Nano Islands Research Articles

Improving the switching behavior of TaOx/HfO2-based non-volatile memristors by embedded Ti and Pt nano-islands

To investigate the effects of embedded metal nano-island (NI) arrays on reducing the variations of the device switching parameters, we fabricated Pt/HfO2/TiN, Pt/TaOx/HfO2/TiN devices, as well as devices with embedded NI arrays, including Pt/TaOx/HfO2/Pt NI/TiN and Pt/TaOx/HfO2/Ti NI/TiN devices. Compared to devices without nano-islands, the Pt/TaOx/HfO2/Pt NI/TiN devices with abrupt resistive switching behavior exhibit more stable resistance states (coefficient of variations (CVs) of RHRS and RLRS are 11.9 % and 13.0 %, respectively), and a large on/off ratio (>103), representing a high performance level among the HfO2-based non-volatile memristors reported to date, but the devices require a Forming process. The Pt/TaOx/HfO2/Ti NI/TiN devices with analog resistive switching behavior show low operating voltage (≤1 V), low resistance variations (CVs of RHRS, and RLRS are 15.8 %, and 17.6 %, respectively), but their on/off ratio (<10) is significantly reduced. The results indicate that embedding metal nano-island arrays decreases the fluctuations in device switching parameters, the different properties of nano-island materials significantly affect the abrupt/analog switching behavior, on/off ratio and the Forming of the non-volatile memristors. The methods employed in this study can be extended or evolved for other memristors to enhance their performance and applicability.

Comparative study of homoepitaxial Au (111) and Ag (111) layers: Insights from DFT simulations

Density Functional Theory (DFT) was employed for the first time in the investigation of Single-layer Nano islands on Ag (111) and Au (111) substrates. This study entailed performing first-principles calculations to assess their electronic and optical characteristics using the ab-initio approach with the full potential linearized augmented plane wave method. The results suggest that Single-layer Nano islands on Ag (111) and Au (111) surfaces exhibit considerable possibility for a range of technical uses, Due to their distinct chemical traits and metallic aspects, such as electrical conductivity. A systematic and comprehensive examination of these structures provides insights into their properties, enabling the exploration of new configurations for technological requirements. In this research paper, we offer a comprehensive analysis of the structural, electronic, and optical features of the newly projected Single-layer Nano islands on Ag (111) and Au (111) surfaces. We compare our findings with first-principles density functional theory. Additionally, we investigate the density of states in the material to figure out the atomic and orbital causes of electronic states. The analysis of the band structure and electronic properties reveals that the valence and conduction bands are predominantly influenced by Ag (111)/Ag (111)–s, Ag (111)/Ag (111)–d orbitals and Ag (111)/Ag (111)–p, Au (111)/Au (111)–p orbitals, respectively around the Fermi level. The Fermi surfaces of two distinct materials are characterized by the presence of three sheets, each populated by both electron and hole states. To investigate the bonding characteristics of these materials, an examination of electronic charge density within the (111) crystallographic planes is undertaken. This analysis reveals the presence of covalent bonding between Ag-Ag and Au-Au atoms. By looking at the dielectric function and associated optical features, such as conductivity, extinction coefficient, refractive index, energy loss function, and reflectivity throughout an energy range of 0 to 14 eV, optical properties are calculated. These materials may be suitable for use in optoelectronic devices, according to research into their optical properties.

Polymer Backbone Stabilized Methylammonium Lead Bromide Perovskite Nano Islands.

Organic-inorganic hybrid perovskite materials continue to attract significant interest due to their optoelectronic application. However, the degradation phenomenon associated with hybrid structures remains a challenging aspect of commercialization. To overcome the stability issue, we have assembled the methylammonium lead bromide nano islands (MNIs) on the backbone of poly-3-dodecyl-thiophene (PDT) for the first time. The structural and morphological properties of the MNI-PDT composite were confirmed with the aid of X-ray diffraction (XRD) studies, Field emission scanning electron microscope (FESEM), and X-ray photoelectron spectroscopy (XPS). The optical properties, namely absorption studies, were carried out by ultraviolet-visible spectroscopy. The fluorescent behavior is determined by photoluminescence (PL) spectroscopy. The emission peak for the MNI-PDT was observed at 536 nm. The morphology studies supported by FESEM indicated that the nano islands are completely covered on the surface of the polymer backbone, making the hybrid (MNI-PDT) stable under environmental conditions for three months. The interfacial interaction strategy developed in the present work will provide a new approach for the stabilization of hybrids for a longer time duration.

A highly reliable, integration-time and laser-power independent, self-referenced SERS sensor with an extended dynamic range for the detection of melamine in milk

An ultrasensitive nanosculptured thin film (nSTF) based self-referenced SERS sensing platform for the detection of melamine in milk samples is developed. The self-referenced SERS platform consists of a monolayer of 4-aminothiophenol (4-ATP), sandwiched between Ag nSTF and Ag nanoislands (NIs), deposited over a Si substrate. The SERS signal from the sandwiched 4-ATP monolayer acts as a self-referenced signal. The self-referenced platform offers the advantage of independence of Raman signal on the laser power, integration time of the detector of the spectrometer, or ambient conditions. The dynamic range of the sensor, mostly limited by the limits on laser power and integration time of spectrometer, can now be extended due to the independence of the sensor from these two parameters. A significant enhancement in the Raman signal of rhodamine 6G of the order of 1013 is achieved for the SERS active substrate. The self-referenced SERS sensor offers a linear response over the extended dynamic range from 0.001 to 10 ppm for melamine in spiked milk samples. The achieved limit of detection for melamine in spiked milk samples is 1 ppb. The self-referenced sensor will be of great value for real-time detection of melamine in milk samples, and food safety.

Growth of highly oriented crystalline gold nanoislands on MgO(001) substrates for surface-enhanced Raman scattering chips by pulsed laser deposition

Highly oriented crystalline gold nanoislands (NIs) are self-assembled on MgO(001) substrates by pulsed laser deposition. Morphologies of the gold NIs are significantly dependent on the substrate temperature during gold deposition. Symmetrical-shaped NIs with Au(111) orientation are existence parallel to the MgO(001) substrate at low temperatures deposition (350 and 550 °C), while square-shaped and hexagonal-shaped gold NIs are co-existence whose crystallinity was Au(001) and Au(111), respectively. Extinction spectra of the gold NIs on MgO(001) substrates show that wide-range of photo-energy is disappeared. For a simple and useful plasmonic device, the produced gold NIs on MgO(001) substrates are applied to the surface-enhanced Raman scattering (SERS) chips. The SERS properties of the chips are evaluated using 4-MBA as a model analyte. From the SERS signal of a 4-MBA ring breathing mode, we obtain a significant enhancement factor over 107, which is approximately 10 times higher than that of a conventional SERS chip.

Pt Single Atoms as Co‐Catalysts on CdS‐Sensitized Single‐Crystalline TiO2 Nanoflakes for Enhanced Visible Light Photocatalytic H2 Generation

AbstractStudies on single‐atom catalysts (SACs) with individually isolated metal atoms anchored on specific supports have gained great interest in photocatalysis due to their enhanced catalytic activity and optimal atom utilization. By providing an optimized number of active sites and enhancing their intrinsic activity, SACs afford a distinctive platform for photocatalysis at the atomic level. In this study, we investigate the photocatalytic H2 generation of Pt single atoms (SAs) anchored on CdS‐sensitized single crystalline anatase TiO2 nanoflakes (ATNF) in the visible spectral range. Vertically‐aligned ATNF were synthesized on fluorine‐doped tin oxide substrates by a hydrothermal process, which were further sensitized by CdS nanoislands (NIs) using the successive ionic layer adsorption and reaction (SILAR) technique. Finally, a reactive‐deposition approach was used to successfully anchor Pt SAs on CdS‐sensitized ATNF. Under optimized conditions, the highest photocatalytic H2 evolution on Pt‐anchored single atom CdS sensitized ATNF was 17.8 μL h−1 under visible light illumination, which is 15.8, 7.5, and 6.7‐fold higher than bare CdS/FTO, PtSA/CdS/FTO, and ATNF, respectively. Overall, the density of Pt SAs plays a vital role via strong trapping of the photogenerated electrons and significantly improves the efficiency of electron‐hole separation, making PtSA/ATNF efficient solar‐driven photocatalysts.

The Effects of Ag Nanoislands on the Volatile Threshold-Switching Behaviors of Au/Ag/HfO2/Ag Nanoislands/Au Devices

Volatile threshold-switching (TS) devices have been used as selectors and to simulate neurons in neural networks. It is necessary to find new ways to improve their performance. The randomness of conductive filament (CF) growth and the endurance of the devices are urgent issues at present. Here, we explored embedded Ag nanoislands (NIs) in HfO2-based TS devices to limit the position of the CF and facilitate its growth at the same time. The Au/Ag(2 nm)/HfO2(4 nm)/Ag NIs/Au volatile TS devices exhibited forming-free characteristics with improved endurance compared with the devices without Ag NIs, which was ascribed to the enhanced localization of the electrical field and increased oxygen vacancies in HfO2 induced by the Ag NIs. A mechanism was proposed to explain the volatile TS behaviors of the devices. The Ag NIs and the thickness of the HfO2 layers played key roles in whether the devices required forming. This work shows that the use of metal NIs is an effective and convenient way to improve the performance of TS devices.

Deterministic Conductive Filament Formation and Evolution for Improved Switching Uniformity in Embedded Metal-Oxide-Based Memristors─A Phase-Field Study

The extreme device-to-device variation of switching performance is one of the major obstacles preventing the applications of metal-oxide-based memristors in large-scale memory storage and resistive neural networks. Recent experimental works have reported that embedding metal nano-islands (NIs) in metal oxides can effectively improve the uniformity of the memristors, but the underlying role of the NIs is not fully understood. Here, to address this specific problem, we develop a physical model to understand the origin of the variability and how the embedded NIs can improve the performance and uniformity of memristors. We find that due to the dimension confinement effect, embedding metal NIs can modulate the electric field distribution and lead to a more deterministic formation of the conductive filament (CF) from their vicinity, in contrast to the random growth of CFs without embedded NIs. This deterministic CF formation, via vacancy nucleation, further reduces the forming, reset, and set voltages and enhances the uniformity of the operation voltages and current ON/OFF ratios. We further demonstrate that modifying the shapes of the metal NIs can modulate the field strengths/distributions around the NIs and that choosing the NI metal composition and shape that chemically facilitate vacancy formations can further optimize the CF morphology, reduce the operation voltages, and improve the switching performance. Our work thus provides a fundamental understanding of how embedded metal NIs improve the resistive switching performance in oxide-based memristors and could potentially guide the selection of embedded NIs to realize a more uniform memristor that also operates at a higher efficiency than present materials.

Characterizing the Water-Forming Reaction on Graphite- and Ceria-Supported Palladium Nanoparticles and Nanoislands by the Work Function

The water-forming reaction (WFR) between oxygen and hydrogen on metal surfaces is an important reaction in heterogeneous catalysis. Related research mostly focused on crystalline metal surfaces and thick films; however, supported nanoparticles (NP) have been rarely considered as well as a possible influence of the support on the NP catalytic activity. Here, we report on the WFR on graphite-supported palladium NPs and nanoislands (NI), which are characterized at room temperature and under ultrahigh vacuum conditions (UHV) by scanning tunneling microscopy (STM), noncontact atomic force microscopy (nc-AFM), Kelvin probe force microscopy (KPFM), and X-ray photoemission spectroscopy (XPS). We show that during the first cycles of sequential O2 and H2 pulses, atomic H reacts off preadsorbed atomic O, which can be followed by KPFM via monitoring the change in work function (WF) at the NPs and NIs. However, after a few WFR cycles, the WF changes get smaller and the mean WF of the Pd increases due to an irreversible deactivation of the catalyst: a filament structure is formed on the facets by O and C, which the latter probably gets released from the graphite during the WFR. In strong contrast to the Pd/graphite catalyst, the WFR can be followed without any changes during an unlimited number of cycles on a carbon-free Pd/cerium oxide/Cu(111) catalyst, which clearly shows that the support plays a role in the WFR on nanometer-sized Pd catalysts.

Toward Plasmonic Neural Probes: SERS Detection of Neurotransmitters through Gold-Nanoislands-Decorated Tapered Optical Fibers with Sub-10nm Gaps.

Integration of plasmonic nanostructures with fiber-optics-based neural probes enables label-free detection of molecular fingerprints via surface-enhanced Raman spectroscopy (SERS), and it represents a fascinating technological horizon to investigate brain function. However, developing neuroplasmonic probes that can interface with deep brain regions with minimal invasiveness while providing the sensitivity to detect biomolecular signatures in a physiological environment is challenging, in particular because the same waveguide must be employed for both delivering excitation light and collecting the resulting scattered photons. Here, a SERS-active neural probe based on a tapered optical fiber (TF) decorated with gold nanoislands (NIs) that can detect neurotransmitters down to the micromolar range is presented. To do this, a novel, nonplanar repeated dewetting technique to fabricate gold NIs with sub-10nm gaps, uniformly distributed on the wide (square millimeter scale in surface area), highly curved surface of TF is developed. It is experimentally and numerically shownthat the amplified broadband near-field enhancement of the high-density NIs layer allows for achieving a limit of detection in aqueous solution of 10-7 m for rhodamine 6G and 10-5 m for serotonin and dopamine through SERS at near-infrared wavelengths. The NIs-TF technology is envisioned as a first step toward the unexplored frontier of in vivo label-free plasmonic neural interfaces.

In Situ Porousized MoS2 Nano Islands Enhance HER/OER Bifunctional Electrocatalysis.

2D molybdenum disulfide (MoS2 ) is developed as a potential alternative non-precious metal electrocatalyst for energy conversion. It is well known that 2D MoS2 has three main phases 2H, 1T, and 1T'. However, the most stable 2H-phase shows poor electrocatalysis in its basal plane, compared with its edge sites. In this work, a facile one-step hydrothermal-driven in situ porousizing of MoS2 into self-supporting nano islands to maximally expose the edges of MoS2 grains for efficient utilization of the active stable sites at the edges of MoS2 is reported. The results show that such active, aggregation-free nano islands greatly enhance MoS2 's hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) bifunctional electrocatalytic activities. At a low overpotential of 248 and 300 mV, the porous MoS2 nano islands can generate a current density of 10 mA cm-2 in HER and OER, which is much better than typical nanosheet morphology. Surprisingly, the porous MoS2 nano islands even exhibit better performance than the current commercial RuO2 catalyst in OER. This discovery will be another effective strategy to promote robust 2H-phase, instead of 1T/1T'-phase, MoS2 to achieve efficient endurable bifunctional HER/OER, which is expected to further replace precious metal catalysts in industry.

Synergy between plasmonic nanocavities and random lasing modes: a tool to dequench plasmon quenched fluorophore emission.

Metal nanoparticles (NPs) can be employed to modify the emission level of a dye emitter by tailoring the spectral overlap of the optical gain and localized surface plasmon resonance (LSPR). In the case of plasmonic random lasers, tuning the spectral overlap by manipulating metal NPs changes the scattering properties of the system, which is crucial in random lasers (RLs). In order to overcome this drawback, the emitter gain spectrum across the LSPR is tuned by appropriately choosing various dye emitters. A system with Au nanoislands (NIs) randomly distributed on the surface of vertically aligned ZnO nanorods on a glass substrate coated with three different dye emitters has been employed to study the metal-gain interaction as a function of spectral overlap. It is observed that the photoluminescence is quenched in the presence of Au NIs for all the three dye emitters; however, the degree of quenching is found to be directly proportional to the extent of spectral overlap of the LSPR and the fluorophore emission spectrum, with the resonantly coupled systems exhibiting higher random lasing thresholds. However, a dequenching of the emission is observed under spectrally off-resonant conditions, leading to a lower threshold RL. The effect of tailoring of the metal-gain interaction on the coherent and incoherent intensity components of RL emission is studied to elucidate the contrasting results of photoluminescence and RL emission. As the optical gain shifts away from the LSPR peak, the RL emission is dominated by the coherent intensity. The speckle-like field distributions of the RL modes couple to the plasmonic nanocavities along with a reduced absorption loss for the off-resonant case, leading to an enhanced stimulated emission. Hence, a synergy between random laser modes, plasmonic nanocavities and optimum spectral overlap has been utilized as a tool to dequench the plasmon quenched fluorophore emission.

Tip-enhanced Raman imaging of plasmon-driven dimerization of 4-bromothiophenol on nickel-decorated gold nanoplate bimetallic nanostructures.

We used tip-enhanced Raman spectroscopy (TERS) to examine plasmon-driven dimerization of 4-bromothiophenol (4-BTP) into thiophenol (TP) and 4,4'-biphenyldithiol (4,4'-BPDT) on Au and Ni@AuNPs. TERS revealed that cross-coupling of these molecular reactants into 4,4'-BPDT occurred primarily on Ni nano islands rather than the surrounding Au on the surface of Ni@AuNPs.

Endorsing a Hidden Plasmonic Mode for Enhancement of LSPR Sensing Performance in Evolved Metal-insulator Geometry Using an Unsupervised Machine Learning Algorithm.

Large-area nanoplasmonic structures with pillared metal-insulator geometry, also called nanomushrooms (NM), consist of an active spherical-shaped plasmonic material such as gold as its cap and silicon dioxide as its stem. NM is a geometry which evolves from its precursor, nanoislands (NI) consisting of aforementioned spherical structures on flat silicon dioxide substrates, via selective physical or chemical etching of the silicon dioxide. The NM geometry is well-known to provide enhanced localized surface plasmon resonance (LSPR) sensitivity in biosensing applications as compared to NI. However, precise optical phenomenon behind this enhancement is unknown and often associated with the existence of electric fields in the large fraction of the spatial region between the pillars of NM, usually accessible by the biomolecules. Here, we uncover the association of LSPR enhancement in such geometries with a hidden plasmonic mode by conducting magneto-optics measurements and by deconvoluting the absorbance spectra obtained during the local refractive index change of the NM and NI geometries. By the virtue of principal component analysis, an unsupervised machine learning technique, we observe an explicit relationship between the deconvoluted modes of LSPR, the differential absorption of left and right circular polarized light, and the refractive index sensitivity of the LSPR sensor. Our findings may lead to the development of new approaches to extract unknown properties of plasmonic materials or establish new fundamental relationships between less understood photonic properties of nanomaterials.

Plasmonic Effect of Ag/Au Composite Structures on the Material Transition

Noble metal nanostructures can produce the surface plasmon resonance under appropriate photoexcitation, which can be used to promote or facilitate chemical reactions, as well as photocatalytic materials, due to their strong plasmon resonance in the visible light region. In the current work, Ag/Au nanoislands (NIs) and Ag NIs/Au film composite systems were designed, and their thermocatalysis performance was investigated using luminescence of Eu3+ as a probe. Compared with Ag NIs, the catalytic efficiency and stability of surface plasmons of Ag/Au NIs and Ag NIs/Au film composite systems were greatly improved. It was found that the metal NIs can also generate strong localized heat at low temperature environment, enabling the transition of NaYF4:Eu3+ to Y2O3: Eu3+, and anti-oxidation was realized by depositing gold on the surface of silver, resulting in the relative stability of the constructed complex.

Demonstration of enhanced resistance switching performance of HfO2/WOx-based bilayer devices embedded with Ti nano island array by applying a rapid thermal annealing process

In this work, a novel set of methods is prοposed for tuning the oxygen vacancy distribution through the combination of several effects. More specifically, the incorporation of a Ti nano-island (NI), as well as the insertion of a thin layer of HfO 2 with 10 nm thickness and the subsequent enforcement of an annealing step at 400 ℃ are employed to improve the performance of the resistive switching memory devices. The acquired results indicate that the embedded Ti NI array can significantly reduce the switching voltage and the statistical dispersion of the switching characteristics, whereas the increase of both the high resistance state (HRS) and low resistance state (LRS) resistance levels and the reduction of the operating current values are attributed to the existence of the HfO 2 layer. Subsequently, the annealing process under air conditions can effectively reduce the oxygen vacancy content within the device and further improve the R HRS and on/off ratio. The reduction of the oxygen vacancy concentration is caused by the diffusion of oxygen ions in the air to the dielectric layer during annealing. Hence, it is concluded that the simultaneous incorporation of a Ti NI, a functional layer and a rapid thermal annealing step are regarded as a novel promising and practical technology for significantly improving the whole performance of the memristive elements. • Ti NI can significantly improve the whole performance of the memristive elements. • A rapid thermal annealing can improve the performance of the memristive elements. • The annealing can effectively reduce the oxygen vacancy concentration within the device.

Experimentally evaluating plasmonic sensing performance of silver film over nanosphere surface (AgFON)

In the present work, Silver film over nanosphere surface (AgFON) structures were fabricated on a self-assembled monolayer (SAM) of polystyrene spheres (200 nm) by a simple and cost effective drop-casting followed by thermal evaporation techniques. The thickness of Ag thin film was varied from 20 nm to 100 nm in a step of 20 nm. Field emission scanning electron microscopy (FESEM) revealed that the morphology of AgFON changes from nano island to nanoshells with increasing thickness. Reflection spectra of AgFON of thickness >60 nm exhibited a sharp minimum due to the excitation of cavity mode plasmon. Plasmonic sensing capabilities of AgFON have been investigated with respect its thickness. AgFON of 100 nm exhibited a bulk sensitivity of 632.54 nm/RIU while 80 nm showed a sensitivity of 365 nm/RIU towards a thin layer of volatile organic compounds such as ethanol, toluene and isopropyl alcohol. Biological molecules such as urea, creatinine, glucose, melamine and glutathione have been tested with the AgFON. The AgFON displays a good capability of detecting 1 mM creatinine in an aqueous solution. A successful attempt has been made to detect the creatinine of >1 mM in human urine.

Plasmonic Gold Nanoisland Film for Bacterial Theranostics.

Plasmonic nanomaterials have been intensively explored for applications in biomedical detection and therapy for human sustainability. Herein, plasmonic gold nanoisland (NI) film (AuNIF) was fabricated onto a glass substrate by a facile seed-mediated growth approach. The structure of the tortuous gold NIs of the AuNIF was demonstrated by scanning electron microscopy and energy-dispersive X-ray spectroscopy. Based on the ultraviolet-visible spectrum, the AuNIF revealed plasmonic absorption with maximum intensity at 624 nm. With the change to the surface topography created by the NIs, the capture efficiency of Escherichia coli (E. coli) by the AuNIF was significantly increased compared to that of the glass substrate. The AuNIF was applied as a surface-enhanced Raman scattering (SERS) substrate to enhance the Raman signal of E. coli. Moreover, the plasmonic AuNIF exhibited a superior photothermal effect under irradiation with simulated AM1.5 sunlight. For photothermal therapy, the AuNIF also displayed outstanding efficiency in the photothermal killing of E. coli. Using a combination of SERS detection and photothermal therapy, the AuNIF could be a promising platform for bacterial theranostics.

A novel WOx-based memristor with a Ti nano-island array

A novel WOx-based memristor with Ti nano-island arrays was developed in this study. A 100 nm thick Pt bottom electrode was deposited, and an ultrathin anodic aluminum oxide (AAO) template was used to obtain the Ti nano-island arrays. The WOx/Ti nano-island (NI)/Pt devices were prepared by magnetron sputtering using a WOy (y=2.7–2.9) target to obtain a 30 nm deposition layer of WOx. Scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and semiconductor analysis confirmed that the WOx-based memristor could be successfully produced with a highly ordered Ti nano-island array. The size and density of the NIs could be controlled by selecting the aperture of the AAO template. The oxygen interaction between the Ti nano-islands and WOx led to the creation of oxygen vacancies in their vicinity, resulting in the formation of an oxygen vacancy conductive filament (CF) without the need for a forming process. NIs tend to strengthen the electric field along the bias voltage direction, fostering the generation of the CF. The absolute values of VSET and VRESET were about 0.19 V and 0.69 V, respectively. Compared with the devices without the Ti NI arrays, the variation coefficients of VSET and VRESET of the WOx/Ti NI/Pt devices were reduced by about 84.9% and 83.7%, respectively. With smaller and more concentrated VSET and VRESET, the WOx/Ti NIs/Pt device showed a significantly improved switching stability.

Structural Dynamics of Ultrathin Cobalt Oxide Nanoislands under Potential Control

AbstractCobalt oxide is a promising earth abundant electrocatalyst and one of the most intensively studied oxides in electrocatalysis. In this study, the structural dynamics of well‐defined cobalt oxide nanoislands (NIs) on Au(111) are investigated in situ under potential control. The samples are prepared in ultra‐high vacuum and the system is characterized using scanning tunneling microscopy (STM). After transfer into the electrochemical environment, the structure, mobility, and dissolution is studied via in situ electrochemical (EC) STM, cyclic voltammetry, and EC on‐line inductively coupled plasma mass spectrometry. Cobalt oxide on Au(111) forms bilayer (BL) and double‐bilayer NIs (DL), which are stable at the open circuit potential (0.8 VRHE). In the cathodic scan, the cobalt oxide BL islands become mobile at potentials of 0.5 VRHE and start dissolving at potentials below. In sharp contrast to the BL islands, the DL islands retain their morphology up to much lower potential. The re‐deposition of Co aggregates is observed close to the reduction potential of Co2+ to Co3+. In the anodic scan, both the BL and DL islands retain their morphology up to 1.5 VRHE. Even under these conditions, the islands do not show dissolution during the oxygen evolution reaction (OER) while maintaining their high OER activity.