface energy of isolated single-atoms (SAs) during postsynthetic treatment processes or catalytic reactions. Extensive efforts have been made to develop new methodologies for strengthening the interactions between SAs and supports, which could ensure the desired stability of the active catalytic sites and their full utilization by SACs. This review covers the recent progress in SACs development while emphasizing the association between the regulation of coordination environments (e.g., coordination atoms, numbers, sites, structures) and the electrocatalytic performance of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The crucial role of coordination chemistry in modifying the intrinsic properties of SACs and manipulating their metal-loading, stability, and catalytic properties is elucidated. Finally, the future challenges of SACS development and the industrial outlook of this field are discussed.

Atomically Defined Undercoordinated Copper Active Sites over Nitrogen-Doped Carbon for Aerobic Oxidation of Alcohols

Selective aerobic oxidation of alcohols offers an attractive means to address challenges in the modern chemical industry, but the development of non-noble metal catalysts with superior efficacy for this reaction remains a grand challenge. Here, this study reports on such a catalyst based on atomically defined undercoordinated copper atoms over nitrogen-doped carbon support as an efficient, durable, and scalable heterogeneous catalyst for selective aerobic oxidation of alcohols. This catalyst exhibits extremely high intrinsic catalytic activity (TOF of 7692 h^-1 ) in the oxidation of cinnamyl alcohol to afford cinnamaldehyde, along with exceptional recyclability (at least eight cycles), scalability, and broad substrate scope. DFT calculations suggest that the high activity derives from the low oxidation state and the unique coordination environment of the copper sites in the catalyst. These findings pave the way for the design of highly active and stable single atom catalysts to potentially address challenges in synthetic chemistry.

N-Doped Graphene Supported Cu Single Atoms: Highly Efficient Recyclable Catalyst for Enhanced C-N Coupling Reactions

Heterogenization of homogeneous catalysis through supported single-atom catalysts (SACs) provided a feasible solution to recycling catalysts while keeping its efficiency in chemical synthesis. In this work, Cu SACs anchored on N-doped graphene (Cu SACs/NG) were prepared and first used for C-N coupling reactions. During the preparation, Cu-N-C structures, including Cu-N₄ moieties, were formed in a one-step pyrolysis method. As-prepared Cu SACs/NG exhibited excellent catalytic activity toward C-N coupling reactions with a broad scope of substrates and showed outstanding performance of recycling. Compared with Cu nanoparticles (Cu NPs/NG), the advantages of single-atom catalysts were validated via experimental and theoretical calculations. The enhanced performances were attributed to increasing the number of active sites and increasing the intrinsic activity of each active site. This work provides an alternative synthetic strategy for fabricating atomically dispersed SACs and represents a significant advance for coupling reactions.

Pd Speciation on Black Phosphorene in CO and C2H4 Atmosphere: A First-principles Investigation

Deposited transition metal clusters and nanoparticles are widely used as catalysts and have long been thought stable in reaction conditions. We investigated the electronic structure and stability of freestanding and...

Promotion Effect of the X-Zeolite Host on Encapsulated Platinum Clusters for Selective Hydrogenation of Phenylacetylene to Styrene

The microenvironment surrounding the metal clusters on a carrier produces a tremendous influence on its catalytic performance. In this work, the promotion effect of the zeolitic inner host on catalytic performance of encapsulated platinum nanoclusters is reported. In the reaction of phenylacetylene semihydrogenation to styrene, Pt@X-zeolite, where platinum nanoclusters are encapsulated into the inner microporosity of the X-zeolite, exhibits an ∼3.37 times increased turnover frequency and a much better selectivity of 87.6% in comparison to the referenced Pt/X-zeolite of 79.3% selectivity to styrene at the same reaction conditions, in which the platinum nanoclusters are located at the exterior of the zeolite. Meanwhile, the Pt@X-zeolite displays a higher stability after 10 cycles of the reaction. Through the detailed characteristics, the excellent performance of Pt@X-zeolite is mainly due to the promotion of the zeolitic framework on the encapsulated Pt clusters, resulting in "electron-deficient" Pt clusters, leading to a stronger interaction with the π* molecular orbitals of phenylacetylene and thus enhancing the activation and conversion of phenylacetylene. The zeolite cavity wrapped with encapsulated Pt clusters regulates the adsorption trend of phenylacetylene through the acetylene group on it, promotes the desorption of styrene, and strengthens its selectivity. Meanwhile, Pt@X-zeolite has an excellent stability through the zeolite framework, which protects the Pt species from being lost. This investigation reveals the importance of the zeolitic microenvironment on the catalytic performance of encapsulated metal species and deepens the cognition for this type of catalyst.

Hexagonal Boron Nitride Meeting Metal: A New Opportunity and Territory in Heterogeneous Catalysis

Two dimensional (2D) hexagonal boron nitride (h-BN) has been ignored for a long time in catalysis research because of its chemical inertness. Recently there has been a significant advance highlighting the role of metal/h-BN interfaces in catalytic applications. In this Perspective, we summarize state-of-the-art progress regarding h-BN-involved metal catalysts. Vacancy- and defect-rich h-BN sheets are able to anchor and modify supported metals, in which the interfacial metal-support interaction effect helps to enhance catalytic performance. Oxidative etching of h-BN sheets causes encapsulation of metal catalysts via boron oxide (BO_x) species, which work synergistically with neighboring metal sites in catalysis. Covering a metal surface with ultrathin h-BN shells creates a 2D nanoreactor featuring confinement effect, providing a novel way to modulate metal-catalyzed reactions. Given all those fascinating combinations of metal catalyst and h-BN, the emerging opportunity when h-BN meets metal in heterogeneous catalysis is clearly underlined. The outlook, especially the challenges in the field, are discussed as well.