Atom Catalysis Research Articles

Bismuth Nanoparticles and Single Iron Atoms on Carbon Derived from a Covalent Organic Framework Synergistically Catalyze the Oxygen Reduction Reaction.

The utilization of catalysts comprising metal nanoparticle has been beneficial for enhancing the performance of oxygen reduction reaction (ORR). However, the inadequate intrinsic activity of these catalysts still presents a significant challenge, limiting their overall effectiveness. This issue can be addressed by introducing single atoms, which can create a synergistic effect with the nanoparticles to catalyse and thereby improve performance. Nevertheless, the synergistic catalysis of nanoparticles and single atoms is still under investigation. In this study, we fabricated a core-shell structured carbon framework incorporating Fe single atoms and Bi nanoparticles through the pyrolysis of COF and MOF core-shell structures. Introducing Fe single atoms into ZIF-8, with Fe-ZIF-8 as the core and Bi-containing COF as the shell, resulted in higher ORR activity. The catalyst exhibited a half-wave potential of 0.867 V and a high current density of 6.68 mA cm-2 in 0.1 M KOH, which were comparable to those of Pt/C equivalent. This study provides new research concepts for exploring the application of single atoms and nanoparticles in catalytic oxygen reduction reactions through synergistic effects.

Synergistic Catalysis of Cobalt Single Atoms and Clusters Loaded on Carbon Film: Enhancing Peroxymonosulfate Activation for Degradation of Norfloxacin

AbstractMany existing research focuses on the differences or performance comparisons between single‐atom or small‐sized nanocluster catalysts, but there is a lack of comprehensive research on the coupling relationship between the structure and activity and the mechanism of synergy. This study investigates the combined catalytic potential of cobalt single atoms (SAs) and nanoclusters (NCs) for enhanced peroxymonosulfate (PMS) activation to degrade norfloxacin (NFX). A novel CoSAs‐NCs/CN/TiO2 catalyst is synthesized, featuring cobalt SAs and NCs uniformly dispersed on the carbon film wrapping TiO2, and the degradation efficiency of the NFX solution is almost completely degraded, with a mineralization rate of 76.35%. Density functional theory (DFT) calculations indicate that the synergistic interaction between cobalt SAs and NCs promotes more efficient PMS adsorption and activation and significantly reduces the activation energy barrier, which enhances electron transfer and increases reactive oxygen species (ROS) generation. This research highlights the robust and versatile nature of this novel catalyst system in addressing various contaminants. This study elucidates the activation mechanism of catalysts, providing new ideas for advanced oxidation processes (AOPs) in environmental remediation, linking the structure and performance of catalysts, and emphasizes the practicality and importance of the CoSAs‐NCs/CN/TiO2 catalyst in effectively and long‐term remediation of water pollutants.

Transition metal atom on the two-dimensional Dirac structure RhB4/OsB4: A novel multifunctional electrocatalyst

The design of low-cost multifunctional electrocatalysts with high carrier mobility, high surface free energy and base surface activity facilitates hydrogen evolution reactions (HER) and oxygen reduction reactions (ORR), which are essential for the development of clean energy. Recent studies have shown significant progress in developing HER/ORR bifunctional catalysts, such as transition metal alloys, oxides, sulfides, and carbon-based composites. These materials are highly efficient in catalysis and help reduce costs. In this work, density functional theory is used to predict the performance of single atom catalysis (SACs) embedded with transition metal (TM) using two-dimensional (2D) Dirac node-ring semi-metal RhB4/OsB4 monolayer as substrate. Systematic calculations show that the TM@RhB4/OsB4 structure with thermodynamic and kinetic stability presents multiple active sites on the basal surface. Notably, Fe@RhB4 is an excellent hydrogen evolution reaction HER catalyst because Dirac cones occur near the Fermi level of this structure, providing high carrier densities and accelerating charge transfer between the catalyst and reaction intermediates. When the substrate RhB4/OsB4 is modified by Sc and Cu atoms, the band gap of the structure becomes small, which increases the conductivity of the original structure. The ΔGH* values of Sc@RhB4 and Cu@OsB4 were 0.118, and 9.38 meV, respectively, outperforming the ideal catalyst Pt. In addition, it is found that Fe@RhB4, and Mn@OsB4 exhibit outstanding catalytic properties for the oxygen reduction reaction (ORR), with overpotentials of 0.41V, and 0.40V, respectively, surpassing the performance of the reference catalyst Pt. It is exciting that the Fe@RhB4 exhibits ideal HER/ORR bifunctional electrocatalytic properties. This study will provide a theoretical basis for the development of multifunctional electrocatalysts in the field of Dirac nodal ring semi-metal materials by single atom doping technology.

Rare Earth Single-Atom Catalysis for High-Performance Li-S Full Battery with Ultrahigh Capacity.

Lithium-sulfur (Li-S) batteries have many advantages but still face problems such as retarded polysulfides redox kinetics and Li dendrite growth. Most reported single atom catalysts (SACs) for Li-S batteries are based on d-band transition metals whose d orbital constitutes active valence band, which is inclined to occur catalyst passivation. SACs based on 4f inner valence orbital of rare earth metals are challenging for their great difficulty to be activated. In this work, we design and synthesize the first rare earth metal Sm SACs which has electron-rich 4f inner orbital to promote catalytic conversion of polysulfides and uniform deposition of Li. Sm SACs enhance the catalysis by the activated 4f orbital through an f-d-p orbital hybridization. Using Sm-N3C3 modified separators, the half cells deliver a high capacity over 600 mAh g-1 and a retention rate of 84.3 % after 2000 cycles. The fabricated Sm-N3C3-Li|Sm-N3C3@PP|S/CNTs full batteries can provide an ultra-stable cycling performance of a retention rate of 80.6 % at 0.2 C after 100 cycles, one of the best full Li-S batteries. This work provides a new perspective for the development of rare earth metal single atom catalysis in electrochemical reactions of Li-S batteries and other electrochemical systems for next-generation energy storage.

Rare Earth Single‐Atom Catalysis for High‐Performance Li−S Full Battery with Ultrahigh Capacity

AbstractLithium‐sulfur (Li−S) batteries have many advantages but still face problems such as retarded polysulfides redox kinetics and Li dendrite growth. Most reported single atom catalysts (SACs) for Li−S batteries are based on d‐band transition metals whose d orbital constitutes active valence band, which is inclined to occur catalyst passivation. SACs based on 4f inner valence orbital of rare earth metals are challenging for their great difficulty to be activated. In this work, we design and synthesize the first rare earth metal Sm SACs which has electron‐rich 4f inner orbital to promote catalytic conversion of polysulfides and uniform deposition of Li. Sm SACs enhance the catalysis by the activated 4f orbital through an f‐d‐p orbital hybridization. Using Sm‐N3C3 modified separators, the half cells deliver a high capacity over 600 mAh g−1 and a retention rate of 84.3 % after 2000 cycles. The fabricated Sm‐N3C3‐Li|Sm‐N3C3@PP|S/CNTs full batteries can provide an ultra‐stable cycling performance of a retention rate of 80.6 % at 0.2 C after 100 cycles, one of the best full Li−S batteries. This work provides a new perspective for the development of rare earth metal single atom catalysis in electrochemical reactions of Li−S batteries and other electrochemical systems for next‐generation energy storage.

Probing Basal and Prismatic Planes of Graphitic Materials for Metal Single Atom and Subnanometer Cluster Stabilization.

Supported metal single atom catalysis is a dynamic research area in catalysis science combining the advantages of homogeneous and heterogeneous catalysis. Understanding the interactions between metal single atoms and the support constitutes a challenge facing the development of such catalysts, since these interactions are essential in optimizing the catalytic performance. For conventional carbon supports, two types of surfaces can contribute to single atom stabilization: the basal planes and the prismatic surface; both of which can be decorated by defects and surface oxygen groups. To date, most studies on carbon-supported single atom catalysts focused on nitrogen-doped carbons, which, unlike classic carbon materials, have a fairly well-defined chemical environment. Herein we report the synthesis, characterization and modeling of rhodium single atom catalysts supported on carbon materials presenting distinct concentrations of surface oxygen groups and basal/prismatic surface area. The influence of these parameters on the speciation of the Rh species, their coordination and ultimately on their catalytic performance in hydrogenation and hydroformylation reactions is analyzed. The results obtained show that catalysis itself is an interesting tool for the fine characterization of these materials, for which the detection of small quantities of metal clusters remains a challenge, even when combining several cutting-edge analytical methods.

Visualizing Dynamic Single Atom Catalysis.

Many industrial chemical processes, including for producing fuels, foods, pharmaceuticals, chemicals and environmental controls, employ heterogeneous solid state catalysts at elevated temperatures in gas or liquid environments. Dynamic reactions at the atomic level play a critical role in catalyst stability and functionality. In situ visualization and analysis of atomic-scale processes in real time under controlled reaction environments can provide important insights into practical frameworks to improve catalytic processes and materials. This review focuses on innovative real time in situ electron microscopy (EM)methods, including recent progress in analytical insitu environmental (scanning) transmission EM (E(STEM), incorporating environmental scanning TEM (ESTEM) and environmental transmission EM (ETEM), with single atom resolution for visualizing and analysing dynamic single atom catalysis under controlled flowing gas reaction environments. ESTEM studies of single atom dynamics of reactions, and of sintering deactivation, contribute to a better-informed understanding of the yield and stability of catalyst operations. Advances in in situ technologies, including gas and liquid sample holders, nanotomography, and higher voltages, as well as challenges and opportunities in tracking reacting atoms, are highlighted. The findings show that the understanding and application of fundamental processes in catalysis can be improved, with valuable economic, environmental, and societal benefits.

Single atom catalysis—Back to the future

Single atom catalysis—Back to the future

Ultrasensitive and selective hydrogen sensing of SnO2 nanofibers decorated with Pd single atoms

Highly accurate and sensitive hydrogen detection particularly at (sub)ppb level is crucial for large-scale use of green hydrogen energy. However, state-of-the-art hydrogen sensors usually have a ppm-level limit of detection (LOD). In this work, SnO2 nanofibers were decorated with Pd single atoms using a scalable two-step annealing method, which remarkably boosted the H2 sensing properties. The Pd-SnO2 nanofiber sensor exhibited a response of 224 to 1000 ppm H2 at the optimum operation temperature of 300°C, which was 107 times higher than that of SnO2, achieving an LOD as low as 0.6 ppb. Moreover, a fast response time of 8.4 s, excellent selectivity, and humidity tolerance were observed. The superior H2 sensing performance of Pd-SnO2 nanofiber was ascribed to excellent catalysis of Pd single atoms and formation of heterojunction.

Tailoring Si12C12 nanocluster with late first-row transition metals: A promising approach during single-atom catalysis toward hydrogen evolution reaction (HER)

Hydrogen evolution reaction (HER) has gained a great interest in recent years because it provides the cleanest fuel (H2). One of the most demanding things required for this reaction is an efficient and cost-effective catalyst. Single atom catalysis is one of the most remarkable strategies in this regard. Herein, transition metals adsorbed silicon carbide nanocages (TM@Si12C12; TM = Zn, Fe, Co, Cu, Ni) are investigated as single atom catalysts in order to search less expensive electrocatalysts with excellent efficiency for HER. The pure and hydrogen adsorbed TM@Si12C12 show geometric and thermodynamic stability which illustrates their practical utility. Interaction energies obtained range from −0.70 to −5.73 eV, and it is suggested that Cu@Si12C12 may play an excellent role in HER due to its lowest Gibbs free energy of −0.17 eV (near to zero). In this work, we investigated electronic properties through natural bond orbital (NBO) analysis of selected TM@SiC. According to NBO calculations, it is observed that charge is transferred from adsorbed transition metals towards nanocage. After H adsorption, NBO charge is transferred to hydrogen which shows the adsorption properties of H. In case of HOMO-LUMO energy gap, it is observed that transition metal adsorbed complexes have small energy gaps between 2.17 and 2.77 eV but after adsorption of hydrogen, this energy gap increases to lie in the range of to change from 2.93 to 3.12 eV, which also verified the electronic stability of H adsorbed species. The noncovalent interactions are estimated through NCI analysis. The density of states analysis gives insight about the energy states of occupied and unoccupied orbitals of electrons. The highest thermodynamic stability and electronic conductivity of transition metal adsorbed silicon carbide suggested it as an excellent supportive surface for HER.

Exploring the energetics of Suzuki cross-coupling reaction: A computational study of palladium and nickel catalysts

The present study employed density-functional theory (DFT) calculations to investigate the Suzuki-Miyaura Cross-Coupling reaction using single atom catalysis (SAC) via palladium or nickel. The reaction barriers for chloride bond cleavage in phenyl chloride were found to be 34.68 kJ/mol and 24.24 kJ/mol for palladium and nickel catalysts, respectively. During the transmetalation process, the energy barrier for boronic acid release from phenyl trihydroxyboronate using SAC via palladium and SAC via nickel was calculated to be 74.17 kJ/mol and 65.22 kJ/mol, respectively. The results indicated that in the oxidative addition and transmetalation reactions, the SAC via nickel outperforms the SAC via palladium, while the SAC via palladium excels in the reductive elimination reaction. These findings suggest the effectiveness of a SAC via nickel as a substitute for SAC via palladium in the synthesis of biphenyls in the Suzuki-Miyaura cross-coupling reaction.

Superstructure-Assisted Single-Atom Catalysis on Tungsten Carbides for Bifunctional Oxygen Reactions.

Single-atom catalysis (SAC) attracts wide interest for zinc-air batteries that require high-performance bifunctional electrocatalysts for oxygen reactions. However, catalyst design is still highly challenging because of the insufficient driving force for promoting multiple-electron transfer kinetics. Herein, we report a superstructure-assisted SAC on tungsten carbides for oxygen evolution and reduction reactions. In addition to the usual single atomic sites, strikingly, we reveal the presence of highly ordered Co superstructures in the interfacial region with tungsten carbides that induce internal strain and promote bifunctional catalysis. Theoretical calculations show that the combined effects from superstructures and single atoms strongly reduce the adsorption energy of intermediates and overpotential of both oxygen reactions. The catalyst therefore presented impressive bifunctional activity with an ultralow potential gap of 0.623 V and delivered a high power density of 188.5 mW cm-2 for assembled zinc-air batteries. This work opens up new opportunities for atomic catalysis.

Imparting Chemiresistor with Humidity-Independent Sensitivity toward Trace-Level Formaldehyde via Substitutional Doping Platinum Single Atom.

The modification of metal oxides with noble metals is one of the most effective means of improving gas-sensing performance of chemiresistors, but it is often accompanied by unintended side effects such as sensor resistance increases up to unmeasurable levels. Herein, a carbonization-oxidation method is demonstrated using ultrasonic spray pyrolysis technique to realize platinum (Pt) single atom (SA) substitutional doping into SnO2 (named PtSA-SnO2). The substitutional doping strategy can obviously enhance gas-sensing properties, and meanwhile decrease sensor resistance by two orders of magnitude (decreased from ≈850 to ≈2 MΩ), which are attributed to the tuning of band gap and fermi-level position, efficient single atom catalysis, and the raising of adsorption capability of formaldehyde, as validated by the state-of-the-art characterizations, such as spherical aberration-corrected scanning transmission electron microscopy (Cs-corrected STEM), in situ diffuse reflectance infrared Fourier transformed spectra (in situ DRIFT), CO temperature-programmed reduction (CO-TPR), and theoretical calculations. As a proof of concept, the developed PtSA-SnO2 sensor shows humidity-independent (30-70% relative humidity) gas-sensing performance in the selective detection of formaldehyde with high response, distinguishable selectivity (8< Sformaldehyde/Sinterferant <14), and ultra-low detection limit (10 ppb). This work presents a generalized and facile method to design high-performance metal oxides for chemical sensing of volatile organic compounds (VOCs).

Degradation of Tolonium Chloride Dye by Phosphate Ion in Aqueous Acidic Solution: Kinetic Approach

The degradation of tolonium chloride (TC+) dye by phosphate ion (PO43-) in an aqueous acidic solution was studied using spectrophotometric analysis at 301 K, I= 1.0 M, [TC+]= 1.5 × 10-5 M, [H+]= 1.0×10-3 M, and ʎmax 600 nm. To determine the potency and rate of the reactant species, an aqueous acidic medium was employed. The reaction's direction and tendency were predicted using a thermodynamic analysis at an interval of 5.0 K and a temperature range of 301-321 K. Without the presence of intermediate complex/free atoms formation, a reaction that produced phenyl sulphoxide, phenylamine, and HPO32- as products of the reaction was obtained with a molar ratio of 1:1 for both reactants. First-order tolonium chloride reactivity was found in the reaction and first-order for the phosphate ion, resulting in a second-order reaction overall. The reaction process accelerated as the concentration of hydrochloric acid rose. The response time decreased with an increase in ionic strength concentration and added Ca2+ and Cl- did catalyze the reaction positively. A straight line that went through the origin was produced by plotting 1/ko vs PO43- concentration. The spectroscopic analysis showed no discernible shift from λmax of 600 nm. Additionally, an increase in temperature accelerated the reaction process. The reaction has a negative free energy change, G (-3.13–1.12 KJ/mol) which indicates that it is spontaneous and that the reactants have more free energy than that of the products. While the enthalpy of activation, H is positive and indicates that the reaction was endothermic and followed an associative path, the entropy of activation, S, is also negative (-7.45–1.10 KJ/mol), indicating that the reaction is less disordered. Due to the added ions catalysis and absence of free atoms during the course of the reaction, an outer-sphere mechanism was suggested for the reaction.

Enhanced catalysis of Pd single atoms on Sc2O3 nanoparticles for hydrogen storage of MgH2

The controlled preparation of novel catalysts in solid-state hydrogen storage materials has attracted significant scholarly attention. In this study, a catalyst consisting of Pd single atoms supported on Sc2O3 nanoparticles (PdSA@Sc2O3) was synthesized by a simple method. The peak dehydrogenation temperature of MgH2 with the addition of 10 wt% PdSA@Sc2O3 is 310.1 °C, which is 62.5 °C lower than that of pure MgH2, showing a positive catalytic effect. Specifically, the MgH2-10 wt%PdSA@Sc2O3 with a low Pd content of 0.5 wt% can release 5.18 wt% of hydrogen at 300 °C in 15 min, with an initial release rate of 0.43 wt%/min. It can absorb 5.98 wt% of hydrogen at 250 °C in 3 min, and still uptake 5.17 wt% of hydrogen at 150 °C in 1 h. This indicates its ability to absorb hydrogen rapidly at high temperatures and continuously at low temperatures. For the catalytic mechanism, theoretical calculations indicate a significant electronic interaction between Pd and Sc2O3. The Pd single atoms loaded on Sc2O3 have nanoparticles higher hydrogen adsorption energy, which greatly improves the catalytic activity of Pd. Sc0 generated in-situ during dehydrogenation can destabilize the Mg-H bond and promote hydrogen dissociation. The Mg-Pd alloy produced during the hydrogen absorption and desorption process has an efficient hydrogen pumping effect, which contributes greatly to the kinetic properties of MgH2. The synergistic catalytic mechanism of Pd single atoms and Sc2O3 on de/hydriding of Mg/MgH2 was systematically investigated, which provides ideas for the commercial production of new controllable and prepared nanocatalysts.

Discovery of highly efficient dual-atom catalysts for propane dehydrogenation assisted by machine learning.

Propane dehydrogenation (PDH) is a highly efficient approach for industrial production of propylene, and the dual-atom catalysts (DACs) provide new pathways in advancing atomic catalysis for PDH with dual active sites. In this work, we have developed an efficient strategy to identify promising DACs for PDH reaction by combining high-throughput density functional theory (DFT) calculations and the machine-learning (ML) technique. By choosing the γ-Al2O3(100) surface as the substrate to anchor dual metal atoms, 435 kinds of DACs have been considered to evaluate their PDH catalytic activity. Four ML algorithms are employed to predict the PDH activity and determine the relationship between the intrinsic characteristics of DACs and the catalytic activity. The promising catalysts of CuFe, CuCo and CoZn DACs are finally screened out, which are further validated by the whole kinetic reaction calculations, and the highly efficient performance of DACs is attributed to the synergistic effects and interactions between the paired active sites.

Single cobalt atom catalysis for the construction of quinazolines and quinazolinones via the aerobic dehydrocyclization of ethanol

It is still a significant and challenging for the synthesis of N-heterocycles through the aerobic dehydrocyclization of ethanol since ethanol is the largest renewable small molecule feedstock but with high...

CO Oxidation over Ligand Coordinated Single Site Rh Catalyst: Identification of Active Complex

Single atom catalysis has evolved as a promising strategy to enhance atom utilization efficiency, lower reaction temperatures, and control reaction pathways in heterogeneous catalytic reactions. An important challenge using supported...

Prospects of single atom catalysts for dendrite-free alkali metal batteries

This work provides a comprehensive understanding of single atom catalysis and its mechanisms towards advanced and sustainable alkali metal batteries.

Understanding the synergistic catalysis effect on the dual-metal-N4 embedding single-walled carbon nanotubes from first principles

Developing high-efficiency electrocatalysts for the oxygen evolution reaction (OER) remains a crucial bottleneck on the way to the water splitting for producing clean fuel (H2). Compared with single atom catalysis (SACs), dual-atom catalysts (DACs) have attracted great interest due to higher OER catalytic efficiency. In this work, the OER properties of dual-metal-N4 embedding armchair single-walled carbon nanotubes (D-MN4/CNTs) were systematic studied by density functional theory (DFT) simulations. Our results indicate that CoN4 embedding armchair CNTs exhibit higher OER activity than the corresponding planar structure, especially for CoN4 embedding in armchair CNT (4, 4) (CNT4). For MN4-CoN4 co-embedding CNTs, the TiN4-CoN4/CNTs have good OER synergistic effect with the lowest overpotential. Besides, the diameter of CNTs have a significant impact on the OER efficiency. The lowest reaction overpotential 0.47 V were obtained in TiN4-CoN4/CNT4 with a 5.69 Å tube diameter. Interestingly, compressive stress will further enhance the synergistic effect between two metal atoms in the OER reaction. The OER overpotential of CoN4-TiN4 embedding armchair CNT4 can reduce to 0.40 V under the −4 % uniaxial compression strain. These works were expected to better understand the synergistic mechanisms and design high-efficiency dual-atom OER electrocatalysts.