MnO2/ZnCo2O4 with binder-free arrays on nickel foam loaded with graphene as a high performance electrode for advanced asymmetric supercapacitors

ZnCo₂O₄ nanosheets were successfully arrayed on a Ni foam surface with graphene using a hydrothermal method followed by annealing treatment; then MnO₂ nanoparticles were electrodeposited on the ZnCo₂O₄ nanosheets to obtain a synthesized composite binder-free electrode named MnO₂/ZnCo₂O₄/graphene/Ni foam (denoted as MnO₂/ZnCo₂O₄/G/NF). After testing the binder-free composite electrode of MnO₂/ZnCo₂O₄/G/NF via cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy testing, we found that it exhibited ultrahigh electrochemical properties, with a high specific areal capacitance of 3405.21 F g⁻¹ under a current density of 2 A g⁻¹, and wonderful cycling stability, with 91.2% retention after 5000 cycles. Moreover, an asymmetric supercapacitor (ASC) based on MnO₂/ZnCo₂O₄/G/NF//G/NF was successfully designed. When tested, the as-designed ASC can achieve a maximum energy density of 46.85 W h kg⁻¹ at a power density of 166.67 W kg⁻¹. Finally, the ASC we assembled can power a commercial red LED lamp successfully for more than 5 min, which proves its practicability. All these impressive performances indicate that the MnO₂/ZnCo₂O₄/graphene composite material is an outstanding electrode material for electrochemical capacitors.

Schematic illustration of formation process of MnO₂/ZnCo₂O₄/G/NF composite electrode.     

Free-standing graphene/bismuth vanadate monolith composite as a binder-free electrode for symmetrical supercapacitors

Preparation of new types of electrode material is of great importance to supercapacitors. Herein, a graphene/bismuth vanadate (GR/BiVO₄) free-standing monolith composite has been prepared via a hydrothermal process. Flexible GR sheets act as a skeleton in the GR/BiVO₄ monolith composites. When used as a binder-free electrode in a three-electrode system, the GR/BiVO₄ composite electrode can provide an impressive specific capacitance of 479 F g⁻¹ in a potential window of −1.1 to 0.7 V vs. SCE at a current density of 5 A g⁻¹. A symmetrical supercapacitor cell which can be reversibly charged–discharged at a cell voltage of 1.6 V has been assembled based on this GR/BiVO₄ monolith composite. The symmetrical capacitor can deliver an energy density of 45.69 W h kg⁻¹ at a power density of 800 W kg⁻¹. Moreover, it ensures rapid energy delivery of 10.75 W h kg⁻¹ with a power density of 40 kW kg⁻¹.

A symmetrical supercapacitor with a high energy density has been assembled based on a free-standing GR/BiVO₄ monolith composite.     

High mass loading flower-like MnO2 on NiCo2O4 deposited graphene/nickel foam as high-performance electrodes for asymmetric supercapacitors

The implementation of high mass loading MnO₂ on electrochemical electrodes of supercapacitors is currently challenging due to the poor electrical conductivity and elongated electron/ion transport distance. In this paper, a NiCo₂O₄/MnO₂ heterostructure was built on the surface of three-dimensional graphene/nickel foam (GNF) by a hydrothermal method. The petal structured NiCo₂O₄ loaded on graphene played a wonderful role as a supporting framework, which provided more space for the growth of high mass loading MnO₂ microflowers, thereby increasing the utilization rate of the active material MnO₂. The GNF@NiCo₂O₄/MnO₂ composite was used as a positive electrode and achieved a high areal capacitance of 1630.5 mF cm⁻² at 2 mA cm⁻² in the neutral Na₂SO₄ solution. The asymmetric supercapacitor assembled with the GNF@NiCo₂O₄/MnO₂ positive electrode and activated carbon negative electrode possessed a wide voltage window (2.1 V) and splendid energy density (45.9 Wh kg⁻¹), which was attributed to the satisfactory electroactive area, low resistance, quick mass diffusion and ion transport caused by high mass loading MnO₂.

A NiCo₂O₄/MnO₂ heterostructure with high mass loading MnO₂ microflowers was built on the surface of 3D graphene/nickel foam for the preparation of an asymmetric supercapacitor with splended energy density (45.9 Wh kg⁻¹).     

A high energy density asymmetric supercapacitor utilizing a nickel phosphate/graphene foam composite as the cathode and carbonized iron cations adsorbed onto polyaniline as the anode

This work presents the effect of different contents of graphene foam (GF) on the electrochemical capacitance of nickel phosphate Ni₃(PO₄)₂ nano-rods as an electrode material for hybrid electrochemical energy storage device applications. Pristine Ni₃(PO₄)₂ nano-rods and Ni₃(PO₄)₂/GF composites with different GF mass loadings of 30, 60, 90 and 120 mg were synthesised via a hydrothermal method. The electrochemical behavior of pristine Ni₃(PO₄)₂ and Ni₃(PO₄)₂/GF composites were analysed in a three-electrode cell configuration using 6 M KOH electrolyte. The Ni₃(PO₄)₂/90 mg GF composite sample exhibited the highest specific capacity of 48 mA h g⁻¹ at a current density of 0.5 A g⁻¹. The electrochemical behavior of the Ni₃(PO₄)₂/90 mg GF composite was further analysed in a two-electrode hybrid asymmetric device. A hybrid asymmetric device was fabricated with Ni₃(PO₄)₂/90 mg GF as the cathode and carbonized iron cations (Fe³⁺) adsorbed onto polyaniline (PANI) (C-FP) as the anode material (Ni₃(PO₄)₂/90 mg GF//C-FP) and tested in a wide potential window range of 0.0–1.6 V using 6 M KOH. This hybrid device achieved maximum energy and power densities of 49 W h kg⁻¹ and 499 W kg⁻¹, respectively, at 0.5 A g⁻¹ and had long-term cycling stability.

This work presents the effect of different contents of graphene foam (GF) on the electrochemical capacitance of nickel phosphate Ni₃(PO₄)₂ nano-rods as an electrode material for hybrid electrochemical energy storage device applications.     

Electrodeposited Pd/graphene/ZnO/nickel foam electrode for the hydrogen evolution reaction

Efficient electrocatalysts are crucial to water splitting for renewable energy generation. In this work, electrocatalytic hydrogen evolution from Pd nanoparticle-modified graphene nanosheets loaded on ZnO nanowires on nickel foam was studied in an alkaline electrolyte. The high electron mobility stems from the cylindrical ZnO nanowires and the rough surface on the graphene/ZnO nanowires increases the specific surface area and electrical conductivity. The catalytic activity arising from adsorption and desorption of intermediate hydrogen atoms by Pd nanoparticles improves the hydrogen evolution reaction efficiency. As a hydrogen evolution reaction (HER) catalyst, the Pd/graphene/ZnO/Ni foam (Pd/G/ZnO/NF) nanocomposite exhibits good stability and superior electrocatalytic activity. Linear sweep voltammetry (LSV) revealed an overpotential of −31 mV and Tafel slope of 46.5 mV dec⁻¹ in 1 M KOH. The economical, high-performance, and environmentally friendly materials have excellent prospects in hydrogen storage and hydrogen production.

Efficient electrocatalysts are crucial to water splitting for renewable energy generation.     

Correction: A high energy density asymmetric supercapacitor utilizing a nickel phosphate/graphene foam composite as the cathode and carbonized iron cations adsorbed onto polyaniline as the anode

Correction for ‘A high energy density asymmetric supercapacitor utilizing a nickel phosphate/graphene foam composite as the cathode and carbonized iron cations adsorbed onto polyaniline as the anode’ by A. A. Mirghni et al., RSC Adv., 2018, 8, 11608–11621.

Sekhar C. Ray was incorrectly spelled in the published article; the corrected version is shown above.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.     

Magnetite ultrafine particles/porous reduced graphene oxide in situ grown onto Ni foam as a binder-free electrode for supercapacitors

Here, we report a simple and green electrochemical route to fabricate a porous network of a Fe₃O₄ nanoparticle-porous reduced graphene oxide (p-rGO) nanocomposite supported on a nickel-foam substrate, which is directly used as a binder-free charge storage electrode. Through this method, pristine Fe₃O₄ NPs/Ni, p-rGO/Ni and Fe₃O₄ NPs@p-rGO/Ni electrodes are fabricated and compared. In the fabricated Fe₃O₄ NPs@p-rGO/Ni electrode, the porous rGO sheets served as a conductive network to facilitate the collection and transportation of electrons during the charge/discharge cycles, improving the conductivity of magnetite NPs and providing a larger specific surface area. As a result, the Fe₃O₄ NPs@p-rGO/Ni exhibited a specific capacitance of 1323 F g⁻¹ at 0.5 A g⁻¹ and 79% capacitance retention when the current density is increased 20 times, where the Fe₃O₄ NPs/Ni electrode showed low specific capacitance of 357 F g⁻¹ and 43% capacity retention. Furthermore, the composite electrode kept 95.1% and 86.7% of its initial capacitances at the current densities of 1 and 4 A g⁻¹, respectively, which were higher than those of a Fe₃O₄/NF electrode at similar loads (i.e. 80.4% and 65.9% capacitance retentions at 1 and 4 A g⁻¹, respectively). These beneficial effects proved the synergistic contribution between p-rGO and Fe₃O₄. Hence, such ultrafine magnetite particles grown onto a porous reduced GO network directly imprinted onto a Ni substrate could be a promising candidate for high performance energy storage aims.

Here, we report a simple and green electrochemical route to deposition of Fe₃O₄ nanoparticle-porous reduced graphene oxide (p-rGO) nanocomposite onto nickel foam substrate, which is directly used as a binder-free charge storage electrode.     

Performance enhancement of asymmetric supercapacitors with bud-like Cu-doped Mn3O4 hollow and porous structures on nickel foam as positive electrodes

Cu-doped Mn₃O₄ hollow nanostructures supported on Ni foams as high-performance electrode materials for supercapacitors were successfully synthesized through a facile hydrothermal method and subsequent calcination. The morphology, structure, and electrochemical performance of the as-prepared Mn₃O₄ nanostructures can be tuned just by varying the Cu doping content. Benefiting from the unique bud-like hollow structure, the 1.5 at% Cu-doped Mn₃O₄ sample has a high specific capacitance of 257.6 F g⁻¹ at 1 A g⁻¹ and remarkable stability (about 90.6% retention of its initial capacitance after 6000 electrochemical cycles). Besides, an asymmetric supercapacitor (ASC) cell based on the 1.5 at% Cu-doped Mn₃O₄ exhibits a high specific capacitance of 305.6 F g⁻¹ at 1 A g⁻¹ and an energy density of 108.6 W h kg⁻¹ at a power density of 799.9 W kg⁻¹. More importantly, the ASC shows good long-term stability with 86.9% capacity retention after charging/discharging for 6000 cycles at a high current density of 5 A g⁻¹.

The effect of Cu doping on the electrochemical performance of bud-like Mn₃O₄ nanostructures for supercapacitor application was comparatively investigated.     

Electrochemical properties of TiOx/rGO composite as an electrode for supercapacitors

Transition metal oxides are known as the active materials for capacitors. As a class of transition metal oxide, Magnéli phase TiO_x is particularly attractive because of its excellent conductivity. This work investigated the electrochemical characteristics of TiO_x and its composite with reduced graphene oxide (rGO). Two types of TiO_x, i.e. low and high reduction extent, were employed in this research. Electrochemical impedance spectroscopy revealed that TiO_x with lower reduction extent delivered higher electro-activity and charge transfer resistance at the same time. However, combining 10% of low-reduction state TiO_x and rGO using a simple mixing process delivered a high specific capacitance (98.8 F g⁻¹), which was higher than that of standalone rGO (49.5 F g⁻¹). A further improvement in the specific capacitance (102.6 F g⁻¹) was given by adding PEDOT:PSS conductive polymer. Results of this research gave a basic understanding in the electrochemical behavior of Magnéli phase TiO_x for the utilization of this material as supercapacitor in the future.

This work investigated the electrochemical characteristics of TiO_x and its composite with reduced graphene oxide.     

In situ self-assembly of Ni3S2/MnS/CuS/reduced graphene composite on nickel foam for high power supercapacitors

Transition metal sulfides (TMS), as promising electroactive materials for asymmetric supercapacitors, have been limited due to their relatively poor conductivity and cycle stability. Here ternary Ni₃S₂/MnS/CuS composites were assembled in situ on nickel foam (NF) using a hydrothermal method via electrostatic adsorption of Ni⁺, Mn²⁺ and Cu²⁺ ions on a reduced graphene (rGO) nanosheet template. The chemical structure was characterized by various analytic methods. Ni₃S₂/MnS/CuS has spherical morphology assembled from closely packed nanosheets, while Ni₃S₂/MnS/CuS@rGO has a three-dimensional porous spherical structure with much lower diameter because rGO nanosheets can play the role of a template to induce the growth of Ni₃S₂/MnS/CuS. At a current density of 1 A g⁻¹, the specific capacitance was obtained to be 1028 F g⁻¹ for Ni₃S₂/MnS/CuS, 628.6 F g⁻¹ for Ni₃S₂/MnS@rGO, and 2042 F g⁻¹ for Ni₃S₂/MnS/CuS@rGO, respectively. Charge transfer resistance (R_ct) of Ni₃S₂/MnS/CuS@rGO (0.001 Ω) was much lower than that of Ni₃S₂/MnS@rGO by 0.02 Ω, and lower than that of Ni₃S₂/MnS/CuS by 0.017 Ω. After 5000 cycles, the Ni₃S₂–MnS–CuS@RGO electrode maintains 78.3% of the initial capacity at 20 A g⁻¹. An asymmetric supercapacitor was subsequently assembled using Ni₃S₂/MnS/CuS@rGO as the positive electrode and rGO as the negative electrode. The specific capacitance of asymmetric batteries was maintained at 90.8% of the initial state after 5000 GCD.

Transition metal sulfides (TMS), as promising electroactive materials for asymmetric supercapacitors, have been limited due to their relatively poor conductivity and cycle stability.     

Synthesis of a MnS/NixSy composite with nanoparticles coated on hexagonal sheet structures as an advanced electrode material for asymmetric supercapacitors

Herein, a facile hydrothermal method was designed to synthesize a novel structure of micro-flowers decorated with nanoparticles. The micro-flower structure consists of enormous cross-linked flat hexagonal nanosheets with sufficient internal space, providing fluent ionic channels and enduring volume change in the electrochemical storage process. As expected, the MnS/Ni_xS_y (NMS) electrode exhibits a relatively high specific capacitance of 1073.81 F g⁻¹ (at 1 A g⁻¹) and a good cycling stability with 82.14% retention after 2500 cycles (at 10 A g⁻¹). Furthermore, the assembled asymmetric supercapacitor achieves a high energy density of 46.04 W h kg⁻¹ (at a power density of 850 W kg⁻¹) and exhibits excellent cycling stability with 89.47% retention after 10 000 cycles. The remarkable electrochemical behavior corroborates that NMS can serve as an advanced electrode material.

A MnS/Ni_xS_y composite with nanoparticles coated on hexagonal sheets was successfully synthesized and exhibited enhanced performance.     

Preparation of a MoS2/carbon nanotube composite as an electrode material for high-performance supercapacitors

MoS₂ and MoS₂/carbon allotrope (MoS₂/C) composites for use as anodes in supercapacitors were prepared via a facile hydrothermal method. In this study, we report the effects of various carbon-based materials (2D graphene nanosheet (GNS), 1D carbon nanotube (CNT), and 0D nano carbon (NC)) on the electrochemical performances. Among all nanocomposites studied, MoS₂/CNT exhibited the best electrochemical performance. Specifically, the MoS₂/CNT composite exhibits remarkable performances with a high specific capacitance of 402 F g⁻¹ at a current density of 1 A g⁻¹ and an outstanding cycling stability with 81.9% capacitance retention after 10 000 continuous charge–discharge cycles at a high current density of 1 A g⁻¹, making it adaptive for high-performance supercapacitors. The superiority of MoS₂/CNT was investigated by field emission scanning electron microscopy and transmission electron microscopy, which showed that MoS₂ nanosheets were uniformly loaded into the three-dimensional interconnected network of nanotubes, providing an excellent three dimensional charge transfer network and electrolyte diffusion channels while effectively buffering the collapse and aggregation of active materials during charge–discharge processes. Overall, the MoS₂/CNT nanocomposite synthesized by a simple hydrothermal process presents a new and promising candidate for high-performance anodes for supercapacitors.

The effect of carbon supports on the electrochemical performance of MoS₂ nanosheets for supercapacitor applications was investigated.     

Diaminopyrene modified reduced graphene oxide as a novel electrode material for excellent performance supercapacitors

In this paper, novel reduced graphene oxide (rGO) composites (DAPrGOs) modified by diaminopyrene (DAP) were successfully synthesized via a facile solvothermal reaction method and used for supercapacitors. Compared with the pristine rGO, the DAPrGO1 electrode showed distinctly better performance (397.63 F g⁻¹vs. 80.29 F g⁻¹ of pristine rGO at 0.5 A g⁻¹) with small charge transfer resistance. When a symmetric device was fabricated using DAPrGO1 as the active material, it also exhibited a high capacitance of 82.70 F g⁻¹ at 0.5 A g⁻¹ with an energy density of 25.84 W h kg⁻¹ at a power density of 375 W kg⁻¹, and even offered a high power density of 7500 W kg⁻¹ (18.71 W h kg⁻¹) at 10 A g⁻¹. Moreover, the device possessed good electrochemical stability up to 20 000 cycles, implying promising applications in energy storage fields.

Schematic illustration of the facile synthesis process of DAPrGOs nanocomposites, Ragone plots and the superior cyclic stability of the assembled DAPrGO1//DAPrGO1 SSS.     

Optimized NiCo2O4/rGO hybrid nanostructures on carbon fiber as an electrode for asymmetric supercapacitors

The NiCo₂O₄ nanowires and reduced graphene oxide (rGO) hybrid nanostructure has been constructed on carbon fibers (NiCo₂O₄/rGO/CF) via a hydrothermal method. The effects of graphene oxide (GO) concentration on the structure and performance of the NiCo₂O₄/rGO/CF were investigated in detail to obtain the optimized electrode. When the GO concentration was 0.4 mg ml⁻¹, the rGO/NiCo₂O₄/CF composite exhibited a maximum specific capacitance of 931.7 F g⁻¹ at 1 A g⁻¹, while that of NiCo₂O₄/CF was 704.9 F g⁻¹. Furthermore, the NiCo₂O₄/rGO/CF//AC asymmetric supercapacitor with a maximum specific capacitance of 61.2 F g⁻¹ at 1 A g⁻¹ was fabricated, which delivered a maximum energy density (24.6 W h kg⁻¹) and a maximum power density (8477.7 W kg⁻¹). Results suggested that the NiCo₂O₄/rGO/CF composite would be a desirable electrode for flexible supercapacitors.

The NiCo₂O₄ nanowires and rGO hybrid nanostructure was constructed on carbon fibers (NiCo₂O₄/rGO/CF) via a hydrothermal method.     

Highly flexible reduced graphene oxide@polypyrrole–polyethylene glycol foam for supercapacitors

A flexible and free-standing 3D reduced graphene oxide@polypyrrole–polyethylene glycol (RGO@PPy–PEG) foam was developed for wearable supercapacitors. The device was fabricated sequentially, beginning with the electrodeposition of PPy in the presence of a PEG–borate on a sacrificial Ni foam template, followed by a subsequent GO wrapping and chemical reduction process. The 3D RGO@PPy–PEG foam electrode showed excellent electrochemical properties with a large specific capacitance of 415 F g⁻¹ and excellent long-term stability (96% capacitance retention after 8000 charge–discharge cycles) in a three electrode configuration. An assembled (two-electrode configuration) symmetric supercapacitor using RGO@PPy–PEG electrodes exhibited a remarkable specific capacitance of 1019 mF cm⁻² at 2 mV s⁻¹ and 95% capacitance retention over 4000 cycles. The device exhibits extraordinary mechanical flexibility and showed negligable capacitance loss during or after 1000 bending cycles, highlighting its great potential in wearable energy devices.

A flexible and free-standing 3D reduced graphene oxide@polypyrrole–polyethylene glycol (RGO@PPy–PEG) foam was developed for wearable supercapacitors.     

A self-supported electrode for supercapacitors based on nanocellulose/multi-walled carbon nanotubes/polypyrrole composite

A robust self-supported electrode based on nanocellulose fibers (CNF), multi-walled carbon nanotubes (CNT), and polypyrrole (PPy) was prepared by a facile combination of ultrasonic dispersion and consequent in situ polymerization. In addition, the feasibility of utilizing this ternary composite as an electrode for supercapacitors was studied. The results revealed that the obtained CNF/CNT/PPy composite exhibited a large specific capacitance of 200.8 F g⁻¹ at 0.5 A g⁻¹. Equally important, the electrode capacitance retained about 90% of its initial value after 5000 charge/discharge cycles at a current density of 1 A g⁻¹, which thus demonstrated its excellent cycling stability. The simple integration route and outstanding electrochemical properties distinguish this new composite as a prospective candidate for use as a high-performance electrode in supercapacitors.

A robust self-supported electrode was prepared by a facile combination of ultrasonic dispersion and consequent in situ polymerization.     

Fabrication of composite material of RuCo2O4 and graphene on nickel foam for supercapacitor electrodes

Supercapacitors are energy storage devices with the advantage of rapid charging and discharging, which need a higher specific capacitance and superior cycling stability. Hence, a composite material consisting of RuCo₂O₄ and reduced graphene oxide with a nanowire network structure was synthesized on nickel foam using a one-step hydrothermal method and annealing process. The nanowire network structure consists of nanowires with gaps that provide more active sites for electrochemical reactions and shorten the diffusion path of electrolyte ions. The prepared electrodes exhibit outstanding electrochemical performance with 2283 F g⁻¹ at 1 A g⁻¹. When the current density is 10 A g⁻¹, the specific capacitance of the electrodes is 1850 F g⁻¹, which maintains 81% of the initial specific capacitance. In addition, the prepared electrodes have a long-term cycling life with capacitance retention of 92.60% after 3000 cycles under the current density of 10 A g⁻¹. The composite material is a promising electrode material for high-performance supercapacitors.

The RuCo₂O₄/rGO@NF composite electrode has been prepared by a one-step hydrothermal method and annealing process, with high specific capacitance and excellent cycle stability.     

Solution-processed graphene oxide electrode for supercapacitors fabricated using low temperature thermal reduction

We present a low temperature and solution-based fabrication process for reduced graphene oxide (rGO) electrodes for electric double layer capacitors (EDLCs). Through the heat treatment at 180 °C between the spin coatings of graphene oxide (GO) solution, an electrode with loosely stacked GO sheets could be obtained, and the GO base coating was partially reduced. The thickness of the electrodes could be freely controlled as these electrodes were prepared without an additive as a spacer. The GO coating layers were then fully reduced to rGO at a relatively low temperature of 300 °C under ambient atmospheric conditions, not in any chemically reducing environment. Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) results showed that the changes in oxygen functional groups of GO occurred through the heat treatments at 180 and 300 °C, which clearly confirmed the reduction from GO to rGO in the proposed fabrication process at the low thermal reduction temperatures. The structural changes before and after the thermal reduction of GO to rGO analyzed using Molecular Dynamic (MD) simulation showed the same trends as those characterized using Raman spectroscopy and XPS. An EDLC composed of the low temperature reduced rGO-based electrodes and poly(vinyl alcohol)/phosphoric acid (PVA/H₃PO₄) electrolyte gel was shown to have high specific capacitance of about 240 F g⁻¹ together with excellent energy and power densities of about 33.3 W h kg⁻¹ and 833.3 W kg⁻¹, respectively. Furthermore, a series of multiple rGO-based EDLCs was shown to have fast charging and slow discharging properties that allowed them to light up a white light emitting diode (LED) for 30 min.

We present a low temperature and solution-based fabrication process for reduced graphene oxide (rGO) electrodes for electric double layer capacitors (EDLCs).     

Construction of a graphene/polypyrrole composite electrode as an electrochemically controlled release system

A new class of stimuli responsive drug delivery systems is emerging to establish new paradigms for enhancing therapeutic efficacy. To date, most electro-responsive systems rely on noble metal electrodes that likely cause the limitations for implantation applications. Herein, a graphene/polypyrrole composite electrode (GN–PPy–FL) was fabricated based on two-dimensional (2D) graphene (GN) film and conductive and biocompatible polypyrrole (PPy) nanoparticles loaded with a negative drug model of fluorescein sodium (FL) via chemical oxidation polymerization. The conductive composite electrode was utilized as a drug carrier to realize the electrically controlled release of the FL. The release rate from conductive nanoparticles can be controlled by the applied voltages. The study provides a multi-stimuli responsive drug release system, demonstrating the potential applications of the controlled release of various drugs, peptides or proteins.

A biocompatible conductive composite electrode GN–PPy–FL can realize controlled release of a drug model triggered by low voltages.