Salt-Assisted, In Situ Current Nanowelding of an Interfacial Au Nanoparticle Film for a High-Performance Electrocatalyst

Interfacial self-assembly is a well-established method for the preparation of a two-dimensional (2D) metal nanofilm from nanoscale building blocks. However, the as-prepared nanofilm exhibits limited conductivity because of the large contact resistance at the junctions among its building blocks. Here, we report a salt-assisted, in situ current nanowelding strategy to weld an interfacial Au nanoparticle (NP) film for downstream applications, such as high-performance electrocatalysts. Particularly, we found that salt-assisted interfacial assembly can reduce the size of the nanogaps among neighboring Au NPs and, in turn, greatly improve the conductivity of the resultant Au NP film. Consequently, the Au NP film can be readily welded using current, and the welding extent can be monitored in real-time by looking at the passing current. The welding finally produces a nanoporous Au film (NPGF) with a network nanostructure, high conductivity, and abundant active sites so that it delivers a large current density of 86.96 μA·cm-2 (1.81 times higher than that from the pristine Au NP film) and shows improved cycling stability for methanol electrooxidation. Thus, these results offer a low-cost, solution-processable approach for the fabrication of a large-area, interconnected nanofilm from nanoscale building blocks beyond Au NPs, which may find diverse downstream applications.

Functionalized Copper Nanoparticles with Gold Nanoclusters: Part I. Highly Selective Electrosynthesis of Hydrogen Peroxide

Copper nanoparticles (CuNPs) and gold nanoclusters (AuNCs) show a high catalytic performance in generating hydrogen peroxide (H2O2), a property that can be exploited to kill disease-causing microbes and to carry carbon-free energy. Some combinations of NPs/NCs can generate synergistic effects to produce stronger antiseptics, such as H2O2 or other reactive oxygen species (ROS). Herein, we demonstrate a novel facile AuNC surface decoration method on the surfaces of CuNPs using galvanic displacement. The Cu-Au bimetallic NPs presented a high selective production of H2O2 via a two-electron (2e-) oxygen reduction reaction (ORR). Their physicochemical analyses were conducted by scanning electron microscopy (SEM), transmitting electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). With the optimized Cu-Au1.5NPs showing their particle sizes averaged in 53.8 nm, their electrochemical analysis indicated that the pristine AuNC structure exhibited the highest 2e- selectivity in ORR, the CuNPs presented the weakest 2e- selectivity, and the optimized Cu-Au1.5NPs exhibited a high 2e- selectivity of 95% for H2O2 production, along with excellent catalytic activity and durability. The optimized Cu-Au1.5NPs demonstrated a novel pathway to balance the cost and catalytic performance through the appropriate combination of metal NPs/NCs.

Stability of Single Gold Atoms on Defective and Doped Diamond Surfaces

Polycrystalline boron-doped diamond (BDD) is widely used as a working electrode material in electrochemistry, and its properties, such as its stability, make it an appealing support material for nanostructures in electrocatalytic applications. Recent experiments have shown that electrodeposition can lead to the creation of stable small nanoclusters and even single gold adatoms on the BDD surfaces. We investigate the adsorption energy and kinetic stability of single gold atoms adsorbed onto an atomistic model of BDD surfaces by using density functional theory. The surface model is constructed using hybrid quantum mechanics/molecular mechanics embedding techniques and is based on an oxygen-terminated diamond (110) surface. We use the hybrid quantum mechanics/molecular mechanics method to assess the ability of different density functional approximations to predict the adsorption structure, energy, and barrier for diffusion on pristine and defective surfaces. We find that surface defects (vacancies and surface dopants) strongly anchor adatoms on vacancy sites. We further investigated the thermal stability of gold adatoms, which reveals high barriers associated with lateral diffusion away from the vacancy site. The result provides an explanation for the high stability of experimentally imaged single gold adatoms on BDD and a starting point to investigate the early stages of nucleation during metal surface deposition.

Entropic contributions to the stability of electrochemically adsorbed anion layers on Au(111): a microcalorimetric study

We measure the entropy of formation of the interface upon anion adsorption (Cl^-, Br^- I^- and SO₄^2-) on Au(111) as an important indicator for the structure, order and composition of the interface. The entropy of formation of the interface exhibits a rather universal behaviour for all anions with a steep decrease upon initial adsorption followed by a shallow minimum at intermediate anion coverages and a strong increase close to the completion of the adsorbate adlayer. The strong variation of the entropy signals significant entropic contributions to the free enthalpy of the adsorption process and thus the stability of the adsorbed phase. At low anion coverages, close to the potential of zero charge, we attribute the entropy variations to the rearrangement of the interfacial water structure. At intermediate and high anion coverages, a comparison with the results of a lattice-gas model, considering pairwise repulsive interactions within the quasi-chemical approximation, shows that the entropy changes upon anion adsorption can be explained by the configurational entropy of the adsorbed phase. Thus, entropic contributions from both the solvent and the adsorbate are important for the stability of surface phases, particularly for disordered systems.

Mesoporous Gold Nanostructures: Synthesis and Beyond

Mesoporous metal nanostructures have offered multiple advantages that cannot be realized elsewhere. These materials have been attracting more research attention in catalysis and electrocatalysis owing to their functional structures and compositions. Of the various mesoporous metals available, mesoporous gold (mesoAu) nanostructures are of special interest in surface-enhanced Raman scattering (SERS) and related applications because of their strong electromagnetic field (localized surface plasmon resonance). In the last few decades, various synthesis strategies have been developed to prepare mesoAu nanostructures with controllable morphologies that exhibit fascinating physicochemical properties and increase applications in SERS, catalysis, and electrocatalysis. In this Perspective, we systematically summarize recent advances in synthesis and applications of mesoAu nanostructures. Four synthesis strategies, including dealloying, nanocasting, electrochemical deposition, and intermediate template, are discussed in detail. Moreover, physicochemical properties and promising applications of mesoAu nanostructures are presented. Finally, we describe current challenges and give a general outlook to explore further directions in synthesis and applications of mesoAu nanostructures.

How to Predict the pK a of Any Compound in Any Solvent

Acid-base properties of molecules in nonaqueous solvents are of critical importance for almost all areas of chemistry. Despite this very high relevance, our knowledge is still mostly limited to the pK _a of rather few compounds in the most common solvents, and a simple yet truly general computational procedure to predict pK _a's of any compound in any solvent is still missing. In this contribution, we describe such a procedure. Our method requires only the experimental pK _a of a reference compound in water and a few standard quantum-chemical calculations. This method is tested through computing the proton solvation energy in 39 solvents and by comparing the pK _a of 142 simple compounds in 12 solvents. Our computations indicate that the method to compute the proton solvation energy is robust with respect to the detailed computational setup and the construction of the solvation model. The unscaled pK _a's computed using an implicit solvation model on the other hand differ significantly from the experimental data. These differences are partly associated with the poor quality of the experimental data and the well-known shortcomings of implicit solvation models. General linear scaling relationships to correct this error are suggested for protic and aprotic media. Using these relationships, the deviations between experiment and computations drop to a level comparable to that observed in water, which highlights the efficiency of our method.

Identification of electrochemically adsorbed species via electrochemical microcalorimetry: sulfate adsorption on Au(111)

We investigate compositional changes of an electrochemical interface upon polarization with electrochemical microcalorimetry. From the heat exchanged at a Au(111) electrode upon sulfate adsorption, we determine the reaction entropy of the adsorption process for both neutral and acidic solutions, where the dominant species in solution changes from SO₄²⁻ to HSO₄⁻. In neutral solution, the reaction entropy is about 40 J mol⁻¹ K⁻¹ more positive than that in acidic solution over the complete sulfate adsorption region. This entropy offset is explicable by a deprotonation step of HSO₄⁻ preceding sulfate adsorption in acidic solution, which shows that the adsorbing species is SO₄* in both solutions. The observed overall variation of the reaction entropy in the sulfate adsorption region of ca. 80 J mol⁻¹ K⁻¹ indicates significant sulfate‐coverage dependent entropic contributions to the Free Enthalpy of the surface system.

Highly active and selective oxygen reduction to H2O2 on boron-doped carbon for high production rates

Oxygen reduction reaction towards hydrogen peroxide (H₂O₂) provides a green alternative route for H₂O₂ production, but it lacks efficient catalysts to achieve high selectivity and activity simultaneously under industrial-relevant production rates. Here we report a boron-doped carbon (B-C) catalyst which can overcome this activity-selectivity dilemma. Compared to the state-of-the-art oxidized carbon catalyst, B-C catalyst presents enhanced activity (saving more than 210 mV overpotential) under industrial-relevant currents (up to 300 mA cm^-2) while maintaining high H₂O₂ selectivity (85-90%). Density-functional theory calculations reveal that the boron dopant site is responsible for high H₂O₂ activity and selectivity due to low thermodynamic and kinetic barriers. Employed in our porous solid electrolyte reactor, the B-C catalyst demonstrates a direct and continuous generation of pure H₂O₂ solutions with high selectivity (up to 95%) and high H₂O₂ partial currents (up to ~400 mA cm^-2), illustrating the catalyst's great potential for practical applications in the future.

Enhanced Methanol Electro-Oxidation Activity of Nanoclustered Gold

Size-selected 3 nm gas-phase Au clusters dispersed by cluster beam deposition (CBD) on a conducting fluorine-doped tin oxide template show strong enhancement in mass activity for the methanol electro-oxidation (MEO) reaction compared to previously reported nanostructured gold electrodes. Density functional theory-based modeling on the corresponding Au clusters guided by experiments attributes this high MEO activity to the high density of exposed under-coordinated Au atoms at their faceted surface. In the description of the activity trends, vertices and edges are the most active sites due to their favorable CO and OH adsorption energies. The faceted structures occurring in this size range, partly preserved upon deposition, may also prevent destructive restructuring during the oxidation-reduction cycle. These results highlight the benefits of using CBD in fine-tuning material properties on the nanoscale and designing high-performance fuel cell electrodes with less material usage.

The Importance of Acid-Base Equilibria in Bicarbonate Electrolytes for CO2 Electrochemical Reduction and CO Reoxidation Studied on Au(hkl) Electrodes

Among heterogeneous electrocatalysts, gold comes closest to the ideal reversible electrocatalysis of CO2 electrochemical reduction (CO2RR) to CO and, vice versa, of CO electroxidation to CO2 (COOR). The nature of the electrolyte has proven to crucially affect the electrocatalytic behavior of gold. Herein, we expand the understanding of the effect of the widely employed bicarbonate electrolytes on CO2RR using gold monocrystalline electrodes, detecting the CO evolved during CO2RR by selective anodic oxidation. First, we show that CO2RR to CO is facet dependent and that Au(110) is the most active surface. Additionally, we detect by in situ FTIR measurements the presence of adsorbed COtop only on the Au(110) surface. Second, we highlight the importance of acid-base equilibria for both CO2RR and COOR by varying the electrolyte (partial pressure of CO2 and the concentration of the bicarbonate) and voltammetric parameters. In this way, we identify different regimes of surface pH and bicarbonate speciation, as a function of the current and electrolyte conditions. We reveal the importance of the acid-base bicarbonate/carbonate couple, not only as a buffering equilibrium but also as species involved in the electrochemical reactions under study.

Electrochemical Stability and Degradation Mechanisms of Commercial Carbon-Supported Gold Nanoparticles in Acidic Media

Electrochemical stability of a commercial Au/C catalyst in an acidic electrolyte has been investigated by an accelerated stress test (AST), which consisted of 10,000 voltammetric scans (1 V/s) in the potential range between 0.58 and 1.41 V_RHE. Loss of Au electrochemical surface area (ESA) during the AST pointed out to the degradation of Au/C. Coupling of an electrochemical flow cell with ICP-MS showed that only a minor amount of gold is dissolved despite the substantial loss of gold ESA during the AST (∼35% of initial value remains at the end of the AST). According to the electrochemical mass spectrometry experiments, carbon corrosion occurs during the AST but to a minor extent. By using identical location scanning electron microscopy and identical location transmission electron microscopy, it was possible to discern that the dissolution of small Au particles (<5 nm) within the polydisperse Au/C sample is the main degradation mechanism. The mass of such particles gives only a minor contribution to the overall Au mass of the polydisperse sample while giving a major contribution to the overall ESA, which explains a significant loss of ESA and minor loss of mass during the AST. The addition of low amounts of chloride anions (10^-4 M) substantially promoted the degradation of gold nanoparticles. At an even higher concentration of chlorides (10^-2 M), the dissolution of gold was rather effective, which is useful from the recycling point of view when rapid leaching of gold is desirable.

Understanding the Voltammetry of Bulk CO Electrooxidation in Neutral Media through Combined SECM Measurements

Recently, the bulk electrooxidation of CO on gold or platinum has been used to detect CO produced during CO₂ reduction in neutral media. The CO bulk oxidation voltammetry may show two distinct peaks depending on the reaction conditions, which up to now have not been understood. We have used scanning electrochemical microscopy (SECM) to probe CO oxidation and pH in the diffusion layer during CO₂ reduction. Our results show that the two different peaks are due to diffusion limitation by two different species, namely, CO and OH^-. We find that between pH 7 and 11, CO oxidation by water and OH^- gives rise to the first and second peak observed in the voltammetry, respectively. Additional rotating disc experiments showed that specifically in this pH range the current of the second peak is diffusion limited by the OH^- concentration, since it is lower than the CO concentration.

Inexpensive, Three-Dimensional, Open-Cell, Fluid-Permeable, Noble-Metal Electrodes for Electroanalysis and Electrocatalysis

This study describes the fabrication of three-dimensional, open-cell, noble-metal (Au, Ag, and Pt) electrodes that have a complex geometry, i.e., wire mesh, metallic foam, "origami" wire mesh, and helix wire mesh. The electrodes were fabricated using an ultrasonication-assisted electroplating method that deposits a thin, continuous, and defect-free layer of noble metal (i.e., Au, Ag, or Pt) on an inexpensive copper substrate that has the desired geometry. The method is inexpensive, easy to use, and capable of fabricating noble-metal electrodes of complex geometries that cannot be fabricated using established techniques like screen printing or physical vapor deposition. By minimizing the amount of the pure noble metal in the electrodes, their cost drops significantly and could become low enough even for single-use applications; for example, the cost of metal in a Au wire-mesh electrode is $0.007/cm² of exposed area that is about 400 times lower than that of a wire-mesh electrode composed entirely of Au. The electrodes exhibit an almost identical electrochemical performance to noble-metal electrodes of similar shape composed of bulk noble metal; therefore, these electrodes could replace two-dimensional noble-metal electrodes (e.g., rods, disks, foils) in numerous electroanalytical and electrocatalytical systems or even allow the use of noble-metal electrodes in new applications such as flow-based electrochemical systems. In this study, wire-mesh and metallic foam noble-metal electrodes have been successfully used as working electrodes for the electrocatalytical oxidation of methanol and for the electrochemical detection of redox mediators, lead ions, and nitrobenzene using various electroanalytical techniques.

Facet-Dependent Long-Term Stability of Gold Aerogels toward Ethylene Glycol Oxidation Reaction

In this work, a series of Au_PNR^6 - 50 aerogels with different percentages of {110} facets (from ∼12 to 36%) were controllably prepared and then used to investigate their performance (specific activity and long-term stability) toward ethylene glycol oxidation reaction (EGOR), in which PNR represents the particle number ratio of 6 nm Au NPs to 50 nm Au NPs. It is found that their specific activity and long-term stability highly depend on the sum of the percentage of the {100} and {111} facets and the percentage of {110} facets, respectively. In addition, Au₂₄^6 - 50 aerogels with the highest percentage of {110} facets can possess excellent long-term stability (retaining about 95% of the initial current) but still have excellent specific activity (about 90.42 mA cm^-2). Thus, the specific activity and long-time stability of Au_PNR^6 - 50 aerogels toward EGOR can be well balanced by controlling the proper percentage of {110} facets on their surfaces. Therefore, the successful fabrication of Au_PNR^6 - 50 aerogels with greatly improved long-term stability and excellent specific activity not only provides a novel method for the design of electrocatalysts but also would boost the commercial development of direct ethylene glycol fuel cells.

On-Chip Electrical Transport Investigation of Metal Nanoparticles: Characteristic Acidic and Alkaline Adsorptions Revealed on Pt and Au Surface

Metal nanocrystals have been extensively explored as efficient and tailorable electrocatalysts for various sustainable energy technologies. Precise understanding of molecular interactions at the electrode-electrolyte interfaces during electrochemical processes, which mostly relies on the interpretation of spectroscopic surface information, is crucial to the innovations in catalyst design and optimization of reaction conditions. Here, we demonstrate the first in situ electrical transport evidence of pH-dependent surface anionic adsorptions on metal nanoparticles (MNPs), enabled by the on-chip electrical transport spectroscopy (ETS) of continuous nanoparticle (NP) thin films. Our results on platinum and gold NPs reveal the significant (and distinct) impacts of acid-base environments on their surface adsorption features, which contributes to the further understanding of gold- and platinum-based electrocatalytic systems. The successful employment of ETS on metal nanoparticles achieves a more general transport-based signaling technique that conveniently fits the abundance of catalytic materials with zero-dimension morphology.

Highly Catalytic Electrochemical Oxidation of Carbon Monoxide on Iridium Nanotubes: Amperometric Sensing of Carbon Monoxide

The nanotubular structures of IrO₂ and Ir metal were successfully synthesized without any template. First, IrO₂ nanotubes were prepared by electrospinning and post-calcination, where a fine control of synthetic conditions (e.g., precursor concentration and solvent composition in electrospinning solution, temperature increasing rate for calcination) was required. Then, a further thermal treatment of IrO₂ nanotubes under hydrogen gas atmosphere produced Ir metal nanotubes. The electroactivity of the resultant Ir metal nanotubes was investigated toward carbon monoxide (CO) oxidation using linear sweep voltammetry (LSV) and amperometry. The anodic current response of Ir metal nanotubes was linearly proportional to CO concentration change, with a high sensitivity and a short response time. The amperometric sensitivity of Ir metal nanotubes for CO sensing was greater than a nanofibrous counterpart (i.e., Ir metal nanofibers) and commercial Pt (20 wt% Pt loading on carbon). Density functional theory calculations support stronger CO adsorption on Ir(111) than Pt(111). This study demonstrates that metallic Ir in a nanotubular structure is a good electrode material for the amperometric sensing of CO.

Highly Strained Au Nanoparticles for Improved Electrocatalysis of Ethanol Oxidation Reaction

Au is an ideal noble metal for use as an electrocatalyst for the ethanol oxidation reaction owing to its high performance-to-cost ratio. The catalyst usually exists as nanoparticles (NPs) for high surface area-to-volume ratio. In the present work, a nontraditional physical approach has been developed to fabricate ultrasmall and homogeneous single-crystalline Au NPs by ion bombardment in a precision ion polishing system. Transmission electron microscopy characterizations show that the Au NPs produced with 5 keV Ar⁺ are highly strained to form twinned crystals, which accumulate a large amount of surface energy, and this was found to be an underlying reason causing strong catalysis. Electrochemistry tests reveal that in alkaline medium the C1 pathway occurs much more preferentially with the strained Au NPs than the normal Au NPs. The surface area-to-volume ratio is no longer the only factor that affects the performance; instead, surface energy might play a more important role in enhancing the catalytic activities.

Recent advances in the electrooxidation of biomass-based organic molecules for energy, chemicals and hydrogen production

The recent developments in biomass-derivative fuelled electrochemical converters for electricity or hydrogen production together with chemical electrosynthesis have been reviewed.

An intrinsically stretchable and compressible Zn–air battery

An intrinsically 300% stretchable and 85% compressible Zn–air rechargeable battery with good electrochemical performances was fabricated for the first time.

Dewetted Gold Nanostructures onto Exfoliated Graphene Paper as High Efficient Glucose Sensor

Non-enzymatic electrochemical glucose sensing was obtained by gold nanostructures on graphene paper, produced by laser or thermal dewetting of 1.6 and 8 nm-thick Au layers, respectively. Nanosecond laser annealing produces spherical nanoparticles (AuNPs) through the molten-phase dewetting of the gold layer and simultaneous exfoliation of the graphene paper. The resulting composite electrodes were characterized by X-ray photoelectron spectroscopy, cyclic voltammetry, scanning electron microscopy, micro Raman spectroscopy and Rutherford back-scattering spectrometry. Laser dewetted electrode presents graphene nanoplatelets covered by spherical AuNPs. The sizes of AuNPs are in the range of 10-150 nm. A chemical shift in the XPS Au4f core-level of 0.25-0.3 eV suggests the occurrence of AuNPs oxidation, which are characterized by high stability under the electrochemical test. Thermal dewetting leads to electrodes characterized by faceted not oxidized gold structures. Glucose was detected in alkali media at potential of 0.15-0.17 V vs. saturated calomel electrode (SCE), in the concentration range of 2.5μM-30 mM, exploiting the peak corresponding to the oxidation of two electrons. Sensitivity of 1240 µA mM^-1 cm^-2, detection limit of 2.5 μM and quantifications limit of 20 μM were obtained with 8 nm gold equivalent thickness. The analytical performances are very promising and comparable to the actual state of art concerning gold based electrodes.

The Effect of Anions and pH on the Activity and Selectivity of an Annealed Polycrystalline Au Film Electrode in the Oxygen Reduction Reaction-Revisited

Aiming at a better understanding of correlations between the activity and selectivity of Au electrodes in the oxygen reduction reaction (ORR) under controlled transport conditions, we have investigated this reaction by combined electrochemical and in situ FTIR measurements, performed in a flow cell set‐up in an attenuated total reflection (ATR) configuration in acid and alkaline electrolytes. The formation of incomplete reduction products (hydrogen peroxyde/peroxyls) was detected by a collector electrode, the onset of OH_ad formation was probed by bulk CO oxidation. Using an electroless‐deposited, annealed Au film on a Si prism as working electrode and three different electrolytes for comparison (sulfuric acid, perchloric acid, sodium hydroxide solution), we could derive detailed information on the anion adsorption behavior, and could correlate this with the ORR characteristics. The data reveal pronounced effects of the anions and the pH on the ORR characteristics, indicated e. g., by a grossly different activity and selectivity for the 4‐electron pathway to water/hydroxyls, with the onset ranging from ca. 1.0 V in alkaline electrolyte to 0.6 V in sulfuric acid electrolyte, and the selectivity for the 4‐electron pathway ranging from 100 % (alkaline electrolyte, low overpotentials) to 40 % (acidic electrolytes, alkaline electrolyte at high overpotentials). In contrast, the effect of the ORR on the anion adsorption characteristics is small. Anion effects as well as correlations between anion adsorption and ORR are discussed.

Mesoporous gold nanospheres via thiolate-Au(i) intermediates

This manuscript reports a facile yet effective surfactant-templated synthesis methodology to grow in situ metallic gold mesoporous nanospheres for methanol electrooxidation.

Mesoporous gold (mesoAu) nanospheres support enhanced (electro)catalytic performance owing to their three-dimensional (3D) interior mesochannels that expose abundant active sites and facilitate electron/mass transfers. Although various porous Nanostructured Au has been fabricated by electrochemical reduction, alloying–dealloying and hard/soft templating methods, successful synthesis of mesoAu nanospheres with tailorable sizes and porosities remains a big challenge. Here we describe a novel surfactant-directed synthetic route to fabricate mesoAu nanospheres with 3D interconnected mesochannels by using the amphiphilic surfactant of C₂₂H₄₅N⁺(CH₃)₂–C₃H₆–SH (Cl^–) (C₂₂N–SH) as the mesopore directing agent. C₂₂N–SH can not only self-reduce trivalent Au(iii)Cl₄^– to monovalent Au(i), but also form polymeric C₂₂N–S–Au(i) intermediates via covalent bonds. These C₂₂N–S–Au(i) intermediates facilitate the self-assembly into spherical micelles and inhibit the mobility of Au precursors, enabling the crystallization nucleation and growth of the mesoAu nanospheres via in situ chemical reduction. The synthetic strategy can be further extended to tailor the sizes/porosities and surface optical properties of the mesoAu nanospheres. The mesoAu nanospheres exhibit remarkably enhanced mass/specific activity and improved stability in methanol electrooxidation, demonstrating far better performance than non-porous Au nanoparticles and previously reported Au nanocatalysts. The synthetic route differs markedly from other long-established soft-templating approaches, providing a new avenue to grow metal nanocrystals with desirable nanostructures and functions.

Design of Therapeutic Self-Assembled Monolayers of Thiolated Abiraterone

The aim of our work was to synthetize of a new analogue of abiraterone-thiolated abiraterone (HS-AB) and design a gold surface monolayer, bearing in mind recent advances in tuning monolayer structures and using them as efficient drug delivery systems. Therapeutic self-assembled monolayers (TSAMs) were prepared by chemically attaching HS-AB to gold surfaces. Their properties were studied by voltammetry and atomic force microscopy (AFM). A gold electrode with immobilized thioglycolic acid (HS-GA) was used for comparison. The surface concentration of HS-AB on the gold surface was 0.572 nmol/cm², determined from the area of the voltammetric reduction peaks (desorption process). The area per one molecule estimated from the voltammetry experiments was 0.291 nmol/cm². The capacity of thus prepared electrode was also tested. The calculated capacity for the HS-AB modified electrode is 2.90 μF/cm². The obtained value indicates that the monolayer on the gold electrode is quite well ordered and well-packed. AFM images show the formation of gold nanoparticles as a result of immersing the HS-AB modified gold electrode in an aqueous solution containing 1 mM HAuCl₄·3H₂O. These structures arise as a result of the interaction between the HS-AB compound adsorbed on the electrode and the AuCl₄^- ions. The voltammetric experiments also confirm the formation of gold structures with specific catalytic properties in the process of oxygen reduction.