Characterization of phosphate modified red mud-based composite materials and study on heavy metal adsorption

In this paper, Bayer red mud (RM) and lotus leaf powder (LL) were used as the main materials, and KH2PO4 was added to modify the material. Under the condition of high-temperature carbonization, RMLL was prepared and phosphate modified red mud matrix composite (PRMLL) was prepared based on KH2PO4 modification, which can effectively remove Pb2+ from water. The optimum preparation and application conditions were determined through orthogonal experiment: dosage 0.1g, ratio 1:1, and temperature 600 °C. The effects of pH, dosage, and initial concentration on the adsorption of Pb2+ were studied. The pseudo-first-order, pseudo-second-order, and Elovich kinetic models were fitted to the experimental data. It was found that RMLL and PRMLL were more consistent with the pseudo-second-order kinetic model and chemisorption. Langmuir, Freundlich, Timkin, and Dubinin-Radushkevich isothermal adsorption models were used to fit the experimental data. It was found that RMLL and PRMLL were more consistent with Langmuir model. In addition, the maximum adsorption capacity of RMLL and PRMLL was 188.1 mg/g and 213.4 mg/g, respectively. It is larger than the adsorption capacity of their monomers. Therefore, the use of RMLL and PRMLL as the removal of Pb2+ from water is a potential application material.

Effect of repeating hydrothermal growth processes and rapid thermal annealing on CuO thin film properties

This paper presents an investigation into the influence of repeating cycles of hydrothermal growth processes and rapid thermal annealing (HT+RTA) on the properties of CuO thin films. An innovative hydrothermal method ensures homogeneous single-phase films initially. However, their electrical instability and susceptibility to cracking under the influence of temperature have posed a challenge to their utilization in electronic devices. To address this limitation, the HT+RTA procedure has been developed, which effectively eliminated the issue. Comprehensive surface analysis confirmed the procedure's ability to yield continuous films in which the content of organic compounds responsible for the formation of cracks significantly decreases. Structural analysis underscored the achieved improvements in the crystalline quality of the films. The implementation of the HT+RTA procedure significantly enhances the potential of CuO films for electronic applications. Key findings from Kelvin probe force microscopy analysis demonstrate the possibility of modulating the work function of the material. In addition, scanning capacitance microscopy measurements provided information on the changes in the local carrier concentration with each repetition. These studies indicate the increased usefulness of CuO thin films obtained from the HT+RTA procedure, which expands the possibilities of their applications in electronic devices.

Fabrication of binary metal-organic frameworks of Ni-Mn@ZIFs(Cox·Zn1-xO) decorated on CF/CuO nanowire for high-performance electrochemical pseudocapacitors

Herein, metal-organic frameworks (MOFs) derived nanoflower-like based binary transition metal (Ni-Mn) are successfully fabricated by a simple synthesis method. The fabricated nanoflower-like structure displays a unique nanoflower-like architecture and internal porous channels constructed by MOF coated on CuO/CF/ZIFs (Cox·Zn1-xO) substrate, which is beneficial for the penetration of electrolyte and electron/ion transportation. The as-prepared CF/CuO/ZIFs (Cox·Zn1-xO)@BMOF(Ni-Mn) electrode materials present significant synergy among transition metal ions, contributing to enhanced electrochemical performances. The as-prepared CF/CuO/ZIFs (Cox·Zn1-xO)@BMOF(Ni-Mn) hybrid nanoflower-like display a high specific capacity of 1249.99 C g-1 at 1 A g-1 and the specific capacitance retention is about 91.74% after 5000 cycles. In addition, the as-assembled CF/CuO/ZIFs (Cox·Zn1-xO)@BMOF(Ni-Mn)//AC asymmetric supercapacitor (ASC) device exhibited a maximum energy density of 21.77 Wh·kg-1 at a power density of 799 W kg-1, and the capacity retention rate after 5000 charge and discharge cycles was 88.52%.

Elucidating the Role of Copper-Induced Mixed Phases on the Electrochemical Performance of Mn-Based Thin-Film Electrodes

Manganese oxide is a fascinating material for use as a thin-film electrode in supercapacitors. Herein, the consequences of copper incorporation on spray pyrolyzed manganese oxide thin films and their electrochemical performance were investigated. The Cu-incorporated manganese oxide thin films were deposited by spray pyrolysis, and their structural and electrochemical properties were thoroughly evaluated. The formation of the spinel Mn3O4 phase with effective Cu incorporation was confirmed by X-ray diffraction investigation. Through Raman studies, it was noticed that mixed phases of manganese oxide tend to form after Cu incorporation, and this result was also reflected in X-ray photoelectron spectroscopic studies. The surface morphology and roughness were also altered by the addition of copper. However, electrochemical measurements implied a reduction in the specific capacitance upon copper inclusion. The cyclic voltammetry test indicated a specific capacitance of 132 F/g for Mn3O4 electrodes, but a substantial drop for copper-incorporated samples due to the mixed manganese phase. The decremental tendency was further supported by galvanostatic charge-discharge studies and electrochemical impedance spectroscopic measurements. These results provide valuable insights into the effects of copper addition in manganese oxide thin-film-based electrodes for energy storage applications.

Two-Dimensional Copper/Nickel Metal-Organic Framework Nanosheets for Non-Enzymatic Electrochemical Glucose Detection

Metal-organic frameworks (MOFs) have broad potential applications in electrochemical glucose detection. Herein, a green ultrasonic synthesis process is presented for preparing two-dimensional (2D) copper-nickel metal-organic framework nanosheets (CuNi-MOFNs) for glucose detection. The synthesized CuNi-MOFNs were characterized using scanning electron microscopy (SEM), scanning transmission electron microscope (STEM), X-ray diffractometer (XRD), and X-ray photoelectron spectrometer (XPS). The CuNi-MOFN nanocomposites were used to cover the glassy carbon electrode (GCE) and the CuNi-MOFNs-modified electrode was studied in alkaline media. Cyclic voltammetry (CV) and amperometric i-t curves indicated that the CuNi-MOFNs-modified electrode revealed great electrochemical performances towards glucose oxidation. Due to the ease of access to active metal sites in large specific surface of nanosheets, the CuNi-MOFNs-modified electrode can effectively improve the electronic transfer rate and enhance electrocatalytic activity of the CuNi-MOFNs-modified electrode. The CuNi-MOFNs-modified electrode showed electrochemical performances for glucose detection with a linear range from 0.01 mM to 4 mM, sensitivity of 702 μAmM-1cm-2, and detection limit of 3.33 μΜ (S/N = 3). The CuNi-MOFNs-modified electrode exhibited excellent anti-interference ability and high selectivity in glucose measurements. Hence, the CuNi-MOFNs-modified electrode has good, promising prospects in non-enzymatic electrochemical glucose detection.

Three-dimensional ternary NixCuyZnz(CO3)(OH)2 electrodes for supercapacitors: electrochemical properties and applications

Transition metal-based binary and ternary compound arrays were directly grown on a porous Ni foam substrate using a facile one-step hydrothermal method. Transition metals are considered ideal electrode materials for faradaic capacitors because they exhibit a wide range of oxidation states enabling effective redox charge transfer. Furthermore, compounds in which two or more transition metals react can help increase the number of active sites for charge-discharge reactions and provide more valence changes for improved charge transfer. In this work, we fabricated ternary electrodes with Ni, Cu, and Zn ions, exhibiting a larger surface area and higher entropy than those made with binary compounds. The Ni_xCu_yZn_z-based ternary electrode had a shorter diffusion path for the electrolyte ions owing to its larger surface area. Ternary compounds can increase the entropy of the electrode because of the reaction between atoms of different sizes, bringing about a synergistic effect for high characteristic electrochemical values. The optimized Ni_xCu_yZn_z(CO₃)(OH)₂ compound showed a maximum specific capacity of 344 mA h g^-1 at a current density of 3 A g^-1, which was remarkably higher than that of the binary electrode, and a cycling stability of 84.9% after 5000 cycles. An asymmetric supercapacitor produced with this compound as the positive electrode and graphene as the negative electrode exhibited a high energy density of 36.2 W h kg^-1 at a power density of 103.1 W kg^-1 and a current density of 2 A g^-1. The asymmetric supercapacitor fabricated using the Ni_xCu_yZn_z(CO₃)(OH)₂ compound as the positive electrode exhibited excellent electrical properties when used in an illuminated LED device.

One-pot synthesis of a highly disperse core–shell CuO–alginate nanocomposite and the investigation of its antibacterial and catalytic properties

Sodium alginate extracted from native algae of the Persian Gulf for use in the synthesis of a highly disperse CuO–alginate nanocomposite, which is used as an antibacterial agent as well as a catalyst in the synthesis of amides.

Construction of a Cu-Based Metal-Organic Framework by Employing a Mixed-Ligand Strategy and Its Facile Conversion into Nanofibrous CuO for Electrochemical Energy Storage Applications

Recently, metal-organic frameworks (MOFs) have been widely employed as a sacrificial template for the construction of nanostructured materials for a range of applications including energy storage. Herein, we report a facile mixed-ligand strategy for the synthesis of a Cu-MOF, [Cu₃(Azopy)₃(BTTC)₃(H₂O)₃·2H₂O]_n (where BTTC = 1,2,4,5-benzenetetracarboxylic acid and Azopy = 4,4'-azopyridine), via a slow-diffusion method at room temperature. X-ray analysis authenticates the two-dimensional (2D)-layered framework of Cu-MOF. Topologically, this 2D-layered structure is assigned as a 4-connected unimodal net with sql topology. Further, nanostructured CuO is obtained via a simple precipitation method by employing Cu-MOF as a precursor. After analysis of their physicochemical properties through various techniques, both materials are used as surface modifiers of glassy carbon electrodes for a comparative electrochemical study. The results reveal a superior charge storage performance of CuO (244.2 F g^-1 at a current density of 0.8 A g^-1) with a high rate capability compared to Cu-MOF. This observation paves the pathway for the strategic design of high-performing supercapacitor electrode materials.

Anchoring γ-MnO2 within β-NiCo(OH)2 as an Interfacial Electrode Material for Boosting Power Density in an Asymmetric Supercapacitor Device and for Oxygen Evolution Catalysis

The great challenge is to improve the high-competence electrochemical supercapacitor (ES) and oxygen evolution reaction (OER) electrocatalyst with earth-abundant transition metals rather than using limited noble metals. Herein, we developed a facile strategy to introduce two different phases such as α-MnO₂ or γ-MnO₂ on porous hexagonal bimetallic β-NiCo(OH)₂-layered double hydroxide (LDH) nanosheets for an enhanced bifunctionality and to ease out interfacial redox reaction kinetics. Due to the rational intend of LDH morphology and well-retained starlike γ-MnO₂ nanostructures, the bifunctional LDHs exhibit commendable activities toward ESs and in the OER study. Importantly, the γ-MnO₂ phase loaded at β-NiCo(OH)₂ LDHs shows superior ESs or electrocatalytic OER performance in comparison with the α-MnO₂ phase on LDHs. Besides, the assembled fabricated asymmetric supercapacitor (FASC) device possesses convincing energy (24.43 W h/kg) and power densities (5312 W/kg) and enabled us to glow a 1.4 V light-emitting diode for 45 s. Accordingly, three-/two-electrode systems or the solid-state FASC device has exhibited high efficiency in ESs. Also, the optimized γ-MnO₂ phase on β-NiCo(OH)₂ LDHs with the detailed mass ratio of Ni and Co has displayed the OER performance comparable to commercial RuO₂. The electrochemical studies and structural classifications offer in-depth analysis on the electrochemical behaviors, especially the stability in both ES and OER studies, signifying a promising aspirant in the alternative energy field.

Electrosynthesized CuOx/graphene by a four-electrode electrolysis system for the oxygen reduction reaction to hydrogen peroxide

Here a facile four-electrode electrolysis system is firstly applied to synthesize a CuOx/graphene hybrid. The exfoliation of graphite via high electrolytic voltage and dissolution of copper via low electrolytic voltage are achieved simultaneously. CuOx/G with the highest content of CuOx shows superior electrocatalytic activity for oxygen reduction to hydrogen peroxide.

Synthesis of cetyl trimethyl ammonium bromide (CTAB) capped copper oxide nanocubes for the remediation of organic pollutants using photocatalysis and catalysis

The aim of this report is to synthesize copper oxide nanocubes (CuO NCs) at room temperature, using sodium borohydride as a reducing agent, and Cetyl Trimethyl Ammonium Bromide (CTAB) as a stabilizing agent. The crystallinity and morphology of the synthesized CuO NCs are investigated via X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscope (TEM). The optical properties were analyzed by means of UV-visible absorbance and Raman spectroscopy. The existence of specific functional groups and structural stability were established via FTIR spectroscopy and thermogravimetric analysis (TGA). Furthermore, the catalytic efficiency of the as-prepared CuO NCs was tested using catalytic and photocatalytic studies of para-nitrophenol (p-NP) reduction and methylene blue (MB) degradation, respectively. The catalytic results demonstrated the nanocubes' excellent catalytic and photocatalytic responses with respect to the abatement of p-NP and MB within 50 s and 240 min, with kinetic rate constants of 3.9 × 10^-2 s^-1 and 6.47 × 10^-3 min^-1, respectively.

NiP/CuO composites: Electroless plating synthesis, antibiotic photodegradation and antibacterial properties

This work reports a simple method to prepare nickel-phosphorus (Ni-P) alloy modified CuO (Ni-P/CuO) composite, which shows excellent performance in terms of photodegradation antibiotics, particularly regarding the antibacterial properties. The Ni-P/CuO composites were prepared via two steps. The first step was to produce CuO by the hydrothermal method and the second step was to grow Ni-P in-situ on the surface of CuO through electroless plating. After loading of Ni-P, the photocatalytic activity of CuO for the decomposition of antibiotics is significantly increased under visible light irradiation. The photocatalytic activity of Ni-P/CuO with 4 wt% Ni-P loading is 25 times higher than that of CuO. Compared with CuO, the antibacterial activity of Ni-P/CuO with 4 wt% Ni-P loading against Escherichia coli is strongly increased. Based on the photoluminescence and photocurrent measurements of CuO and Ni-P/CuO, Ni-P cocatalyst improves the separation and transfer of the photogenerated charge in CuO, and enhances the photocatalytic activity of antibacterial performance. This work reveals that using Ni-P as the cocatalyst can strengthen the photocatalytic performance of CuO, which has great application potential in water purification and antibacterial treatments.

Soft-template-assisted synthesis: a promising approach for the fabrication of transition metal oxides

The past few decades have witnessed transition metal oxides (TMOs) as promising candidates for a plethora of applications in numerous fields. The exceptional properties retained by these materials have rendered them of paramount emphasis as functional materials. Thus, the controlled and scalable synthesis of transition metal oxides with desired properties has received enormous attention. Out of different top-down and bottom-up approaches, template-assisted synthesis predominates as an adept approach for the facile synthesis of transition metal oxides, owing to its phenomenal ability for morphological and physicochemical tuning. This review presents a comprehensive examination of the recent advances in the soft-template-assisted synthesis of TMOs, focusing on the morphological and physicochemical tuning aided by different soft-templates. The promising applications of TMOs are explained in detail, emphasizing those with excellent performances.

Biosynthesis of Flower-Shaped CuO Nanostructures and Their Photocatalytic and Antibacterial Activities

Copper oxide nanoflowers (CuO-NFs) have been synthesized through a novel green route using Tulsi leaves-extracted eugenol (4-allyl-2-methoxyphenol) as reducing agent. Characterizations results reveal the growth of crystalline single-phase CuO-NFs with monoclinic structure. The prepared CuO-NFs can effectively degrade methylene blue with 90% efficiency. They also show strong barrier against E. coli (27 ± 2 mm) at the concentration of 100 µg mL-1, while at the concentration of 25 µg mL-1 weak barrier has been found against all examined bacterial organisms. The results provide important evidence that CuO-NFs have sustainable performance in methylene blue degradation as well as bacterial organisms.

Superior supercapacitive performance of grass-like CuO thin films deposited by liquid phase deposition

First report on deposition and supercapacitive performance of grass-like CuO thin films by liquid phase deposition on flat and mesh stainless steel (SS). The maximum specific capacitances on flat and mesh SS are 552 and 849 F g⁻¹.

Synthesis of Three-Dimensional Hierarchical Urchinlike Tungsten Trioxide Microspheres for High-Performance Supercapacitor Electrode

In this work, hierarchical three-dimensional (3D) urchinlike WO3 microspheres with a self-assembled nanorod core, and a connected and quasiconnected nanothorn network shell were synthesized with the hydrothermal method. For the surface or near-surface regions of pseudocapacitive materials that are involved in the Faradaic reaction, the urchinlike WO3 special microstructure provided more effective charge-storage area, exhibiting a high specific capacitance of 488.78 F g−1, low average equivalent-series resistance of 0.966 Ω cm−2, and excellent cycling stability (84.75% of its initial value after the 10,000 cycles). This performance indicates the urchinlike WO3 microspheres are promising electrode materials for high-performance supercapacitors.

Ultrasound-assisted biosynthesis of CuO-NPs using brown alga Cystoseira trinodis: Characterization, photocatalytic AOP, DPPH scavenging and antibacterial investigations

This contribution reports the biosynthesis of CuO NPs via ultrasound method using the Cystoseira trinodis extracts as an eco friendly and time saving process. The characterization of cupric oxide NPs was performed using XRD, FE-SEM, EDX, TEM, AFM, photoluminescence, UV-Vis, Raman and FT-IR spectroscopy investigations. SEM images show the spherical structure with the average crystallite size 6nm to 7.8nm of CuO. XRD analysis approved the formation of pure monoclinic crystallite structures of CuO NPs. These observations were confirmed by TEM analysis. The photocatalytic studies reveal the activity of the prepared CuO NPs as an efficient catalyst for the degradation of methylene blue (MB) in the presence of UV and Sunlight. CuO NPs under varying experimental parameters such as dye concentration, catalytic load, pH. The results of the in vitro biological screening effect of CuO NPs (zone of growth inhibition and minimal inhibitory concentrations) in comparison with cephalexin (as a standard compound) using the disc diffusion method was demonstrated the significant bactericidal activity against some bacteria strain including Escherichia coli (E. coli), Enterococcus faecalis (E. faecalis), Salmonella typhimurium (S. typhimurium), Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), and Streptococcus faecalis (S. faecalis). Furthermore, the Nps found to inhibit the activity of 1,1-Diphenyl-2-picrylhydrazyl (DPPH) free radicals effectively. This study introduces a facile, green and low coast method for the synthesis of monoclinic CuO NPs with catalytic, antioxidant and antibacterial properties.

A high-performance supercapacitor electrode based on tremella-like NiC2O4@NiO core/shell hierarchical nanostructures on nickel foam

Tremella-like nickel oxalate@nickel oxide (NiC₂O₄@NiO) core/shell hierarchical nanostructures have been successfully synthesized on nickel foam, using Ni foam as a current collector, a Ni source and a three-dimensional (3D) substrate, through a facile hydrothermal method followed by an electrochemical activation process. The prepared samples can be directly used as binder-free electrodes for supercapacitors. The tremella-like morphology, together with the NiC₂O₄ nanoblocks on 3D Ni foam, significantly increases the amount of active sites for redox reactions and the conductivity of the electrode material, shortens the diffusion pathway for ions, facilitates the effective penetration of the electrolyte, and lowers the intrinsic equivalent series resistance, demonstrating good potential for energy storage application. This material has a high specific capacitance of 2287.09 F g^-1 at 1 A g^-1, a good cycling stability (remaining 95% after 10 000 cycles) and a good rate capability (83.2% retention upon increasing the current density by 10 times).

Sonochemical synthesis of Zn-promoted porous MgO-supported lamellar Cu catalysts for selective hydrogenation of dimethyl oxalate to ethanol and their long-term stability

Zn-doped lamellar Cu nanocrystals supported on MgO NPs catalyst was developed and employed as novel and robust catalyst for the production of Ethanol from the environmentally benign hydrogenation reaction of dimethyl oxalate.

Low-temperature solution synthesis of CuO/Cu2O nanostructures for enhanced photocatalytic activity with added H2O2: synergistic effect and mechanism insight

The morphological transformation was observed after photodegradation and the as-grown samples exhibited relatively good durability as photocatalysts.

Construction of leaf-like CuO–Cu2O nanocomposites on copper foam for high-performance supercapacitors

Leaf-like CuO–Cu₂O nanosheets have been prepared on copper foam by a one-step simple anodization method, which can be used as an advanced binder-free supercapacitor electrode.

Versatile Metal Nanowiring Platform for Large-Scale Nano- and Opto-Electronic Devices

A versatile metal nanowiring platform enables the fabrication of Ag nanowires (AgNW) at a desired position and orientation in an individually controlled manner. A printed, flexible AgNW has a diameter of 695 nm, a resistivity of 5.7 μΩ cm, and good thermal stability in air. Based on an Ag nanowiring platform, an all-NW transistors array, as well as various optoelectronic applications, are successfully demonstrated.

Indirect Phase Transformation of CuO to Cu2O on a Nanowire Surface

The reduction of CuO nanowires (NWs) to Cu2O NWs undergoes an indirect phase transformation on the surface: from single crystalline CuO, to a disordered Cu2-δO phase, and then to crystalline Cu2O. A 9-12 nm disordered Cu2-δO is formed on the NW surface by exposing CuO NWs to CO at 1 Torr, 300 °C for 30 min. After 60 min, this layer decreases to 2-3 nm and is eliminated after 180 min. Energy dispersive X-ray spectroscopy using a scanning tunneling electron microscope and across a single NW reveals the disordered layer to be O-rich with respect to Cu2O with a maximum at. % Cu:O = 1.8. X-ray photoelectron spectroscopy shows adsorbed CO on the surface as evidence of the reduction reaction. Micro-Raman spectroscopy tracks the transformation in NWs as a function of reduction time. A CO enabled surface reduction reaction coupled to diffusion-limited transport of "nonlattice" O to the surface is proposed as a mechanism for Cu2-δO formation. The initial buildup of out-diffusing O to the surface appears to aid the formation of the disordered surface layer. The transformation follows Ostwald-Lussac's law which predicts formation of unstable phases over stable phases, when phase transformation rates are limited by kinetic or diffusional processes. The study provides a generalized approach for facile growth of few nanometer transient layers on multivalent, metal oxide NW surfaces.

Solvothermal synthesis of CuO–MgO nanocomposite particles and their catalytic applications

CuO–MgO nanocomposites were prepared by a solvothermal procedure.

Enhanced photoelectrochemical performance of novel p-type MoBiCuSe4 thin films deposited by a simple surfactant-mediated solution route

Nanostructured MoBiCuSe₄ thin films with different morphologies deposited using different surfactants, such as PEG, SDS and TOPO, through a surfactant-mediated modified chemical route for PEC application.

Bath temperature controlled phase stability of hierarchical nanoflakes CoS2 thin films for supercapacitor application

In the present study, CoS₂ thin-film electrodes are synthesized at different bath temperatures using a simple chemical bath deposition (CBD) method.

Comparative studies on MWCNTs, Fe2O3 and Fe2O3/MWCNTs thin films towards supercapacitor application

Fe₂O₃/MWCNTs hybrid thin film exhibits superior electrochemical supercapacitor behaviour in terms of specific capacitance, energy density and power density than the individual Fe₂O₃ and MWCNTs thin films.

3D Hierarchical Bi2S 3 Nanostructures by Polyvinylpyrrolidone (PVP) and Chloride Ion-Assisted Synthesis and Their Photodetecting Properties

A solvothermal method has been employed to synthesize bismuth sulfide (Bi2S3) with three-dimensional (3D) hierarchical architectures. The influences of different types of surfactants and Cl(-) species on the size and morphology were investigated. A possible formation mechanism was also proposed on the basis of time-dependent experiments. The photoresponse properties show that the conductivity of Bi2S3 micro-flowers is significantly enhanced and the photocurrent is approximately two orders of magnitude larger than the dark current. The response and decay times are estimated to be 142 and 151 ms, respectively. It is expected that hierarchical architectures Bi2S3 may provide a new pathway to develop advanced nanomaterial for high-speed and high-sensitivity photoelectrical switches and photodetecting devices.

On-chip supercapacitors with ultrahigh volumetric performance based on electrochemically co-deposited CuO/polypyrrole nanosheet arrays

We introduce a new method for fabricating unique on-chip supercapacitors based on CuO/polypyrrole core/shell nanosheet arrays by means of direct electrochemical co-deposition on interdigital-like electrodes. The prepared all-solid-state device demonstrates exceptionally high specific capacitance of 1275.5 F cm(-3) (∼40 times larger than that of CuO-only supercapacitors) and high-energy-density of 28.35 mWh cm(-3), which are both significantly greater than other solid-state supercapacitors. More importantly, the device maintains approximately 100% capacity retention at 2.5 A cm(-3) after 3000 cycles. The in situ co-deposition of CuO/polypyrrole nanosheets on interdigital substrate enables effective charge transport, electrode fabrication integrity, and device integration. Because of their high energy, power density, and stable cycling stability, these newly developed on-chip supercapacitors permit fast, reliable applications in portable and miniaturized electronic devices.