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1.
A novel Ni9S8/C electrocatalyst for methanol oxidation reaction (MOR) is synthesized by a simple, cost-effective and one-pot strategy. The electrocatalyst Ni9S8 composed of micro and nanoparticles encapsulated inside carbon layers serves as carbon-supporter and fast ion and electron mobilization through the Ni9S8/C support materials. The sizes of Ni9S8/C nanoparticles range from 2.4 to 7.99 nm, reveals large surface area availability with plenty of active sites for electro-oxidation of methanol. The oxidation performance of electrocatalyst is determined in different solution of methanol and alcohol at various scan rates. At a scan rate of 50 mV s−1, the Ni9S8/C catalyst delivers total 52 mA cm−2 current density for 1.75 V potential (vs RHE) for 1 M KOH and 0.5 M methanol. The electrocatalyst shows low Rct circle and linear chronoamperometric graph for 5000 s, which demonstrate the outstanding stability of the electrocatalyst for methanol electro-oxidation reaction.  相似文献   

2.
Water splitting is an appealing way of producing hydrogen fuel, which requires efficient and affordable electrode materials to make the overall process viable. In the last couple years, abundant transition metals (and their compounds and hybrids) attracted ever-growing attention as the alternatives of noble metals. Particularly the layered transition metal dichalcogenide (TMDs) are interesting with their stability and promising electrocatalytic performance for hydrogen evolution reaction (HER). However, the neat TMDs are often poor in terms of the abundance of catalytically active sites and electrical conductivity, which limit their application potential significantly. Herein, as a proof-of-concept, we report on the design of a high-performance electrocatalyst system formed by the decoration of ultrasmall molybdenum sulfide (MoS2) nanosheets on carbon nanotubes (CNTs). The ultrasmall MoS2 nanosheets provide distorted lattice, confined size and rich defects, which endows the resulting electrocatalysts (MoS2/CNT) with abundant active sites. The CNTs, on the other hand, serve as the conductive net for ensuring electrocatalytic performance. As a result, the hybrid electrocatalyst exhibits excellent electrocatalytic performance for HER, achieving a large current density of 100 mA cm−2 at overpotential of only 281 mV and a small Tafel slope of 43.6 mV dec−1 along with a decent stability. Our results are of high interest for electrocatalyst technologists as well as hydrogen fuel researchers.  相似文献   

3.
In the present work, a porous carbonaceous platform containing zirconium oxide was used for spreading Ni nanoparticles, and applied to methanol oxidation. The platform was obtained by calcination of a metal-organic framework (MOF) attached to graphene oxide. Nickel nanoparticles were then deposited on the nanocomposite by chemical reduction from a Ni2+ solution. The obtained electrocatalyst was characterized by different methods. An excellent electrocatalytic behavior was observed towards methanol oxidation in alkaline medium (j ~ 240 mA cm?2 or ~ 626 mA mg?1 in 1.0 M methanol). The results of methanol oxidation by various electrochemical studies (cyclic voltammetry, electrochemical impedance spectroscopy, chronoamperometry and chronopotentiometry) revealed the effective synergy between reduced graphene oxide, porous carbon material, ZrO2 metal oxide and Ni nanoparticles. Good durability and stability of the proposed electrocatalyst and significantly increased current density of methanol oxidation suggest it as a potential alternative for Pt-based electrocatalysts in direct methanol fuel cells.  相似文献   

4.
The electrooxidation of methanol and ethanol was investigated in acidic media on the platinum–nickel nanoparticles carbon-ceramic modified electrode (Pt–Ni/CCE) via cyclic voltammetric analysis in the mixed 0.5 M methanol (or 0.15 M ethanol) and 0.1 M H2SO4 solutions. The Pt–Ni/CCE catalyst, which has excellent electrocatalytic activity for methanol and ethanol oxidation than the Pt–Ni particles glassy carbon modified electrode (Pt–Ni/GCE), Pt nanoparticles carbon-ceramic modified electrode (Pt/CCE) and smooth Pt electrode, shows great potential as less expensive electrocatalyst for these fuels oxidation. These results showed that the presence of Ni in the structure of catalyst and application of CCE as a substrate greatly enhance the electrocatalytic activity of Pt towards the oxidation of methanol and ethanol. Moreover, the presence of Ni contributes to reduce the amount of Pt in the anodic material of direct methanol or ethanol fuel cells, which remains one of the challenges to make the technology of direct alcohol fuel cells possible. On the other hand, the Pt–Ni/CCE catalyst has satisfactory stability and reproducibility for electrooxidation of methanol and ethanol when stored in ambient conditions or continues cycling making it more attractive for fuel cell applications.  相似文献   

5.
The electrocatalytic performance of Polypyrrole-Copper oxide particles modified carbon paste electrode (Cu2O/PPy/CPE) for electrocatalytic oxidation of ethanol was reported for the first time in alkaline media. The composite Cu2O/PPy was prepared using a facile approach consisting on the deposition of Polypyrrole film on CPE using galvanostatic mode then followed by the deposition of Copper particles at a constant potential. Scanning electron spectroscopy (SEM), infrared spectroscopy (FTIR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed to characterize the structural and electrochemical properties of the Cu2O/PPy/CPE and to explain the mechanism of electrooxidation of ethanol. The experimental parameters that influence the electrooxidation of ethanol were investigated and optimized. Our findings suggest that the electrodeposition of Copper particles on Polypyrrole film enhanced the catalytic activity towards the ethanol oxidation with a peak current density of 2.25 mA cm−2 at 0.8 V vs Ag/AgCl, which is 2.6 times higher than the peak current density obtained by PPy/CPE electrode. It important to note that the saturation limit reaches a value of 5 M. To summarize, the good catalytic activity, stability and easy preparation make the Cu2O/PPy composite as an excellent electrocatalyst for ethanol oxidation.  相似文献   

6.
Hierarchically porous carbon sheets decorated with transition metal carbides nanoparticles and metal-nitrogen coordinative sites have been proposed as the promising non-precious metal oxygen electrocatalysts. In this work, we demonstrate a facile and low-cost strategy to in situ form Fe/N codoped hierarchically porous graphene-like carbon nanosheets abundant in Fe-Nx sites and Fe3C nanoparticles (Fe–N/C) from pyrolyzing chestnut shell precursor. The as-prepared Fe–N/C samples with abundant Fe-Nx sites and Fe3C nanoparticles show superior electrocatalytic activity to oxygen reduction reaction (ORR) in the alkaline medium as well as high stability and methanol tolerance due to the integration of multi-factors: the high content of Fe-Nx active sites, the coexistence of Fe3C, the unique hierarchically porous structure and high conductivity of carbon matrix. The optimal Fe–N/C-2-900 sample exhibits a more positive half-wave potential (−0.122 V vs. Ag/AgCl (3 M) reference electrode) than commercial 20 wt% Pt/C catalyst. This study provides a facile approach to synthesize Fe3C nanoparticles decorated Fe/N co-doped hierarchically porous carbon materials for effective oxygen electrocatalyst.  相似文献   

7.
The development of highly active and efficient heterogeneous catalytic oxidation system has become an attractive research field. In this paper, a catalyst (RuCo/N-CNT@PEDOT-OH/Pt) from platinum nanoparticles (Pt NPs) supported on hydroxyl-grafted poly(3,4-ethylenedioxythiophene) (PEDOT–OH)-modified RuCo, N-tridoped bamboo-like carbon nanotubes (RuCo/N-CNT) are used for direct methanol fuel cell (DMFC). The electrocatalytic activity of RuCo/N-CNT@PEDOT-OH/Pt is systematically compared with RuCo/N-CNT/Pt (Pt NPs supported on RuCo/N-CNT without PEDOT-OH) in the methanol oxidation reaction (MOR). The growth mechanism of carbon nanotubes and the role of heteroatom doping in the electrocatalytic process is explored. The catalysts show excellent electrocatalytic performance with high stability for MOR. It is found that the mass activity (MA) of the RuCo/N-CNT@PEDOT-OH/Pt (1961.3 mA mg?1Pt) for MOR was higher than that of RuCo/N-CNT/Pt (1470.1 mA mg?1Pt) and the commercial Pt/C catalysts (281.0 mA mg?1Pt), indicating the positive effect of the PEDOT-OH in the electrocatalytic MOR. In addition, density functional theory (DFT) calculations verify the possible mechanism pathways of the obtained RuCo/N-CNT@PEDOT-OH/Pt catalyst. This presented catalyst offers new inspiration for designing efficient electrocatalysts for methanol oxidation.  相似文献   

8.
Developing non-noble metal catalysts with excellent electrocatalytic performance and stability is of great significance to hydrogen production by water electrolysis, but there are still problems of low activity, complex preparation and high cost. Herein, we fabricated a novel Ni3S2/Ni(OH)2 dual-functional electrocatalyst by a one-step fast electrodeposition on nickel foam (NF). While maintaining the electrocatalytic performance of Ni3S2, the existence of heterostructure and Ni(OH)2 co-catalyst function greatly improves the overall water splitting performance of Ni3S2/Ni(OH)2–NF. Hence, It shows a low overpotential of 66 mV at 10 mA cm?2 for HER and 249 mV at 20 mA cm?2 for OER. The dual-functional electrocatalyst needs only 1.58 V at 20 mA cm?2 when assembled two-electrode electrolytic cell. Impressively, the electrocatalyst also shows outstanding catalytic stability for about 800 h when 20 and 50 mA cm?2 constant current was applied, respectively which demonstrates a potential electrocatalyst for overall water splitting.  相似文献   

9.
This study pulse-electrodeposits Pt nanoparticles on amorphous carbon-coated silicon nanocones (ACNCs) and explores them as the electrocatalyst for methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) for direct methanol fuel cell applications. The work prepares silicon nanocones on the Si wafer using porous anodic aluminum oxide as the template and then deposits the amorphous carbon layer on the nanocones by microwave plasma chemical vapor deposition. According to Raman scattering and X-ray photoelectron spectroscopies (XPS), the surface of the ACNC support is composed of a nanocrystalline graphitic structure, and rich in oxygen-containing adspecies. The Pt nanoparticles pulse-electrodeposited on the highly ordered ACNC support disperses well with a large electrocatalytic surface area. The Pt/ACNC electrode exhibits excellent electrocatalytic activity and stability toward both MOR and ORR. This study suggests the abundant oxygen-containing surface species and the nanometer size of the Pt catalyst as the two major factors enhancing electrocatalytic performance of Pt/ACNC electrode. The XPS study suggests the occurrence of charge transfer from π-sites of the graphitic structure to the Pt nanoparticle, thereby improving the electrochemical stability of the electrode.  相似文献   

10.
Binary nano-composites of palladium and a metal (Fe or Cu) manganite on graphene nanosheets (GNS) have been prepared by a microwave-assisted polyol reduction method and investigated as electrocatalysts for the methanol oxidation reaction (MOR) in 1 M KOH at 25 °C. Structural and electrocatalytic surface characterizations of composites are carried out by X-ray diffraction, transmission electron microscopy, X-ray photoelectron microscopy, cyclic voltammetry and chronoamperometry. Results show that new composite catalysts, particularly 40 wt%Pd–x wt%FeMn2O4/GNS (where x = 5, 8, 10 & 15) are MOR active and that the activity is the greatest with the catalyst containing 8 wt% of the oxide. The composite, Pd–8 wt%FeMn2O4/GNS, exhibits much superior catalytic activity as well as stability compared to the base (Pd/GNS) electrode. The enhanced catalytic activity and stability of the Pd/GNS catalyst in presence of the oxide can be ascribed to increased population of adsorbed OH ions/OH radicals at the electrode surface.  相似文献   

11.
The development of efficient and low-cost electrocatalysts for hydrogen evolution reaction (HER) is of importance. Herein, we demonstrate a self-supported Ni2P nanostructure with nanorod arrays morphology, fabricated by directly growing metal-organic frameworks (MOFs) on the commercial nickel foam prior to phosphorization treatment, as an electrocatalyst for HER. This electrocatalyst exhibits remarkable electrocatalytic HER activity in an alkaline electrolyte, affording current densities of 10 and 100 mA cm?2 at the overpotentials of 120 and 168 mV, respectively, accompanied with a low Tafel slope of 37 mV dec?1. Furthermore, this electrocatalyst shows a current density of 105 mA cm?2, and this current density can be retained for more than 20 h, suggesting its superior stability. This remarkable HER performance is believed a result of superiority for its structural integrality and mechanical stability.  相似文献   

12.
The metal-free carbonaceous catalysts are one of the promising candidates for efficient electrocatalytic hydrogen production. Aiming at demonstrating the high electrocatalytic activity of the hydrogen evolution reaction (HER), we synthesized the biomass rice husk-derived corrugated graphene (RH-CG) nanosheets via the KOH activation. The 700 °C-activated RH-CG nanosheets exhibited the large specific surface area as well as the high electrical conductivity. When using the RH-CG nanosheets as a HER electrocatalyst in 0.5 M H2SO4, the excellent HER activities with a small overpotential (9 mV at 10 mA/cm2) and a small Tafel slope (31 mV/dec) were achieved. The results provide a new strategy for materializing the superb biomass-derived electrocatalyst for highly efficient hydrogen production.  相似文献   

13.
The synthesis of high performance and economical electrocatalysts in the process of overall water splitting is very important for the production of hydrogen energy and has become one of the most important challenges. Here, various Ni, Ni–Fe, Ni–Mn nanosheets and Ni–Fe–Mn ternary nanosheets were created using cost-effective, versatile and binder-free electrochemical deposition methods, and the electrocatalytic activity of various electrodes for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) were investigated in an alkaline environment. Due to the high electrochemical active surface area due to the fabrication of nanosheets, the synergistic effect between different elements on the electronic structure, the high wettability due to the formation of nanosheets and the quick detachment of formed gasses from the electrode, the Ni–Fe–Mn nanosheets electrode showed excellent electrocatalytic activity. In order to deliver the 10 mA cm−2 current density in HER and OER processes, this electrode required values of 64 mV and 230 mV overpotential, respectively. Also, the stability test showed that after 10 h of electrolysis at a current density of 100 mA cm−2, the overpotential changes was very small (less than 4%), indicating that the electrode was excellent electrostatic stability. Also, when using as a bi-functional electrode in the full water splitting system, it only needed a cell voltage of 1528 V to deliver a current of 10 mA cm−2. The results of this study indicate a new strategy for the synthesis of active and stable electrocatalysts.  相似文献   

14.
It is essential to search highly active, steady and cheap non-noble electrocatalyst for hydrogen evolution reaction (HER). At present, nickel phosphides are extensively used in electrochemical hydrogen evolution due to its excellent stability and activity. Hence, we report a facile, effective and feasible strategy to synthesis of Ni5P4 nanosheets/nanoparticles structure on carbon cloth, which was fabricated by electroless nickel plating on carbon cloth followed via straightforward thermal phosphidation treatment with NaH2PO2 as phosphorus source. The as-prepared CC@Ni–P electrocatalyst exhibits HER activity with low overpotentials (93 mV vs. RHE) to attain current density 10 mA/cm2 as well as small Tafel slope (58.2 mV/dec), which outperforms most nickel phosphides electrocatalysts. The excellent HER performance can be ascribed to the large electrochemically active surface area, and phosphorus-rich Ni5P4 phase can supply further bridges sites of Ni and P. Significantly, as-prepared CC@Ni–P catalyst electrode exhibits no apparent HER activity decay after continuous stability test. Beyond that, the approach can be readily used to fabricate large size (5 × 5 cm) nickel phosphide electrocatalyst with excellent HER performance, which may be conducive to the proton exchange membrane (PEM) water electrolyser applications in future. This work opens an effective way to construct excellent performance transition-metal phosphides for HER.  相似文献   

15.
It is significant but challenging to develop noble-metal-free electrocatalysts exhibiting high activity and long-term stability toward hydrogen evolution reaction (HER) to satisfy the ever-increasing demand for clean and renewable energy. Herein, an environment-friendly and low-temperature electroless deposition method is developed for the synthesis of Co–Ni–P hollow nanospheres anchored on reduced graphene oxide nanosheets (Co–Ni–P/RGO). By optimizing the molar ratio of Ni/Co precursor, composition dependent electrocatalytic performances toward HER of nanostructured Co–Ni–P/RGO electrocatalyst are investigated in 1.0 M KOH solution. The results suggest that when the molar ratio of Ni/Co precursor is 3/7, as-prepared ternary Co–Ni–P/RGO electrocatalyst exhibits a remarkably enhanced HER activity in comparison to binary Ni–P/RGO and Co–P/RGO electrocatalysts, delivering a current density of 10 mA cm−2 at the overpotential of only 207 mV. The value of Tafel slope for nanostructured Co–Ni–P/RGO electrocatalyst reveals that HER process undergoes Volmer-Heyrovsky mechanism. Besides, nanostructured Co–Ni–P/RGO electrocatalyst features superior stability under alkaline condition. The results suggest that nanostructured composite of Co–Ni–P hollow nanospheres/RGO is a potential candidate for hydrogen production through water splitting.  相似文献   

16.
Addressed herein, a glassy carbon electrode was modified by cobalt nanoparticles stuck to the activated carbon (CoNP/AC/GCE). The electrocatalytic oxidation of methanol and ethanol on the surface of the modified electrode in acidic setting was investigated using cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronoamperometry as the first report. The effect of some parameters such as the potential scan rate, type of electrolyte solution and concentration effect of methanol and ethanol on the modified electrode was investigated. The kinetic parameters such as I0 (exchange current) and k0 (intrinsic heterogeneous rate constant) for methanol and ethanol were obtained through Tafel plots. By comparing the values obtained for I0 and K0, it would be clear that the effect of electrode modification on the electro-oxidation kinetics of ethanol and methanol is very significant. Finally, the response trends for electrooxidation of the alcohols by the CoNP/AC/GCE confirmed the quantitative application of the modified electrode.  相似文献   

17.
Seeking the efficient and robust electrocatalysts necessarily enhances performance of hydrogen evolution reaction (HER). Increasing the surface active sites is a means to improve the performance. Herein, we use the Ni0·85Se anchored on reduction of graphene oxide (Ni0·85Se/rGO) hybrid material skillfully established by one-step facile hydrothermal method as a robust and stable electrocatalyst applying to hydrogen evolution reaction (HER). In terms of morphology, Ni0·85Se nanospheres composed of many nanosheets are uniformly distributed on the graphene sheet layer. We also detailedly analyze its properties. Based on the interaction between Ni0·85Se and rGO, and the roles of graphene are as a substrate to heighten conductivity, possesses more active surface area by limiting growth of Ni0·85Se, and increases dispersion for exposing more active surface area and enlarge ion/electron transfer rate. In HER, the Ni0·85Se/rGO catalyst displays the overpotential of 128 mV with a common current density of 10 mA cm−2, a small Tafel slope of 91 mV dec−1, an extremely low onset potential of 37 mV, outstanding stability that a high current retention of 97.7% after 1000 cycles and well long-term stability for 18 h, outperforming the capability of Ni0·85Se nanospheres in alkaline solution for HER. The above results indicate that the Ni0·85Se/rGO hybrid material is a good HER ability and non-noble metal electrocatalyst has potential value in HER.  相似文献   

18.
Mixed valence spinel oxides have emerged as an attractive and inexpensive anode electrocatalyst for water oxidation to replace noble metals based electrocatalysts. The present work demonstrates the facile synthesis of Zn substituted MnCo2O4 supported on 3D graphene prepared by simple hydrothermal technique and its application as an electrocatalyst for water oxidation and methanol oxidation. The physico-chemical properties of the nanocatalyst were studied using various microscopic, spectroscopic and diffraction analyses confirming the formation of the composite. The electrocatalytic performance of the prepared electrocatalyst was evaluated using potentiodynamic, potentiostatic and impedance techniques. The synthesized Zn1-xMnxCo2O4/rGO electrocatalyst with x = 0.2 and 0.4 offered the same onset potential and overpotential at 10 mA/cm2. However, catalyst x = 0.4 delivered a higher current density indicating the superiority of the same over other compositions which is attributed to better kinetics that it possessed for OER as revealed by the smallest Tafel slope (80.6 mV dec−1). The prepared electrocatalysts were tested for methanol oxidation in which electrocatalyst Zn1-xMnxCo2O4/rGO with x = 0.4 shows a better electrochemical performance in oxidizing methanol with the higher current density of 142.3 mA/cm2. The above catalyst also revealed excellent stability and durability during both MOR and OER, suggesting that it can be utilized in practical applications.  相似文献   

19.
The combination of anodic biomass electrooxidation and cathodic hydrogen evolution reaction is an effective strategy to realize energy saving hydrogen production and high value chemical products. Herein, we synthesized dense NiO nanosheet arrays on Ni foam using different heat-treatment temperature, including 400, 450 and 500 °C. The NiO prepared under 500 °C owns the highest oxygen defect concentration (58.1%) and Ni3+/Ni2+ ratio (3.13), giving the highest intrinsic activity for methanol electrocatalytic oxidation reaction. However, the NiO prepared at 400 °C (named as NiO-400) owns highest catalyst surface area and electrochemical surface area, giving the highest practical activity. Based on the above results, a facile method of surface modification by ultraviolet oxidation is proposed to improve the oxygen defect concentration (from 34.7% to 36.8%) and Ni3+/Ni2+ ratio (from 2.94 to 3.19) of NiO-400, and the catalytic current was increased by about 48.9%. This work provides some theoretical basis for improving the activity of biomass electrocatalytic oxidation of Ni-based materials.  相似文献   

20.
Developing the low-cost, durable, and efficient bifunctional electrocatalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) plays an important role in the commercial implementation of the Zn-air batteries. Herein, we design and synthesize the MnO and Co nanoparticles coated with N-doped carbon (MC@NC) as an excellent bifunctional oxygen electrocatalyst. It is found that the optimal MC@NC-0.3 exhibits outstanding ORR performance with a positive half-wave potential of 0.82 V and excellent OER activity with a small overpotential of 360 mV at 10 mA cm−2. When applied in the liquid Zn-air battery, MC@NC-0.3 displays a high maximum power density of 153 mW cm−2, a large specific capacity of 776 mAh g−1 and the excellent cycling stability with a negligible increase after 300 h. Furthermore, the fiber-shaped all-solid-state Zn-air battery also displays remarkable stability at high current density. This study offers a facile strategy to construct a high-efficient, low-cost, and durable transitional metal-based bifunctional electrode for renewable energy applications.  相似文献   

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