rGO Electrode Research Articles

Reduced graphene oxide supported meso-pyridyl BODIPY-Cobaloxime complexes for electrocatalytic hydrogen evolution reaction

Creating innovative catalysts utilizing nonprecious metals for the electrocatalytic hydrogen evolution reaction (HER) poses a significant difficulty. We present a cobaloxime (Cox) complex having pyridine (2-Cox) and tetrafluorophenyl-thio-pyridine (4-Cox) functional groups, which contains a 4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) moiety. This combination serves as a catalyst for proton reduction and is immobilized onto reduced graphene oxide (rGO) by π–π stacking between the cobaloxime complex and rGO. Moreover, the unique complex's structures were determined through the application of ultraviolet–visible spectroscopy (UV–Vis), Fourier Transform Infrared spectroscopy (FT-IR), X-ray diffraction spectroscopy (XRD), and scanning electron microscopy (SEM). The electrocatalytic activity of the two rGO/2-Cox and rGO/4-Cox electrodes towards hydrogen (H2) were examined under both alkaline and acidic conditions. The cobaloxime-modified rGO electrodes demonstrate superior electrocatalytic performance for the HER under acidic conditions compared to alkaline conditions. The overpotential at a current density of 10 mA cm−2 for rGO/2-Cox in 0.5 M H2SO4 is −0.342 V, which is notably lower than the overpotential of rGO/4-Cox (−0.496 V). The Tafel slope for the rGO/2-Cox electrode in a 0.5 M H2SO4 solution is 111 mV.dec−1, but for the rGO/4-Cox electrode it is 156 mVdec−1. This discrepancy suggests that the rGO/2-Cox electrode demonstrates better performance in the HER compared to the rGO/4-Cox electrode.

Study of electrochemical behavior of rGO and Metal-Organic Framework nanocomposite electrodes for supercapacitive applications

Abstract This research studied the electrochemical performance of reduced Graphene Oxide (rGO) and a nanocomposite comprising rGO and Metal-Organic Framework-5 (MOF-5) for supercapacitor applications. The nanocomposite, synthesized through a solvothermal method, aimed to capitalize on the synergistic effects of combining rGO with MOF-5 under normal laboratory conditions without utilizing autoclave. By adjusting the concentration of the oxidizing agent, the oxidation degree of rGO was effectively regulated, thereby influencing its structural properties. Utilizing the optimized rGO, electrodes were fabricated for both rGO and MOF5-rGO configurations. Electrochemical studies were carried out using a three-electrode (3E) system with a 6M KOH electrolyte. The MOF-5, reduced graphene oxide (rGO), and MOF5-rGO nanocomposite samples were characterized using X-ray powder diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) to determine their chemical composition and structural information. The Electrochemical Impedance Spectroscopy (EIS) spectra show low internal resistance (Rs) and charge transfer resistance (Rct), indicating higher conductivity of rGO and nanocomposite. The rGO electrode in the 3E system showed a specific capacitance of 65 Fg-1 whereas MOF5-rGO displayed 73 Fg-1 at a current density of 1.2 Ag-1. MOF5-rGO nanocomposite demonstrates better capacitor retention (96%) compared to rGO (90%) at 5A/g. These results indicate that the MOF5-rGO sample is a promising electrode for supercapacitor application.

The g-C3N4/rGO composite for high-performance supercapacitor: Synthesis, characterizations, and time series modeling and predictions

Supercapacitors have gathered significant interest in addressing the increasing need for energy storage devices with high power and energy densities. This study introduces a composite framework designed to enhance supercapacitor performance by leveraging the synergistic effects of g-C3N4/rGO composite. The composite electrode, which combines rGO for high conductivity and g-C3N4 for rapid ion diffusion, demonstrates excellent supercapacitor performance. The synthesized materials were characterized using different analytical tools such as X-ray diffraction, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller, Scanning and Transmission electron microscope, and X-ray photoelectron spectroscopy. The composite electrode exhibited outstanding performance characteristics, including a specific capacitance of 407.7 F/g, an energy density of 11.4 W h/kg, and a high power density of 186.7 W/kg. Kinetic analysis revealed that the g-C3N4/rGO composite electrode has a dominant diffusive controlled process. The g-C3N4/rGO electrode also demonstrated exceptional durability, maintaining remarkable capacitance retention even after the 5000th charge/discharge cycles. Moreover, the cyclic stability and Coulombic efficiency of the g-C3N4/rGO electrode were modeled and predicted by utilizing the time series analysis technique (Holt-Winters exponential smoothing). Considering the overall results, the g-C3N4/rGO composite electrode has a great potential for energy storage applications.

Integrated construction improving electrochemical performance of loadable supercapacitors based on porous cement-based solid electrolytes

Emerging integrated loadable supercapacitors (ILSs) are prominent candidates for zero-energy buildings with both load-bearing/energy storage capacity. However, the development of solid electrolytes with good mechanical and electrochemical performance remains a major challenge in realizing an integrated electro-mechanical system. Herein, the porous cement-based solid electrolytes (PCSEs) with the combined characteristics of high ionic conductivity and certain compressive strength are successfully developed by a facile “killing two birds with one stone” chemical foaming strategy using potassium iodide (KI) as the reaction modifier, and hydrogen peroxide (H2O2) and Portland cement as the foaming agent and substrate, respectively. The KI is introduced to balance the paradoxical relationship between ionic conductivity and compressive strength while improving the pseudocapacitance of the electrode. Benefiting from these intriguing integrated characteristics, the symmetrical ILS assembled with PCSE and reduced graphene oxide (rGO) electrodes can deliver a maximal energy density of 21.6 Wh kg−1 and a power density of 1106.2 W kg−1. Meanwhile, the ILS exhibits stable electrochemical behavior when withstanding external forces, which is a rarely studied aspect in other reports. Our results provide the basis for simple and universally applicable systems that fulfill the requirements of structural energy storage for civil engineering.

All-in-All: Dead Lithium-Ion Battery to Active Lithium-Ion Capacitor.

Here, we have developed lithium-ion capacitors (LICs) with all the components, except the electrolyte solution, effectively recycled from the spent Lithium-ion batteries (LIBs). Hybrid capacitors, such as LICs, are potential breakthroughs in electrochemical energy storage devices, where most research is focused. These devices can simultaneously guarantee high energy and power by hybridizing battery-type and capacitive-type electrodes with two different reaction mechanisms. We have successfully upcycled the graphite, current collector, separator, etc., from the spent LIBs to fabricate a high-performance LIC. Our LIC consists of recovered graphite (RG) coated over recovered copper foil as an anode, recycled polypropylene as the separator, and reduced graphene oxide (rGO) synthesized from RG as the cathode. The RG half-cell exhibited an excellent specific capacity of 302 mAh g-1 even after 75 charge-discharge cycles with a coulombic efficiency of >99 %. The Li/rGO displayed remarkable cycling performance for over 1000 cycles with high stability and reversibility. Subsequently, the pre-lithiated RG (p-RG) electrode is paired with the rGO electrode under the balanced loading conditions to construct LIC, rGO/p-RG, delivering a maximum energy density of 185 Wh kg-1 with ultra-long durability of more than 10,000 cycles. The possibility of LIC under different climatic conditions is also explored, and its remarkable performance under various temperature conditions is worth mentioning.

3D-Printed Hierarchically Microgrid Frameworks of Sodiophilic Co3O4@C/rGO Nanosheets for Ultralong Cyclic Sodium Metal Batteries.

Herein, hierarchically structured microgrid frameworks of Co3O4 and carbon composite deposited on reduced graphene oxide (Co3O4@C/rGO) are demonstrated through the three-dimensioinal (3D)printing method, where the porous structure is controllable and the height and width are scalable, for dendrite-free Na metal deposition. The sodiophilicity, facile Na metal deposition kinetics, and NaF-rich solid electrolyte interphase (SEI) formation of cubic Co3O4 phase are confirmed by combined spectroscopic and computational analyses. Moreover, the uniform and reversible Na plating/stripping process on 3D-printed Co3O4@C/rGO host is monitored in real time using in situ transmission electron and optical microscopies. In symmetric cells, the 3D printed Co3O4@C/rGO electrode achieves a long-term stability over 3950 at 1mA cm-2 and 1 mAh cm-2 with a superior Coulombic efficiency (CE) of 99.87% as well as 120h even at 20mA cm-2 and 20 mAh cm-2, far exceeding the previously reported carbon-based hosts for Na metal anodes. Consequently, the full cells of 3D-printed Na@Co3O4@C/rGO anode with 3D-printed Na3V2(PO4)3@C-rGO cathode (≈15.7mg cm-2) deliver the high specific capacity of 97.97 mAh g-1 after 500 cycles with a high CE of 99.89% at 0.5 C, demonstrating the real operation of flexible Na metal batteries.

On the Electrochemical Activation of Nanoporous Reduced Graphene Oxide Electrodes Studied by In Situ/Operando Electrochemical Techniques

AbstractDue to the difficult access of the electrolyte into the nanoconfined space of nanoporous reduced graphene oxide (rGO) electrodes, achieving the optimal electrochemical performance of these devices becomes a challenge. In this work, the dynamics of interfacial‐governed phenomena are investigated during a voltage‐controlled electrochemical activation of nanoporous rGO electrodes that leads to an enhanced electrochemical performance in terms of areal capacitance and electrochemical impedance. In situ/operando characterization techniques are used to reveal the dynamics of the irreversible material changes introduced during the activation process, including ionic diffusion and water confinement within the nanopores, along with the reduction of oxygenated groups and the decrease of the rGO interlayer distance. Furthermore, operando techniques are used to uncover the origin of the complex polarization‐dependent dynamic response of rGO electrodes. The study reveals that the reversible protonation/deprotonation of remaining functional groups and the cation electro‐adsorption/desorption process in the graphene basal plane govern the pseudocapacitive performance of nanoporous rGO electrodes. This work brings new understanding of the complex interplay between surface chemistry, ion confinement, and desolvation processes occurring during electrochemical cycling in nanoporous rGO electrodes, offering new insights for designing high‐performing electrodes based on nanoporous rGO.

Inhibition of chlorinated byproducts formation by boron-doped rGO electrodes during electrooxidation of trace organic contaminants

To minimize toxic inorganic chlorinated byproducts formation by anodic oxidation of chloride containing water, an electrode was fabricated by coating boron-doped reduced graphene oxide (BDrGO) on carbon paper. The BDrGO electrode only converted 0.03 to 0.4 % of the initial chloride (5–25 mM) to byproducts across a wide pH range (3−10), which is approximately two orders of magnitude lower than other commonly used anodes. The mechanism for inhibiting chlorinated byproducts was attributed to the higher overpotential for the chlorine evolution reaction on the BDrGO electrode and the slower reaction rates (< 2 × 10−11 M s–1) of pathways responsible for chlorinated byproducts formation. The BDrGO electrode was capable of oxidizing contaminants, with oxidation pathways predominated by chlorine radicals (e.g., ClO•, Cl•, Cl2•–) (> 50 %). During electrolysis of authentic surface water, the BDrGO electrode transformed trace organic contaminants (> 90 %) without producing unacceptable levels of chlorinated byproducts.

Reduced graphene oxide nanosheets as electron sink for MnFe2O4 nanoparticles: A synergistically boosted supercapacitance

Spinel ferrite structures have shown promise for energy storage. However, they are insulators and need a conductive substrate for better charge transfer. Here, we utilized a simple hydrothermal technique to in-situ coat a nickel foam with few-layer nanosheets of reduced graphene oxide (rGO) decorated with manganese ferrite (MnFe2O4) nanoparticles. We then studied the supercapacitance/pseudocapacitance properties of the rGO/MnFe2O4 composite. X-ray diffraction patterns, energy-dispersive X-ray maps, and X-ray photoelectron spectra of the composite were investigated to confirm its structural, elemental, and surface chemical composition, respectively. Scanning electron microscopy and transmission electron microscopy images demonstrated the decoration of rGO nanosheets with MnFe2O4 nanoparticles. In a three-electrode setup, the rGO/MnFe2O4 nanocomposite exhibits a specific capacitance per loaded material mass (2446 F/g at 1 A/g) which is higher than the sum of rGO (304 F/g) and MnFe2O4 (1084 F/g) electrodes, suggesting a synergistic effect between rGO and MnFe2O4. The energy density and power density of the rGO/MnFe2O4 electrode were also calculated 58.24 Wh/kg and 260.82 W/kg (at 1 A/g), respectively. We found that the resistance of the rGO/MnFe2O4 electrode (2.53 Ω) is much lower than the MnFe2O4 electrode (6.15 Ω), and the interfacial resistance of the rGO/MnFe2O4 electrode with electrolyte was found low, confirming the rGO role as a conductive substrate for insulating MnFe2O4 nanoparticles. We also showed that surface-related capacitance, rather than pseudocapacitance, is more dominant in the rGO/MnFe2O4 composite electrode than in the separate rGO and MnFe2O4 electrodes. We also demonstrated the practical performance of the rGO/MnFe2O4 electrode in a two-electrode setup. Finally, density functional theory calculations showed the considerable potential drop (16.5 eV) between MnFe2O4 and graphene that leads to a strong built-in electric field from graphene towards MnFe2O4. This indicates the role of graphene as a wide electron sink for MnFe2O4 nanoparticles that results in better charge distribution and storage.

Reduced graphene oxide electrodes meet lateral flow assays: A promising path to advanced point-of-care diagnostics

Research in electrochemical detection in lateral flow assays (LFAs) has gained significant momentum in recent years. The primary impetus for this surge in interest is the pursuit of achieving lower limits of detection, especially given that LFAs are the most widely employed point-of-care biosensors. Conventionally, the strategy for merging electrochemistry and LFAs has centered on the superposition of screen-printed electrodes onto nitrocellulose substrates during LFA fabrication. Nevertheless, this approach poses substantial limitations regarding scalability. In response, we have developed a novel method for the complete integration of reduced graphene oxide (rGO) electrodes into LFA strips. We employed a CO2 laser to concurrently reduce graphene oxide and pattern nitrocellulose, exposing its backing to create connection sites impervious to sample leakage. Subsequently, rGO and nitrocellulose were juxtaposed and introduced into a roll-to-roll system using a wax printer. The exerted pressure facilitated the transfer of rGO onto the nitrocellulose. We systematically evaluated several electrochemical strategies to harness the synergy between rGO and LFAs. While certain challenges persist, our rGO transfer technology presents compelling potential for setting a new standard in electrochemical LFA fabrication.

La-doped CeO2/rGO hybrid with high oxygen vacancy to enhance phosphorus adsorption by capacitive deionization

Cerium oxide is one of the most attractive electrode materials in capacitive deionization (CDI) technology for selective phosphate adsorption due to the specific interaction. However, Ce3+/Ce4+ ratio and material conductivity of cerium oxide electrode determine the adsorption performance. Herein, a dual strategy was exploited with polyol-solvothermal reaction in the presence of graphite oxide and cerium salt followed by hydrothermal La-doping to obtain the three-dimensional (3D) assembly of La-doped CeO2 at the reduced graphene oxide (La-CeO2/rGO). The as-prepared La-CeO2/rGO hybrid exhibited interconnected structure with CeO2 uniformly distributed on the rGO support. La3+, by partially replacing Ce4+ in the lattice, was evenly fused into CeO2 nanosphere, enhancing the content of Ce3+ and oxygen vacancies and inhibiting lattice distortion. As a CDI positive electrode, the La0.15-CeO2/rGO with optimal La doping achieved the maximum theoretical adsorption capacity of 118.7 mg P/g with high separation factor (αSO42-P = 13.9), superior to the CeO2/rGO (67.8 mg P/g, αSO42-P = 10.1). In addition, the La-CeO2/rGO electrode is extremely robust, with excellent adsorption performance in wide pH range and good regeneration ability, compared to CeO2/rGO. This work proves that the synergy of trace La doping and 3D rGO support effectively improves the adsorption performance of La-CeO2/rGO electrodes and enhances the cycling stability of CDI devices. The corresponding adsorption mechanism was demonstrated.

Metastable 2D amorphous Nb2O5 for aqueous supercapacitor energy storage

Nb2O5 is a promising electrode material of energy storage due to its high specific capacity and phase transition resistance. However, the facile generation of niobic acid poses a challenge, hindering controlled growth and impeding improvements in electrical conductivity and structural stability, especially in realizing two-dimensional (2D) Nb2O5. Herein, we have discerned that the addition of hexamethylenetetramine (HMTA) in ethanol solvent facilitates the controlled and restricted growth of metastable 2D amorphous Nb2O5 (a-Nb2O5) within graphene domains. Nitrogen atoms within HMTA, rich in lone pair electrons, strongly interact with niobium ions, promoting 2D amorphous growth on graphene interface. This unique 2D amorphous interface offers high surface area, enhanced electron mobility, rapid ion transport, and superior structural stability compared to crystalline counterparts. The prepared metastable 2D a-Nb2O5/rGO electrode exhibits unprecedented cycle life in aqueous asymmetric supercapacitor. This confined growth strategy offers a novel approach for the innovative design of metastable 2D materials.

GO induces ZIF-8 to produce hollow nanobox CoSe2@ZnSe/rGO for high-performance supercapacitors

Reasonable use of graphene oxide (GO) conductive network structure can enhance the charge storage and transfer of electrode materials. In this paper, the deposition of ZIF-8 on the surface of graphene oxide (GO) was induced by Cokendall effect and selenization, and the unique matching method of Co2+ and ZIF-8 was used to obtain CoSe2@ZnSe/rGO electrode materials with reduced graphene oxide (rGO) as the growth substrate. The capacity of a three-electrode test with a current density of 1.0 A g−1 is as high as 2075.43 F g−1, and the capacity retention rate is 83.09 % after the circulation of 10,000 times. The assembled asymmetric supercapacitor GCZS-2//AC has a high power density of 1279.95 W kg−1 at an energy density of 85.33 Wh kg. The improvement of electrochemical properties benefits from the unique structure structure of the unique hollow nano box skeleton. In addition, DFT theoretical calculations show that CoSe2@ZnSe grown on rGO has stronger charge mobility and conductivity. This work provides a strategy for fabricating electrode materials with unique structures using rGO as a growth template.

Fabrication of a supporting kapok‑carbon/rGO electrode via self-assembly with enhanced capacitance

To address the limitations associated with biomass mass transfer and improve the capacitance of graphene oxide (GO), a supporting Kapok Fiber carbon/reduced GO (CKF/rGO) electrode was constructed via an effective combination of CKF and GO. The carbon electrode (CKF-800/rGO-1:1) fabricated by mixing GO with CKF-800 in a 1:1 ratio showed a specific capacitance of 721.6 mF·cm−2 at a current density of 0.5 mA·cm−2. Moreover, the capacitance retention rate of this film was 95.71 % after 5000 cycles at a current density of 10 mA·cm−2. The use of GO as a stable support system, combined with the kapok carbon's large surface area and a unique tubular transmission channel for carbon electrodes, contributed to this result. Furthermore, the combination prevents agglomeration and restacking between graphene layers, ensuring effective electron and ion transport and providing a CKF/rGO composite carbon-supported electrode with excellent electrochemical properties. Therefore, CKF-800/rGO-1:1 represents a promising material for use as a supporting biomass-based carbon electrode.

Electrochemical investigation of phosphorous and boron heteroatoms incorporated reduced graphene oxide electrode material for supercapacitor applications

Graphene-based nanomaterials are becoming common components for consumer products due to their outstanding charge carrier ability, high surface area, high thermal stability, and great potential for environmental decontamination. Nowadays, heteroatoms added carbon allotropes are providing better electrochemical performances in the field of supercapacitors as an electrode material. In this present work, boron and phosphorus heteroatoms were introduced in the network of reduced graphene oxide to increase the capacitance of the supercapacitor. The B and P incorporated rGO (PB-rGO) electrode material was prepared by the hydrothermal method. The properties of the electrode material were analyzed using structural, morphological, and elemental analysis. The prepared electrode material was used as a working electrode material in supercapacitors. In 1 M H2SO4 aqueous electrolyte medium, a maximum specific capacitance of 436 F g−1 was found for PB-rGO in a three-electrode configuration. In a symmetric configuration, a power density of 394 W kg−1 and an energy density of 12.48 Wh kg−1 were observed for the PB-rGO electrode. The cyclic stability analysis showed 97.6 % retention after 10,000 cycles at the current density of 3 A g−1.

Biomimetic Mineralization Synthesis of Flower-Like Cobalt Selenide/Reduced Graphene Oxide for Improved Electrochemical Deionization.

Rationally and precisely tuning the composition and structure of materials is a viable strategy to improve electrochemical deionization (EDI) performances, which yet faces enormous challenges. Herein, an eco-friendly biomimetic mineralization synthetic strategy is developed to synthesize the flower-like cobalt selenide/reduced graphene oxide (Bio-CoSe2/rGO) composites and used as advanced sodium ion adsorption electrodes. Benefiting from the slow and controllable reaction kinetics provided by the biomimetic mineralization process, the flower-like CoSe2 is uniformly constructed in the rGO, which is endowed with robust architecture, substantial adsorption sites and rapid charge/ion transport. The Bio-CoSe2/rGO electrode yields the maximum salt adsorption capacity and salt adsorption rate of 56.3mg g-1 and 5.6mg g-1 min-1 respectively, and 92.5% capacity retention after 60 cycles. These results overmatch the pristine CoSe2 and irregular granular CoSe2/rGO synthesized by a hydrothermal method, proving the structural superiority of the Bio-CoSe2/rGO composites. Furthermore, the in-depth adsorption kinetics study indicates the chemisorption nature of sodium ion adsorption. The structures of the Bio-CoSe2/rGO composites after long term EDI cycles are intensively studied to unveil the mechanism behind such superior EDI performances. This study offers one effective method for constructing advanced EDI electrodes, and enriches the application of the biomimetic mineralization synthetic strategy.

Capacitive immunosensing at gold nanoparticle-decorated reduced graphene oxide electrodes fabricated by one-step laser nanostructuration

Nanostructured electrochemical biosensors have ushered in a new era of diagnostic precision, offering enhanced sensitivity and specificity for clinical biomarker detection. Among them, capacitive biosensing enables ultrasensitive label-free detection of multiple molecular targets. However, the complexity and cost associated with conventional fabrication methods of nanostructured platforms hinder the widespread adoption of these devices. This study introduces a capacitive biosensor that leverages laser-engraved reduced graphene oxide (rGO) electrodes decorated with gold nanoparticles (AuNPs). The fabrication involves laser-scribed GO-Au3+ films, yielding rGO-AuNP electrodes, seamlessly transferred onto a PET substrate via a press-stamping methodology. These electrodes have a remarkable affinity for biomolecular recognition after being functionalized with specific bioreceptors. For example, initial studies with human IgG antibodies confirm the detection capabilities of the biosensor using electrochemical capacitance spectroscopy. Furthermore, the biosensor can quantify CA-19-9 glycoprotein, a clinical cancer biomarker. The biosensor exhibits a dynamic range from 0 to 300 U mL−1, with a limit of detection of 8.9 U mL−1. Rigorous testing with known concentrations of a pretreated CA-19-9 antigen from human fluids confirmed their accuracy and reliability in detecting the glycoprotein. This study signifies notable progress in capacitive biosensing for clinical biomarkers, potentially leading to more accessible and cost-effective point-of-care solutions.

Investigation of Hybrid Electrodes of Polyaniline and Reduced Graphene Oxide with Bio-Waste-Derived Activated Carbon for Supercapacitor Applications.

Graphene-based materials have been widely studied in the field of supercapacitors. However, their electrochemical properties and applications are still restricted by the susceptibility of graphene-based materials to curling and agglomeration during production. This study introduces a facile method for synthesizing reduced graphene oxide (rGO) nanosheets and activated carbon based on olive stones (OS) with polyaniline (PAni) surface decoration for the development of supercapacitors. Several advanced techniques were used to examine the structural properties of the samples. The obtained PAni@OS-rGO (1:1) electrode exhibits a high electrochemical capacity of 582.6 F·g-1 at a current density of 0.1 A·g-1, and an energy density of 26.82 Wh·kg-1; thus, it demonstrates potential for efficacious energy storage. In addition, this electrode material exhibits remarkable cycling stability, retaining over 90.07% capacitance loss after 3000 cycles, indicating a promising long cycle life. Overall, this research highlights the potential of biomass-derived OS in the presence of PAni and rGO to advance the development of high-performance supercapacitors.

Harnessing laser technology to create stable metal halide perovskite-rGO conjugates as promising electrodes for Zn-ion capacitors.

We report that the direct conjugation of metal halide perovskite nanocrystals on rGO sheets can provide high performance and stable electrodes for Zn-ion capacitors. It is the first time that metal halide nanocrystals have been used to enhance the energy storage of 2D materials in capacitors by introducing an additional pseudocapacitance mechanism. In particular, we present a simple, rapid and room temperature laser-induced method to anchor CsPbBr3 nanocrystals on rGO sheets without affecting the initial morphology and crystal structure of the two components. The flexible and high surface area of the rGO sheets enables the conjugation of individual metal halide perovskite nanocrystals, giving rise to new synergetic functionalities. As a result, the specific capacitance of the perovskite-rGO conjugated electrodes can be enhanced by 178- and 152-times compared to those of the plain rGO and perovskite electrodes respectively.

Graphene-based microelectrodes with bidirectional functionality for next-generation retinal electronic interfaces.

Neuroelectronic prostheses are being developed for restoring vision at the retinal level in patients who have lost their sight due to photoreceptor loss. The core component of these devices is the electrode array, which enables interfacing with retinal neurons. Generating the perception of meaningful images requires high-density microelectrode arrays (MEAs) capable of precisely activating targeted retinal neurons. Achieving this precision necessitates the downscaling of electrodes to micrometer dimensions. However, miniaturization increases electrode impedance, which poses challenges by limiting the amount of current that can be delivered, thereby impairing the electrode's capability for effective neural modulation. Additionally, it elevates noise levels, reducing the signal quality of the recorded neural activity. This report focuses on evaluating reduced graphene oxide (rGO) based devices for interfacing with the retina, showcasing their potential in vision restoration. Our findings reveal low impedance and high charge injection limit for microscale rGO electrodes, confirming their suitability for developing next-generation high-density retinal devices. We successfully demonstrated bidirectional interfacing with cell cultures and explanted retinal tissue, enabling the identification and modulation of multiple cells' activity. Additionally, calcium imaging allowed real-time monitoring of retinal cell dynamics, demonstrating a significant reduction in activated areas with small-sized electrodes. Overall, this study lays the groundwork for developing advanced rGO-based MEAs for high-acuity visual prostheses.