Bulk Electrolyte Solution Research Articles

Development and application of hybrid AIMD/cDFT simulations for atomic-to-mesoscale chemistry.

Many important chemical processes involve reactivity and dynamics in complex solutions. Gaining a fundamental understanding of these reaction mechanisms is a challenging goal that requires advanced computational and experimental approaches. However, important techniques such as molecular simulation have limitations in terms of scales of time, length, and system complexity. Furthermore, among the currently available solvation models, there are very few designed to describe the interaction between the molecular scale and the mesoscale. To help address this challenge, here, we establish a novel hybrid approach that couples first-principles plane-wave density functional theory with classical density functional theory (cDFT). In this approach, a region of interest described by abinitio molecular dynamics (AIMD) interacts with the surrounding medium described using cDFT to arrive at a self-consistent ground state. cDFT is a robust but efficient mesoscopic approach to accurate thermodynamics of bulk electrolyte solutions over a wide concentration range (up to 2M concentrations). Benchmarking against commonly used continuum models of solvation, such as SMD, as well as experiments, demonstrates that our hybrid AIMD-cDFT method is able to produce reasonable solvation energies for a variety of molecules and ions. With this model, we also examined the solvent effects on a prototype SN2 reaction of the nucleophilic attack of a chloride ion on methyl chloride in the solution. The resulting reaction pathway profile and the solution phase barrier agree well with experiment, showing that our AIMD/cDFT hybrid approach can provide insight into the specific role of the solvent on the reaction coordinate.

A Multiscale, Dynamic Elucidation of Li Solubility in the Alloy and Metallic Plating Process.

Li-containing alloys and metallic deposits offer substantial Li+ storage capacities as alternative anodes to commercial graphite. However, the thermodynamically in sequence, yet kinetically competitive mechanism between Li solubility in the solid solution and intermediate alloy-induced Li deposition remains debated, particularly across the multiple scales. The elucidation of the mechanism is rather challenging due to the dynamic alloy evolution upon the non-equilibrium, transient lithiation processes under coupled physical fields. Here, influential factors governing Li solubility in the Li-Zn alloy are comprehensively investigated as a demonstrative model, spanning from the bulk electrolyte solution to the ion diffusion within the electrode. Through real-time phase tracking and spatial distribution analysis of intermediate alloy/Li metallic species at varied temperatures, current densities and particle sizes, the driving force of Li solubility and metallic plating along the Li migration pathway are probed in-depth. This study investigates the correlation between kinetics (pronounced concentration polarization, miscibility gap in lattice grains) and rate-limiting interfacial charge transfer thermodynamics in dedicating the Li diffusion into the solid solution. Additionally, the lithiophilic alloy sites with the balanced diffusion barrier and Li adsorption energy are explored to favor the homogeneous metal plating, which provides new insights for the rational innovation of high-capacity alloy/metallic anodes.

Atomic insights into the heterogeneity and the interface interactions of nanoconfined aqueous electrolyte solution

The structure and properties of nanoconfined electrolyte (nano electrolyte) solutions are important subjects in biochemistry, electrochemistry, separation science, etc. In the present work, neutron scattering and data driven reverse Monte Carlo were employed to quantitatively reveal the microstructure of aqueous CaCl2 solution in mesoporous silica MCM-41 at the atomic level. The electrolyte solution distributes in-homogeneously in the pores of mesoporous silica along the radial direction, which can be divided into the core, the transition, and the interface regions. The hydrogen bond structure of water in nano electrolytes is strengthened in the core region, analogous to that of nano water confined in nanochannels, and the ion association was enhanced in the transition region. The structure of the solution in the interface region was analogous to the bulk electrolyte solution under high pressure because of the confinement and interface effects. When the package ratio of nano electrolyte solution is insufficient, small amount of solution quasi-monolayer adsorb on the internal surface of mesoporous silica, the majority solution preferentially forms clusters with different sizes to adhere to the wetted interface. The anomalous hydrogen-bonding structure and ion association found in the present work improve our understanding of nanoconfined electrolyte solutions.

The Metal-Oxide Nanoparticle-Aqueous Solution Interface Studied by Liquid-Microjet Photoemission.

ConspectusThe liquid-microjet technique combined with soft X-ray photoelectron spectroscopy (PES) has become an exceptionally powerful experimental tool to investigate the electronic structure of liquid water and nonaqueous solvents and solutes, including nanoparticle (NP) suspensions, since its first implementation at the BESSY II synchrotron radiation facility 20 years ago. This Account focuses on NPs dispersed in water, offering a unique opportunity to access the solid-electrolyte interface for identifying interfacial species by their characteristic photoelectron spectral fingerprints. Generally, the applicability of PES to a solid-water interface is hampered due to the small mean free path of the photoelectrons in solution. Several approaches have been developed for the electrode-water system and will be reviewed briefly. The situation is different for the NP-water system. Our experiments imply that the transition-metal oxide (TMO) NPs used in our studies reside close enough to the solution-vacuum interface that electrons emitted from the NP-solution interface (and from the NP interior) can be detected.We were specifically exploring aqueous-phase TMO NPs that have a high potential for (photo)electrocatalytic applications, e.g., for solar fuel generation. The central question we address here is how H2O molecules interact with the respective TMO NP surface. Liquid-microjet PES experiments, performed from hematite (α-Fe2O3, iron(III) oxide) and anatase (TiO2, titanium(IV) oxide) NPs dispersed in aqueous solutions, exhibit sufficient sensitity to distinguish between free bulk-solution water molecules and those adsorbed at the NP surface. Moreover, hydroxyl species resulting from dissociative water adsorption can be identified in the photoemission spectra. An important aspect is that in the NP(aq) system the TMO surface is in contact with a true extended bulk electrolyte solution rather than with a few monolayers of water, as is the case in experiments using single-crystal samples. This has a decisive effect on the interfacial processes that can occur since NP-water interactions can be uniquely investigated as a function of pH and provides an environment allowing for unhindered proton migration. Our studies confirm that water is dissociatively adsorbed at the hematite surface and molecularly adsorbed at the TiO2 NP surface at low pH. In contrast, at near-basic pH the water interaction is dissociative at the TiO2 NP surface.The liquid-microjet measurements presented here also highlight the multiple aspects of photoemission necessary for a full characterization of TMO nanoparticle surfaces in aqueous environments. For instance, we exploit the ability to increase species-specific electron signals via resonant photoemission, so-called partial electron yield X-ray absorption (PEY-XA) spectra, and from valence photoelectron and resonant Auger-electron spectra. We also address the potential of these resonance processes and the associated ultrafast electronic relaxations for determining charge transfer or electron delocalization times, e.g., from Fe3+ located at the hematite nanoparticle interface into the aqueous-solution environment.

Boosting Nitrate to Ammonia Electroconversion through Hydrogen Gas Evolution over Cu-foam@mesh Catalysts.

The hydrogen evolution reaction (HER) is often considered parasitic to numerous cathodic electro-transformations of high technological interest, including but not limited to metal plating (e.g., for semiconductor processing), the CO2 reduction reaction (CO2RR), the dinitrogen → ammonia conversion (N2RR), and the nitrate reduction reaction (NO3-RR). Herein, we introduce a porous Cu foam material electrodeposited onto a mesh support through the dynamic hydrogen bubble template method as an efficient catalyst for electrochemical nitrate → ammonia conversion. To take advantage of the intrinsically high surface area of this spongy foam material, effective mass transport of the nitrate reactants from the bulk electrolyte solution into its three-dimensional porous structure is critical. At high reaction rates, NO3-RR becomes, however, readily mass transport limited because of the slow nitrate diffusion into the three-dimensional porous catalyst. Herein, we demonstrate that the gas-evolving HER can mitigate the depletion of reactants inside the 3D foam catalyst through opening an additional convective nitrate mass transport pathway provided the NO3-RR becomes already mass transport limited prior to the HER onset. This pathway is achieved through the formation and release of hydrogen bubbles facilitating electrolyte replenishment inside the foam during water/nitrate co-electrolysis. This HER-mediated transport effect "boosts" the effective limiting current of nitrate reduction, as evidenced by potentiostatic electrolyses combined with an operando video inspection of the Cu-foam@mesh catalysts under operating NO3-RR conditions. Depending on the solution pH and the nitrate concentration, NO3-RR partial current densities beyond 1 A cm-2 were achieved.

A Gaussian field approach to the planar electric double layer structures in electrolyte solutions.

In this work, the planar, electric, double-layer structures of non-polarizable electrodes in electrolyte solutions are studied with Gaussian field theory. A response function with two Yukawa functions is used to capture the electrostatic response of the electrolyte solution, from which the modified response function in the planar symmetry is derived analytically. The modified response function is further used to evaluate the induced charge density and the electrostatic potential near an electrode. The Gaussian field theory, combined with a two-Yukawa response function, can reproduce the oscillatory decay behavior of the electric potentials in concentrated electrolyte solutions. When the exact sum rules for the bulk electrolyte solutions and the electric double layers are used as constraints to determine the parameters of the response function, the Gaussian field theory could at least partly capture the nonlinear response effect of the surface charge density. Comparison with results for a planar electrode with fixed surface charge densities from molecular simulations demonstrates the validity of Gaussian field theory.

Size dependence of second-harmonic scattering from nanoparticles: Disentangling surface and electrostatic contributions.

Polarimetric angle-resolved second-harmonic scattering (AR-SHS) is an all-optical tool enabling the study of unlabeled interfaces of nano-sized particles in an aqueous solution. As the second harmonic signal is modulated by interference between nonlinear contributions originating at the particle's surface and those originating in the bulk electrolyte solution due to the presence of a surface electrostatic field, the AR-SHS patterns give insight into the structure of the electrical double layer. The mathematical framework of AR-SHS has been previously established, in particular regarding changes in probing depth with ionic strength. However, other experimental factors may influence the AR-SHS patterns. Here, we calculate the size dependence of the surface and electrostatic geometric form factors for nonlinear scattering, together with their relative contribution to the AR-SHS patterns. We show that the electrostatic term is stronger in the forward scattering direction for smaller particle sizes, while the ratio of the electrostatic to surface terms decreases with increasing size. Besides this competing effect, the total AR-SHS signal intensity is also weighted by the particle's surface characteristics, given by the surface potential Φ0 and the second-order surface susceptibility χs,2 2. The weighting effect is experimentally demonstrated by comparing SiO2 particles of different sizes in NaCl and NaOH solutions of varying ionic strengths. For NaOH, the larger χs,2 2 values generated by deprotonation of surface silanol groups prevail over the electrostatic screening occurring at high ionic strengths; however, only for larger particle sizes. This study establishes a better connection between the AR-SHS patterns and surface properties and predicts trends for arbitrarily-sized particles.

Accelerated constant-voltage quantum mechanical/molecular mechanical method for molecular systems at electrochemical interfaces.

The structure and electronic properties of a molecule at an electrochemical interface are changed by interactions with the electrode surface and the electrolyte solution, which can be significantly modulated by an applied voltage. We present an efficient self-consistent quantum mechanics/molecular mechanics (QM/MM) approach to study a physisorbed molecule at a metal electrode-electrolyte interface under the constant-voltage condition. The approach employs a classical polarizable double electrode model, which enables us to study the QM/MM system in the constant-voltage ensemble. A mean-field embedding approximation is further introduced in order to overcome the difficulties associated with statistical sampling of the electrolyte configurations. The results of applying the method to a test system indicate that the adsorbed molecule is no less or slightly more polarized at the interface than in the bulk electrolyte solution. The geometry of the horizontally adsorbed molecule is modulated by their electrostatic interactions with the polarizable electrode surfaces and also the interactions with cations attracted toward the interface when the adsorbate is reduced. We also demonstrate that the approach can be used to quantitatively evaluate the reorganization energy of a one electron reduction reaction of a molecule in an electrochemical cell.

A Molecular Theory of Polypeptide Adsorption at Inorganic Surfaces

A faithful description of polypeptide adsorption at ionizable surfaces remains a theoretical challenge from a molecular perspective due to the strong coupling of local thermodynamic nonideality and ionizations of both the adsorbate and substrate that are sensitive to the solution condition such as pH, ion valence, and salt concentration. Building upon a recently developed coarse-grained model for natural amino acids in bulk electrolyte solutions, here we report a molecular theory applicable to polypeptide adsorption on ionizable inorganic surfaces over a broad range of inhomogeneous conditions. Our thermodynamic model is able to account for diverse solution effects as well as the amino-acid sequence on polypeptide adsorption and surface association such as hydrogen bonding or bidentate coordination. The theoretical predictions have been validated by extensive comparison with experimental data for the adsorption isotherms of three representative polypeptides at a titanium surface.

Anomalous ion hydration and association in confined aqueous CaCl2 solution

On the contrary, in the bulk electrolyte, an abnormal ion association between Ca 2+ and Cl - in the CNTs with diameters from 1.085 nm to 1.220 nm is observed, where Ca 2+ and Cl - mainly exist in the form of contact ion pair (CIP) • An abnormal ion association between Ca 2+ and Cl - in 1.085 nm to 1.220 nm CNT. • Confinement enhances the hydration capacity of Ca 2+ in sub-nanoscale CNTs (d < 1.085 nm), while that of Cl - is greatly reduced. • The weakening of hydration capacity by confinement is the internal driving force for the ion association. Confined aqueous CaCl 2 solution plays an important role in biochemistry, geochemistry, electrochemistry, etc . In the present work, molecular dynamics simulation is employed to investigate the structures of aqueous CaCl 2 solution in carbon nanotubes (CNTs) with different diameters. An abnormal ion association between Ca 2+ and Cl - in the CNT with a diameter from 1.085 nm to 1.220 nm is observed, being completely different from the bulk electrolyte solution, where Ca 2+ and Cl - exist mainly in the form of contact ion pair. Confinement enhances the hydration capacity of Ca 2+ in subnanoscale CNTs (d < 1.085 nm), whereas the hydration capacity of Cl - is greatly reduced, although both Ca 2+ and Cl - have different degrees of dehydration. The hydration capacity of Cl - and Ca 2+ is the weakest in 1.085 nm and 1.220 nm CNTs, respectively, and the weakening of hydration capacity by confinement is the internal driving force for the ion association.

Supramolecular Gel Electrolyte-Based Supercapacitors with a Comparable Dependence of Electrochemical Performances on Electrode Thickness to Those Based on Bulk Electrolyte Solutions

Supramolecular Gel Electrolyte-Based Supercapacitors with a Comparable Dependence of Electrochemical Performances on Electrode Thickness to Those Based on Bulk Electrolyte Solutions

Specific Ion Effects in Different Media: Current Status and Future Challenges.

We discuss the current state of research as well as the future challenges for a deeper understanding of specific ion effects in protic and aprotic solvents as well as various additional media. Despite recent interest in solute or interfacial effects, we focus exclusively on the specific properties of ions in bulk electrolyte solutions. Corresponding results show that many mechanisms remain unknown for these simple media, although theoretical, computational, and experimental studies have provided some insights into explaining individual observations. In particular, the importance of local interactions and electronic properties is emphasized, which enabled a more consistent interpretation of specific ion effects over the past years. Despite current insufficient knowledge, we also discuss future challenges in relation to dynamic properties as well as the influence of different concentrations, different solvents, and solute contributions to gain a deeper understanding of specific ion effects for technological applications.

Molecular thermodynamics for amino‐acid adsorption at inorganic surfaces

AbstractThe interaction of polypeptides and proteins with an inorganic surface is intrinsically dependent on the interfacial behavior of amino acids and sensitive to solution conditions such as pH, ion type, and salt concentration. A faithful description of amino‐acid adsorption remains a theoretical challenge from a molecular perspective due to the strong coupling of local thermodynamic nonideality and inhomogeneous ionization of both the adsorbate and substrate. Building upon a recently developed coarse‐grained model for natural amino acids in bulk electrolyte solutions, here we report a molecular theory to predict amino‐acid adsorption on ionizable inorganic surfaces over a broad range of solution conditions. In addition to describing the coupled ionization of amino acids and the underlying surface, the thermodynamic model is able to account for both physical binding and surface associations such as hydrogen bonding or bidentate coordination. It is applicable to all types of natural amino acids regardless of the solution pH, salt type and concentration. The theoretical predictions have been validated by extensive comparison with experimental data for the adsorption of acidic, basic, and neutral amino acids at rutile (α‐TiO2) surfaces.

Interphasial Engineering via Individual Moiety Functionalized Organosilane Single-Molecule for Extreme Quick Rechargeable SiO/NCM811 Lithium-Ion Batteries.

The individual moiety-functionalized organosilane single molecule, that is, 1,1,1,5,5,5-hexamethyl-3-[(trimethylsilyl)oxy]-3-vinyltrisiloxane (TMSV), is investigated as an electrolyte additive for a less charge-consuming and viscoelastic solid electrolyte interphase (SEI) forming agent, finally accomplishing extremely quick (6 min) rechargeable SiO/NCM811 lithium-ion batteries. The moiety of the vinyl group serves with a poly(ethylene oxide)-like viscoelastic SEI film on the SiO electrode, which provides a physicochemically stable interphase during long-term cycling. The increase of DC-iR due to electrolyte decomposition on the continuously exposed SiO surface with cycling is inhibited by the alternated SEI composition. Degradation of bulk electrolyte solution caused by thermal decomposition of the LiPF6 salt is also suppressed by the trimethylsilyl moiety in the TMSV additive, which scavenges HF. Owing to the multifunctionality of TMSV, the cycle performance of laminated pouch full cells comprising high-nickel-contented NCM811 positive electrode and SiO-enriched negative electrode is significantly improved at both room and elevated temperatures. Furthermore, the 6 min quick recharging cycle performance is also enhanced by the TMSV additive.

Core and Valence Level Photoelectron Spectroscopy of Nanosolvated KCl.

The solvation of alkali and halide ions in the aqueous environment has been a subject of intense experimental and theoretical research with multidisciplinary interests; yet, a comprehensive molecular-level understanding has still not been obtained. In recent years, electron spectroscopy has been increasingly applied to study the electronic and structural properties of aqueous ions with implications, especially in atmospheric chemistry. In this work, we report core and valence level (Cl 2p, Cl 3p, and K 3p) photoelectron spectra of the common alkali halide, KCl, doped in gas-phase water clusters in the size range of a few hundred water molecules. The results indicate that the electronic structure of these nanosolutions shows a distinct character from that observed at the liquid–vapor interface in liquid microjets and ambient pressure setups. Insights are provided into the unique solvation properties of ions in a nanoaqueous environment, emerging properties of bulk electrolyte solutions with growing cluster size, and sensitivity of the electronic structure to varying solvation configurations.

A Systematic Way to Extend the Debye-Hückel Theory beyond Dilute Electrolyte Solutions.

An extended Debye-Hückel theory with fourth order gradient term is developed for electrolyte solutions; namely, the electric potential φ(r) of the bulk electrolyte solution can be described by ∇2φ(r) = κ2φ(r) + LQ2∇4φ(r), where the parameters κ and LQ are chosen to reproduce the first two roots of the dielectric response function of the bulk solution. Three boundary conditions for solving the electric potential problem are proposed based upon the continuity conditions of involving functions at the dielectric boundary, with which a boundary element method for the electric potential of a solute with a general geometrical shape and charge distribution is derived. Solutions for the electric potential of a spherical ion and a diatomic molecule are found and used to calculate their electrostatic solvation energies. The validity of the theory is successfully demonstrated when applied to binary as well as multicomponent primitive models of electrolyte solutions.

Surface electrostatic force in presence of dimer counter-ion

Combining classical density functional theory with modified interfacial statistical associating fluid theory, we investigate the surface electrostatic force (SEF) between two negatively and similarly charged planar surfaces immersed in electrolyte solution consisting of monomer anion and dimer cation. The dimer cation is comprised of two hard spheres (HSs) tangentially bonded together and freely rotating on the top of each other; one of the two HS sites is positively charged and the other is neutral. New findings about novel properties of the SEF caused by the dimer counter-ion are summarized below. (i) In the presence of only univalent counter-ion, the SEF always becomes more and more repulsive with increasing of the dimer counter-ion neutral site size, whether the bulk electrolyte solution is dense or not, and the surface charge strength is small, moderate, or large; repulsion strength of the SEF always reduces with the bulk concentration, and at equal surface distance rapidly increases with the surface charge strength. (ii) In the presence of bivalent counter-ion of monomer or dimer, rather complex SEF behavior emerges. Specifically, (a) at low surface charge strength, the dimer counter-ion with small neutral site size induces one obvious like-charge attraction (LCA) at lower bulk concentrations; whereas at higher bulk concentrations, a repulsive SEF emerges instead, whose strength monotonously decreases with the neutral site size. (b) For high surface charge strengths, the SEF curves exhibit oscillatory structure with the LCA feature; moreover, the dimer counter-ion always induces larger LCA position and strength than the monomer counter-ion does; the LCA strength decreases with the counter-ion neutral site size, and the LCA position always reduces with increase of the surface charge strength. (c) Dependence of the LCA strength on the bulk concentration is conditional on the surface charge strengths considered; to speak specifically, for very high surface charge strength, the LCA strength reduces with the bulk concentration, whereas for not so high value, the opposite is true. The above observations can be analyzed from fluctuation and balance of the three factors: osmotic pressure difference between inside and outside the plates; hard sphere repulsion in congested space, and “hydrogen bond” formation.

Multi-rail transmission-line model as an equivalent circuit for electrochemical impedance of a porous electrode

Abstract A new type of transmission-line model (TLM) as an equivalent circuit for the electrochemical impedance is developed to describe a porous electrode impregnated with an electrolyte solution. Two kinds of TLMs, i.e., one for diffusion-migration and the other for a porous electrode, are combined. To describe the double-layer capacitance strictly, the interfacial impedance is explicitly divided into the faradaic impedance and double-layer capacitance, and the latter is distributed into contributions of each ionic species. The obtained model describes diffusion, migration, and concentration changes of all ionic species within a porous electrode. In combination with a TLM for a bulk electrolyte solution, an equivalent circuit for a whole cell is also made. This should be a powerful tool for analyzing the impedances of devices with porous electrodes, such as batteries and electric double-layer capacitors, especially in the low-frequency region.

Probing the electrical double layer by operando X‐ray photoelectron spectroscopy through a graphene‐carbon nanotube composite window

AbstractThe electrical double layer is known to spontaneously form at the electrode‐electrolyte interface, impacting many important chemical and physical processes as well as applications including electrocatalysis, electroorganic synthesis, nanomaterial preparation, energy storage, and even emulsion stabilization. However, it has been challenging to study this fundamental phenomenon at the molecular level because the electrical double layer is deeply “buried” by the bulk electrolyte solution. Here, we report a quantitative probing of the electrical double layer of ionic liquids from the solid side of a photoelectron‐transparent graphene‐carbon nanotube hybrid membrane electrode using X‐ray photoelectron spectroscopy. The membrane window is ultrathin (1‐1.5 nm), large (~1 cm2), and robust, enabling a tight seal of the electrolyte and quantitative measurement with excellent photoelectron signals. By operando monitoring the population changes of cations and anions in response to the applied electrical potentials, we experimentally resolve the chemical structure and dynamics of the electrical double layer, which corroborate results from molecular dynamics simulations.image

Electrochemical Modification of Ni-Rich Bimetallic Ni1-x Mx (M= Bi, Pd and Au) Nanoparticles for Glycerol Electro-Oxidation in Alkaline Media

Glycerol partial electro-oxidation to produce various chemicals has attracted a great amount of attention in the decade [1]. Glycerol is the main by-product of biodiesel production and could be converted into high value-added chemicals. The control of catalyst selectivity and activity could be achieved through formulation of novel, nano-structured electrocatalysts. Nickel (Ni) is an attractive material for glycerol electro-oxidation (GEOR) in alkaline media [2], due to its natural abundance, anti-poising and good stability in alkaline media. Designing inexpensive nano-structured 3D Ni electrodes could improve the catalytic activity of Ni, whereas its selectivity could be modified by adding second metal [1].In the present work, GEOR was investigated on Ni-based mono and bi-metallic Ni x Au 1-x, Ni x Bi 1-x and Ni x Pd 1-x (x = 98, 95 and 90 at. %) nanoparticles in 1M KOH. Ni nanoparticles were synthesized by heatless chemical reduction in ethanol using sodium borohydride (NaBH4) as the reducing agent. Resulting Ni-based NPs were characterized using XRD, XPS, TEM, SEM, EDS mapping, HAADF imaging and EELS. Electrochemical measurements were carried out on Ni-based NPs using cyclic voltammetry (CV), chronoamperometry (CA) and linear sweep voltammetry (LSV) at room temperature. Results showed that Ni, NiAu and NiBi NPs are active for GEOR and that reaction proceeds through the formation of NiOOH active phase similar to bulk Ni electrodes [3]. Coupling CA with in-situ polarization modulation infrared-reflection absorption spectroscopy (PM-IRRAS) for the simultaneous analysis of products in the bulk electrolyte solution and on the Ni surface demonstrated that the main reaction products on Ni surface are glyceraldehyde, carbonyl and carboxylate ions. Whereas HPLC analysis reveals that Au, Bi and Pd adatoms strongly influence the reaction products by suppressing the pathways with C–C bond cleavage, hindering the formation of formate and enhancing the production of C2 and C3 products at different applied potentials (1.3, 1.4 and 1.55 V) and temperatures (25 and 50 oC).The correlation of electrocatalytic activity and selectivity with nanoparticle will be discussed in terms of mass activities and product distribution during GEOR.