UWCScholar :: Browsing by Author "Wang, Rongfang"

Browsing by Author "Wang, Rongfang"

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Amorphous Pt@dCu/CNT catalyst for methanol elextrooxidation
(South African Chemical Institute (SACI), 2013) Wang, Hui; Ji, Shan; Wang, Wei; Wang, Rongfang
A multi-walled carbon nanotube-supported, Pt decorated nano-sized amorphous PdCu alloy cores (denoted as Pt@PdCu/CNT) catalyst with lower Pt loading is synthesized via a galvanic displacement reaction. The structure is examined using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The electrochemical activity of the Pt@PdCu/CNT catalyst is tested by cyclic voltammogrametry (CV) and compared to that of PtRu/CNT catalysts. The results show that amorphous Pt@PdCu/CNT catalyst exhibits better electro-catalytic performances for methanol oxidation than its crystalline counterpart.
Beef-derived mesoporous carbon as highly efficient support for PtRuIr electrocatalysts and their high activity for CO and methanol oxidation
(SACI, 2014) Wang, Hui; Wang, Rongfang; Ji, Shan; Da, Huahua
In this work, a low-cost and nitrogen-containing carbon with mesoporous pores and high surface area was synthesized by carbonizing a natural biomass precursor, i.e. beef. It is found that the prepared material has excellent textural properties such as high specific surface areas and large pore diameters. TEM images showed that the PtRuIr nanoparticles were well dispersed on the surface of carbonized beef (C-Beef). PtRuIr/C-Beef was highly active for methanol electro-oxidation. PtRuIr/C-Beef showed superior catalytic activity to PtRuIr/C, i.e. lower onset potential and higher oxidation current density. Cyclic voltammograms of CO electro-oxidation showed that PtRuIr/C-Beef catalyst was kinetically more active for CO electro-oxidation than PtRuIr deposited on conventional carbon support. The highly porous structure and low cost of carbonized beef can be widely used as support for highly dispersed metal nanoparticles to increase their electrochemical performance as electrocatalysts.
Biomass-derived activated carbon as high-performance non-precious electrocatalyst for oxygen reduction
(Royal Society of Chemistry, 2013) Wang, Keliang; Wang, Hui; Ji, Shan; Feng, Hanqing; Linkov, Vladimir; Wang, Rongfang
A new type of Fe and N doped carbon material is synthesized by pyrolyzing ferric chloride doped egg white (EW) and the proposed synthetic route is easy, green, and low-cost. In addition, the as-prepared sample exhibits a feasible magnetism and comparable oxygen reduction reaction (ORR) activity to commercial Pt/C.
CNx-modified Fe3O4 as Pt nanoparticle support for the oxygen reduction reaction
(Springer, 2013) Wang, Rongfang; Jia, Jingchun; Wang, Hui; Wang, Qizhao; Ji, Shan; Tian, Zhongqun
A novel electrocatalyst support material, nitrogendoped carbon (CNx)-modified Fe3O4 (Fe3O4-CNx), was synthesized through carbonizing a polypyrrole-Fe3O4 hybridized precursor. Subsequently, Fe3O4-CNx-supported Pt (Pt/Fe3O4-CNx) nanocomposites were prepared by reducing Pt precursor in ethylene glycol solution and evaluated for the oxygen reduction reaction (ORR). The Pt/Fe3O4-CNx catalysts were characterized by X-ray diffraction, Raman spectra, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The electrocatalytic activity and stability of the as-prepared electrocatalysts toward ORR were studied by cyclic voltammetry and steady-state polarization measurements. The results showed that Pt/ Fe3O4-CNx catalysts exhibited superior catalytic performance for ORR to the conventional Pt/C and Pt/C-CNx catalysts.
Effect of ni core structure on the electrocatalytic activity of pt-ni/c in methanol oxidation.
(MDPI, 2013) Kang, Jian; Wang, Rongfang; Wang, Hui; Liao, Shijun; Key, Julian; Linkov, Vladimir; Ji, Shan
Methanol oxidation catalysts comprising an outer Pt-shell with an inner Ni-core supported on carbon, (Pt-Ni/C), were prepared with either crystalline or amorphous Ni core structures. Structural comparisons of the two forms of catalyst were made using transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), and methanol oxidation activity compared using CV and chronoamperometry (CA). While both the amorphous Ni core and crystalline Ni core structures were covered by similar Pt shell thickness and structure, the Pt-Ni(amorphous)/C catalyst had higher methanol oxidation activity. The amorphous Ni core thus offers improved Pt usage efficiency in direct methanol fuel cells.
The effect of PtRuIr nanoparticle crystallinity in electrocatalytic methanol oxidation
(MDPI, 2013) Ma, Yanjiao; Wang, Rongfang; Wang, Hui; Liao, Shijun; Key, Julian; Linkov, Vladimir; Ji, Shan
Two structural forms of a ternary alloy PtRuIr/C catalyst, one amorphous and one highly crystalline, were synthesized and compared to determine the effect of their respective structures on their activity and stability as anodic catalysts in methanol oxidation. Characterization techniques included TEM, XRD, and EDX. Electrochemical analysis using a glassy carbon disk electrode for cyclic voltammogram and chronoamperometry were tested in a solution of 0.5 mol L−1 CH3OH and 0.5 mol L−1 H2SO4. Amorphous PtRuIr/C catalyst was found to have a larger electrochemical surface area, while the crystalline PtRuIr/C catalyst had both a higher activity in methanol oxidation and increased CO poisoning rate. Crystallinity of the active alloy nanoparticles has a big impact on both methanol oxidation activity and in the CO poisoning rate.
Effect of the structure of Ni nanoparticles on the electrocatalytic activity of Ni@Pd/C for formic acid oxidation
(Elsevier, 2013) Wang, Rongfang; Wang, Hui; Wang, Xingli; Liao, Shijun; Linkov, Vladimir; Ji, Shan
Ni@Pd/C catalysts were synthesized, using Ni/C with different crystalline structures prepared with various ligands. A series of characterizations were performed by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy. The results indicated the electrocatalysts with amorphous/crystalline (denoted as Nia and Nic) Ni structures decorated with Pd. The formic acid electrocatalytic oxidation results showed that the peak current of Nia@Pd/C was about 1.2 times higher than that of Nic@Pd/C. The good electrochemical performance and stability of Pd-modified amorphous Ni substrate reveals that the core structure plays an important role in the electrocatalytic activity and the change of the structure can improve the activity and stability of electrocatalysts.
Ethanol oxidation activity and structure of carbon-supported Pt-modified PdSn-SnO2 influenced by different stabilizers
(Elsevier, 2013) Wang, Hui; Liu, Ziyue; Ji, Shan; Wang, Keliang; Zhou, Tianbao; Wang, Rongfang
PdSn-SnO2 nanoparticles supported on Vulcan XC-72 carbon were synthesized by chemical reduction in the presence of three different stabilizing agents: ethylene diamine tetra-acetic acid (EDTA), sodium citrate (Nacitrate) and hexamethylenetetramine (HMTA). TEM analysis showed that PdSn-SnO2 /C catalyst made using the HMTA stabilizer produced the smallest particle size. XRD analysis detected the presence of PdSn alloy and the SnO2 phase in all three PdSn-SnO2 /C samples, and showed that PdSn-SnO2 (HMTA) had the smallest lattice parameter. After PdSn-SnO2 samples were modified by Pt, the particle size distribution and average size of nanoparticles of Pt-PdSn-SnO2 did not obviously change, and the fcc structure of PdSn in all three samples was retained. XPS measurement showed a higher upshift of Pt 4f binding energy occurred for Pt/PdSn-SnO2 /C (HMTA) compared to those of Pt/PdSn-SnO2 /C (EDTA) and Pt/PdSn-SnO2 /C (Nacitrate). Pt/PdSn-SnO2 /C (HMTA) was also found to have the highest CO and ethanol oxidation activity among the three catalysts.
An Fe@Fe3C-inserted carbon nanotube/graphite composite supportproviding highly dispersed Pt nanoparticles for ethanol oxidation
(Elsevier, 2014) Wang, Rongfang; Key, Julian
Iron/iron carbide-inserted carbon nanotube/graphite composite (Fe-C) was prepared by pyrolyzing amixture of melamine and iron (III) chloride to form a support for high loading of Pt nanoparticles as adirect ethanol fuel cell anode catalyst. The obtained Fe-C was characterized by Raman spectroscopy, X-raydiffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The Fe-C surfacecharacteristics supported a high (40 wt%) loading of Pt nanoparticles with uniform dispersion and smallparticle size. Compared to Vulcan carbon-supported Pt (40 wt%), Fe-C-supported Pt exhibited enhancedcatalytic activity for CO and ethanol oxidation, and high stability due to the effect of the Fe-C supportmaterial.
Montmorillonite modified by CNx supported Pt for methanol oxidation
(Elsevier, 2013) Wang, Rongfang; Zhou, Tianbao; Qiu, Xiaoli; Wang, Hui; Wang, Qizhao; Feng, Hanqing; Linkov, Vladimir; Ji, Shan
A composite support based on nature clay, i.e. montmorillonite (MMT), shows great promise as support materials for Pt electrocatalyst for the methanol oxidation reaction in fuel cell anodes. The reported composite support (CNx-MMT) was prepared via carbonizing MMT which was covered by N-contented polymer. X-ray diffraction and transmission electron microscopy results showed that Pt nanoparticles can be well-dispersed on the composite support with highly dispersed tiny crystal Pt nanoparticles. Cyclic voltammetry measurements showed that the Pt/CNx-MMT has the enhanced electrocatalytic activity in methanol oxidation reaction. The developed Pt catalyst supported on new composite support is catalytically more active for methanol electrooxidation than Pt supported on the conventional carbon support and shows good stability, offering promising potential for application of MMT as support for fuel cell electrocatalysis.
Nanoparticulate TiO2-promoted PtRu/C catalyst for methanol oxidation: TiO2 nanoparticles promoted PtRu/C catalyst for MOR
(Springer, 2013) Wang, Wei; Wang, Hui; Key, Julian; Linkov, Vladimir; Ji, Shan; Wang, Rongfang
To improve the electrocatalytic properties of PtRu/C in methanol electrooxidation, nanoparticulate TiO2-promoted PtRu/C catalysts were prepared by directly mixing TiO2 nanoparticles with PtRu/C. Using cyclic voltammetry, it was found that the addition of 10 wt% TiO2 nanoparticles can effectively improve the electrocatalytic activity and stability of the catalyst during methanol electro-oxidation. The value of the apparent activation energy (Ea) for TiO2-PtRu/C was lower than that for pure PtRu/C at a potential range from 0.45 to 0.60 V. A synergistic effect between PtRu and TiO2 nanoparticles is likely to facilitate the removal of CO-like intermediates from the surface of PtRu catalyst and reduce the poisoning of the PtRu catalysts during methanol electrooxidation. Therefore, we conclude that the direct introduction of TiO2 nanoparticles into PtRu/ C catalysts offers an improved facile method to enhance the electrocatalytic performance of PtRu/C catalyst in methanol electrooxidation.
Nitrogen-doped carbon coated ZeO2 as a support to Pt nanoparticles in the oxygen reduction reaction
(Elsevier, 2013) Wang, Rongfang; Wang, Keliang; Wang, Hui; Wang, Qizhao; Key, Julian; Linkov, Vladimir; Ji, Shan
A new nitrogen-doped carbon (CNx) support for Pt electrocatalysts was prepared by carbonizing polypyrrole on the surface of ZrO2 (ZrO2@CNx) at high temperature. Well-dispersed Pt nanoparticles were easily formed on the ZrO2@CNx. The electrocatalyst was characterized by FT-IR, XRD, TEM, XPS. The electrochemical performances indicate that the presence of ZrO2 modified the electro-structure of Pt on the catalyst surface and that ZrO2@CNx had superior oxygen reduction activity compared to a nitrogen-doped carbon coated carbon (C@CNx).
Palygorskite hybridized carbon nanocomposite as a high-performance electrocatalyst support for formic acid oxidation
(South African Chemical Institute (SACI), 2013) Linkov, Vladimir; Ji, Shan; Wang, Keliang; Wang, Hui; Wang, Rongfang; Key, Julian
A nanocomposite, in which acid-treated palygorskite was hybridized with carbon, was prepared and designed as an efficient support for electrocatatlysts. Pd nanoparticles were deposited on the hybrid support as an electrocatalyst for formic acid oxidation. The hybrid supports and electrocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS).TEMandXRDresults showed that acid treatment had an effective impact on the morphology of palygorskite, but did not destroy its architecture. XPS results indicated that the introduction of palygorskite resulted in a negative shift of binding energy of Pd deposited on it. The electrochemical results showed that the addition of palygorskite into the carbon facilitated the formation ofOHads orOads on the surface of Pd/C-PLS, and further improved the formic acid electrooxidation activity. Therefore, considerable improvements in electrocatalytic activity toward formic acid oxidation was achieved by using this hybrid support when compared with conventional carbon support, suggesting that the introduction of SiO2-based porous palygoriskite was an excellent and cost-efficient way to improve the electrocatalytic performance of carbon support.
Platinum overlaid PdCulr/C: an Improved Methanol Oxidation Elextrocatalyst
(ESG, 2013) Ma, Yanjiao; Wang, Rongfang; Wang, Hui; Ji, Shan
A platinum overlaid PdCuIr/C (Pt-PdIrCu/C) anodic catalyst for direct methanol fuel cell was prepared by a two-step reduction method. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) results show that the metal nano-particles had a large surface area and even distribution. The Pt mass activity of the catalyst was about 6.6 times larger than that of a Pt/C catalyst and 1.2 times larger than that of a Pt-PdCu/C catalyst. The high electrocatalytic activities could be attributed to the synergistic effect between Pt and PdIrCu.
Selectivity of oxygen evolution reaction on carbon cloth-supported δ-mno2 nanosheets in electrolysis of real seawater
(Molecules, 2023) Linkov, Vladimir; Ji, Shan; Yan, Haofeng; Wang, Xuyun; Wang, Rongfang
Electrolysis of seawater using solar and wind energy is a promising technology for hydrogen production which is not affected by the shortage of freshwater resources. However, the competition of chlorine evolution reactions and oxygen evolution reactions on the anode is a major obstacle in the upscaling of seawater electrolyzers for hydrogen production and energy storage, which require chlorine-inhibited oxygen evolution electrodes to become commercially viable. In this study, suchan electrode was prepared by growing δ-MnO2 nanosheet arrays on the carbon cloth surface. The selectivity of the newly prepared anode towards the oxygen evolution reaction (OER) was 66.3% after 30 min of electrolyzer operation. The insertion of Fe, Co and Ni ions into MnO2 nanosheets resulted in an increased number of trivalent Mn atoms, which had a negative effect on the OER selectivity. Good tolerance of MnO2/CC electrodes to chlorine evolution in seawater electrolysis indicates its suitability for upscaling this important energy conversion and storage technology
Selenium functionalized carbon for high dispersion of platinumeruthenium nanoparticles and its effect on the electrocatalytic oxidation of methanol
(Elsevier, 2013) Wang, Rongfang; Da, Huahua; Wang, Hui; Ji, Shan; Tian, Zhongqun
Using selenium functionalized carbon as supports, platinumeruthenium nanoparticles were highly dispersed on the carbon surface, and showed improved electrochemical properties for methanol electrooxidation. The method provides a new route for functionalization of the carbon surface on which to disperse noble metal nanoparticles for application as electrocatalysts in fuel cells.
Selenium-functionalized carbon as a support for platinum nanoparticles with improved electrochemical properties for the oxygen reduction reaction and CO tolerance
(Electrochemical Society, 2013) Wang, Hui; Da, Huahua; Ji, Shan; Liao, Shijun; Wang, Rongfang
Using selenium-functionalized carbon as supports, platinum nanoparticles were uniformly dispersed on the carbon surface, and showed improved electrochemical properties for the oxygen reduction reaction. At the same time the CO tolerance is improved. The method provides a new route for functionalization of the carbon surface on which to disperse noble metal nanoparticles for use as electrocatalysts in the oxygen reduction reaction.
Synthesis of carbon-supported PdSn–SnO2 nanoparticles with different degrees of interfacial contact and enhanced catalytic activities for formic acid oxidation
(Royal Society of Chemistry, 2013) Wang, Hui; Liu, Ziyue; Ma, Yanjiao; Julian, Key; Ji, Shan; Linkov, Vladimir; Wang, Rongfang
The conjunction of the PdSn alloy and SnO2 is of interest for improving catalytic activity in formic acid oxidation (FAO). Here, we report the synthesis of PdSn–SnO2 nanoparticles and a study of their catalytic FAO activity. Different degrees of interfacial contact between SnO2 and PdSn were obtained using two different stabilizers (sodium citrate and EDTA) during the reduction process in catalyst preparation. Compared to the PdSn alloy, PdSn–SnO2 supported on carbon black showed enhanced FAO catalytic activity due to the presence of SnO2 species. It was also found that interfacial contact between the PdSn alloy and the SnO2 phase has an impact on the activity towards CO oxidation and FAO.

Browsing by Author "Wang, Rongfang"

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