Metal Atoms Research Articles

Transition-metal atoms embedded MoTe2 single-atom catalyst for efficient electrocatalytic hydrogen evolution reaction

As an attractive catalyst for the electrochemical hydrogen evolution reaction(HER), MoTe2 has attracted great interest. However, scarce catalytic sites and unsatisfactory catalytic activity of pristine MoTe2 basal plane impeded its practical application. The incorporation of single metal atom into 2D-substrate have been demonstrated as an effective strategy to tune HER activity of materials. Herein, we systematically investigated a series of transition-metal atoms(Fe, Co, Ni, Cu, Ru, Rh, Pd and Ag) embedded MoTe2 plane and edge single-atom catalysts(SAC, TM-MoTe2) for HER performance by employing density functional theory calculations. All TM-MoTe2 catalysts exhibit good thermodynamically and electrochemical stability. Compared with pristine MoTe2, HER catalytic activity of TM-MoTe2 are significantly enhanced due to effective modulation of charge transfer on embedded metal, which attribute to synergy interaction between embedded TM and surrounding Mo atoms. Specially, 2 candidate catalysts with Ru-MoTe2 plane and Fe-MoTe2 edge are found to show higher HER catalytic performance with low overpotential of only 10 mV and 60 mV, respectively. Furthermore, we found a key descriptor Δdd′ to well predict HER-activity trend of MoTe2-based material, which is closely correlated with H adsorption energy(ΔEH). This work provides in-depth theoretical insights for understanding active sites and designing high-efficiency MoTe2-based HER catalysts.

Design, synthesis, characterization, theoretical calculations, molecular docking studies, and biological evaluation of new Fe(II) and Cu(II) complexes of 2-acetylpyridine derivative sulfonyl hydrazone Schiff base

Sulfonylhydrazones and their metal complexes are known to have potential biological activity. In this study, new Fe(II) (1) and Cu(II) (2) complexes of the 2-acetylpyridine derivative sulfonyl hydrazone (LH) were prepared. The new metal complexes were characterized by elemental analysis, IR spectroscopy, UV spectroscopy, and magnetic moment measurements. The molecular structure of (2) was elucidated by X-ray diffraction analysis, and the crystal package was obtained in three-dimensional space. To support the intermolecular interactions obtained from the X-ray diffraction results, Hirshfeld surface analysis and two-dimensional fingerprint maps of (2) were generated. The optimized molecular structures, total energies, molecular orbital energy values, molecular electrostatic potential maps, percentage distributions of the atomic orbitals to the molecular orbital energy levels, and global reactivity parameters of LH, 1, and 2 are obtained by using DFT/B3LYP/6–311G(d, p) for LH and DFT/B3LYP/LanL2DZ for 1 and 2 is 1:2. Elemental analysis showed that the stoichiometric metal/ligand ratio for 1 and 2. All data indicate that the ligand coordinates with the metal atoms via pyridine imine /nitrogens and sulfonyl oxygen. The well-diffusion approach was also used to test the antibacterial properties of the ligand and complexes against harmful microbes. The compounds were tested for DNA cleavage using agarose gel electrophoresis. Complex 1 was found to be effective on the plasmid DNA of pBR322. Finally, molecular docking studies of LH, 1, and 2 with A-DNA (PDB ID:3V9D), and B-DNA (PDB ID:1BNA) were presented to compare the experimental and theoretical results.

Study on the synthesis of CoFe/CoFe2O4@NCNTs derived from ZnFeCo-ZIF with abundant heterostructures and oxygen vacancies as bifunctional catalyst for ORR/OER in zinc-air batteries

The rational design of bifunctional catalysts for oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) in alkaline electrolyte is of great significance for zinc-air batteries (ZABs). In this study, different types of Fe/Co compounds and nitrogen-doped carbon-based composite catalysts from trimetallic zeolitic-imidazole-framework-derived (ZnFeCo-ZIF) were synthesized by adjusting the ratio of Zn/Fe/Co. Among them, the synthesized CoFe/CoFe2O4-N-doped carbon nanotubes (CoFe/CoFe2O4@NCNTs) have abundant Fe-Nx and Co-Nx activity sites, heterostructures and oxygen vacancies. The experimental results reveal that the electrons of CoFe are transferred to CoFe2O4 at the interface of CoFe/CoFe2O4, which not only enhances the electron transfer ability, but also induces oxygen vacancies to improve the adsorption/desorption capacity of O2 and intermediates. Meanwhile, metal atoms are uniformly dispersed in the N-doped carbon nanotubes to form metal–N sites with high catalytic activity. Therefore, the CoFe/CoFe2O4@NCNTs exhibit excellent electrocatalytic performance, possessing a half-wave potential (E1/2) of 0.878 V and a prominent limiting-current densities (JL) of 6.281 mA cm−2 for ORR, and a low overpotential of 344 mV at 10 mA cm−2 for OER. In particular, the CoFe/CoFe2O4@NCNTs-equiped ZAB possesses a higher open-circuit voltage (1.50 V), a greater maximum power density (193.42 mW cm−2) and a longer cycling performance (160 h). The density functional theory (DFT) calculations show that the CoFe/CoFe2O4 heterostructure can induce the rapid transfer of electrons at the CoFe/CoFe2O4 interface, which promotes the change of the surface electronic structure of the catalyst, and thus helps to enhance the ability of the catalyst to transfer electrons.

Cobalt and nitrogen co-doped hollow periodic mesoporous organosilica spheres activated by potassium chloride for selective oxidation of ethylbenzene.

Enhancing the exposure of metal active sites and maximizing metal atom utilization are critical challenges in heterogeneous catalysis. To solve these issues, heterogeneous catalysts are usually activated by chemicals. Herein, potassium chloride (KCl) was used as an activator to prepare cobalt-nitrogen co-doped (Co-Nx) hollow periodic mesoporous organosilica spheres (Co-Nx/HPMOs-KCl). Co-Nx/HPMOs-KCl showed outstanding catalytic activity for the selective oxidation of ethylbenzene to acetophenone, with a conversion of up to 94.0% for ethylbenzene and a high selectivity of 98.4% towards acetophenone. Additionally, Co-Nx/HPMOs-KCl maintained excellent catalytic performance for the oxidation of ethylbenzene after six cycles. The excellent performance of Co-Nx/HPMOs-KCl was attributed to the activation of KCl, which increased the specific surface area of the catalyst and thus facilitated the exposure of more metal active sites. After the removal of unstable metal species through further acid treatment, the remaining metal active sites were thus fully exposed and stably embedded in the framework of the hollow periodic mesoporous organosilica spheres (HMPOs). This work presents an efficient catalyst and offers new insights for the improvement of heterogeneous catalysts.

Data-Driven Design of Single-Atom Electrocatalysts with Intrinsic Descriptors for Carbon Dioxide Reduction Reaction

The strategic manipulation of the interaction between a central metal atom and its coordinating environment in single-atom catalysts (SACs) is crucial for catalyzing the CO2 reduction reaction (CO2RR). However, it remains a major challenge. While density-functional theory calculations serve as a powerful tool for catalyst screening, their time-consuming nature poses limitations. This paper presents a machine learning (ML) model based on easily accessible intrinsic descriptors to enable rapid, cost-effective, and high-throughput screening of efficient SACs in complex systems. Our ML model comprehensively captures the influences of interactions between 3 and 5d metal centers and 8 C, N-based coordination environments on CO2RR activity and selectivity. We reveal the electronic origin of the different activity trends observed in early and late transition metals during coordination with N atoms. The extreme gradient boosting regression model shows optimal performance in predicting binding energy and limiting potential for both HCOOH and CO production. We confirm that the product of the electronegativity and the valence electron number of metals, the radius of metals, and the average electronegativity of neighboring coordination atoms are the critical intrinsic factors determining CO2RR activity. Our developed ML models successfully predict several high-performance SACs beyond the existing database, demonstrating their potential applicability to other systems. This work provides insights into the low-cost and rational design of high-performance SACs.

Mass spectrometry provides insights into the structures of polyoxovanadate alkoxide clusters substituted with Fe and W heterometals

Atom-by-atom substitution is a promising strategy for tailoring the electronic properties of transition metal oxide clusters. This approach typically generates a mixture of species that are difficult to separate using conventional methods. As a result, the characterization of their structures and electronic properties remains challenging. Herein, we use collision-induced dissociation (CID) to study the fragmentation of well-defined Fe- and W-doped Lindquist polyoxovanadate methoxides synthesized as a mixture of singly and doubly substituted species. Fragmentation reveals that Fe heteroatoms are efficiently retained within the metal oxide core. In contrast, one W atom is incorporated into the primary WO2(OCH3)2 neutral loss from both the singly and doubly substituted W-containing clusters. Collision energy-resolved CID provides insights into the fragmentation pathways, which are compared to those of the homometallic polyoxovanadate methoxide species. The incorporation of Fe into the cluster reduces its stability towards fragmentation, which could be attributed to the increase in the relative stability of Fe-containing fragment ions with four metal atoms in comparison with their homometallic analog. The observed fragmentation is rationalized by assuming that Fe atoms are incorporated within the low valent plane, while one W atom occupies the axial out-of-plane position in the cluster.

Charge transfer in alkaline-earth metal graphite intercalation compounds

The charge transfer from a metal atom towards the carbon layers in first stage graphite intercalation compounds (GIC) is a fundamental issue to explain under which conditions superconductivity sets in and the electronic properties of such ground state. To study in detail the transfer process and its evolution as a function of the nature of the intercalated metal, and especially taking in consideration the interlayer distance, we performed detailed X-Ray Diffraction and Raman scattering measurements on very high-quality bulk intercalated CaC6, SrC6 and BaC6 samples. We combined both the experimental results with detailed density functional theory calculations to give a coherent picture in which it is possible to follow the evolution of the charge transfer to the carbon layer in full agreement with the experimental data. The full comprehension of such mechanism remains a fundamental issue to explain the variation of the superconducting ground state in first stage GIC.

Structures, simulated photoelectron spectroscopy, and electronic properties of CuASix(A = Sc, Cu, x ≤ 13) clusters: Relatively stable neutral pentagonal bipyramid structures of CuASi5

Structural design and optimization, simulated photoelectron spectroscopy, electronic properties and chemical bond analysis of CuASix(A = Sc, Cu, x ≤ 13) clusters were systematically studied using the PBE scheme to integrate with global search program of ABCluster. Firstly, neutral MS (the most stable structures) of CuASi5 of the basic 1 + 5 + 1 structures (1 metal + 5 silicons + 1 metal atoms) can be found as the basic units for assembling more lager clusters under the condition of neglecting distortions and minor changes. If the Cu atoms in Cu2Six(x ≤ 13) systems was replaced by one Sc atom, the geometries of MS will be reconstructed. Compared with the wheel geometries of Cu2Si12 and Cu2Si13, CuScSi12 and CuScSi13 clusters belong to near-wheel geometries with peripheral metal atoms. The neutral CuScSi5 and Cu2Si5 clusters possess relatively higher stability in all of cluster sizes. A combination of NPA analysis of CuASi5, sp of the Cu atom and spd of the Sc atom hybridizations were crucial to the chemical bonds of A–Si in the neutral CuASi5 clusters. In view of the higher SED value of the Cu2Si5 molecule, chemical bond analysis was carried out using MO, HLg and AdNDP analysis. 18 localized bonds and four delocalized bonds can play a positive role for the relative stabilities of neutral pentagonal bipyramid structures of Cu2Si5. Thus, the Cu2Si5 cluster with a lager HLg(1.80 eV) may be a good candidate for the basic unit of silicon-based semiconductor material assembly.

In situ Construction of Single‐Atom Electronic Bridge on COF to Enhance Photocatalytic H2 Production

AbstractPhotocatalytic hydrogen production is one of the most valuable technologies in the future energy system. Here, we designed a metal‐covalent organic frameworks (MCOFs) with both small‐sized metal clusters and nitrogen‐rich ligands, named COF‐Cu3TG. Based on our design, small‐sized metal clusters were selected to increase the density of active sites and shorten the distance of electron transport to active sites. While another building block containing nitrogen‐rich organic ligands acted as a node that could in situ anchor metal atoms during photocatalysis and form interlayer single‐atom electron bridges (SAEB) to accelerate electron transport. Together, they promoted photocatalytic performance. This represented the further utilization of Ru atoms and was an additional application of the photosensitizer. N2‐Ru‐N2 electron bridge (Ru‐SAEB) was created in situ between the layers, resulting in a considerable enhancement in the hydrogen production rate of the photocatalyst to 10.47 mmol g−1 h−1. Through theoretical calculation and EXAFS, the existence position and action mechanism of Ru‐SAEB were reasonably inferred, further confirming the rationality of the Ru‐SAEB configuration. A sufficiently proximity between the small‐sized Cu3 cluster and the Ru‐SAEB was found to expedite electron transfer. This work demonstrated the synergistic impact of small molecular clusters with Ru‐SAEB for efficient photocatalytic hydrogen production.

Tailoring Oxygen Reduction Reaction on M-N-C Catalysts via Axial Coordination Engineering.

The development of fuel cells and metal-air batteries is an important link in realizing a sustainable energy supply and a green environment for the future. Oxygen reduction reaction (ORR) is the core reaction of such energy conversion devices. M-N-C catalysts exhibit encouraging ORR catalytic activity and are the most promising candidates for replacing Pt/C. The electrocatalytic performance of M-N-C catalysts is intimately related to the specific metal species and the coordination environment of the central metal atom. Axial coordination engineering presents an avenue for the development of highly active ORR catalysts and has seen considerable progress over the past decade. Nevertheless, the accurate control over the coordination environment and electronic structure of M-N-C catalysts at the atomic scale poses a big challenge. Herein, the diverse axial ligands, characterization techniques, and modulation mechanisms for axial coordination engineering are encompassed and discussed. Furthermore, some pressing matters to be solved and challenges that deserve to be explored and investigated in the future for axial coordination engineering are proposed.

Constructing Unsaturated Ru Atom Arrays Confined in Mn Oxides to Boost Neutral Water Reduction.

Recently, Ru single atoms supported on carbon nanomaterials have demonstrated ultrahigh activity for acid hydrogen evolution reaction (HER), however their neutral HER activity remains low due to the sluggish kinetics for both the water dissociation step to generate H* intermediates and subsequent H* recombination in neutral electrolytes. Here, we synthesize ordered low-coordinated Ru atom arrays confined in Mn oxides (i.e., Li4Mn5O12) for concurrently boosting the water dissociation and H* recombination, thus achieving a 6-fold HER activity enhancement than commercial Pt/C in neutral media. Control experiments indicate that low-coordinated Ru atoms with strong affinity to oxygen atoms of water molecules facilitate the water dissociation to rapidly generate H*. More importantly, both electrochemical and theoretic results uncover that the array-like structure allows the activation of two water molecules on two adjacent Ru atoms for enabling direct H*-H* recombination via the Tafel step, while isolated Ru atoms can only activate water one by one for recombining H* via the sluggish Heyrovsky step. Clearly, this work paves new avenues to boosting the electrocatalytic activity by constructing ordered metal atoms assembles with controllable coordination environments.

Constructing Unsaturated Ru Atom Arrays Confined in Mn Oxides to Boost Neutral Water Reduction

Recently, Ru single atoms supported on carbon nanomaterials have demonstrated ultrahigh activity for acid hydrogen evolution reaction (HER), however their neutral HER activity remains low due to the sluggish kinetics for both the water dissociation step to generate H* intermediates and subsequent H* recombination in neutral electrolytes. Here, we synthesize ordered low‐coordinated Ru atom arrays confined in Mn oxides (i.e., Li4Mn5O12) for concurrently boosting the water dissociation and H* recombination, thus achieving a 6‐fold HER activity enhancement than commercial Pt/C in neutral media. Control experiments indicate that low‐coordinated Ru atoms with strong affinity to oxygen atoms of water molecules facilitate the water dissociation to rapidly generate H*. More importantly, both electrochemical and theoretic results uncover that the array‐like structure allows the activation of two water molecules on two adjacent Ru atoms for enabling direct H*–H* recombination via the Tafel step, while isolated Ru atoms can only activate water one by one for recombining H* via the sluggish Heyrovsky step. Clearly, this work paves new avenues to boosting the electrocatalytic activity by constructing ordered metal atoms assembles with controllable coordination environments.

Effects of sulfation on the flotation capacity of oleic acid in the dolomite and fluorapatite system: A combined experimental and DFT study

Dolomite cannot be efficiently separated from fluorapatite (FA) by oleic acid in an acidic slurry, due to the poor collecting ability of oleic acid. In this work, sulfation was used to improve the flotation performance of oleic acid. Flotation tests showed that the sulfating collector exhibited stronger flotation ability for dolomite. However, the H2SO4-treated FA could not be floated by the sulfating collector. The solubility of the sulfating collector at pH 4.5 was higher than that of HOL at the same pH. Thus, more sulfating molecules and anions were generated in the collector solution, which accounted for the high flotation efficiency of the sulfating reagent. The sulfating collector molecule and anion could adsorb on the H2SO4-treated dolomite surface. Moreover, the reaction of the sulfating collector anions with the dolomite surface generated alkyl Mg/Ca salts.Furthermore, DFT calculations were employed to evaluate the interactions of the sulfating reagent with the H2SO4-treated dolomite surface. The sulfation produced two isomers. The most stable isomer, i.e., 10-sulfooxy stearic acid (SOA), was used in the calculations. The SOA anion could vertically or paralelly adsorb onto the dolomite. The parallel structure was more stable, where the COO− and OSO3− groups of SOA anion bonded with two metal atoms on the dolomite surface. These findings suggest that the sulfation collector is suitable for the reverse flotation of collophane.

Transition metal atoms embedded into B/N co-doped graphene as electrocatalysts toward nitrogen reduction reaction: Search for the optimal combination

The catalytic performance of a series of single transition metal (TM = 3d, 4d, and 5d series) atoms anchored on B/N co-doped graphene (BxNy@Gra) toward electrocatalytic nitrogen reduction reaction (eNRR) was systematically investigated by first-principles calculations. Among 180 possible materials, four catalysts (Tc-B1N3@Gra, Os-B2N2α@Gra, Re-B2N2γ@Gra, Nb-B3N1@Gra) feature the highest activity with UL no higher than 0.31 V. Interestingly, a volcano curve between UL and ΔEads(*NNH) can be established, so ΔEads(*NNH) can be applied as a descriptor to unveil the structure-activity relationship and characterize the activity of catalysts. The properties, thermal stability, and selectivity for the four catalysts were analyzed. Os-B2N2α@Gra is identified as a promising catalyst in this work for catalyzing N2 electroreduction to NH3 owing to its potent catalytic activity (UL = −0.28 V), high stability and distinct selectivity. This work can give some meaningful guidance for rapid screening and the rational design of efficient single-atom catalysts for electrocatalytic ammonia synthesis and other related electrochemical reaction. We expect that the present study will inspire and promote the efforts from both experimental and theoretical in this direction.

Advanced design of metal single-atom (Pt, Mn, Fe or Cu) loaded S-Ni(OH)2 nanosheets array catalysts to achieve high-performance overall water splitting

Designing catalysts at atomic level fine-tune the electronic structure of surface-active site for efficient water splitting, is a highly desirable approach but also poses significant challenges. This study focuses on the synthesis of a series of electronically tunable metal single-atom (M−SAs) catalysts: M9@S-Ni(OH)2 (M=Pt, Mn, Fe or Cu). Experimental results reveal that introduction of trace S-heteroatoms and metal atoms into Ni(OH)2 lattice can effectively modulate the electronic structure of M9@S-Ni(OH)2 through modulation of p-d and d-d orbital hybridization, resulting in exceptional performance in water electrolysis. Among M9@S-Ni(OH)2, Pt9@S-Ni(OH)2 and Fe9@S-Ni(OH)2 exhibit excellent hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performance, respectively, the overpotential requiring only 7 mV and 269 mV, respectively, at current density of 10 mA cm−2. (−) Pt9@S-Ni(OH)2||Fe9@S-Ni(OH)2 (+) presents a high current density of 531.07 mA cm−2 at cell-voltage of 1.80 V in overall-water splitting (OWS), which is 14.07 times higher than that of the commercial (−) Pt/C||IrO2 (+) (37.86 mA cm−2) system. This work achieves the development of cost-effective and stable electrocatalysts, offering a solution for large-scale and sustainable water-hydrogen conversion.

Detection of harmful gases (NO, NO2) by GaN@MoSSe heterostructures embedded with transition metal (Cu, Fe and Mn) atoms: A DFT study

Monitoring and identifying air pollutants, such as NO and NO2, is crucial due to their detrimental impact on both the environment and human health. This work employs density functional theory (DFT) with the PBE + U functional to investigate the adsorption and sensing performance of NO and NO2 on transition metal (TM)-doped GaN@MoSSe heterostructures. The adsorption energy, charge transfer, electron localization functions, charge density difference, spin density, band gaps and density of states are analyzed. The findings reveal that a transition from physisorption to chemisorption occurs after TM atoms doping. Also, when the surface is embedded with Cu, Fe and Mn atoms, there is a significant improvement in the behavior related to gas adsorption. The bandgap and its variations lead to the change in surface electrical conductivity, thereby affecting the gas sensitivity of the adsorption system. Particularly, the CuGa-GaN@MoSSe and FeGa-GaN@MoSSe systems exhibit improved gas sensitivity toward NO due to their significant band gap reduction. Meanwhile, the CuSe−MoSSe@GaN, CuGa-GaN@MoSSe, FeGa-GaN@MoSSe and MnGa-GaN@MoSSe systems also demonstrate enhanced sensing capabilities for NO2. This work offers valuable theoretical insights for exploring the potential applications of TM-GaN@MoSSe heterostructures in gas sensing.

A high-throughput screening of catalyst for efficient nitrogen fixation: Transition metal single-atom anchored on an emerging synthesized biphenyl network

Synthesizing efficient and selective green ideal catalysts has been an increasingly critical, yet unsolved, issue for the ammonia synthesis industry, hindering the growing global demand for environmental protection and energy efficiency. Electrocatalytic nitrogen reduction reaction (eNRR) is a promising technology for low-energy ammonia synthesis. However, designing efficient electrocatalysts for NRR remains challenging. The emergence of graphene-like substrates offers exciting prospects for addressing this challenge and facilitating single-atom catalysts in eNRR. Here, we report the innovative selection of a recently synthesized two-dimensional biphenyl network (2D BPN) compound as a substrate. Its excellent conductivity and porosity enable stable transition metal atoms (TMs) support for constructing eNRR electrocatalysts. we evaluated the feasibility of 23 TMs anchored on BPN for eNRR by high-throughput first-principles calculations. Through a systematic five-step strategy, we identified several single-atom catalysts (SACs) with potential for eNRR, including Mo@BPN, V@BPN, W@BPN, and Re@BPN. Among them, Mo@BPN exhibited the best balance in the adsorption of key reaction intermediates (e.g., N2H and NH3) and demonstrated a low limiting potential (-0.37 V). In addition, the underlying mechanism of NRR activity was elucidated by analyzing the extrinsic patterns revealed through the screened catalysts. A triangular volcano diagram, incorporating the initial protonation step, adsorption free energy, and final protonation step, revealed the NRR activity trend. Overall, this study provides a solid theoretical foundation and valuable guidance for future experimental exploration of efficient electrocatalysts for ammonia synthesis on BPN. Crucial insights into the theoretical design of efficient electrocatalysts are also offered.

Dative Bonding in Quasimetallatranes Containing Group 15 Donors (Y = N, P, and As) and Group 14 Acceptors (M = Si, Ge, Sn, and Pb).

Metallatranes and their analogous fused ring [3.3.0] bicyclic compounds, quasimetallatranes, have emerged as fascinating molecular systems with intriguing structural, bonding, and conformational properties. We present a comprehensive investigation aimed at unraveling the nature of dative bonding and exploring the conformational flexibility of these compounds. We extensively characterize the dative bond between the metal center and the electron pair donor, using a range of modeling techniques. Our analyses involve structural optimizations, molecular orbital examinations, and covalency ratio calculations, which provide a thorough understanding of the bonding interactions responsible for the stability of these systems. The results confirmed the presence of dative bonds, supported by the close proximity between the metal and the electron-donating group, and the observation of overlapping electron density. Our studies reveal a correlation between the size of the electron-donor and the coordinating metal atom, and the strength of the dative interaction, as indicated by the bond length and the Wiberg bond indices. This bond strength, in turn, influences the conformational preferences adopted by these compounds. This investigation sheds light on the fundamental aspects of the fused ring [3.3.0] bicyclic quasimetallatrane compounds and offers valuable insights into their unique properties.

Elementary steps of catalytic reactions occurring on metallic alloy nanoparticles

Catalytic reactions occurring in an adsorbed overlayer on metallic alloy nanoparticles are of high interest in the context of applications in the chemical industry. The understanding of the corresponding kinetics is, however, still limited. One of the reasons of this state of the art is the interplay between adsorption and adsorbate‐influenced segregation of metal atoms inside alloy nanoparticles. I scrutinize this interplay by using a generic field model of segregation and the mean‐field approximation in order to describe adsorption, desorption, and elementary catalytic reactions. Under steady‐state conditions, the segregation is demonstrated to be manifested in the change of the dependence of the activation energies of desorption or elementary reactions on coverage, and the sign of this change is positive. The effect of this change on the apparent reaction orders is briefly discussed as well.

Phosphorescent metallaknots of Au(I)-bis(acetylide) strands directed by Cu(I) π-coordination

Knots containing metal atoms as part of their continuous strand backbone are termed as metallaknots. While several metallaknots have been synthesized through one-pot self-assembly, the designed synthesis of metallaknots by controlling the arrangement of entanglements and strands connectivity remains unexplored. Here, we report the synthesis of metallaknots composed with Au(I)-bis(acetylide) linkages and templated by Cu(I) ions. Varying the ratio of the building blocks results in the switchable formation of two trefoil knots with different stoichiometries and symmetries (C2 or D3) and an entangled metalla-complex. While the entangled complex formed serendipitously, the strand ends can be subsequently linked through coordinative closure to generate a 41 metallaknot in a highly designable fashion. The comparable structural characteristics of resulting metalla-complexes allow us to probe the correlations between their topologies and photophysical properties, showing the backbone rigidity of knots endows complexes with excellent phosphorescent properties. This strategy, in conjunction with the coordinative closure approach, provides a straightforward route for the formation of highly phosphorescent metallaknots that were previously challenging to access.