Formation Of Atoms Research Articles

Self-healable metal-organic gel membranes as anodes with high lithium storage

Amorphous metal-organic gel (MOG) can be applied as anode for lithium ion batteries (LIBs) due to its advantages of the controllable structure and the adjustable pore size. In this work, M-MOGs (M=Ni, Zr, Fe, Al, Cr) membranes were fabricated by drop casting method and used as LIB anodes for the first time. They exhibited the excellent electrochemical performance, which were much better than metal-organic frameworks (MOFs) or MOGs without membrane formation of the same metal atom. There was no need to add carbon black, binder or organic solvent when fabricating the membrane electrode which can be attributed to the excellent electronic conductibility of membrane and the viscosity of MOGs. At the same time, the prepared MOGs have the self-healable property which can effectively restrain volume expansion during the lithium ion intercalation/extraction process. In five membrane electrodes, Ni-MOG membrane had a great specific capacity reaching to 1710.1 mA h g−1 at the current density of 100 mA g−1, and remained at 1245.5 mA h g−1 after 30 cycles with high rate performance. Furthermore, the coulombic efficiency was nearly 100% after 100 cycles at a high current density of 2 A g−1 or 5 A g−1. The conductivities of the five MOG membranes were between 10−8 and 10−7 S m−1, indicating that the membrane anodes had semiconductor property. It can be seen that amorphous MOG membrane is a promising anode material for LIBs. [Display omitted]

Gallium-gallium weak bond that incorporates nitrogen at atomic steps during GaN epitaxial growth

Growth of high-quality epitaxial thin films of GaN is indispensable for the energy-saving power electronics and the clarification of the mechanism of the epitaxial growth, which is unachieved yet, is essential to advance nanoscience and technology. We here report quantum-theory-based first-principles calculations that elucidate atomic structures and formation energies of the surface steps of GaN (0001) surfaces, unveil atom-scale elementary processes of N incorporation at the step edges, and then provide a microscopic picture of the step-flow epitaxial growth of GaN for the first time. We find that the NH unit produced after the decomposition of NH3 on the surface terrace diffuses to the stable step edges and is incorporated in the GaN thin film, thus clarifying an elementary process of the step-flow epitaxial growth. Our calculations indicate that the essential factor to promote the epitaxial growth is the presence of the Ga-Ga weak bond on the growing surface.

Mechanical behavior of multilayer graphene reinforced epoxy nano-composites via a hierarchical multi-scale technique

In this paper, a multi-scale technique is presented to study the mechanical behavior of nano-composites by linking the atomistic information from lower scale to the continuum model in upper scale. Molecular dynamics simulations are employed to compute the material properties of graphene/epoxy nano-composites using the COMPASS interatomic force field. In order to obtain the atomistic stress surfaces used to evaluate the mechanical properties of material in upper scale, the biaxial loading is applied to different representative volume elements. On the continuum level, the hyperelastic strain energy functions are utilized to calculate the material parameters using the hyperelastic functions from atomistic data. The stress and elasticity tensors are obtained by computing the first and second order derivatives of hyperelastic functions with reference to the components of the right Cauchy–Green deformation tensor. The stress–strain surfaces of hyperelastic functions in lower scale are used to calculate the properties of nano-composite material in upper scale. The efficiency and applicability of the proposed technique is presented through various numerical examples. It is shown that the proposed multi-scale technique is able to solve large problems within acceptable computational time, which is not possible using conventional molecular dynamics approaches.

Spatially Confined Formation of Single Atoms in Highly Porous Carbon Nitride Nanoreactors

Reducing the size of a catalyst to a single atom (SA) level can dramatically change its physicochemical properties and significantly boost its catalytic activity. However, the massive synthesis of SA catalysts still remains a grand challenge mainly because of the aggregation and nucleation of the generated atoms during the reaction. Here, we design and implement a spatially confined synthetic strategy based on a porous-hollow carbon nitride (p-CN) coordinated with 1-butyl-3-methylimidazole hexafluorophosphate, which can act as a nanoreactor and allow us to obtain metal SA catalysts (p-CN@M SAs). This relatively easy and highly effective method provides a way to massively synthesize single/multiple atoms (p-CN@M SAs, M = Pt, Pd, Cu, Fe, etc.). Moreover, the amorphous NiB-coated p-CN@Pt SAs can further increase the loading amount of Pt SAs to 3.7 wt %. The synthesized p-CN@Pt&NiB electrocatalyst exhibits an extraordinary hydrogen evolution reaction activity with the overpotential of 40.6 mV@10 mA/cm-2 and the Tofel slope of 29.26 mV/dec.

Influence of angled dispersion gas on coaxial atomization, spray and flame formation in the context of spray-flame synthesis of nanoparticles

Liquid atomization determines the initial conditions for flame formation and particle synthesis. Without a stable flame, high droplet velocities and thus short droplet residence time in the flame may lead to droplets being injected into an extinguished flame, which influences synthesis and final particle output. An experimental investigation of spray formation and flame stability is performed through high-speed visualization. Targeted variation of nozzle geometry is applied to improve spray-flame interaction and compared to a standardized burner. Timescales of spray density and flame fluctuations are quantified and compared, where the latter were significantly larger and hence not correlated. Instead, dispersion gas forms a barrier between spray phase and pilot flame; hence, ignition depends on large liquid lumps with high radial momentum to break through the dispersion gas for spray ignition. Angling of dispersion gas flow increases radial shear and turbulence and leads to refined atomization and improved flame stability. To investigate the nozzle influence on particle formation, particle characteristics are examined by online and offline analytics with focus on particle structures and product purity. The modified nozzle produced smaller primary particle sizes, thus indicating a sensitivity of sintering dominance on the nozzle geometry. Impurities impact the examination of particle structures and general particle functionality. Carbon contamination was apparent in synthesized particles and also indicated sensitivity to nozzle geometry. Discrepancies to literature data are discussed regarding differences in flame activity and droplet characteristics. The report highlights, how product characteristics can differ crucially due to changes in nozzle geometry despite comparable operating conditions.Graphic abstract

Physical Separation of H2 Activation from Hydrogenation Chemistry Reveals the Specific Role of Secondary Metal Catalysts.

An electrocatalytic palladium membrane reactor (ePMR) uses electricity and water to drive hydrogenation without H2 gas. The device contains a palladium membrane to physically separate the formation of reactive hydrogen atoms from hydrogenation of the unsaturated organic substrate. This separation provides an opportunity to independently measure the hydrogenation reaction at a surface without any competing H2 activation or proton reduction chemistry. We took advantage of this feature to test how different metal catalysts coated on the palladium membrane affect the rates of hydrogenation of C=O and C=C bonds. Hydrogenation occurs at the secondary metal catalyst and not the underlying palladium membrane. These secondary catalysts also serve to accelerate the reaction and draw a higher flux of hydrogen through the membrane. These results reveal insights into hydrogenation chemistry that would be challenging using thermal or electrochemical hydrogenation experiments.

Physical Separation of H2 Activation from Hydrogenation Chemistry Reveals the Specific Role of Secondary Metal Catalysts

AbstractAn electrocatalytic palladium membrane reactor (ePMR) uses electricity and water to drive hydrogenation without H2 gas. The device contains a palladium membrane to physically separate the formation of reactive hydrogen atoms from hydrogenation of the unsaturated organic substrate. This separation provides an opportunity to independently measure the hydrogenation reaction at a surface without any competing H2 activation or proton reduction chemistry. We took advantage of this feature to test how different metal catalysts coated on the palladium membrane affect the rates of hydrogenation of C=O and C=C bonds. Hydrogenation occurs at the secondary metal catalyst and not the underlying palladium membrane. These secondary catalysts also serve to accelerate the reaction and draw a higher flux of hydrogen through the membrane. These results reveal insights into hydrogenation chemistry that would be challenging using thermal or electrochemical hydrogenation experiments.

Effect of air pockets in drug delivery via jet injections

Needle-free jet injections are actuated by a pressure impulse that can be delivered by different mechanisms to generate high-speed jets (Vj~O102 m/s). During filling and transportation of disposable cartridges and ampoules, bubbles can form, which can be problematic especially for viscous fluids. Here, we report on the effect of location and size of entrapped air pockets in cartridges used in spring-powered jet injections. As air bubbles pass through the orifice, they undergo depressurization, which results in intermittent atomization and spray formation, temporarily increasing the jet dispersion. Atomization and dispersion of the jet can lead to product loss during an injection. We find that the effect of bubble location on the jet exit speed, delivery efficiency, and the projected area of the blebs formed after the injection was statistically significant (p<0.05). The findings of this study have implications for the development of pre-filled cartridges for jet injection applications.

Kinetic Study of the Gas-Phase C(3P) + CH3CN Reaction at Low Temperatures: Rate Constants, H-Atom Product Yields, and Astrochemical Implications

Rate constants have been measured for the C(3P) + CH3CN reaction between 50 and 296 K using a continuous-flow supersonic reactor. C(3P) atoms were created by the in situ pulsed laser photolysis of CBr4 at 266 nm, while the kinetics of C(3P) atom loss were followed by direct vacuum ultraviolet laser-induced fluorescence at 115.8 nm. Secondary measurements of product H(2S) atom formation were also made, allowing absolute H-atom yields to be obtained by comparison with those obtained for the C(3P) + C2H4 reference reaction. In parallel, quantum chemical calculations were performed to obtain the various complexes, adducts, and transition states relevant to the title reaction over the 3A″ potential energy surface, allowing us to better understand the preferred reaction pathways. The reaction is seen to be very fast, with measured rate constants in the range of (3–4) × 10–10 cm3 s–1 with little or no observed temperature dependence. As the C + CH3CN reaction is not considered in the current astrochemical networks, we test its influence on interstellar methyl cyanide abundances using a gas-grain dense interstellar cloud model. Its inclusion leads to predicted CH3CN abundances that are significantly lower than the observed ones.

Investigating the Effects of Surface Adsorbates on Gold and Palladium Deposition on Carbon

Surface functional groups have a strong influence on the deposition and final state of nanoparticles adsorbed on to the surface, a role discussed by Professor Spencer in his work. This tribute to Spencer explores the formation of hydroxyls, thiosulfates, sulfites and sulfur atoms on carbon (HOPG) surfaces and their effect on the deposition of gold and palladium from aqueous solutions. Hydroxyls formed from ammonium hydroxide treatment have identical behaviour to those formed by acid treatment, and gold adsorption from Au3+ solutions gives Au0 initially, with Au3+ formed at higher concentrations on these surfaces. In contrast, palladium adsorption is hindered by the presence of the hydroxyls and there is no indication of any reduction to the metallic state. Ammonium thiosulfate adsorbs dissociatively from aqueous solutions on HOPG if the surface is pre-activated by the presence of surface hydroxyls. At low concentrations of ammonium thiosulfate, adsorbed sulfite and sulfur are formed in equimolar concentrations whereas adsorption of high concentrations of ammonium thiosulfate gives some degree of molecular adsorption, with evidence in XP spectra for an ammonium ion and a sulfur 2p peak at 282.9 eV attributed to the undissociated thiosulfate ion. Both sulfur and the sulfite are stable at the surface in neutral solutions but the sulfite desorbs when treated with acidified solutions (~ pH ≤ 6). These two groups are also stable at 373 K but begin to desorb by 473 K. Exposure to a weak chloroauric acid solution causes the desorption of the sulfite and formation of a gold species with an XP binding energy of 84.6 eV; we cannot determine from the present data whether this peak is due to a Au(I) state or very small nanoparticles of Au(0).Graphic

Redox-Induced Interconversion of Two Au8 Nanoclusters: the Mechanism and the Structure-Bond Dissociation Activity Correlations.

The interconversion of atomically precise nanoclusters represents an excellent platform to understand the structural correlations of nanomaterials at the atomic level. Herein, density functional theory calculations were performed to elucidate the mechanism of the redox-induced interconversion of [Au8(dppp)4]2+ and [Au8(dppp)4Cl2]2+ (dppp is short for 1,3-bis(diphenylphosphino)propane) nanoclusters. Reduction is the driving force for the conversion of [Au8(dppp)4Cl2]2+ to [Au8(dppp)4]2+, while the Au-Au and first Au-Cl bond dissociations occur asynchronously on the two different corner Au atoms to avoid the formation of an electron-deficient Au atom. By contrast, the reduced electron density of [Au8(dppp)4]2+ by oxidation with O2 weakens the outmost Au-Au bond therein and facilitates the coordination of the electron-rich chloride(s). The reduction- and oxidation-induced activations, respectively, of Au-Cl and Au-Au bonds and the elucidated principles on the structure-activity correlations might also be generalized to other size conversions upon redox treatment.

Cosmic antihelium-3 nuclei sensitivity of the GAPS experiment

The General Antiparticle Spectrometer (GAPS) is an Antarctic balloon experiment designed for low-energy (0.1–0.3 GeV/n) cosmic antinuclei as signatures of dark matter annihilation or decay. GAPS is optimized to detect low-energy antideuterons, as well as to provide unprecedented sensitivity to low-energy antiprotons and antihelium nuclei. The novel GAPS antiparticle detection technique, based on the formation, decay, and annihilation of exotic atoms, provides greater identification power for these low-energy antinuclei than previous magnetic spectrometer experiments. This work reports the sensitivity of GAPS to detect antihelium-3 nuclei, based on full instrument simulation, event reconstruction, and realistic atmospheric influence simulations. The report of antihelium nuclei candidate events by AMS-02 has generated considerable interest in antihelium nuclei as probes of dark matter and other beyond the Standard Model theories. GAPS is in a unique position to detect or set upper limits on the cosmic antihelium nuclei flux in an energy range that is essentially free of astrophysical background. In three 35-day long-duration balloon flights, GAPS will be sensitive to an antihelium flux on the level of 1.3−1.2+4.5·10−6 m-2sr-1s-1(GeV/n)-1 (95% confidence level) in the energy range of 0.11–0.3 GeV/n, opening a new window on rare cosmic physics.

Theoretical new insights into hydrogen interaction with single-atom Zn- and co-doped copper metal catalysts

Transition metal atoms, usually as active sites on the single-atom alloy catalysts, may access remarkable properties by tuning surface electronic structures of the matrix metals. Herein, we present a comprehensive study of the whole process of hydrogen interaction with the single-atom Zn- and Co-doped Cu(100) and Cu(111) surfaces by using density functional theory (DFT) calculations and microkinetic modelling. It is found that, the repulsive interaction of hydrogen and Zn dopant strongly increases the H2 dissociation barrier, the hydrogen adsorption energy and the surface diffusion/permeation barrier. In contrast, the Co-doped Cu surfaces yield some favorable reaction characters such as easy formation of subsurface hydrogen species. DFT-based microkinetic modelling further reveals that the coverage of surface and subsurface hydrogen on the Zn- and Co-doped Cu surfaces is strongly pressure-dependent. The formation of hot atoms involving subsurface hydrogen species observed on the Co-doped Cu catalysts under realistic reaction conditions may provide a new reaction pathway to accelerate surface hydrogenation reactions.

Metal-Polymer Nanocomposites Based on Pyrolyzed Polyacrylonitrile with Fe–Ni–Co Inclusions

The paper presents the results of the computational modeling and quantum-chemical investigations of metal-polymer composites based on pyrolyzed polyacrylonitrile (PAN) consisting of the ternary Fe–Ni–Co compound. The proposed model of pyrolyzed PAN monolayer contains three atoms of iron, nickel, and cobalt instead of eight atoms of the basal polymer substance. Determined are the geometry and electronic and energetic properties of the nanocomposite. It is found that the introduction of the metal atoms leads to a decrease in the energy gap of the metal-polymer composite due to the layer formation of the interstitial metal atoms (nickel, cobalt) in the valence band or at the conduction band edge (iron), which, in turn, modifies the conductive properties of the obtained nanocomposite. The analysis of the charge redistribution in the system shows that in applying the electric field, the appeared charge carriers contribute to the ordered motion of free charged particles in the metal-polymer composite, thereby changing its magnetic properties.

Effect of activation temperature on surface basicity of natural aluminosilicates

Montmorillonite and nontronite are layered aluminosilicates of smectite group minerals widely demanded in many industries owing to their unique physical-chemical and other properties. By thermal activation of raw clays there are variations in their porosity, surface area and physical-chemical properties, including formation and redistribution of surface active site of acid-base or redox character. The aim of present studies included investigation of the effect of thermal activation on the character of distribution and a number of basic sites on the surface of natural layered aluminosilicates by means of the new method of inverse thermoprogrammed desorption of СО2.&#x0D; Samples of natural aluminosilicates rich in montmorillonite (Montmorillonite 67%, illite 5%, quartz 5%, feldspars 21%) and nontronite (nontronite 70%, illite 10%, kaolinite 5%, quartz 10%, feldspars 8%) were characterized by XRD, XRF, BET N2 adsorption techniques. To probe surface basicity and determine the number of basic sites a new iTPD-CO2 was used. Prior the iTPD-CO2 measurement 100 mg of a sample was activated at 200, 300, 400oC, then cooled down and loaded with CO2 (3ml/min flow rate of CO2 for30 min). Next, the reactor was flushed by 5 ml/min N2-flow to desorb weakly sorbed CO2. The iTPD-CO2 profiles were recorded within 20-800oC at a 20oC/min heating rate and treated using ChemStation software.&#x0D; The experimental profiles of CO2 desorption for Mt and Nt samples observed two temperature regions. Low temperature peaks evolved around 80-90oC for Mt and between 110-127oC for Nt were most likely related to the weak basic sites, whereas high temperature peaks around 510 and 620oC for Mt and above 320oC for Nt testified to stronger ones. The reasoning of the obtained iTPD-profiles was done considering thermal behavior of layered aluminosilicates.&#x0D; The total basicity of Nt and Mt samples was 359.2 and 209.9 mmol/g respectively. The 1.6 times higher basicity of Nt was, obviously, caused by its phase and chemical composition and developed surface area and porosity. At higher activation temperatures the number of weak basic sites related to hydroxyl groups of adsorbed water molecules gradually decreased, namely, by 21 times for Mt and by 2.8 times for Nt.&#x0D; Dehydroxylation of structural Al-OH, Fe-OH, Mg-OH above 200oC, which becomes irreversible above 300oC, provided formation of residual oxygen atoms and their contribution to population of stronger basic sites. In accordance with thermal behavior of dioctahedral smectites, is assumed that strong basic sites of Mt are trans- and cis-vacant Al-OH groups dehydroxylating correspondingly at ~550 and 650oC. Fe-rich sample of Nt rapidly lost hydroxyls at rather lower temperatures that resulted in more heterogeneous distribution of strong basic sites of varying strength. At higher activation temperatures the ratio of stronger sites number to weak sites increased from 23 to 200 for Mt, whereas for Nt this ratio varied between 54-67 times. In general, total basicity of Mt and Nt decreased by 2.2-2.3 times as a result of their dehydration and dehydroxylation by thermal activation. The normalized values of basicity per unit surface area (BΣ/S, mmol/m2) were 1,5 times higher for Mt surface, testifying to higher occupancy and density of active sites for Mt than that of Nt.

Chemical effect on muonic atom formation through muon transfer reaction in benzene and cyclohexane samples

Abstract To investigate the chemical effect on the muon capture process through a muon transfer reaction from a muonic hydrogen atom, the formation rate of muonic carbon atoms is measured for benzene and cyclohexane molecules in liquid samples. The muon transfer rate to carbon atoms of the benzene molecule is higher than that to the carbon atoms of the cyclohexane molecule. Such a deviation has never been observed among those molecules for gas samples. This may be because the transfers occur from the excited states of muonic hydrogen atoms in the liquid system, whereas in the gas system, all the transfers occur from the 1s (ground) state of muon hydrogen atoms. The muonic hydrogen atoms in the excited states have a larger radius than those in the 1s state and are therefore considered to be affected by the steric hindrance of the molecular structure. This indicates that the excited states of muonic hydrogen atoms contribute significantly to the chemical effects on the muon transfer reaction.

Microscopic spray characteristics of ethanol and methanol blended gasoline in a direct injection spark ignition engine

Renewable fuels are continuously being refined/ upgraded for automotive applications to reduce dependence on conventional fossil fuels. However, optimized use of these renewable fuels in existing and new engines/ vehicles requires comprehensive characterization and understanding of spray atomization and fuel-air mixture formation processes. Spray atomization and mixture formation depends on fuel injection pressure (FIP), fuel injection quantity and ambient conditions. This study is aimed at exploring microscopic spray characteristics of ethanol and methanol blended gasoline for automotive applications, particularly in direct injection Spark Ignition (DISI) engines. Phase Doppler interferometer (PDI) technique was used for comparative microscopic spray characterization in a constant volume spray chamber (CVSC) at ambient pressure condition, to evaluated spray droplet size-velocity distributions and joint probability density function (JPDF) of different test fuels. In this study, two gasohol mixtures [15% v/v ethanol and methanol blended with 85% v/v gasoline] and baseline gasoline were experimentally evaluated for comparing spray droplet size-velocity distributions at two different FIPs of 80 and 160 bars, at two different fuel injection quantities of 12 and 28 mg/injection, which are typical representative conditions for a DISI engines. The results from this experimental investigation are valuable for automotive and fuel industries, and spray community, which are continuously upgrading renewable and oxygenated fuels and engine technologies for efficiency improvement and emission reduction.

Electrochemical investigations of spray pyrolysed ruthenium incorporated Co3O4 electrodes prepared via aqueous route

The present study reports on the preparation and potential electrochemical properties of spray pyrolysed ruthenium incorporated cobalt oxide thin film electrodes prepared via aqueous route. The effect of Ru incorporation is analyzed by means of X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Elemental Diffraction Analysis (EDAX), X-ray Photoelectron Spectroscopy (XPS) and electrochemical characterizations followed by cyclic voltammetry (CV), chronopotentiometry (charge-discharge-CD) and electrochemical impedance spectroscopy (EIS) analysis. XRD and SEM depict nano-crystalline face centered cubic phase for Co3O4 and tetragonal structure for RuO2 exhibiting semi-porous revolutionary mixed nano-structured morphology. XPS confirms the atomic states and formation of Co3O4 and RuO2 phase. Electrochemical study reveals mixed-capacitive behavior at the scan rate 1 mV/s with optimum specific capacitance 900.0 F/g using 1 M KOH electrolyte, exhibiting excellent electrochemical stability. Charge-discharge study was carried out to evaluate specific energy, specific power and columbic efficiency at numerous current densities, the maximum estimated values are 34.4 Wh/kg, 50.90 kW/kg and 93.31% respectively. The EIS analysis was carried out for a frequency 1 mHz to 1 MHz range to investigate the internal resistance and capacitive behavior of the prepared electrodes. These modified electrodes can be the excellent candidates for supercapacitor application.

Silver Single‐Atom Catalyst for Efficient Electrochemical CO2 Reduction Synthesized from Thermal Transformation and Surface Reconstruction

AbstractWe report an Ag1 single‐atom catalyst (Ag1/MnO2), which was synthesized from thermal transformation of Ag nanoparticles (NPs) and surface reconstruction of MnO2. The evolution process of Ag NPs to single atoms is firstly revealed by various techniques, including in situ ETEM, in situ XRD and DFT calculations. The temperature‐induced surface reconstruction process from the MnO2 (211) to (310) lattice plane is critical to firmly confine the existing surface of Ag single atoms; that is, the thermal treatment and surface reconstruction of MnO2 is the driving force for the formation of single Ag atoms. The as‐obtained Ag1/MnO2 achieved 95.7 % Faradic efficiency at −0.85 V vs. RHE, and coupled with long‐term stability for electrochemical CO2 reduction reaction (CO2RR). DFT calculations indicated single Ag sites possessed high electronic density close to Fermi Level and could act exclusively as the active sites in the CO2RR. As a result, the Ag1/MnO2 catalyst demonstrated remarkable performance for the CO2RR, far surpassing the conventional Ag nanosized catalyst (AgNP/MnO2) and other reported Ag‐based catalysts.

Silver Single-Atom Catalyst for Efficient Electrochemical CO2 Reduction Synthesized from Thermal Transformation and Surface Reconstruction.

We report an Ag1 single-atom catalyst (Ag1 /MnO2 ), which was synthesized from thermal transformation of Ag nanoparticles (NPs) and surface reconstruction of MnO2 . The evolution process of Ag NPs to single atoms is firstly revealed by various techniques, including in situ ETEM, in situ XRD and DFT calculations. The temperature-induced surface reconstruction process from the MnO2 (211) to (310) lattice plane is critical to firmly confine the existing surface of Ag single atoms; that is, the thermal treatment and surface reconstruction of MnO2 is the driving force for the formation of single Ag atoms. The as-obtained Ag1 /MnO2 achieved 95.7 % Faradic efficiency at -0.85 V vs. RHE, and coupled with long-term stability for electrochemical CO2 reduction reaction (CO2 RR). DFT calculations indicated single Ag sites possessed high electronic density close to Fermi Level and could act exclusively as the active sites in the CO2 RR. As a result, the Ag1 /MnO2 catalyst demonstrated remarkable performance for the CO2 RR, far surpassing the conventional Ag nanosized catalyst (AgNP /MnO2 ) and other reported Ag-based catalysts.