Exceptional Catalytic Performance Research Articles

Two-Dimensional Cu(II)-MOF with Lewis Acid-Base Bifunctional Sites for Chemical Fixation of CO2 and Bioactive 1,4-DHP Synthesis via Hantzsch Condensation.

Five- and six-membered heterocycles containing nitrogen or oxygen have been considered as privileged scaffolds in organic chemistry and the chemical industry because of their usage in high-value commodities. Herein, we report a two-dimensional (2D) Cu(II)-based MOF catalyst, IITKGP-40, via the strategic employment of ample Lewis acid-base bifunctional sites (open metal nodes and free pyrazine moieties) along the pore wall. IITKGP-40 could convert toxic CO2 to cyclic carbonates in an atom-economical manner under solvent-free conditions and aromatic aldehyde to bioactive 1,4-DHPs via Hantzsch condensation. Exceptional catalytic performance (99%) and turnover number under mild reaction conditions for CO2 fixation using sterically hindered styrene oxide, and good-to-excellent yields for a wide range of aromatic aldehydes toward 1,4-dihydropyridines (1,4-DHPs) make IITKGP-40 promising as a multipurpose heterogeneous catalyst. Moreover, to demonstrate the practical utility of the catalyst, two biologically important drug molecules, diludine and nitrendipine analogue, have also been synthesized. IITKGP-40 is recyclable for at least three consecutive runs without significant loss of activity, making it promising for real-time applications.

Ni Single‐Atoms Supported on N‐Doped Carbon Prepared by Cation Exchange: Ultrafast Catalyst For The Reduction of Nitroarene Compounds Under Ambient Conditions

We present a highly efficient single‐atom catalyst (SAC) tailored for nitroarene reduction using NaBH4 under ambient conditions. Employing a unique approach, we harnessed NaCl under high temperature to create host materials enriched with negatively charged nitrogenous and oxygenated functional groups, capable of anchoring and stabilizing Ni ions within the aromatic structure. The nickel single sites were prepared by a straightforward cation exchange method. STEM‐HAADF imaging confirmed the presence of nickel single‐atoms, while XPS, FTIR, and Raman spectra validated nickel coordination within the catalyst. Remarkably, the CN‐Ni catalyst exhibited exceptional catalytic performance under ambient conditions, achieving a high catalytic activity with NaBH4 (TOF 2374 h‐1 and 177 mmolg‐1min‐1). It also demonstrated remarkable conversion exceeding 90% and outstanding selectivity. Equally impressive was its ability to maintain full catalytic activity over multiple reaction cycles, highlighting its robustness. This work is a significant leap in SAC design, offering a versatile and highly effective preparation method for SAC based on N‐doped carbon with far‐reaching implications in industrial reduction reactions.

Heterogeneous Oxidase-Type Catalysis for H2 Generation at Low Temperatures.

The long-term objective in the field of heterogeneous catalysis is to develop an enzyme-like catalytic pathway that can achieve exceptional catalytic performance even at low temperatures. Herein, we have demonstrated a heterogeneous oxidase-type catalysis on the ZnO-supported Ru clusters (Ru/ZnO) for efficient H2 generation from an aqueous solution of formaldehyde (HCHO) at low temperatures. Due to its unique reaction pathway, the Ru/ZnO catalysts exhibited a temperature-insensitive activity for H2 generation at the temperature of 15 to 45 °C. Remarkably, even at a low temperature of 5 °C, the Ru/ZnO catalysts still enabled an H2 generation rate of 13.8 mmol gcat-1 h-1 with a turnover frequency (TOF) of 1678 h-1. Additionally, instead of producing a CO2/CO molecule, the HCHO molecule underwent a transformation into formic acid and/or formate as the byproduct. This finding presents a novel class of heterogeneous catalysts to expand the potential application scenarios of liquid hydrogen storage and transportation systems.

Selective benzene hydroalkylation: Ni/Ni PS/HY catalysts for enhanced cyclohexylbenzene formation

The potential for synthesizing cyclohexylbenzene through one-step hydroalkylation of benzene is significant, but the selectivity is hindered by the deep hydrogenation of benzene to cyclohexane. In this study, Ni-containing phyllosilicate (Ni PS) was incorporated between Ni nanoparticles and zeolite (HY) using the deposition–precipitation technique, thereby creating Ni/Ni PS/HY. A conventional Ni/HY catalyst was also prepared using the impregnation method for comparison. Ni/Ni PS/HY demonstrates outstanding catalytic performance even at a low temperature of 130 °C and a high WHSV of up to 42.21 h−1, achieving a benzene conversion of ∼25 % and a cyclohexylbenzene selectivity of ∼85 %, which remained stable for 300 h. By contrast, the conventional Ni/HY catalyst yields a mere 2.5 % benzene conversion under identical conditions. Comprehensive characterizations and density functional theory (DFT) calculations reveal that Ni PS plays crucial roles in the hydroalkylation of benzene to cyclohexylbenzene. The formation of Ni PS leads to high Ni dispersion, generating more active sites for hydrogenation. Concurrently, the robust interaction between Ni PS and Ni reduces the reactivity of adsorbed H species, impeding the deep hydrogenation of benzene to cyclohexane, while still effectively allowing the formation of cyclohexene. After being adsorbed by the strong acid sites within Ni PS, the intermediate cyclohexene can be smoothly transported through the mesoporous structure of Ni PS to HY for alkylation. All these factors culminate in the exceptional catalytic performance of Ni/Ni-PS/HY.

Catalytic membranes assembled by Co–Fe Prussian blue analogues functionalized graphene oxide nanosheets for rapid removal of contaminants

The catalytic membrane, combining confinement effect with advanced oxidation processes, exhibits great potential as an efficient technology for removing contaminants and mitigating membrane fouling. Herein, the Prussian blue analogues (PBAs) functionalized graphene oxide (GO) membranes, referred as PGMs, was successfully fabricated. It exhibited a package-like confined structure where Co–Fe PBAs were encapsulated within interconnected GO nanosheets. The surface properties, internal structure as well as the catalytic performance of PGMs were controlled by adjusting the amount of Co–Fe PBAs anchored on GO nanosheets. The designed PGM as efficient peroxymonosulfate activator exhibited exceptional catalytic performance, achieving complete removal of bisphenol A (BPA) with a retention time of 31 ms. The corresponding first-order rate constant was 6000 min−1, which surpassed conventional batch system by four orders of magnitude (0.2194 min−1). Moreover, the redox cycle involving Fe2+ and Co3+, coupled with the effective suppression of ion leaching from Co–Fe PBAs nanoparticles (<10 μg/L) through GO protective layers, ensured the stable catalytic performance of PGM over 144 h. This study employs a novel approach to confine catalytic nanoparticles within two-dimensional nanosheets, demonstrating the potential applications of the resulting confined membrane in water treatment.

Electronic Structure Engineering of Pt-Ni Alloy NPs by Coupling of Gold Single Atoms on N-Doped Carbon for Highly Efficient Oxygen Reduction Reaction and Hydrogen Evolution Reaction.

Improving the catalytic activity and durability of platinum-based alloy catalysts remains a formidable challenge in the context of renewable energy electrolysis applications. Herein, a facile and rapid photochemical deposition strategy for the synthesis of gold single atoms (Au SAs) anchored on N-doped carbon is presented. These Au SAs serve as a charge redistribution support for Pt-Ni alloy nanoparticles (PtNiNPs/AuSA-NDC), creating an extended electron-donating interface with Pt-Ni alloy sites. Consequently, the PtNiNPs/AuSA-NDC hybrid catalyst manifests exceptional catalytic performance and durability in both the oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) under acidic conditions. Specifically, in ORR, it exhibits a half-wave potential (0.92V vs RHE), with a mass activity 20.4 times superior to Pt/C at 0.9V. In HER, PtNiNPs/AuSA-NDC demonstrates a notably reduced overpotential of 19.1mV vs RHE at 10mAcm-2 and a mass activity 38 times higher than Pt/C (at 0.25mV). Furthermore, this hybrid catalyst displays outstanding durability, with only an 8.0mV decay observed for ORR and a 6.9mV decay for HER after 10000 cycles. Theoretical calculations provide insight into the mechanism, demonstrating that isolated Au sites effectively modulate the electronic structure of Pt-Ni alloy sites, facilitating intermediate adsorption and enhancing reaction kinetics.

Encapsulating stable perovskite catalysts in hollow nanoreactors for enhanced pollutants degradation

Creating a microenvironment for enhanced peroxymonosulfate (PMS) activation is vital in advanced oxidation processes. The objective of this study was to fabricate nanoshells composed of titanium dioxide embedded with cobalt titanate nanoparticles of perovskite to act as nanoreactors for effectively initiating PMS and degrading contaminants. The unique porous structure and confined space of the nanoreactor facilitated reactant absorption and mass transfer to the active sites, resulting in exceptional catalytic performance for pollutant elimination. Experimental findings revealed close to 100% decomposition efficiency of 4-chlorophenol (4-CP) within an hour utilizing the nanoreactors over a wide pH range. The TiO2/CoTiO3 hollow nanoshells catalysts also displayed adaptability in disintegrating organic dyes and antibiotics. The radicals SO4•-, •OH, and non-radicals 1O2 were determined to be accountable for eliminating pollutants, as supported by trapping experiments and electron paramagnetic resonance spectra. The catalyst was confirmed as an electron donor and PMS as an electron acceptor through electrochemical tests and density functional theory calculations. This study underscores the potential of incorporating stable perovskite catalysts in hollow nanoreactors to enhance wastewater treatment.

Construction of a Dual-Function Mo-ZIS@Ti for Photocatalytic Benzyl Alcohol Oxidation and Hydrogen Evolution Performance.

The photocatalytic oxidation of benzyl alcohol and the simultaneous evolution of hydrogen from water are efficient dual-optimal routes. It is important to develop composite catalysts that combine redox properties and facilitate electron-hole separation and transport. Herein, the bimetallic-doped Mo-ZIS@Ti photocatalyst was designed and synthesized, and the selective oxidation of benzyl alcohol and hydrogen evolution by water splitting was realized at the same time. Under visible light irradiation, benzyl alcohol was completely converted with more than 99% selectivity for benzaldehyde, and the H2 production rate was 5.6 times higher than the initial ZIS. The exceptional catalytic performance was ascribed to utilizing Ti-MIL-125 as a precursor, wherein slowly releasing-doped Ti formed robust Ti-S bonds that quickly transfer electrons and reduce sites. Meanwhile, doping Mo effectively captures photogenerated holes and acts as active sites for oxidation reactions. Both experimental characterization and work function calculations demonstrate that the bimetallic synergism effectively modulates the electronic structure of ZIS, promotes the directional separation of electrons and holes, and significantly improves the photoactivity and stability of ZIS. This work contributes a route to obtain benzaldehyde and green hydrogen at the same time and also gives new insights for the construction and mechanism study of bimetallic-doping catalysts.

Biochar-Supported FeCo-MOF derivative catalyzes PDS-Mediated degradation of tetracycline

Bimetallic metal–organic framework (MOF) has gained wide attention in the field of advanced oxidative processes (AOPs), however, the agglomeration problem severely limits its active sites and its activation mechanism still needs to be further explored. This study developed the BC@CoFe composite material, utilizing biochar (BC) to support FeCo-MOF derivatives, effectively alleviating their agglomeration and structural collapse. The results of the BC@CoFe activated peroxydisulfate (PDS) system for the degradation of tetracycline (TC) revealed an excellent degradation efficiency up to 97.7 % in 2 h for TC solution (20 mg/L, degradation rate constants k = 7.066 mM-1min−1). Furthermore, the BC@CoFe/PDS system exhibits exceptionally high cyclic stability (73.23 % degradation efficiency after 12 h continuous degradation), a wide range of pH (3–11) and temperature tolerance (20-60℃), resistance to background ion interference (SO42-, H2PO4-, NO3– and HA), and reduced toxicity of the degradation products. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) analyses show that the exceptional catalytic performance of BC@CoFe primarily stems from the synergistic effect between Fe(II)/Co(III) and Fe(III)/Co(II). Regarding the reactive active species involved in TC degradation, the contribution rates of 1O2, SO4•- and ·OH were measured and calculated to be 73.6 %, 14.9 %, and 11.5 %, respectively. Thus, the BC@CoFe/PDS system exhibits outstanding catalytic activity and has broad practical applications in water treatment.

Metal-organic frameworks (MOFs) wrapped palladium nanoparticles-loaded Fe3O4@CFR core-shell magnetic nanohybrid as heterogeneous catalyst with robust catalytic properties

Metal-organic frameworks (MOFs) wrapped palladium nanoparticles supported on Fe3O4@catechol formaldehyde resin (Fe3O4@CFR@Pd@MOF) as magnetic nanohybrid catalyst was successfully fabricated by employing the redox capacity of CFR shell of Fe3O4@CFR core-shell microsphere for in situ formation of Pd NPs, followed by surface coating with Cu-MOF(HKUST-1). The research results demonstrated that the complementary properties of the various components within this hybrid material yielded magnetic recyclable nanocatalysts with exceptional catalytic performance. The Fe3O4@CFR@Pd@MOF catalyst exhibited remarkable advantages in the catalytic reduction of nitrophenol, demonstrating a transformation frequency (TOF) value of up to 4651 h−1. Additionally, the nanocatalyst was proved to have robust catalytic capacity in the reduction of organic dyes and Suzuki-Miyaura reaction. The HKUST-1 framework played a triple role: facilitating dye enrichment, Cu2+ assisting Pd NPs catalysis, and mitigating Pd NPs leaching. Moreover, the synthesized catalyst exhibited favorable magnetic properties, enabling facile separation by magnets for efficient recycling and reutilization.

Solvent-Free Synthesis Enables Encapsulation of Subnanometric FeOx Clusters in Pure Siliceous Zeolites for Efficient Catalytic Oxidation Reactions.

Metal/metal oxide clusters possess a higher count of unsaturated coordination sites than nanoparticles, providing multiatomic sites that single atoms do not. Encapsulating metal/metal oxide clusters within zeolites is a promising approach for synthesizing and stabilizing these clusters. The unique feature endows the metal clusters with an exceptional catalytic performance in a broad range of catalytic reactions. However, the encapsulation of stable FeOx clusters in zeolite is still challenging, which limits the application of zeolite-encapsulated FeOx clusters in catalysis. Herein, we design a modified solvent-free method to encapsulate FeOx clusters in pure siliceous MFI zeolites (Fe@MFI). It is revealed that the 0.3-0.4 nm subnanometric FeOx clusters are stably encapsulated in the 5/6-membered rings intersectional voids of the pure siliceous MFI zeolites. The encapsulated Fe@MFI catalyst with a Fe loading of 1.4 wt % demonstrates remarkable catalytic activity and recycle stability in the direct oxidation of methane, while also promoting the direct oxidation of cyclohexane, surpassing the performance of conventional zeolite-supported Fe catalysts.

Cobalt-silver catalyst with low metal content for highly efficient synthesis of methyl glycolate through synergistic effect

The Co-Agx/TiO2 catalysts with low mass content of Co and Ag were synthesized through the impregnation method and investigated for dimethyl oxalate (DMO) hydrogenation to methyl glycolate (MG). Remarkably, the Co-Ag0.7/TiO2 catalyst with an Ag concentration of 0.7 wt%, exhibited an impressive yield of MG of ∼94.4 %, surpassing the yields of MG obtained with Co/TiO2 (∼54 %) and Ag0.7/TiO2 (∼69 %) catalysts. Various characterizations elucidated that the exceptional catalytic performance of Co-Ag0.7/TiO2 can be ascribed to the synergy between Co and Ag, resulting in the formation of AgCoO2 as high active site can improve the adsorption and activation of DMO and H2 on catalyst surface. Additionally, the doping of a small amount of Ag regulated the contents of Lewis acidic and Brønsted acidic sites, leading to a high conversion of DMO and selectivity of MG. Furthermore, the excellent MG yield and long-term stability (at least 200 h) facilely obtained over our catalyst under mild reaction conditions guarantee a feasible prospect in the industrial application. This study not only unraveled the superior performance of the Co-Ag synergistic catalyst, but also carried significant implications for developing catalysts with low-content in DMO hydrogenation to MG.

Utilizing in situ construction of N-doped hierarchical porous carbon to achieve electronic control of highly dispersed Pd nanoparticles for efficient catalytic hydrogenation of CO2 to formic acid

Hydrogenation of CO2 to produce formic acid/formate is a significant pathway for future energy storage and utilization. The development of heterogeneous catalysts with high activity and stability for this process is still a challenge. In this work, the in-situ N-doped hierarchical porous carbon derived from distiller's grains was used as a support for Pd-based catalysts (Pd/NC) to convert CO2 into valuable chemicals while making high-value use of waste biomass. The optimum catalyst, Pd/NC-800, shown exceptional catalytic performance, achieving a turnover frequency (TOF) of 2060h-1 at 100℃, 4MPa in the catalytic CO2 hydrogenation to formate reaction. Comprehensive experimental results and density functional theory calculations indicate that the electronic effect between the pyridine N in the support and the Pd nanoparticles (NPs) can make the Pd surface reach the state of electron enrichment and enhance the metal-support interaction. Moreover, the synthesized material has hierarchical pore structure, which provides abundant Pd anchor location sites and improves mass transfer efficiency. The results not only provide a feasible strategy for the preparation of efficient CO2 hydrogenation catalysts, but also break a new and effective avenue for the resource utilization of distiller's grains.

Novel nanoporous amorphous/nanocrystalline composite structured RuNiFeCo multicomponent alloys with exceptional catalytic activity for ammonia borane hydrolytic dehydrogenation

The pursuit of high-efficient and cost-effective catalysts for hydrogen generation is imperative to address the energy crisis. Herein, nanoporous RuNiFeCo alloys (np-RuNiFeCo) with high catalytic activity for ammonia borane (AB) hydrolytic dehydrogenation have been prepared by dealloying Fe25NixCo40-xRu5B30 (x = 0–40) high-entropy amorphous alloys with low Ru content. The np-RuNiFeCo are composed of an amorphous/hexagonal close-packed Ru nanocrystalline dual-phase structure and exhibit a uniform nanopore/ligament bicontinuous architecture. The morphology, composition, and AB hydrolysis catalytic properties of the np-RuNiFeCo can be regulated by varying the Ni/Co content in the precursors, and the best catalytic activity with a high turnover frequency value of 148.2 and a low apparent activation energy of 25.3 was obtained when x = 30. Density functional theory simulations indicate that the presence of Ni, synergizing with Fe and Co, promotes electron transfer to Ru and enhances the adsorption energies of both AB and H2O molecules while reducing the activation barrier for cleaving the H2O molecule, leading to enhanced intrinsic catalytic activity of the alloy. The exceptional catalytic performance of the np-RuNiFeCo arises from the synergy of multiple principal elements, nanoporous morphology, and amorphous/nanocrystalline heterogeneous interface. In addition, the mechanisms of dealloying and nanoporous structure formation have been discussed based on surface diffusion.

Integrating metal-organic framework particles on fabric membranes for decontaminating toxic organophosphates

Zirconium-based metal-organic frameworks (Zr-MOFs) with periodic Lewis acidic nodes have demonstrated impressive catalytic activity in the hydrolysis of organophosphorus nerve agents. Nevertheless, the powdered form of Zr-MOFs and the necessity of a base-buffered aqueous solution during the catalytic reaction pose significant challenges to their practical utilization. In this study, we demonstrate the efficient hydrolysis of an organophosphorus nerve agent simulant, dimethyl-4-nitrophenyl phosphate (DMNP), in both pure water and the solid phase under high humidity conditions, catalyzed by a membrane material. This material, denoted as Im@MOF-808/PVDF, was synthesized through the integration of MOF-808 particles onto PVDF membrane fibers, with imidazole (Im) molecular bases incorporated into the pores of MOF-808. Our findings emphasize the excellent flexibility and processability inherent in Im@MOF-808/PVDF. More notably, it exhibits exceptional catalytic performance in the hydrolysis of DMNP in pure water. Additionally, it demonstrates fair catalytic activity for solid-phase DMNP hydrolysis under high humidity conditions. These features position Im@MOF-808/PVDF as one of the most promising protective materials, showcasing substantial practical applicability.

Revealing Hydrogen Spillover on 1T/2H MoS2 Heterostructures for an Enhanced Hydrogen Evolution Reaction by Scanning Electrochemical Microscopy.

The in situ characterization of the heterostructure active sites during the hydrogen evolution reaction (HER) process and the direct elucidation of the corresponding catalytic structure-activity relationships are essential for understanding the catalytic mechanism and designing catalysts with optimized activity. Hence, exploring the underlying reasons behind the exceptional catalytic performance necessitates a detailed analysis. Herein, we employed scanning electrochemical microscopy (SECM) to in situ image the topography and local electrocatalytic activity of 1T/2H MoS2 heterostructures on mixed-phase molybdenum disulfide (MoS2) with 20 nm spatial resolution. Our measurements provide direct data about HER activity, enabling us to differentiate the superior catalytic performance of 1T/2H MoS2 heterostructures compared to other active sites on the MoS2 surface. Combining this spatially resolved electrochemical information with density functional theory calculations and numerical simulations enables us to reveal the existence of hydrogen spillover from the 1T MoS2 surface to 1T/2H MoS2 heterostructures. Furthermore, it has been verified that hydrogen spillover can significantly enhance the electrocatalytic activity of the heterostructures, in addition to its strong electronic interaction. This study not only contributes to the future investigation of electrochemical processes at nanoscale active sites on structurally complex electrocatalysts but also provides new design strategies for improving the catalytic activity of 2D electrocatalysts.

Engineering of uniform dispersed Ni nanoparticles supported on carbon nanosheets for reduction of Nitroarenes to Aminoarenes

Facile synthesis of uniform supported metal catalysts is of great significance yet remains challenging for sustainable catalysis. Herein, a nanopore confinement strategy is developed to efficiently anchor metal ions in suitably sized polymer nanopores via strong coordinate bonds and ensure successful fabrication of uniform carbon-supported metal nanoparticles. Specifically, Ni2+-coordinated polydopamine (PDA) mesoporous layer was coated on GO nanosheets for the confinement of the nickel atoms (GO@PDA-Ni-x, x means pore size of PDA layer), resulting Ni@C-x nanosheets catalysts with uniformly dispersed Ni nanoparticles after pyrolysis in H2/Ar atmosphere. Characterization methods including SEM, TEM, and XPS reveal the intrinsic formation mechanism and physicochemical details. In the catalytic reaction of NaBH4-mediated hydrogenation of 4-nitrophenol (4-NP), the obtained Ni/C-10 exhibits exceptional catalytic performance with a rapid rate constant (0.686 min−1), outperforming many previously reported metal catalysts. Moreover, the catalytic activity remains almost unchanged after being recycled five times, proving the prominent stability. This work opens up an innovative avenue for rational design and synthesis of supported catalysts with controllable size for broad catalytic applications.

Natural sunlight energy harvesting using NiAl2O4@N-rGO hetero-junction for photocatalytic degradation of crystal violet dye: Kinetic and mechanistic insights

In this study, NiAl2O4 (NA) was synthesized by the co-precipitation route and its hetero-junctions were fabricated with N-doped reduced graphene oxide (N-rGO) through the ultra-sonication method. The structural, morphological, magnetic, optical and photocatalytic properties of synthesized NA, N-rGO, and the NA@N-rGO 1–4 hetero-junctions characterized by XRD, FTIR, SEM, VSM, PL and UV–visible spectroscopy, respectively. XRD results showed that crystallite size decreases from 25.01 nm (NA) to 15.20 nm for NA@N-rGO-4 and porosity increases up to 77.7 % for NA@N-rGO-4 making it remarkable for photocatalytic applications and FTIR results confirmed the formation of N-rGO as well as its successful integration into NA matrix, resulting in the formation of hetero-junctions. Magnetic properties were investigated using a vibrating sample magnetometer (VSM), revealing distinctive S-shaped hysteresis loops at 25 °C for both NA and N-rGO, as well as the NA@N-rGO 1–4 hetero-junctions and magnetic saturation decreases with an increase in N-rGO content as for NA@N-rGO-4 Ms drops to 0.0038 emu/g. Notably, the bandgap of NA@N-rGO-4 hetero-junction was effectively reduced from 3.0 eV (in the case of NA) to 2.1 eV, resulting in a discernible decrease in photoluminescence (PL) intensity and increase in e--h+ pair separation. Under visible light, NA@N-rGO-4 exhibited a remarkable 94.68 % efficiency in crystal violet (CV) dye degradation within just 90 min, outperforming NA's 59.05 % degradation efficiency and OH. Radicals play a major contribution to the degradation of dye. The optimization of degradation capabilities was achieved through the manipulation of catalyst dosage, dye concentration and varying pH values for the degradation of CV dye. NA@N-rGO-4 hetero-junction demonstrates the considerable potential for efficient dye degradation in wastewater under visible light, owing to its exceptional catalytic performance.

Graphsene as a novel porous two-dimensional carbon material for enhanced oxygen reduction electrocatalysis

Graphene allotropes with varied carbon configurations have attracted significant attention for their unique properties and chemical activities. This study introduces a novel two-dimensional carbon-based material, termed Graphsene (GrS), through theoretical study. Comprising tetra-, penta-, and dodeca-carbon rings, GrS’s cohesive energy calculations demonstrate its superior structural stability over existing graphene allotropes, including graphyne and graphdiyne families. Phonon dispersion analysis confirms GrS’s dynamic stability and its relatively low thermal conductivity. All calculated GrS elastic constants meet the Born criteria, ensuring mechanical stability. Ab-initio molecular dynamic simulations show GrS maintains its structure at 300 K. HSE06 calculations reveal a narrow electronic bandgap of 20 meV, with the electronic band structure featuring a highly anisotropic Dirac-like cone due to its intrinsic structural anisotropy along armchair and zigzag directions. Notably, GrS is predicted to offer exceptional catalytic performance for the oxygen reduction reaction, favoring the four-electron reduction pathway with high selectivity under both acidic and alkaline conditions. This discovery opens promising avenues for developing metal-free catalyst materials in clean energy production.

Heterogeneous Rhodium Single-Atom-Site Catalyst Enables Chemoselective Carbene N-H Bond Insertion.

Transition-metal-catalyzed carbene insertion reactions of a nitrogen-hydrogen bond have emerged as robust and versatile methods for the construction of C-N bonds. While significant progress of homogeneous catalytic metal carbene N-H insertions has been achieved, the control of chemoselectivity in the field remains challenging due to the high electrophilicity of the metal carbene intermediates. Herein, we present an efficient strategy for the synthesis of a rhodium single-atom-site catalyst (Rh-SA) that incorporates a Rh atom surrounded by three nitrogen atoms and one phosphorus atom doped in a carbon support. This Rh-SA catalyst, with a catalyst loading of only 0.15 mol %, exhibited exceptional catalytic performance for heterogeneous carbene insertion with various anilines and heteroaryl amines in combination with diazo esters. Importantly, the heterogeneous catalyst selectively transformed aniline derivatives bearing multiple nucleophilic moieties into single N-H insertion isomers, while the popular homogeneous Rh2(OAc)4 catalyst produced a mixture of overfunctionalized side products. Additionally, similar selectivities for N-H bond insertion with a set of stereoelectronically diverse diazo esters were obtained, highlighting the general applicability of this heterogeneous catalysis approach. On the basis of density functional theory calculations, the observed selectivity of the Rh-SA catalyst was attributed to the insertion barriers and the accelerated proton transfer assisted by the phosphorus atom in the support. Overall, this investigation of heterogeneous metal-catalyzed carbene insertion underscores the potential of single-atom-site catalysis as a powerful and complementary tool in organic synthesis.