Pure MnO2 Research Articles

Dual-Site Cooperation for High Benzyl Alcohol Oxidation Activity of MnO2 in Biphasic MnOx–CeO2 Catalyst Using Aerial O2 in the Vapor Phase

Selective oxidation of benzyl alcohol to benzaldehyde in the vapor phase has drawn growing interest recently. In this work, MnOx–CeO2 mixed oxide compositions have been prepared by a coprecipitation method and tested for their oxidation activities of benzyl alcohol to benzaldehyde in the vapor phase. Detailed structural analyses have indicated that MnOx–CeO2 catalysts contain two phases, namely, α-MnO2 and fluorite CeO2 phases. The benzyl alcohol oxidation activity of pure MnO2 is more than 7 times higher compared to that of CeO2, indicating a much higher intrinsic oxidation ability of the MnO2 phase. Further, enhancement of the benzyl alcohol oxidation rate over MnO2 in 10%MnOx–CeO2 catalyst by 13 times is observed in relation to pure MnO2. The role of CeO2 in the MnOx–CeO2 catalyst has also been investigated, which indicates that the oxidation activity is almost independent of CeO2. However, stronger adsorption of benzyl alcohol over the MnOx–CeO2 catalysts compared to that of MnO2 points to the role of CeO2 in adsorption. Thus, both the CeO2 and the MnO2 components have different roles in the catalytic process—adsorption of benzyl alcohol on the CeO2 surface and its oxidation on MnO2 at the interface. The cooperation between the two sites toward oxidation could happen due to jumping of adsorbed benzyl alcohol from the surface of the CeO2 phase to the closest Mn4+ site in the MnO2 phase at the contact surface with MnO2 by thermal motion.

Engineering Co3O4/MnO2 nanocomposite materials for oxygen reduction electrocatalysis

Stable and active electrocatalysts preparation for the oxygen reduction reaction (ORR) is essential for an energy storage and conversion materials (e.g. metal-air batteries). Herein, we prepared a highly-active MnO2 and Co3O4/MnO2 nanocomposite electrocatalysts using a facial co-precipitation approach. The electrocatalytic activity was examined in alkaline media with LSV and CV. Additionally, the physicochemical characteristics of the MnO2 and Co3O4/MnO2 composite materials were studied via SEM, XRD, BET, UV-Vis, TGA/DTA, ICP-OES and FTIR. Morphological studies indicated that a pure MnO2 has a spherical flower-like architecture, whereas Co3O4/MnO2 nanocomposites have an aggregated needle-like structure. Moreover, from the XRD investigation parameters such as the dislocation density, micro-strain, and crystallite size were analyzed. The calculated energy bandgaps for the MnO2, Co3O4/MnO2-1-5, and Co3O4/MnO2-1-1 nanocomposites were 3.07, 2.6, and 2.3 eV, correspondingly. The FTIR spectroscopy was also employed to study the presence of M-O bonds (M = Mn, Co). The thermal gravimetric investigation showed that the Co3O4/MnO2 nanocomposite materials exhibited improved thermal stability, confirming an enhanced catalytic activity of ORR for MnO2/Co3O4-1-1 composite materials for ORR. These results confirm that the prepared Co3O4/MnO2 composite materials are promising air electrode candidates for the energy storage and conversion technologies.

Electrochemical mechanisms of activated carbon, α-MnO2 and composited activated carbon-α-MnO2 films in supercapacitor applications

Pure α-MnO2 and activated carbon-MnO2 (AC-MnO2) films coated on Ni foam by electrophoretic deposition were applied as a supercapacitor electrode. The specific capacitance of AC-MnO2 films (155.03 F g−1) surpasses those of the pure AC (110.62 F g−1) and pure MnO2 film in the 1 M NaOH electrolyte. EDX and XPS detect an increase in the Na content and the reduction of Mn4+ to Mn3+ on the discharged MnO2 electrode (at 0.0 V), whereas a decrease in the Na content and the oxidation of Mn3+ to Mn4+ were obtained on the charged MnO2 electrode (at 0.45 V). Computational simulation of the Na inserted α-MnO2 structure displays the connection of Na to O atoms and the increasing electron density on Mn atoms. EDX of the charged AC-MnO2 (at −1.0 V) film detects a rise in the Na and a fall in the O contents, but the discharged AC-MnO2 film (at 0.0 V) shows a decrease in Na and increase in O contents. The AC-MnO2 film could retain 82.29% of the initial specific capacity after 10,000 cycles. Four series-supercapacitor coin cell assembled from the AC-MnO2 anode and MnO2 cathode delivers a power density of 2.79 kW kg−1 and an energy density of 168.8 Wh kg−1.

Synthesis of three-dimensional β-MnO2/PPy composite for high-performance cathode in zinc-ion batteries

Mn-based materials as a cathode have drawn much attention in aqueous zinc-ion batteries (AZIBs) for its advantages of low cost and environmental friendliness. However, the sluggish reaction kinetics and low structural stability still limit the electrochemical application of Mn-based materials. Herein, a β-MnO2/ polypyrrole (PPy) composite was synthesized using a facile hydrothermal method. It delivered a remarkable specific discharge capacity of 361.8 mAh g−1 at a current density of 0.2 A g−1 and great rate performance compared to pure MnO2 powder. And morphological and electrochemical characterizations revealed that the enhanced electrochemical performance of β-MnO2/PPy composite was mainly attributed to the high conductivity of PPy nanowires and the 3D mesoporous microsphere structure, which was assembled by β-MnO2 nanorods and PPy nanowires. This article provided a new sight of synthesizing Mn-based materials/conducting polymer composites for high-performance cathode in zinc-ion batteries.

MnxOy embedded within CNT supporting porous carbon for enhanced lithium storage

Achievement of improved structural stability and conductivity for Mn-based oxides is the crucial premise for them to be high-performance anodes of lithium-ion batteries due to their large volume effect and poor intrinsic conductivity. Herein, the lithium storage performance of the MnxOy nanoparticles containing dominant MnO and slight MnO2 and Mn3O4 has been significantly improved by embedding them into a CNT supporting porous carbon. This composite is therefore denoted as CNT/MnxOy/C. The comparison results of the electrochemical performance of thus CNT/MnxOy/C with CNT/Mn3O4 and pure Mn3O4 nanoparticles demonstrate that the well-designed synergistic effect of high conductive CNT support and flexible spongy porous carbon is responsible for its improved performance, which efficiently enhances not only the structural stability but also the electrochemical kinetics of the CNT/MnxOy/C. As a result, this CNT/MnxOy/C anode shows outstanding performance, obtaining high capacities of 936.5 and 410.5 mAh g-1 at 200 and 1000 mA g-1 after 260 and 800 cycles, respectively. Moreover, this strategy proposed here will be hopefully instructive in constructing other advanced metal oxide nanomaterials toward improved performance of lithium-ion battery anodes.

Influence of nickel doping on MnO2 nanoflowers as electrocatalyst for oxygen reduction reaction

Doping is promising strategy for the alteration of nanomaterials to enhance their optical, electrical, and catalytic activities. The development of electrocatalysts for oxygen reduction reactions (ORR) with excellent activity, low cost and durability is essential for the large-scale utilization of energy storage devices such as batteries. In this study, MnO2 and Ni-doped MnO2 nanowires were prepared through a simple co-perception technique. The influence of nickel concentration on electrochemical performance was studied using linear sweep voltammetry and cyclic voltammetry. The morphological, thermal, structural, and optical properties of MnO2 and Ni-doped MnO2 nanowires were examined by SEM, ICP-OES, FT-IR, XRD, UV–Vis, BET and TGA/DTA. Morphological analyses showed that pure MnO2 and Ni-doped MnO2 had flower-like and nanowire structures, respectively. The XRD study confirmed the phase transformation from ε to α and β phases of MnO2 due to the dopant. It was also noted from the XRD studies that the crystallite sizes of pure MnO2 and Ni-doped MnO2 were in the range of 2.25–6.6 nm. The band gaps of MnO2 and 0.125 M Ni-doped MnO2 nanoparticles were estimated to be 2.78 and 1.74 eV, correspondingly, which can be seen from UV–Vis. FTIR spectroscopy was used to determine the presence of functional groups and M–O bonds (M = Mn, Ni). The TGA/TDA examination showed that Ni-doping in MnO2 led to an improvement in its thermal properties. The cyclic voltammetry results exhibited that Ni-doped MnO2 nanowires have remarkable catalytic performance for ORR in 0.1 M KOH alkaline conditions. This work contributes to the facile preparation of highly active and durable catalysts with improved catalytic performance mainly due to the predominance of nickel.Article HighlightsMnO2 and Ni-doped MnO2 nanowires were synthesized via a facile co-perception approach.Nickel doping in MnO2 induces the formation of wire-like nanostructures.Nickel doping enhances the electrochemical activity and thermal stability of MnO2 nanoflowers.The addition of nickel into MnO2 promoted the catalytic activity for oxygen reduction reaction.A higher catalytic activity was achieved in 0.125 M Ni-MnO2 nanowires.Graphic abstract

Preparation and high-performance lithium storage of intimately coupled MnO2 nanosheets@carbon nanotube-in-nanotube

MnO2 nanosheets@carbon nanotube-in-nanotube is rationally constructed through carbonization of tannic acid-treated zeolitic imidazolate framework-8 string of carbon nanotubes and subsequent chemical reaction of KMnO4 and carbon. The ultrathin MnO2 nanosheets are intimately coupled on the surface of carbon nanotube-in-nanotube. The composite shows large specific surface area (126.6 m2 g−1) and pore volume (0.4 cm3 g−1). Comparative studies of cyclic voltammetry curves and galvanostatic charge-discharge profiles indicate that for MnO2 nanosheets@carbon nanotube-in-nanotube, electrochemical activities and charge-discharge capabilities of MnO2 and carbon are both significantly improved. The cycling measurements reveal that the composite shows much higher reversible capacity and cycling stability than pure MnO2, carbon nanotubes, carbon nanotube-in-nanotube and MnO2 nanosheets@carbon nanotubes. The superior Li storage performance is attributed to synergistic effect of MnO2 nanosheets and carbon nanotube-in-nanotube. The ultrathin nanosheet structure of MnO2 and the unique nanotube-in-nanotube structure of carbon remarkably shorten diffusion paths of Li ions, facilitate transport of electrolyte ions, promote contact between electrode material/electrolyte, improve structural stability of the composite, increase electronic conductivity of MnO2, enhance reaction kinetics.

Enhancing oxygen reduction reaction activity of ε-MnO2 nanoparticles via iron doping

In this study, 3D flower-like MnO2 and Fe–MnO2 nanoparticles were developed using a co-perception method. In the doping manner, the concentration of Fe was raised from 0.025 M to 0.125 M in levels of 0.025 M. The prepared electrocatalysts were calcined at 500 °C. Different analytical techniques, particularly XRD, SEM, UV–Vis, FTIR, TGA/DTA, CV, ICP-OES, BET, and LSV were utilized to analyze the structure, morphology, optical, thermal, and electrochemical activity of 3D flower-like MnO2 and Fe–MnO2 nanoparticles. XRD analysis showed the phase change from ε to λ and the phase of MnO2 and the crystallite sizes of un-doped MnO2 and Fe–MnO2 were between 1.18 and 2.25 nm. Morphological examinations indicated that pure MnO2 and Fe-doped MnO2 have spherical-like flake-flower and agglomerated nanoparticle architectures, respectively. The BET surface area of 0.125 M Fe–MnO2 nanoparticles is 288.2 m2g-1. The bandgap energies of MnO2, 0.05 M Fe-doped MnO2, and 0.125 M Fe-doped MnO2 nanoparticles were determined to be 0.57 eV, 0.18 eV, and 0.14 eV, respectively as evident from UV–Vis. The presence of M − O bonds (M = Mn, Fe) was analyzed by FTIR spectroscopy. The doped MnO2 electrocatalyst shows improved thermal properties owing to the doping effect of iron. The results of CV and LSV measurements reveal that the Fe–MnO2 nanoparticles have an excellent catalytic performance toward the ORR under 0.1 M KOH alkaline conditions.

From manganese oxide to manganese sulphide: Synthesis and its effect on electrochemical energy storage performance

High power pseudocapacitors are extremely relevant to answer specific needs in the current energy transition arena and to implement an efficient renewable energy society. However, literature shows that are still open gaps concerning improvement of their energy density at high power, conversion efficiency, cost and cycle life. Electrodes based on active transition metal compounds, and in particular metal sulphides, evidence high potential to meet these objectives. This work discusses the dependence on the synthesis route of the charge storage mechanism of manganese sulphide-based materials and relates the pseudocapacitive response of these electrodes with their polycrystalline nature. Results reveal that a manganese oxy-sulphide mixture can achieve a high specific capacitance of 231 F.g−1 at 0.5 A/g in a 0.65 V active window. These values represent a 31.5 % increase compared to pure rambergite, γ-MnS, and 436 % compared to pure hausmannite Mn3O4 prepared under the same conditions. Moreover, the results show that manganese oxy-sulphide electrodes are characterized by good charge retention (73%), and superior long term capacity retention (above 86%) after 5000 cycles, evidencing potential for high power energy storage applications.

Tailoring the bandgap of Mn3O4 for visible light driven photocatalysis

The photocatalytic activity of pure Mn3O4 and silver (Ag) modified Mn3O4 nanoparticles have been investigated. The nanoparticles were prepared by using co-precipitation technique. The structural analysis showed that the Ag modified Mn3O4 was successfully synthesized. For instance, a slight shift to lower angle of XRD pattern was observed after Ag doping. Morphological analysis revealed that the particles have an average size of 274 nm, 287 nm and 321 nm for pure, 1% and 3% Ag modified Mn3O4 respectively. The UV–Visible analysis indicated that the bandgap of Mn3O4 decreased with increased Ag content and the band gap is 1.4 eV with the 3% of Ag content. The spectra obtained from DRS were also evaluated through inverse logarithmic derivative method (ILD) to counter check the bandgap values. 3% Ag-modified photocatalysts exhibited the enhanced decolorization efficiency compared to pure Mn3O4 nanoparticles. The pseudo first order kinetic model is used to explain the photocatalytic kinetics of the photocatalyst. The rate constant values are 0.01/min, 0.017/min and 0.024/min for pure Mn3O4, 1% Ag and 3% Ag modified Mn3O4 nanoparticles, respectively.

Using the Interaction between Copper and Manganese to Stabilize Copper Single-atom for CO Oxidation.

The interaction between Cu and Mn has been used to immobilize the Cu single-atom on MnO2 surface by redox-driven hydrolysis. Comprehensive structure and property characterizations demonstrate that the existence of an Cu-Mn interaction on the catalyst surface can effectively restrain the aggregation of Cu single atoms and improve carbon monoxide (CO) oxidation activity. The interaction of forming the Cu-O-Mn entity is beneficial for CO catalytic activity as the migration of reactive oxygen species and the coordination effect of active centers accelerate the reaction. In particular, 3%-Cu1 /MnO2 shows an oxygen storage capacity (OSC) value (342.75 μmol/g) more than ten times that of pure MnO2 (27.79 μmol/g) and has high CO catalytic activity (T90% =80 °C), it can maintain CO conversion of 95 % after 15 cycles. This work offers a reliable method for synthesizing Cu single-atom catalysts and deepens understanding of the interaction effect between single transition metal atoms and supports that can improve the catalytic activity of CO oxidation.

Two-dimensional Mg-doped MnO2@ carbon cloth nanosheets for high performance typical flexible solid supercapacitor

Metal doping MnO2 has better electrochemical performance than pure MnO2. We have demonstrated a facile approach for synthesizing Mg-doped MnO2@ carbon cloth via a typical hydrothermal reaction. The intercalation of Mg2+ rapidly increases the operating window to 1.2 V. Compared to other metal ions (Co2+, Fe3+, Bi2+, Al3+, Cr2+) doping, Mg2+ doping further increases the lattice defects of MnO2, achieving more vacancies, and effectively improving the performance of MnO2. As a flexible symmetric solid supercapacitor (FSSSC), the voltage window can be extended to 2.2 V, and the energy density of FSSSC reaches 2.06 mW h/cm3 at 43.94 mW/cm3. The device can illuminate a 2.2 V LED successfully, showing its huge actual application value.

Hydrothermal Synthesis of Mn3O4/CoS2 as a Promising Photocatalytic Material for Boosting Visible‐Light Photocatalytic Hydrogen Production

Photocatalytic hydrogen evolution has received extensive attention for energy conversion and storage of clean energy. Herein, the composite catalyst Mn3O4/CoS2 is successfully prepared by a hydrothermal method. Photocatalytic hydrogen evolution experiments are conducted by adjusting the amount of Mn3O4. The results show that the composite photocatalyst Mn3O4/CoS2 has higher photocatalytic hydrogen evolution performance. The hydrogen production of the 50 mg Mn3O4/CoS2 composite catalyst at 5 h is 14.95 times and 1.60 times that of pure Mn3O4 and CoS2, respectively, indicating that the 50 mg Mn3O4/CoS2 composite catalyst has good photocatalytic stability. In addition, the structure, morphology, and composition of the prepared catalysts are characterized by scanning electron microcopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET), electrochemical and PL techniques. Compared with Mn3O4 and CoS2, the photocatalytic response of the 50 mg Mn3O4/CoS2 composite catalyst is significantly enhanced, the current density is increased, the fluorescence quenching efficiency is accelerated, and the pore volume and pore size are increased. Therefore, the composite catalyst can accelerate the separation and transfer of photogenerated electrons and holes and improve the photocatalytic efficiency.

Copper-doped manganese tetroxide composites with excellent electrochemical performance for aqueous zinc-ion batteries

Abstract A copper-doped manganese tetroxide (Cu-Mn3O4) composites were prepared for zinc-ion batteries cathode material through a facile synthesis route. The Cu-Mn3O4 is constructed by numerous irregular nanoparticles with a porous micro/nano structure. The Microscopic observation reveals that the Cu2+ embedded in the lattice of manganese oxide by partly substituting Mn3+. Strikingly, at current densities of 100 mA g−1, the Cu-Mn3O4 electrode delivered a higher discharge capacity of 250 mAh g−1 compared with 150 mAh g−1 for the pure Mn3O4 electrode and the coulombic efficiency is almost 100%. The great enhancement of the electrochemical zinc storage performance can be attributed to the improvement of the electronic/ionic conductivity and zinc diffusivity of electrodes. The present results evidence that metal doping can improve the electronic/ionic conductivity of Mn3O4, which may also applicable to other metal oxides.

Co3 O4 Polyhedron@MnO2 Nanotube Composite as Anode for High-Performance Lithium-Ion Batteries.

In this work, a novel lollipop nanostructure of Co3 O4 @MnO2 composite is prepared as anode material in lithium-ion batteries (LIBs). Cobalt metal-organic framework (ZIF-67) is grown on the open end of MnO2 nanotubes via a self-assembly process. The obtained ZIF-67@MnO2 is then converted to Co3 O4 @MnO2 by a simple annealing treatment in air. Scanning electron microscopy, transmission electron microscopy, and X-ray diffraction characterizations indicate that the prepared Co3 O4 @MnO2 takes a lollipop nanostructure with a stick of ≈100nm in diameter, consisting of MnO2 nanotube, and a head part of ≈1µm, consisting of Co3 O4 nanoparticles. The charge-discharge tests illustrate that this unique novel configuration endows the resulting Co3 O4 @MnO2 with excellent electrochemical performances, delivering a capacity of 1080mAh g-1 at 300mA g-1 after 160 cycles, and 696mAh g-1 at 1 A g-1 after 210 cycles, compared with 404mAh g-1 and 590 for pure Co3 O4 polyhedrons and pure MnO2 nanotubes at 300mA g-1 after 160 cycles, respectively. The lollipop configuration consisting of porous Co3 O4 polyhedron and MnO2 nanotube shows excellent structural stability and facilitates lithium insertion/extraction, leading to excellent cyclic stability and rate capacity of Co3 O4 @MnO2 -based LIBs.

Preparation of polyaniline nanorods/manganese dioxide nanoflowers core/shell nanostructure and investigation of electrochemical performances

A hierarchical polyaniline nanorod/manganese dioxide nanoflower (PANI/MnO2) core/shell nanostructure was successfully constructed through in situ polymerization, in which PANI nanorods work as the core and K-birnessite-type MnO2 act as the shell. The core/shell nanostructure effectively increases active surface areas and obviously decreases the ion transmission distance, which is conducive to the efficient contact and transfer of ions. The morphology, the chemical structure, and the crystal phase of PANI/MnO2 were measured by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). Moreover, its supercapacitor behaviors were analyzed by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) tests, showing that this nanostructure exhibits better electrochemical activity and higher capacitance performance than pure PANI nanorods and pure MnO2. In 1.0 M Na2SO4 electrolyte solution, the specific capacitance of PANI/MnO2 is 215 F g−1 at 0.30 A g−1.

α-MnO2 nanorods-polyaniline (PANI) nanocomposites synthesized by polymer coating and grafting approaches for screening EMI pollution

In this work, α-MnO2 nanorods-polyaniline nanocomposites were synthesized using polymer coating and grafting approaches. The synthesized nanocomposites were characterized by XRD, FESEM, EDAX, TEM, TG-DTA and FT-IR techniques. The Electromagnetic properties of prepared samples were measured using vector network analyzer in the 8–18 GHz (X and Ku-Band) frequency region. The α-MnO2-NH2-PANI nanocomposite synthesized by grafting approach showed better electrical conductivity, excellent dielectric loss with superior microwave absorption ability. In comparison with pure MnO2, the microwave absorption characteristics of α-MnO2-NH2-PANI nanocomposite display considerable improvements, with an effective absorption band at 10.8 GHz and 14.5 GHz under −10 dB and minimum reflection loss (RL) of −30.79 dB at 14.5 GHz. The α-MnO2-NH2-PANI sample also showed considerable shielding effectiveness (SE) i.e. −20.85 dB in the 8–18 GHz frequency region. The observed value of RL and SE surpasses the required value for being utilized at a commercial level. These results are surely helpful to explore the microwave absorption study of different combinations of organic/inorganic nanocomposite materials particularly for shielding and microwave absorption applications.

Inhibition of Manganese Dissolution in Mn2O3 Cathode with Controllable Ni2+ Incorporation for High‐Performance Zinc Ion Battery

AbstractManganese‐based materials are considered potential cathode materials for aqueous zinc ion batteries (ZIBs). However, the dissolution of manganese leading to an abrupt decline of capacity and the sluggish electrochemical reaction kinetics are still the main bottlenecks restricting their further development. Herein, a NiMn‐layered double hydroxide‐derived Ni‐doped Mn2O3 (NM) is developed to suppress the dissolution of manganese. The incorporation of Ni2+ can promote electronic rearrangement and enhance the conductivity, ultimately improving the reaction kinetics and electrochemical performance of the NM. Moreover, the doped Ni2+ can effectively stabilize the MnO bond of Mn2O3 by reducing the formation energy. In addition, the storage mechanism based on the simultaneous insertion and transformation of H+ and Zn2+ is demonstrated. Interestingly, the Ni‐doped Mn2O3 shows a high specific capacity of 252 mAh g–1 (0.1 A g–1), three times more than the pure Mn2O3 (72 mAh g–1). The capacity retention (≈85.6% over 2500 cycles at 1.0 A g–1) is also more excellent when comparing with the Mn2O3 cathode (≈49.7%). Significantly, an ultra‐high energy density of 327.6 Wh kg–1 has been achieved using Ni‐doped Mn2O3 cathode, which suggests that the synergistic effect of manganese and other transition metal ions provide a promising strategy for future development of ZIBs.

Assembly of Mn3O4 nanoparticles at low temperature on graphene with enhanced electrochemical property for zinc-ion battery

Zn-ion batteries stand out as an energy storage solution for the large-scale equipment because of the security, nontoxicity as well as relatively low cost. In this work, assembling GO with Mn3O4 at low temperature can not only construct a well-defined nanoscale crystallization, but also surmount the poor electrochemical performance of pure Mn3O4. The typical Mn3O4/GO composites exhibit a stable discharge capacity of 215.6 mA h g−1 at 0.1 A g−1. At high current density of 1 A g−1, the cathode can also exhibit an excellent and satisfactory cycling stability of 85.0% after 500 cycles. It distinctly reveals that this work not only provides a simple strategy to create a well-defined nanoscale crystallization with transition metal oxides, but also make fully utilize to the synergistic effects of the porous structure of the nanoscale Mn3O4 and GO, which presents a promising cathode material for Zn-ion batteries.

Decoration of CeO2 nanoparticles on hierarchically porous MnO2 nanorods and enhancement of supercapacitor performance by redox additive electrolyte

Pure CeO2 nanoparticles (NPs) and MnO2 nanorods (NRs) have been prepared by the hydrothermal technique. The CeO2 NPs were uniformly coated over the MnO2 NRs through a facile ultrasonic technique. The uniform distribution of CeO2 NPs over MnO2 NRs has been analysed by scanning electron microscopy. Crystalline phases of pure CeO2, MnO2, and the formation of CeO2 NPs decorated MnO2 NRs have been studied by XRD analysis. The absence of inorganic residuals over the prepared nanomaterials was confirmed by FT-IR analysis. The surface chemical composition and the formation of CeO2 NPs decorated MnO2 NRs have been studied by XPS analysis. The electrochemical performances of the prepared sample have been studied in 3 M aqueous KOH electrolyte and 0.2 M K4[Fe(CN)6] added 3 M KOH electrolyte. CeO2 nanoparticles decorated MnO2 nanorods exhibited the superior capacitance of 1058.2 Fg−1.