Facile Electrochemical Deposition Research Articles

Decorating Cu2O with Copper Metal (Cu) through Facile Electrochemical Deposition for Methylene Blue Degradation

Cuprous oxide (Cu2O) thin film was decorated with copper metal (Cu) by the simple electrochemical deposition method. This study was motivated to improve the role of Cu as a co-catalyst due to the narrow band gap energy of known photocatalyst Cu2O. Cu was electrodeposited on Cu2O thin film with a substrate of indium tin oxide (ITO) at a voltage of -0.3V and a temperature of 60 °C in CuSO4 (pH 10) under a magnetic stirrer. The structure, phase, and morphology of Cu2O/Cu were characterised by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The electrocatalytic performance of Cu2O/Cu was recorded using linear sweep voltammetry and electrochemical impedance spectroscopy. XRD and SEM results show Cu was successfully deposited covering Cu2O. The current density of Cu2O/Cu increased by 2.7041 mA/cm2 confirming the lower charge current resistance of 2.48 kΩ. The Cu-decorated Cu2O demonstrated an improved photocatalytic activity, as shown by the increase of MB degradation from 46.33% to 50.87%. It was believed from characterisations that Cu deposition leads to more dense carriers and charge transfer, hence higher photocatalytic activity towards MB degradation than bare Cu2O thin film.

3D Nickel–Manganese bimetallic electrocatalysts for an enhanced hydrogen evolution reaction performance in simulated seawater/alkaline natural seawater

In this paper, we report an inexpensive one-step synthesis of self-supported 3D nickel-manganese (NiMn) bimetallic coatings and their application for the hydrogen evolution reaction in simulated seawater (1 M KOH + 0.5 M NaCl) and alkaline natural seawater (1 M KOH + natural seawater). These binary coatings were electrodeposited on a titanium substrate using a facile electrochemical deposition method by a dynamic hydrogen bubble template technique. The as-deposited NiMn coatings with variable Mn amounts produce typical globular and unique porous architecture with abundant pores of different sizes. The activity of these fabricated catalysts towards the hydrogen evolution reaction was investigated by linear sweep voltammetry towards simulated seawater and alkaline natural seawater at different temperatures. The surface morphology and composition of the catalysts were also characterized by scanning electron microscopy and inductively coupled plasma optical emission spectroscopy. The as-prepared NiMn/Ti electrocatalyst, which was electrodeposited using a chemical bath containing Ni2+ and Mn2+ ions with a molar ratio of Ni2+:Mn2+ = 1:5, exhibits excellent hydrogen evolution activity in simulated seawater with an ultra-low overpotential of 64.2 mV to reach a current density of 10 mA cm−2. It is noteworthy that this NiMn/Ti electrocatalyst also achieves a current density of 10 mA cm−2 in alkaline natural seawater with a comparably low overpotential of 79.3 mV. The current densities increase by ca. 1.75–2.35 times with an increase in temperature from 25 °C to 75 °C for hydrogen evolution in both electrolytes. This bimetallic catalyst has shown excellent long-term stability at a constant potential of −0.23 V (vs. RHE) and a constant current density of 10 mA cm−2 for 10 h, which ensures higher durability and robustness for practical application of seawater splitting technology.

Preparation of antimony selenide thin films by electrochemical deposition and application in optoelectronic devices

Antimony selenide (Sb2Se3) has become a potential semiconductor material for a wide range of optoelectronic applications because of its unique one-dimensional crystal structure and corresponding excellent anisotropic optical and electronic properties. Herein, uniform and flat Sb2Se3 thin films with [hk1]-optimized growth orientation are prepared by adjusting the deposition potentials and selenization temperatures using a facile electrochemical deposition method. Then these films are applied in heterojunction-type photodetectors with the structure of Mo/Sb2Se3/CdS/ZnO/ITO/Ag. The best performances are obtained for devices with a deposition potential of −0.55 V and a selenization temperature of 300 °C. At 0 bias, the detector yielded a responsivity of 25.4 mA/W and a detectivity of 1.06 × 1011 Jones at 635 nm visible light with a light intensity of 5 mW. The results show that high-quality Sb2Se3 thin films can be prepared by electrochemical deposition under proper preparation conditions, which lays the foundation for the application of the electrochemical deposition method in the field of optoelectronic devices.

Facile preparation of gold nanoparticles anchored on layered yttrium hydroxide by electrochemical methods for enhanced sensing of hydroquinone and catechol

Gold nanoparticles (AuNPs) have emerged as highly competitive catalysts. However, the precise regulation of intrinsic structural parameters that account for the activity of AuNPs remains a challenge in designing high-performance electrocatalysts. Herein, the layered yttrium hydroxide (LYH) nanosheets supported AuNPs are prepared via a facile electrochemical deposition method. The tunability of morphology in LYH support and their utilization in controlling the growth of small AuNPs with uniform dispersion are emphasized. Finally, a novel sensor is constructed using flower-like AuNPs/LYH modified electrodes, which allows for simultaneous determination of the dihydroxybenzene isomers hydroquinone and catechol with good sensitivity, reproducibility and stability. The excellent performance can be attributed to the synergistic effects between AuNPs and LYHs. The strategy of depositing gold onto LYH nanosheets and the resulting high performance provide new approaches for further developing highly efficient composite electrodes across a wide range of applications.

Enhanced Photocatalytic CO2 Reduction to CH4 Using Novel Ternary Photocatalyst RGO/Au-TNTAs

Photocatalytic CO2 reduction into hydrocarbon fuels is one of the most efficient processes since it serves as a renewable energy source while also lowering atmospheric CO2 levels. The development of appropriate materials and technology to attain greater yield in CO2 photoreduction is one of the key issues facing the 21st century. This study successfully fabricated novel ternary reduced graphene oxide (RGO)/Au-TiO2 nanotube arrays (TNTAs) photocatalysts to promote CO2 photoreduction to CH4. Visible light-responsive RGO/Au-TNTAs composite was synthesized by facile electrochemical deposition of Au nanoparticles (NPs) and immersion of RGO nanosheets onto TNTAs. The synthesized composite has been thoroughly investigated by FESEM, HR-TEM, XRD, XPS, FT-IR, UV-Vis DRS, and PL analyzer to explain structural and functional performance. Under the source of visible light, the maximum yield of CH4 was attained at 35.13 ppm/cm2 for the RGO/Au-TNTAs composite photocatalyst after 4 h, which was considerably higher by a wide margin than that of pure TNTAs, Au-TNTAs and RGO-TNTAs. The CO2 photoreduction of the RGO/Au-TNTAs composite has been improved due to the combined effects of Au NPs and RGO. Due to its surface plasmonic resonance (SPR) mechanism, Au NPs play a crucial role in the absorption of visible light. Additionally, the middle RGO layers serve as effective electron transporters, facilitating better separation of electron-hole pairs. The newly constructed composite would be a promising photocatalyst for future photocatalytic applications in other fields.

Bimetallic 3D Nickel-Manganese/Titanium Bifunctional Electrocatalysts for Efficient Hydrogen and Oxygen Evolution Reaction in Alkaline and Acidic Media

In this work, 3D nickel-manganese (NiMn) bimetallic coatings have been studied as electrocatalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline (1.0 M KOH) media and the HER in acidic (0.5 M H2SO4) media. The catalysts have been deposited on a titanium substrate (1 × 1 cm2) using low-cost and facile electrochemical deposition method through a dynamic hydrogen bubble template technique. The electrocatalytic performance of these fabricated catalysts was investigated by using Linear Sweep Voltammetry (LSV) for HER and OER at different temperatures ranging from 25 up to 75 °C and also was characterized by scanning electron microscopy (SEM) and inductively coupled plasma optical emission spectroscopy (ICP-OES). It was found that fabricated NiMn/Ti-5 electrocatalyst with Ni2+/Mn2+ molar ratio of 1:5 exhibits excellent HER activity in alkaline media with overpotential of 127.1 mV to reach current density of 10 mA cm−2. On the contrary, NiMn/Ti-1 electrocatalyst that fabricated with Ni2+/Mn2+ molar proportion of 1:1 and lowest Mn-loading of 13.43 µgcm−2 demonstrates exceptional OER activity with minimum overpotential of 356.3 mV to reach current density of 10 mA cm−2. The current densities increase ca. 1.8–2.2 times with an increase in temperature from 25 °C to 75 °C for both HER and OER investigation. Both catalysts also have exhibited excellent long-term stability for 10 h at constant potentials as well as constant current density of 10 mA cm−2 that assure their robustness and higher durability regarding alkaline water splitting.

Synergistic effect of electrochemically fabricated polyaniline nanofibers and silver for efficient solar steam generation

Solar steam generation (SSG) has been recognized as a promising and green technology to resolve the scarcity of drinking water in the near future. On the other hand, there are still several challenges associated with SSG system to its practical utilization. Design of suitable photothermal materials with high solar absorption and conversion efficiency is one of the challenges associated with the SSG technology. Herein, we demonstrated a strategy for the fabrication of bilayer structure of porous polyaniline (PANI) nanofibers and conducting silver (Ag) on a carbon cloth (PANI/Ag@CC) substrate using a facile electrochemical deposition approach. As prepared binder-free PANI/Ag@CC showed an excellent steam generation rate of 2.21 kg/m2h with superior evaporation efficiency of 98.0 % under 1 sun illumination when used for the SSG application. Furthermore, the bilayered PANI/Ag@CC exhibited excellent durability, effective seawater desalination and wastewater purification. The superior SSG performance is associated with the synergistic effect of surface plasmon resonance of Ag and porous PANI nanofibers. Therefore, practically simple fabrication, outstanding evaporation rate and water purification properties convince that the PANI/Ag@CC structure can be a promising candidate for SSG applications.

Fast-Charging Capability of Thin-Film Prussian Blue Analogue Electrodes for Aqueous Sodium-Ion Batteries.

Prussian blue analogues are considered as promising candidates for aqueous sodium-ion batteries providing a decently high energy density for stationary energy storage. However, suppose the operation of such materials under high-power conditions could be facilitated. In that case, their application might involve fast-response power grid stabilization and enable short-distance urban mobility due to fast re-charging. In this work, sodium nickel hexacyanoferrate thin-film electrodes are synthesized via a facile electrochemical deposition approach to form a model system for a robust investigation. Their fast-charging capability is systematically elaborated with regard to the electroactive material thickness in comparison to a ″traditional″ composite-type electrode. It is found that quasi-equilibrium kinetics allow extremely fast (dis)charging within a few seconds for sub-micron film thicknesses. Specifically, for a thickness below ≈ 500 nm, 90% of the capacity can be retained at a rate of 60C (1 min for full (dis)charge). A transition toward mass transport control is observed when further increasing the rate, with thicker films being dominated by this mode earlier than thinner films. This can be entirely attributed to the limiting effects of solid-state diffusion of Na+ within the electrode material. By presenting a PBA model cell yielding 25 Wh kg-1 at up to 10 kW kg-1, this work highlights a possible pathway toward the guided design of hybrid battery-supercapacitor systems. Furthermore, open challenges associated with thin-film electrodes are discussed, such as the role of parasitic side reactions, as well as increasing the mass loading.

Unique hierarchical architecture of SnO2 hexagonal interconnected nanolayered arrays as negative electrode for high performance asymmetric supercapacitors

In this research, we report unique hierarchical structures of SnO2 hexagonal interconnected nanolayered arrays (HINLA) fabricated on the carbon cloth (SnO2 HINLA@CC) by a facile electrochemical deposition technique. The structural, morphological evolution and electrochemical properties of as prepared SnO2 HINLA@CC are explored as negative electrode of SCs. SnO2 HINLA@CC has been tested in negative potential widow of −1.0-0 V and demonstrated the high specific capacitance of 325 F g−1 at 1 A g−1, much superior when compared to the previously reported data for SnO2. The EIS analysis confirmed the charge transfer kinetics of SnO2 HINLA@CC, with significant stability due to favorable morphology for swift response. Capacitance retention plot confirmed no structural degradation or pulverization for negative electrode even after 5000 galvanostatic charge with 88.6% capacitance retention. Such high performances of SnO2 HINLA@CC as negative electrode make it an ideal candidate to be useful in ASCs. Moreover, a 2.2 V aqueous ASC has been constructed by employing Na0·5MnO2 nanowall arrays (NWAs) as cathode and SnO2 HINLA@CC as anode. In particular, the 2.2 V Na0·5MnO2 NWAs@CC//SnO2 HINLA@CC ASC has demonstrated the superior energy density of ∼73 Wh kg−1, significant rate capability and excellent cycling ability, outperforming the previously reported SnO2-based ASCs. Present work provides new opportunities for developing promising high-voltage aqueous ASCs with excellent energy density.

Thermoelectric properties of Indium doped skutterudite thick film synthesized by a facile technique of electrochemical deposition

Doped/filled skutterudites are much studied materials due to their excellent thermoelectric performance. However, their synthesis and preparation is complicated. This work synthesized indium (In) doped cobalt triantimonide (CoSb3) skutterudite thick films using a facile electrochemical deposition technique through chronoamperometric steps for 2 h. The nominal composition of In element is found in the range of 0.55–0.23 for a stoichiometric condition of In doped CoSb3 thick films. The early crystal growth of In doped films shows instantaneous nucleation and is controlled by the charge transfer process with diffusion coefficient, D of 10−5 cm2/s. The incorporation of In into the interstitial sites of CoSb3 cages is evident from the lattice constant (a) expansion as observed in XRD. The optimum Seeback coefficient (S) of the 0.5 mmol In doped CoSb3 thick film is −89.84 μV/K at 282 K, due to an increase in the carrier concentration (n ∼1020 cm−3). The negative S is due to the electron donor behaviour of the In. Meanwhile, high electrical conductivity, σ value (14.26 kS/m) contributes to a power factor (S2σ) increment of 115.11 μW/(m·K2). The result shows a promising thermoelectric property of doped skutterudite synthesized by electrochemical deposition technique.

FeV LDH Coated on Sandpaper as an Electrode Material for High-Performance Flexible Energy Storage Devices

Recently, considerable research efforts to achieve advanced design of promising electroactive materials as well as unique structures in supercapacitor electrodes have been explored for high-performance energy storage systems. We suggest the development of novel electroactive materials with an enlarged surface area for sandpaper materials. Based on the inherent micro-structured morphologies of the sandpaper substrate, nano-structured Fe-V electroactive material can be coated on it by facile electrochemical deposition technique. A hierarchically designed electroactive surface is covered with FeV-layered double hydroxide (LDH) nano-flakes on Ni-sputtered sandpaper as a unique structural and compositional material. The successful growth of FeV-LDH is clearly revealed by surface analysis techniques. Further, electrochemical studies of the suggested electrodes are carried out to optimize the Fe-V composition as well as the grit number of the sandpaper substrate. Herein, optimized Fe0.75V0.25 LDHs coated on #15000 grit Ni-sputtered sandpaper are developed as advanced battery-type electrodes. Finally, along with the negative electrode of activated carbon and the FeV-LDH electrode, it is utilized for hybrid supercapacitor (HSC) assembly. The fabricated flexible HSC device indicates high energy and power density by showing excellent rate capability. This study is a remarkable approach to improving the electrochemical performance of energy storage devices using facile synthesis.

Direct electrosynthesis of Ni-, Co-, and Ni,Co-MOF onto porous support for high-performance supercapacitors

In this paper, we fabricated three different MOFs samples including Ni,Co-MOF, Ni-MOF, Co-MOF by a facile electrochemical deposition onto the nickel foam at room temperature and their performances as supercapacitor electrode materials were evaluated and compared. The results of structural analyses proved the formation of MOFs production. Ni-, Co-, and Ni,Co-MOF/NF electrode showed specific capacities of 246 C/g, 74.25 C/g and 329 C/g at the applied current load of 2 A/g, respectively. The results of GCD cycling tests declared that the fabricated bimetal Ni,Co-MOF could show better cycle life as compared with its single-metal ion MOFs (i.e. Ni-MOF, Co-MOF) and reaches 306 C/g at 9000th cycles of the cycling test with the current load of 2 A/g, and also 92.1% capacity retention was observed for bimetal-MOF/NF.

Construction of a hierarchical membrane with angstrom-scale ion channels for enhanced Li+/Mg2+ separation.

A biomimetic hierarchical membrane consisting of ZIF-8 and MXene with controllable morphology could be fabricated by the facile electrochemical deposition method, well-realizing Li+/Mg2+ sieving. This membrane could work stably in real brine with perm-selectivity of Li+/Mg2+ up to 47.4.

Ambipolar operation of progressively designed symmetric bidirectional transistors fabricated using single-channel vertical transistor and electrochemically prepared copper oxide.

In this study, a symmetric bidirectional transistors (SBT) is proposed. The device simultaneously implements the "strong-inversion" and "accumulation" mechanisms of a metal-oxide semiconductor field-effect transistor and TFT, respectively, in different bias directions in a single-channel vertical transistor (V-Tr). This ideal SBT device is designed and fabricated by selecting appropriate materials exhibiting a narrow bandgap and intrinsic characteristics of Sb-doped p-type Cu2O, using a V-Tr to optimize the device structure for high-field-induced short-channel and ambipolar operation, and implementing facile electrochemical deposition for channel and plasma channel treatments. To adopt artificial conductivity control for producing the transporting path of minority electron carriers, the patterned-channel-layer sidewall is locally treated using oxygen plasma, thereby suppressing the minority-carrier self-compensation. The SBT device exhibits an excellent on-current (i.e., symmetric accumulation and strong inversion modes in the p- and n-type channel regions, respectively) and excellent midregion off-current, similar to those of ideal ambipolar transistors. Moreover, owing to multilevel signals and excellent inverter behaviors, the SBT device is suitable for application in complementary-metal-oxide-semiconductors and logic memories.

Highly efficient electrooxidation of ethanol on CuPtPd trimetallic catalyst

Pt-based ternary metal catalysts have excellent catalytic performance and high stability for ethanol oxidation (EOR). In this paper, Cu-Pt-Pd ternary alloy catalysts are prepared by a facile electrochemical deposition method. The morphology and elemental composition are probed by spherical aberration corrected transmission electron microscope (ACTEM) and X-ray photoelectron spectroscopy (XPS). Many hollow nanosphere are uniformly distributed on the surface of Cu-Pt-Pd catalysts. In various Cu-Pt-Pd catalysts, the peak current density and the mass activity of Cu-Pt1Pd3.2 are 166.7 mA⋅cm−2 and 2436 mA⋅mgPt+Pd-1 for EOR, which are 13.4 times and 8.1 times as those of commercial Pt/C catalysts. The Cu-Pt1Pd3.2 also exhibits excellent CO toxicity resistance. The strong interaction and synergistic effect among Cu, Pt and Pd would enhance its electro-catalytic activity. The above research results will be potential useful value in expanding application fields of Pt-based ternary metal catalysts for EOR.

Electrochemically Induced Defects Promotional High-Performance Binder-Free MnO@CC Cathodes for Flexible Quasi-Solid-State Zinc-Ion Battery

Aqueous Zn-ion batteries (ZIBs) have attracted ever-increasing attention because of their features of a cheaper cost, high safety level, and environment protection. Manganese-based oxides stand out among the many cathode material candidates because of their high voltage platform (1.4 V vs Zn2+/Zn). Nevertheless, manganese ion dissolution still is an essential issue in the application of manganese-based cathodes, and the strategy of using manganese ion dissolution to activate electrode materials is rarely achieved. Here, a high-capacity and stable binder-free MnO@CC cathode was prepared by facile electrochemical deposition and carbothermal reduction methods. Based on the MnO@CC cathode and a homemade gel polymer electrolyte, a flexible quasi-solid state ZIB was assembled and exhibited a high reversible capacity, a significant energy output of 345 Wh kg–1, and excellent long-term cycling performance. The ultradispersed and well-crystallized octahedral MnO nanoparticle provides an improved ion transfer interface, and abundant Mn vacancy during the initial charging process provides sufficient inserted channels and available active sites for subsequent ion insertion and storage. In addition, for the as-activated MnO@CC electrode, the reversible coinsertion mechanism (H+ and Zn2+) is also monitored in the aqueous ZIBs. This work may provide insights into manufacturing advanced flexible aqueous ZIBs for wearable electronics via defect engineering.

Surface densification strategy assisted efficient Cu2O heterojunction photocathode for solar water splitting

Photoelectrochemical (PEC) water splitting based on abundant and promising Cu2O photocathode offers new possibilities for energy and climate crisis mitigation. Magnetron sputtering (MS) is a simple, reliable, and commercially proven scalable technique for fabricating Cu2O with excellent electronic properties. However, the small nanograin and cracking nature of the Cu2O nanofilm deposited by MS limited the subsequent heterojunction fabrication indispensable for capable devices. In this work, we have developed a simple surface densification strategy using another facile electrochemical deposition method to address this critical issue. The modified Cu2O-based photocathode presented a photocurrent density of 4 mA/cm2 at H2 evolution potential, which is 10 times higher than the unmodified device and 1.6 times that of the conventional device based on the electrochemical deposition method. Furthermore, we implemented comprehensive photoelectric characterization and energy band simulations to gain insight into the carrier dynamics in Cu2O, revealing the efficient separation of carriers in the modified specimen and the factor that limits the device performance. This paper provides a novel and simple approach to engineer efficient Cu2O photocathodes for PEC H2 generation based on the commercial MS technique.

Pd/PdO Electrocatalysts Boost Their Intrinsic Nitrogen Reduction Reaction Activity and Selectivity via Controllably Modulating the Oxygen Level.

The electrocatalytic nitrogen reduction reaction (eNRR) is regarded as promising sustainable ammonia (NH3) production alternative to the industrial Haber-Bosch process. However, the current electrocatalytic systems still exhibit a grand challenge to simultaneously boost their eNRR activity and selectivity under ambient conditions. Herein, we construct Pd/PdO electrocatalysts with a controlled oxygen level by a facile electrochemical deposition approach at different gas atmospheres. Theoretical calculation results indicate that the introduction of an oxygen atom into a pure Pd catalyst would modulate the electron density of the Pd/PdO heterojunction and thus influence the adsorption energy for nitrogen and hydrogen. The calculation results and experiments show that the Pd/PdO heterojunction with a moderate oxygen level (O-M) exhibits optimal eNRR performance with a high NH3 yield of 11.0 μg h-1 mgcat-1 and a large Faraday efficiency (FE) of 22.2% at 0.03 V (vs RHE) in a 0.1 M KOH electrolyte. The moderate affinity of Pd to N in the Pd/PdO heterojunction and the inhibition of the hydrogen evolution reaction (HER) can facilitate the breaking of the triple bond of N2 and promote the protonation of N, which is confirmed by ex situ X-ray photoelectron spectroscopy (XPS) and in situ Raman spectroscopy. In situ Fourier transform infrared spectroscopy (FTIR) and density functional theory (DFT) calculations further disclose that the O-M catalysts prefer the distal association pathway during the eNRR process. This work opens a new way to construct heterostructures by controlling the oxygen level in other electrochemical fields.

Physicochemical and Electrocatalytic Performance of Chromium doped Iron Pyrite Thin Films

Chromium (Cr3+) doped iron pyrite (FeS2) thin films were deposited on ITO substrate by a facile electrochemical deposition process. The effect of chromium content on structural, optical, electrical, morphological, and electrocatalytic behavior of the pyrite thin films were examined. X - ray diffraction studies confirmed the formation of cubic crystal structure of deposited thin films. Atomic force microscopy results indicate that Cr3+ doping has strong influence on crystallinity, surface roughness and grain size of as-deposited thin films. Further, bandgap reduction was found in Cr3+ doped FeS2 thin films. The interfacial charge resistance of fabricated thin films was investigated by electrochemical impedance spectroscopy and 3 mole % Cr3+ doped FeS2 thin films showed excellent conductivity with a low charge transfer resistance of 49 Ω. Further, the electrocatalytic performance of the prepared pyrite thin films was investigated. Cr doped thin films were found to exhibit better performance. Anti-structural modeling was opted to investigate the characteristics of defects in fabricated thin films and it was established that Cr3+substitutionmay form cation (Fe2+) vacancies which could be responsible for enhanced photochemical and electrochemical activities in Cr-doped FeS2 thin films.

Facile electrodeposition route for the fabrication of Ni/Ni(OH)2 nanocomposite films with different supporting electrolytes and their electrochemical properties

A facile electrochemical deposition method synthesized Ni/Ni(OH)2 nanocomposites with different interlayer anions (Cl− and SO42−). Materials characterization and electrochemical tests (XRD, SEM, TEM, CV, GCD, EIS, etc.) were carried out to study the effect of interlayer anions on the morphology and electrochemical performance. The results demonstrated that the Cl− intercalated Ni/Ni(OH)2 nanocomposites exhibited higher specific capacitance and better cycle performance than SO42− interlayer anions. The Cl− intercalated Ni/Ni(OH)2 nanocomposites show a high specific capacity of 1295 Fg−1 at the current densities of 1 Ag−1 and excellent cycling stability with capacitance retention of 80.1% after 300 cycles.