Decoration Of Pt Nanoparticles Research Articles

Micellar Nanoreactors Enabled Site-Selective Decoration of Pt Nanoparticles Functionalized Mesoporous SiO2 /WO3-x Composites for Improved CO Sensing.

Site-selective and partial decoration of supported metal nanoparticles (NPs) with transition metal oxides (e.g., FeOx ) can remarkably improve its catalytic performance and maintain the functions of the carrier. However, it is challenging to selectively deposit transition metal oxides on the metal NPs embedded in the mesopores of supporting matrix through conventional deposition method. Herein, a restricted in situ site-selective modification strategy utilizing poly(ethylene oxide)-block-polystyrene (PEO-b-PS) micellar nanoreactors is proposed to overcome such an obstacle. The PEO shell of PEO-b-PS micelles interacts with the hydrolyzed tungsten salts and silica precursors, while the hydrophobic organoplatinum complex and ferrocene are confined in the hydrophobic PS core. The thermal treatment leads to mesoporous SiO2 /WO3-x framework, and meanwhile FeOx nanolayers are in situ partially deposited on the supported Pt NPs due to the strong metal-support interaction between FeOx and Pt. The selective modification of Pt NPs with FeOx makes the Pt NPs present an electron-deficient state, which promotes the mobility of CO and activates the oxidation of CO. Therefore, mesoporous SiO2 /WO3-x -FeOx /Pt based gas sensors show a high sensitivity (31±2 in 50ppm of CO), excellent selectivity, and fast response time (3.6s to 25ppm) to CO gas at low operating temperature (66°C, 74% relative humidity).

Piezoelectric effect enhanced plasmonic photocatalysis in the Pt/BaTiO3 heterojunctions

The use of piezoelectric internal field to assist in photocatalysis is important for inexpensive and high-efficiency catalytic techniques. In this study, novel Pt/BaTiO3 heterojunctions were prepared via decoration of Pt nanoparticles (PtNPs) on the surface of piezoelectric BaTiO3 nanocubes through a facile photoreduction process. The photocatalytic, piezo-catalytic, and piezo-photocatalytic activities of the Pt/BaTiO3 heterojunctions for methyl orange (MO) degradation were investigated under ultrasonic excitation and/or full-spectrum light irradiation. The weight percentage of PtNPs, piezoelectric internal field of BaTiO3, and plasmonic effect have been proven important for the photocatalytic activity of the heterojunctions. The Pt0.25/BaTiO3 with 0.25 wt% PtNPs exhibited an optimum photocatalytic degradation performance of 92.5% for MO in 50 min under full-spectrum light and ultrasonic co-excitation, and this value was about 1.35 times higher than the degradation rate under full-spectrum light irradiation alone. Well-dispersed PtNPs in the Pt/BaTiO3 heterojunction can be excited by incident light to generate an electromagnetic field caused by the surface plasmon resonance (SPR) effect, which drives the collective oscillation of electrons and generate hot electron–hole pairs. The piezoelectric internal field generated in BaTiO3 due to ultrasonic excitation can improve the separation efficiency of SPR-induced hot charge carriers and contribute to the production of highly reactive oxidation radicals, thereby enhancing the catalytic capability of the heterojunction to oxidize organic dyes. This study introduces the piezoelectric effect of BaTiO3 into plasma photocatalysis to enhance the photocatalytic activity of Ptx/BaTiO3 heterojunction, and this effect can be extended to other piezoelectric material systems to provide an effective technology for environmental purification.

Piezoelectric Effect Enhanced Photocatalytic Activity of Pt/Bi3.4Gd0.6Ti3O12 Plasmonic Photocatalysis

Novel Pt/Bi3.4Gd0.6Ti3O12 heterojunction was synthesized by a decoration of Pt nanoparticles (PtNPs) on the surface of piezoelectric Bi3.4Gd0.6Ti3O12 (BGTO) through an impregnation process. The photocatalytic, piezo-catalytic, and piezo-photocatalytic activities of the Pt/BGTO heterojunction for methyl orange (MO) degradation were investigated under ultrasonic excitation and whole spectrum light irradiation. The internal piezoelectric field of BGTO and a plasmonic effect have been proven important for the photocatalytic activity of the heterojunctions. Pt/BGTO exhibited an optimum photocatalytic degradation performance of 92% for MO in 70 min under irradiation of whole light spectrum and ultrasonic coexcitation, and this value was about 1.41 times higher than the degradation rate under whole spectrum light irradiation alone. The PtNPs in Pt/BGTO heterojunction can absorb the incident light intensively, and induce the collective oscillation of surface electrons due to the surface plasmon resonance (SPR) effect, thus generating “hot” electron–hole pairs. The internal piezoelectric field produced in BGTO by ultrasonic can promote the separation of SPR-induced “hot” charge carriers and facilitate the production of highly reactive oxidation radicals, thus enhancing Pt/BGTO heterojunction′s photocatalytic activity for oxidizing organic dyes.

Asymmetrically coating Pt nanoparticles on magnetic silica nanospheres for target cell capture and therapy.

AJanus cargo has been developedvia the combination of magnetic mesoporous silica (MMS) with asymmetric decoration of Pt nanoparticles (PtNPs). Mesoporous morphology of MMS provides plenty of space for loading photosensitizers and targeting agents; the magnetic feature endows the as-formed nanospheres with satisfactory isolation function in removal of low abundant target cells. The excellent catalytic ability of PtNPs can effectively alleviate the hypoxia condition of tumor microenvironment via the decomposition of hydrogen peroxide (H2O2), as well as an O2-drived nanomotor for highly efficient drug release. Using CCRF-CEM as the model target cell, the Janus cargo is demonstrated to possess significantly improved performance in cell capture and photodynamic therapy. Specially, owing to the patchy Pt decoration, the loaded photosensitizers exhibit a more efficient release behavior. More importantly, asymmetric O2-emission from one side of the nanocargo acts as a driving force, which could effectively accelerate the motion ability of cargo in cell media, thus leading to an enhanced therapeutic effect compared withthe traditionally symmetric nanocargo. This Janus cargo would offer a new paradigm to design highly efficient drug carrier for gaining an improved photodynamic therapy in hypoxic cancer cells.

Ionic Liquid Mediated Decoration of Pt Nanoparticles on Graphene and Its Electrocatalytic Characteristics

In most of the conventional ionic liquid (IL) or poly-ionic liquid (PIL) mediated Pt carbon catalyst preparations, IL or PIL are covalently linked to the carbon involving complex reaction procedures. IL or PIL acts as the interface between Pt and carbon which increases the internal resistance of the material resulting in high overpotentials for electrocatalysis. In this regard we present a novel methodology to ionically tag IL to graphene that can easily be removed during the chemical reduction procedure for Pt decoration. We successfully prepared platinum nanparticles decorated on ionic liquid treated graphene (Pt-TMIm-rGO) material using a simple and scalable preparation method and systematically characterized. To understand the electrocatalytic efficiency of the material prepared, oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) characterization were studied and benchmarked with commercial counterparts. X-ray photoelectron spectroscopy results revealed a modulation of d-band centre of Pt and strong metal substrate interaction that reduced the over potential and increased durability. Pt-TMIm-rGO showed very high mass activity, low over potential compared to its counterparts in both ORR and MOR catalytic reactions. Pt-TMIm-rGO showed a high mass activity of ∼346 A g−1 at 0.9 V vs RHE in the case of ORR and 195.2 mA g−1 in case of MOR at 0.86 V vs RHE.

High Performance MEMS of Pt Single Atoms Loaded on ALD ZnO Layer

Introduction Single atom catalysts have draw increasing attention of enormous researchers due to its atomically disperation on supports, high efficiency and high catalytic performance. Despite those obvious advantages, there is still rare study about the single atom catalyst’s application in sensors. It was firstly reported the palladium single atoms on TiO2 used as a photocatalytic sensing platform to analyzed organophosphorus pesticide chlorpyrifos[1]. Catalyst-based sensing platform opens up a new pathway for exploring novel strategy of design sensors. Micro-electro-mechanical system (MEMS) process have advantages such as, miniaturization, small size, mechanical parts high resonance frequency, and low power consumption. However, the MEMS prepared by traditional method possess poor stability. Here, we employed the atomic layer deposition to prepare ZnO layer on MEMS. Atomic layer deposition (ALD) is a powerful technique for depositing nanoparticles or thin films and has outstanding advantages, including precise control of size and thickness and excellent uniformity[2], except that the substrate is exposed separately to each gaseous precursor and that the deposition is broken into cycles[3]. ALD functionalized method could gain high performance in thermal stability, mechanical and catalytic performance[4]. It was interesting to obtain single atom MEMS sensors via ALD. Method Prior to ALD, MEMS (Shanghai lingpan Electronic Technology Co., Ltd) were put into ethanol and cleaned by ultrasonic agitation for ten minutes. MEMS were put on quartz wafers and dried in air. ZnO films were deposited onto the MEMS by a hot-wall, closed-chamber ALD reactor. N2 (99.999%) was used as carrier gas. The precursors of ZnO were diethyl zinc and water (H2O). Water acts as an oxidant and enables growth over a wide temperature range. The deposition temperature was 150 °C, and the diethyl zinc was kept at room temperature. After the deposition of ZnO layers, Pt single atoms ALD was subsequently deposited with (methylcyclopentadienyl)trimethylplatinum (MeCpPtMe3) and O3 as precursors at the same temperature as our precious work[2]. Ultimately, the MEMS sensors were tested. Results and Conclusions Fig.1 Response performance for ALD SnO2 layer on MEMS It can be seen from the Fig.1 that sensor response increased with the concentration increase gradually. With the concentration increase for about 1 PPM, response value of sensors gradually reduced. It could also be seen that ALD ZnO sensor have a response time of 90 s and recovery time of 120 s. Baseline with drift less than 4 also demonstrated its good stability. It has little increase in response performance as the concentration increased to 80 PPM, it could be caused by the surface electron transfer arrived balance within high concentrations References [1] X. Ge, P. Zhou, Q. Zhang, Z. Xia, S. Chen, P. Gao, Z. Zhang, L. Gu, S. Guo, Palladium single atoms on TiO2 as a photocatalytic sensing platform for analyzing organophosphorus pesticide chlorpyrifos, Angew Chem Int Ed Engl, (2019).[2] Q. Hu, S. Wang, Z. Gao, Y. Li, Q. Zhang, Q. Xiang, Y. Qin, The precise decoration of Pt nanoparticles with Fe oxide by atomic layer deposition for the selective hydrogenation of cinnamaldehyde, Applied Catalysis B: Environmental, 218 (2017) 591-599.[3] Z. Gao, Y. Qin, Design and Properties of Confined Nanocatalysts by Atomic Layer Deposition, Acc Chem Res, 50 (2017) 2309-2316.[4] M.M. Biener, J. Biener, A. Wichmann, A. Wittstock, T.F. Baumann, M. Baumer, A.V. Hamza, ALD functionalized nanoporous gold: thermal stability, mechanical properties, and catalytic activity, Nano Lett, 11 (2011) 3085-3090. Figure 1

Facile, Rapid, and Well‐Controlled Preparation of Pt Nanoparticles Decorated on Single Surface of Mos2 Nanosheets and Application in HER

AbstractRecently, asymmetrically functionalized two‐dimensional (2D) nanomaterials have attracted fevered interest as excellent candidates for building blocks of multifunctional and multidimensional systems due to the structural symmetry‐breaking. However, their preparation process typically involves high vacuum environment or specific equipment, and the obtained samples have poor stability and low yield. In this study, a facile approach has been developed to achieve the asymmetric deposition of platinum nanoparticles (NPs) onto single side of the molybdenum disulfide (MoS2) nanosheets by pyrogenic decomposition and in‐situ functionalization. By tuning the platinum precursor to MoS2 ratio, the size distribution and morphology of the Pt NPs can be well controlled. The asymmetrical decoration of Pt NPs on MoS2 nanosheets (Pt−MoS2) may result from the superior interactions between Pt NPs and MoS2 basal surface, which are stronger than the van der Waals force between adjacent MoS2 layers. Hydrogen evolution reaction (HER) results show that higher Pt loading yields better HER performance with low overpotential of 120 mV and superior Tafel slope of 28 mV ⋅ dec−1. Significantly, the current synthetic method can be used in the asymmetrical functionalization of other 2D nanosheets as well, and could greatly advance the facile preparation and practical applications of these asymmetric nanostructures.

Phase & morphology engineered surface reducibility of MnO2 nano-heterostructures: Implications on catalytic activity towards CO oxidation

An understanding of the surface reducibility of a catalytically active oxide support is a pre-requisite to understanding its catalytic behavior. In this work, we report that through a stringent control over the phase and morphology of catalytically active MnO2 supports, a control over the surface reducibility can be achieved. Through temperature-programmed reduction (TPR), we prove a higher availability of lattice oxygen for the α-MnO2 phase, compared to that of β-MnO2. Furthermore, by modifying the synthesis method, we could engineer the morphology of the α-phase into nanoflowers which in turn leads to a higher surface area, further enhancing the activity. On the engineered support, decoration of Pt nanoparticles can lower the full conversion temperature for CO oxidation at a considerably low temperature.

Construction of Pt/graphitic C3N4/MoS2 heterostructures on photo-enhanced electrocatalytic oxidation of small organic molecules

Low temperature fuel cells, with the features of clean, environmental friendliness, and high energy density, are considered as ideal future green energy sources. It has been recently demonstrated that the activities and stabilities of traditional fuel cell reactions can be improved by using photo-functional electrodes with assistance of light illumination. Two-dimensional (2D) heterostructure of g-C3N4/MoS2 was demonstrated to be a promising photocatalyst. Herein, we used g-C3N4/MoS2 nanosheets as a photo-functional substrate for the decoration of Pt nanoparticles and then applied on fuel cell electrocatalytic reactions. Comparing with traditional electrocatalytic reactions, the electrocatalytic performances of the as-synthesized Pt/g-C3N4/MoS2 for the oxidation of methanol, ethanol, and formic acid upon visible light illumination are improved with 6.5, 2.2, and 2.5 times, respectively. The decisive factors in the improved catalytic performances are the synergistic effect of photo&electro-process and the effective charge separation in the designed 2D/2D g-C3N4/MoS2 heterostructure.

Pt-Functionalized PdO Nanowires for Room Temperature Hydrogen Gas Sensors.

In this work, we prepared a well-aligned palladium oxide nanowire (PdO NW) array using the lithographically patterned Pd nanowire electrodeposition (LPNE) method followed by subsequent calcination at 500 °C. Sensitization with platinum (Pt) nanoparticles (NPs), which were functionalized on PdO NWs through a simple reduction process, significantly enhanced the detection capability of the Pt-loaded PdO NWs (Pt-PdO NWs) sensors toward hydrogen gas (H2) at room temperature. The well-distributed Pt NPs, which are known chemical sensitizers, activated the dissociation of H2 and oxygen molecules through the spillover effect with subsequent diffusion of these products to the PdO surface, thereby transforming the entire surface of the PdO NWs into reaction sites for H2. As a result, at a high concentration of H2 (0.2%), the Pt-PdO NWs showed an enhanced sensitivity of 62% (defined as Δ R/ Rair × 100%) compared to that (6.1%) of pristine PdO NWs. The Pt-PdO NWs exhibited a response time of 166 s, which was 2.68-fold faster than that of pristine PdO NWs (445 s). In addition, the Pt-PdO NWs responded to a very low concentration of H2 (10 ppm) with a sensitivity of 14%, unlike the pristine PdO NWs, which did not exhibit any response at that concentration. These outstanding results are mainly attributed to a homogeneous decoration of Pt NPs on the surface of well-aligned PdO NWs. In this work, we demonstrated the potential suitability of Pt-PdO NWs as a highly sensitive H2 sensing layer at room temperature.

Pt-decorated SnO2 nanotubes prepared directly on a conducting substrate and their application in solar energy conversion using a solid polymer electrolyte

We report the electrostatic decoration of Pt nanoparticles on SnO2 nanotubes (ST) directly prepared on a conducting substrate and high electrocatalytic activities of the resulting materials. A pre-coating of poly(vinyl acetate) (PVAc) is the key for the direct uniform deposition of the ST, which serves dual functions as a fast electron transport path as well as a physical support for Pt nanoparticles. The self-assembly of Pt nanoparticles on the ST is based on electrostatic interaction between the Pt cations and negatively charged ST surface. A dip-coating method leads to homogeneous decoration of well-connected Pt nanoparticles with a larger surface area. Solar energy conversion devices with a solid polymer electrolyte are fabricated using Pt on ST as the electrocatalyst for the reduction of I3− to I−. The Pt dip-coated ST shows a photovoltaic efficiency of 5.07%, which is higher than those of Pt spin-coated ST (4.88%) and Pt spin-coated on the substrate without ST (4.59%). An increase in the Pt concentration leads to further improvement in the efficiency up to 5.51%, which is a moderate value for solid electrolyte devices. The improved performance is attributed to the decreased electron transfer resistance and increased surface area of the electrode.

Surface Decoration of Pt Nanoparticles via ALD with TiO2 Protective Layer on Polymeric Nanofibers as Flexible and Reusable Heterogeneous Nanocatalysts

Coupling the functional nanoheterostructures over the flexible polymeric nanofibrous membranes through electrospinning followed by the atomic layer deposition (ALD), here we presented a high surface area platform as flexible and reusable heterogeneous nanocatalysts. Here, we show the ALD of titanium dioxide (TiO2) protective nanolayer onto the electrospun polyacrylonitrile (PAN) nanofibrous web and then platinum nanoparticles (Pt-NP) decoration was performed by ALD onto TiO2 coated PAN nanofibers. The free-standing and flexible Pt-NP/TiO2-PAN nanofibrous web showed the enhancive reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) within 45 seconds though the hydrogenation process with the degradation rate of 0.1102 s−1. The TiO2 protective layer on the PAN polymeric nanofibers was presented as an effective route to enhance the attachment of Pt-NP and to improve the structure stability of polymeric nanofibrous substrate. Commendable enhancement in the catalytic activity with the catalytic dosage and the durability after the reusing cycles were investigated over the reduction of 4-NP. Even after multiple usage, the Pt-NP/TiO2-PAN nanofibrous webs were stable with the flexible nature with the presence of Pt and TiO2 on its surface.

Two dimensional perovskite La 2 Ti 2 O 7 nanosheet as Pt catalyst support for photo-assisted methanol oxidation reaction

Abstract In this paper, two dimensional (2D) perovskite La 2 Ti 2 O 7 (LTO) nanosheet was synthesized and used as support for the decoration of Pt nanoparticles. Ultrasmall Pt nanoparticles with a diameter of 4.5 nm were well dispersed on the surface of LTO nanosheets. By using as-prepared Pt-LTO as working electrode, great improvement of photoelectrocatalytic activity for methanol oxidation reaction (MOR) was achieved under light irradiation. The Pt-LTO electrode showed 10.6 times enhanced catalytic activities of MOR under light illumination compared to dark condition. The unique of 2D structures as well as synergistic effect of electrocatalytic and photocatalytic result in the improvement of catalytic performance. The mechanism of above improved photoelectrocatalytic performance is also proposed.

Thermodynamically controlled Pt deposition over graphene nanoplatelets: Effect of Pt loading on PEM fuel cell performance

Graphene is considered as a promising catalyst support for polymer electrolyte membrane (PEM) fuel cells because of its excellent properties. Recent studies showed that electrocatalytic activity, fuel cell performance, catalyst utilization efficiency and long term durability can be improved by using graphene as the catalyst support. In here, we report the synthesis of graphene nanoplatelets (GNPs) supported platinum catalysts using supercritical carbon dioxide (scCO2) deposition technique. The prepared catalysts were characterized in terms of their structure, morphology and thermal behavior by using X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The electrocatalytic and half-cell performances of the as-prepared catalysts were investigated by cyclic voltammetry (CV) and PEM fuel cell performance testing. Small size and well distribution of Pt nanoparticles on GNPs surfaces were achieved by using scCO2 deposition which improves the PEM fuel cell performance. To the best of our knowledge decoration of Pt nanoparticles on GNPs via scCO2 deposition and their detailed fuel cell performances were presented for the first time in the literature.

The precise decoration of Pt nanoparticles with Fe oxide by atomic layer deposition for the selective hydrogenation of cinnamaldehyde

The decoration of noble metal-based catalysts with metal oxides can improve their catalytic performance for the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol (COL) due to the interaction between the noble metal and metal oxides. Here, we used atomic layer deposition (ALD) to decorate Pt nanoparticles precisely with Fe oxides. The selectivity to COL increased from 45% for the bare Pt catalyst to 84% for the Pt-based catalyst after 30 cycles of decoration with Fe oxide by ALD. A series of characterizations demonstrated that the precise blocking of low coordinated Pt sites with Fe oxide by ALD, generating Pt-FeOx interfacial perimeter sites, and the interaction between the Pt nanoparticles and Fe oxide led to high selectivity to COL. This precise decoration and the formation of interfacial perimeter sites by ALD provide a promising route for the design of advanced catalysts.

Chlorobenzene sensor based on Pt-decorated porous single-crystalline ZnO nanosheets

Detection of chlorobenzene is a challenge for metal oxide gas sensors because of its stable molecule structure. In this work, Pt-decorated porous single-crystalline ZnO nanosheets (PSC ZnO NSs) were successfully synthesized via a one-pot hydrothermal method followed by a liquid phase reduction process. The morphology and structure of the as-prepared sample were well characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy dispersive spectrum (EDS) and ICP-MS analysis. From gas-sensing test, it can be found that the decoration of Pt nanoparticles largely enhanced the sensing performance of the PSC ZnO NSs. The Pt-decorated PSC ZnO NSs showed good response to low concentrations of chlorobenzene from 10 to 500ppb. In contrast, the Au and Ag-decorated PSC ZnO NSs had still no response to 500ppb of chlorobenzene. The enhancement sensing mechanism of Pt nanoparticle decoration has also been discussed in detail.

Uniform decoration of Pt nanoparticles on well-defined CdSe tetrapods and the effect of their Pt cluster size on photocatalytic H2generation

Direct decoration of Pt nanoparticles onto CdSe tetrapods with controlled sizes and their photocatalytic H2generation efficiency.

Facile Synthesis of Pt Nanoparticles/ZnO Nanorod Arrays for Photoelectrochemical Water Splitting

A simple and facile chemical route is used to synthesize Pt nanoparticles (NPs) on ZnO nanrods (NRs) for use as photoelectrodes. The EDS and XPS results show that the loading amount of Pt NPs increases with the concentration of Pt precursor, but the metallic state of Pt element in NPs decreases. Photoluminescence and electrochemical impedance measurements demonstrate that the decoration of Pt NPs achieves efficient separation efficiency of photogenerated electron-hole pairs and fast charge transfer, respectively. Notably, the photoelectrochemical (PEC) results clearly show that Pt-decorated ZnO NRs have greater PEC activity and stability compared to pristine ZnO NRs.

Pt Nanoparticle-Decorated ZnO Nanowire Sensors for Detecting Benzene at Room Temperature

Room temperature gas sensing ability for low concentrations of benzene was successfully realized with Pt nanoparticle-decorated networked ZnO nanowire sensors. For decoration of Pt nanoparticles, gamma-ray radiolysis was used. The Pt decoration greatly enhanced benzene sensing performances. Importantly, even at room temperature, ppm level benzene was clearly detected, which is likely to be due to the combined effect of electronic and chemical sensitizations by Pt nanoparticles.

A metal-decorated nickel foam-inducing regulatable manganese dioxide nanosheet array architecture for high-performance supercapacitor applications

Three dimensional manganese dioxide/Pt/nickel foam (shortened to MnPtNF) hybrid electrodes were prepared by double-pulse polarization and potentiostatic deposition technologies for supercapacitor applications. The decoration of Pt nanoparticles onto nickel foam varies the nucleation mechanism of the manganese dioxide species, inducing the formation of manganese dioxide nanosheets. Additionally, controlling the size of the Pt nanoparticles leads to modulated nanosheet architecture and electrochemical properties of the manganese dioxide electrode, as revealed by XRD, Raman spectra, SEM, TEM, cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The nanosheet architecture of the MnPtNF electrode favors the transportation of electrons and ions, which results in the enhanced electrochemical properties. Importantly, the optimized MnPtNF electrode obtains a maximum specific capacitance of 1222 F g(-1) at 5 A g(-1) (89% of the theoretical specific capacitance of MnO2) and 600 F g(-1) at 100 A g(-1). Moreover, the presence of Pt nanoparticles in the MnO2 electrode effectively improves its cycling stability, which is confirmed by the increase of the specific capacitance retention from 14.7% to 90% after 600 cycles.