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1.
The enhancement in intrinsic catalytic activity and material conductivity of an electrocatalyst can leads to promoting HER activity. Herein, a successful nitrogenation of CoS2 (N–CoS2) catalyst has been investigated through the facile hydrothermal process followed by N2 annealing treatment. An optimized N–CoS2 catalyst reveals an outstanding hydrogen evolution reaction (HER) performance in alkaline as well as acidic electrolyte media, exhibiting an infinitesimal overpotential of ?0.137 and ?0.097 V at a current density of ?10 mA/cm2 (?0.309 and ?0.275 V at ?300 mA/cm2), corresponding respectively, with a modest Tafel slope of 117 and 101 mV/dec. Moreover, a static voltage response was observed at low and high current rates (?10 to ?100 mA/cm2) along with an excellent endurance up to 50 h even at ?100 mA/cm2. The excellent catalytic HER performance is ascribed to improved electronic conductivity and enhanced electrochemically active sites, which is aroused from the synergy and mutual interaction between heteroatoms that might have varied the surface chemistry of an active catalyst.  相似文献   

2.
Advanced electrocatalysts for the fabrication of sustainable hydrogen from water splitting are innermost to energy research. Herein, we report the growth of iron diselenide (FeSe2) nanorods on graphene oxide (GO) sheets using two-step process viz., simple hydrothermal reduction and followed by wet chemical process. The orthorhombic phase of FeSe2 incorporated GO nanosheet was developed as a low-cost and efficient electrocatalyst for hydrogen evolution reaction (HER) by water splitting. The phase purity, crystalline structure, surface morphology and elemental composition of the synthesized samples have been investigated by UV–visible absorption spectroscopy (UV–vis), fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray analysis (EDS). Voltammetry and Tafel polarization methods have been utilized to assess the performance of various weight ratio of GO nanosheet in FeSe2 nanorods towards H2 evolution. Detailed electrochemical investigations revealed that the 30% FeSe2/GO composite showed a tremendous electrocatalytic HER activity in acidic medium with high cathodic current density of 9.68 mA/cm2 at η = 250 mV overpotential and with a Tafel slope of 64 mV/dec. The 30% FeSe2/GO composite offers a high synergistic effect towards HER activity, which is mainly due to high electrochemical active catalytic sites, low charge-transfer resistance and enhanced electrocatalytic performances of H2 production. The present analysis revealed the possible application of FeSe2/GO composite as a promising low-cost alternative to platinum based electrocatalysts for H2 production.  相似文献   

3.
Hydrogen evolution reaction (HER) is a critical process in electrocatalytic water splitting for hydrogen production. However, the development of low-cost electrocatalysts for highly efficient HER is still a huge challenge. Hence, we fabricate a multi-metal phosphide on Ni foam, FeCoNiNbxP, through a facile hydrothermal reaction followed by phosphorization. We find that Nb promotes the formation of metal phosphides, and the main phases of the catalysts with Nb are multiphase phosphides. Importantly, the Nb incorporation significantly improves the HER activity of FeCoNiP. We show that FeCoNiNb0.3P has the best HER activity, which only requires an overpotential of 78 mV to achieve a current density of 10 mA cm?2 in 1 M KOH, and demonstrates excellent stability under both constant potential and varied current densities. Our findings show that the multiple-metal compounds are beneficial to the improvement of catalytic activity and provide guidance on the design of novel catalysts for applications.  相似文献   

4.
Besides developing a large number of catalysts for hydrogen evolution reaction (HER) in alkaline electrolytes, its conversion efficiency remained low. Herein, we have developed mixed-dimensional heterostructures of niobium disulfide (NbS2) with graphene foam grown on nickel foam (NbS2-Gr-NF). The strong lateral fusion results in activating the catalytic sites of NbS2, the three-dimensional substrate provides easy access of electrolyte to active sites and increased electrochemically active surface area, while enhanced conductivity provides faster transfer of electrons to and from active sites. Therefore, NbS2-Gr-NF heterostructures resulted in an exceptionally high current density of 500 mA cm−2 at a very low overpotential of 306 mV in 1 M KOH solution and even can achieve the current density values of 914 mAcm−2 at 338 mV only at a slight increase in overpotential (32 mV). Moreover, a Tafel value of ~72 mV dec−1 confirms that as-developed heterostructure provides fast reaction kinetics where the reaction is mainly controlled by the Volmer step. Achieving such high current density at a faster rate with high stability makes NbS2-Gr-NF heterostructures a potential candidate for water-splitting, especially in alkaline electrolytes.  相似文献   

5.
Application of carbonic materials as catalysts has recently been considered due to some advantages like tunable molecular structures, easy synthesis methods, abundance, and high tolerance in acidic and alkaline media. Here, a new metal-free electrocatalyst of halogenated reduced graphene oxide was prepared using cyclic voltammetry X (F, Br, and I)-RGO electrodeposition method. The prepared electrocatalysts were studied as a novel metal-free electrocatalyst for the hydrogen evolution reaction, and the presence of several halogen and oxygen functional groups on the surface of nanosheets was verified by the furrier transform infra-red, FT-IR, spectroscopy, and the presence of doped halogens on the RGO surface was confirmed by energy-dispersive X-ray, EDX, spectroscopy. The structural features and surface morphology of electrocatalysts were investigated by scanning electron microscopy (SEM) analysis. The electrochemical treatment of the X (F, Br, I)-RGO electrode was studied by some techniques like electrochemical impedance spectroscopy, EIS, chronoamperometry, CA, and linear sweep voltammetry, LSV. The X (F, Br, I)-RGO catalyst showed a lower onset potential (?0.81 V. vs. SHE), higher exchange current density (3.1 × ×10?1 mA cm?2), and lower charge transfer resistance (1.09 Ω cm2) related to the RGO catalyst due to the high active sites by heteroatoms and graphene nanosheets.  相似文献   

6.
In this study, polyaniline (PANI) with abundant protonated regions was used for the first time as a palladium (Pd) support for enhanced performance in hydrogen evolution reaction (HER). For this purpose, the hierarchical Pd@PANI nanofiber electrode was easily synthesized by electrochemical polymerization of aniline on Au followed by potential-controlled electrochemical deposition of Pd nanoclusters on the PANI. The reported catalyst was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and field-emission scanning electron microscopy. Linear sweep voltammetry analysis was performed to evaluate the HER performance. Ion transfer behavior was investigated using electrochemical impedance spectroscopy analysis. The electrochemical tests show that the Pd@PANI/Au electrode has a low overpotential of ~60 mV at 10 mA cm?2 and a small Tafel slope of 35 mV dec?1 for HER in acidic media, with high catalytic activity and stability. These features will make the Pd@PANI/Au a promising candidate as a high-performance electrocatalyst for HER applications.  相似文献   

7.
The hydrogen evolution reaction (HER) is a key step for producing hydrogen by water electrolysis, and an economical, facile and environment friendly method of fabricating catalysts for HER is urgent and essential. In this work, we design a high efficient and stable HER catalyst though a simple adsorption and pyrolysis method. The fabricated catalyst presents ruthenium (Ru) quantum dots (QDs) uniformly distributes on the carbon nanofibers (CNF) with a three dimensional (3D) networks structure (Ru@CNF). By means of quantum size effect of Ru QDs and the 3D networks structure of the carbon nanofibers, the former is beneficial to provide more catalytic active sites and the latter is in favour of electron transport. The sample Ru@CNF exhibits a low overpotential of 20 mV at a current density of 10 mA cm−2 and Tafel slope of 31 mV dec−1 in 1 M KOH, which is better than that of Pt/C (28 mV and 36 mV dec−1), and most of reported Ru-based and transition metal catalysts. Furthermore, it exhibits robust stability when testing at an overpotential of 75 mV for 24 h. Therefore, this work provides a low-cost, simple and feasible method for fabricating HER catalyst, which possesses commercial application prospect in the field of producing hydrogen by water electrolysis.  相似文献   

8.
A new chlorobis(2-aminomethylbenzimidazole)zinc(II) perchlorate complex [Zn(AMB)2Cl](ClO4) 1 has been synthesized and characterized. Spectral and X-ray structural features led to the conclusion that the zinc(II) complex has a square-pyramidal environment around zinc(II) center with coordination chromophore ZnN4Cl. Different amounts of complex 1 were supported on glassy carbon (GC) electrode yielding three GC-supported complex 1 electrodes with different loading densities (0.2, 0.4, and 0.8 mg cm?2). These electrodes were tested as molecular electrocatalysts for the hydrogen evolution reaction (HER) in phosphate buffer aqueous solutions (pH 7), employing linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). Results showed that GC-complex 1 catalysts are highly active for the HER, and this catalytic activity enhances with the loading density. The one with the highest loading density (0.8 mg cm?2) exhibited high HER catalytic activity with low onset potential of ?140 mV vs. RHE and a high exchange current density of 0.22 mA cm?2. It required an overpotential of 240 mV to achieve a current density of 10 mA cm?2. It also recorded a turnover frequency (TOF) of 1722 mol of hydrogen per mole of catalyst per hour at overpotential 500 mV, which is comparable with the most active molecular electrocatalysts reported in the literature for H2 generation from aqueous neutral solutions. A catalytic cycle is proposed for the generation of hydrogen by complex 1 and the mechanism of the HER is discussed based on the measured Tafel slope (140 mV dec?1).  相似文献   

9.
Molybdenum silicides are promising electrocatalysts for hydrogen evolution in acidic environment due to their dual characteristics of metal and ceramics as well as high electrical conductivity and acid resistance. At present, most of the transition metal silicides were synthesized at high temperature, resulting in large particle size and small specific surface area, which seriously limits their electrocatalytic applications. Herein, we report a low temperature strategy for the synthesis of ultrafine Mo5Si3 and MoSi2 nanoparticles with diameter of ~5 nm by molten salt method. Results show that both of them demonstrated excellent electrocatalytic hydrogen evolution activity and stability in 0.5 M H2SO4 solution, in which the overpotentials of Mo5Si3 and MoSi2 nanoparticles at 10 mA cm?2 are 80 mV and 94 mV, respectively. This general strategy may light up the preparation of ultrafine transition metal silicides nanoparticles and facilitate their applications in electrocatalytic areas.  相似文献   

10.
Development of electrocatalytic hydrogen production technology is the key to solving environmental and energy problems. Two-dimensional material Mo2TiC2Tx (Tx = –OH, –F) has shown great potential in electrocatalytic hydrogen evolution because of its excellent conductivity and hydrophilicity. However, due to the lack of sufficient active sites of Mo2TiC2Tx itself, its practical applications in electrocatalytic hydrogen evolution are limited. In this work, a highly-efficient hydrogen evolution electrocatalyst, namely Pd@MoS2/Mo2TiC2Tx, is prepared through a simple pyrolysis method. In such a composite, the MoS2 nanoflowers hybridized with the ammonia-treated Mo2TiC2Tx (MoS2/Mo2TiC2Tx) are used as a substrate for loading a small number of Pd nanoparticles (4.27 at.%). Notably, the introduction of Pd nanoparticles into MoS2/Mo2TiC2Tx provides abundant active sites for the hydrogen evolution reaction, improves the conductivity of the electrocatalyst, speeds up the adsorption and desorption of hydrogen, and induces a synergistic effect with the MoS2. As a result, the Pd@MoS2/Mo2TiC2Tx catalyst exhibits excellent electrocatalytic performance and remarkable stability in both acidic and alkaline media. In a 0.5 mol/L H2SO4 electrolyte, the overpotential of Pd@MoS2/Mo2TiC2Tx was 92 mV with a Tafel slope of 60 mV/dec at a current density of 10 mA/cm2. Meanwhile, the catalyst displayed an overpotential of 100 mV associated with a Tafel slope of 80 mV/dec at the current density of 10 mA/cm2 in a 1 mol/L KOH electrolyte. This work shows the great potential of using Mo2TiC2Tx-based material in the field of electrocatalysis.  相似文献   

11.
Tungsten carbides (W2C and WC) materials, as promising non-precious electrocatalysts, possess highly efficient activity for HER. Herein, N-doped graphene supported tungsten carbide (N–W2C/WC) nanocomposite is synthesized by spray drying process followed with a two-step pyrolysis treatment, which exhibits a remarkable hydrogen evolution reaction (HER) activity and excellent stability in acidic solution and alkaline solution. N–W2C/WC displays low overpotentials of 166 mV and 125 mV to achieve a current density of 10 mA cm?2 and small Tafel slopes of 60.97 and 62.66 mV dec?1 in 0.5 M H2SO4 and 1.0 M KOH, respectively. After 1000 cycles, the electrocatalytic activity of N–W2C/WC is almost no change in acidic media but slightly decreases in alkaline media. This work might provide a new way to explore high comprehensive performance tungsten-based electrocatalyst for HER.  相似文献   

12.
In this work, we have developed a method for the synthesis of non-stoichiometric nanocrystalline niobium carbide (NbCy) using special heat treatment of niobium citrate in a vacuum. The powder synthesized was investigated by powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), high-resolution scanning electron microscopy (HRSEM), transmission electron microscopy (TEM), and low-temperature nitrogen sorption-desorption technique. The PXRD results showed that the synthesized niobium carbide nanocrystals had a cubic structure (space group Fm-3m), isometric morphology, and average crystallite size of about 12 nm. The Rietveld method was used to refine the unit cell parameters: a = b = c = 446.8 pm; Rwp = 5.48%. The specific surface area about 212 m2/g (BET) and the porosity about 0.02 cm3/g (BJH) of the sample were determined by adsorption-structural analysis; it was found that niobium carbide had a weakly pronounced microporous structure associated with the presence of interparticle porosity, which was also confirmed by the HRSEM results. The catalytic activity of non-stoichiometric niobium carbide in the process of electrolytic reforming of an aqueous ethanol solution was analyzed. The electrocatalyst has a low hydrogen overpotential value (?245 mV), a Taffel slope (90 mV/dec), and high operational stability: the absolute value of the overvoltage increases by 21 mV after 500 voltammetry cycles, and the current density decreases by 5% after 20 h of chronoamperometry. The results obtained make it possible to consider non-stoichiometric niobium carbide as a promising electrode base for electrocatalytic production of hydrogen from renewable aqueous-alcoholic solutions.  相似文献   

13.
High-performance, low-cost and robust electrocatalysts for the hydrogen evolution reaction (HER) play a critical role in large-scale hydrogen production via water splitting. Herein, we proposed a synthesis strategy for the self-assembly of maize-like CoP nanorod arrays with abundant active sites via a combination of conventional hydrothermal reaction and low-temperature phosphorization. This unique architecture exhibited remarkable catalytic performance for the HER, with a low overpotential of 130 mV at a current density of 10 mA cm?2 and a small Tafel slope of 59 mV dec?1 in 1.0 M KOH electrolyte, as well as good stability as verified by chronoamperometry measurement for 10 h. Density functional theory calculations further revealed that these maize-like CoP nanorod arrays with dense active sites and a high phosphorization degree could boost the HER performance in terms of low adsorption energy and free energy. This work provided a facile strategy towards manipulating morphology engineering to enhance the HER activity of CoP-based catalysts.  相似文献   

14.
There are many tremendous challenges to enhance the hydrogen evolution reaction (HER) activity of MoS2. In this study, nanoflower-like Co–MoS2/NiCoS structure supported on reduced Graphene Oxide (rGO) was rationally developed via a simple hydrothermal route, where the synergistic regulations of both interface structural and electronic conductivity were successfully presented by using controllable interface engineering and Co metal ions doped into MoS2 nanosheets. Ascribed to the 3D flower-like nanostructure with massive active sites, the interface coupling effect between MoS2 and Ni–Co–S phase, and Co-doped MoS2 can modulate its surface electronic density. The optimal Co–MoS2/NiCoS/rGO hybrid exhibits excellent HER activity in 1.0 M KOH, with a small overpotential (η10, 84 mV) at 10 mA cm?2 and a low Tafel slope (46 mV dec?1), accompanied by good stability. This work provides an effective route to produce other electrocatalysts based on interface structure and electronic conductivity engineering for HER in the future.  相似文献   

15.
Hydrogen evolution reaction has been recognized as a green technology in the field of electrochemical energy conversion and storage devices. Nevertheless, it is necessary task to finding an economical and effective electrocatalysts for HER. Among the different HER catalysts, the cobalt disulfide (CoS2) showed an excellent HER activity owing to its low cost, easy to synthesize and good stability. Hence, in this work, we prepared a series of CoS2/CNT composites with different contents CNT from 4 to 12 wt% by a simple one-step hydrothermal method to investigate the influence of CNT on HER activity of CoS2. The structural and morphological properties of the obtained samples were analyzed through XRD, SEM, HR-TEM, and XPS. The SEM images of CoS2/CNT composite showed the spherical-shaped CoS2 covered by the CNT nanostructure. In addition, the electrochemical tests were carried out using 0.5 M H2SO4 solution in order to assess their HER activity. The attained electrochemical results showed that the CoS2/CNT composite with 8% CNT offers an outstanding HER activity with the smallest overpotential of 155 mV at 10 mA cm−2 and lowest Tafel slope of 59 mV dec−1 when compared with other composites. Also, the optimized CoS2/CNT composite provided excellent stability in the acidic medium after 1000 cycles. Therefore, the as-synthesized CoS2/CNT composite will be an efficient, low-cost and Pt-free electrocatalyst for HER application.  相似文献   

16.
Hydrogen evolution reaction (HER) is regarded as a feasible strategy for producing high-purity hydrogen from abundant water. It is significant yet challenging for synthesis of Pt-based pH-universal HER electrocatalysts by substantially reducing the Pt loading without any decay in the activity. Herein, bimetallic PtRh alloyed dendritic nanoassemblies (DNAs) were efficiently prepared by a facile one-pot solvothermal strategy in oleylamine (OAm), coupling with the aid of glycine and cetyltrimethylammonium chloride (CTAC). By virtue of the unique branch-like structures and compositions advantages, the PtRh DNAs catalyst showed steeply enhanced HER activity with small overpotentials (i.e. 28 mV in 1.0 M KOH, 23 mV in 1.0 M phosphate buffer solution and 27 mV in 0.5 M H2SO4) at the current density of 10 mA cm−2, surpassing those of commercial Pt/C under such conditions. This work provides a facile and rational strategy to construct advanced Pt-based bimetallic electrocatalyst for energy-correlated applications.  相似文献   

17.
Molybdenum-based MXene materials (Mo2CTx) have recently demonstrated great potential in electrocatalytic hydrogen production. Herein, we fabricated a novel NiS/Mo2CTx hybrid via chemical etching in an NH4F/HCl solution followed by solvothermal reactions, where nickel sulfide (NiS) clusters were embedded between the interlayers of Mo2CTx. The intrinsic structure and electrochemical properties were experimentally investigated to explore the potential of an electrocatalyst for hydrogen evolution. As expected, the heterostructure by embedding NiS into the Mo2CTx MXene interlayers not only brings about large electrochemical surface areas with abundant active site exposure but also enhances the intrinsic kinetics to facilitate the electrolysis process. Electrochemical tests revealed that the NiS/Mo2CTx catalyst exhibited the HER performance with a small overpotential of 157 mV to drive the current density of 10 mA cm−2 and long-term stable durability, which are superior to that of pristine Mo2CTx MXene and nickel sulfides. This study can provide a synthetic strategy for designing and developing Mo2CTx MXene-based electrocatalysts for hydrogen production.  相似文献   

18.
Electrocatalytic hydrogen evolution reaction (HER) is a simple way to generate environment-friendly hydrogen energy. Due to the high price and low content, the wide application of noble metal-based electrocatalysts is limited. It is of great significance to study inexpensive, high-performance non-precious metal-based electrocatalysts. In this work, bimetallic nitride (Co/WN@NC) was successfully prepared through a one-step high-temperature calcination way using dicyandiamide (DCA), bimetallic polyoxometalates, and cobalt nitrate. Co/WN@NC exhibits outstanding catalytic performance with the same overpotentials of 143 mV in both alkaline and acidic media at 10 mA cm?2. The Tafel slopes are 90 mV dec?1 and 118 mV dec?1, respectively. Co/WN@NC exhibits good stability in acidic and alkaline solutions for up to 30 h. The splendid catalytic performance can be mainly ascribed to the synergistic effect between Co and WN. This work shows experimental guiding significance for preparing simple transition metal-based electrocatalysts.  相似文献   

19.
Exploiting efficient and low-cost electrocatalyst for Hydrogen Evolution Reaction (HER) of water electrolysis remains a challenge. Herein, we designed an efficient electrocatalyst of Ni-induced nitrogen-doped carbon @ molybdenum carbide @ molybdenum disulfide sphere (NC@Mo2C@MoS2-(Ni)) by two simple coating steps following pyrolysis process. Benefiting from the regular spherical morphology, unique structure, synergistic effect between Mo2C and MoS2, inducement effect of elemental Ni that initial added and removed in final synthesis procedure, heteroatom N and P doping. The catalyst NC@Mo2C@MoS2-(Ni) exhibits relatively good catalytic performance of overpotentials of 205 and 216 mV at 10 mA cm?2 and Tafel slopes of 61.4 and 42.7 mV dec?1 in acidic and basic media, respectively. This work not only fabricate the electrocatalyst of NC@Mo2C@MoS2-(Ni) towards HER, but also provides a way to rationally design more efficient other functional electrocatalysts.  相似文献   

20.
The phytic acid-coated titanium (IP6/Ti) electrode was prepared through a simple drop-drying process, with an aim of improving electrocatalytic activity toward the hydrogen evolution reaction (HER). Scanning electron microscope and X-ray photoelectron spectroscopy showed that the IP6 coated the substrate surface uniformly and completely. Evaluation of the electrode activity was carried out in 1.0 M NaOH by linear polarization, electrochemical impedance spectroscopy (EIS) and chronopotentiometry. The kinetic parameters obtained from Tafel curves reveal that the IP6 coating can enhance the exchange current density of the HER by 489 times compared to the bare Ti, and reduce the HER activation energy by nearly 50%. The EIS data prove that the charge transfer resistance of the HER was considerably reduced due to the IP6 coating, with a decrease in real surface area of the electrode. The catalytic effect of IP6 is due to an improvement in the charge transfer kinetics of the HER. This work indicates that IP6 may be a potent candidate as a catalyst for hydrogen energy production.  相似文献   

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