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91.
Guangmei Cai Lihua Zeng Lanqi He Shujian Sun Yexiang Tong Jianyong Zhang 《化学:亚洲杂志》2020,15(13):1963-1969
A series of porphyrin‐based imine gels have been synthesized via dynamic covalent gelation between 5,10,15,20‐tetra(4‐aminophenyl)‐21H,23H‐porphyrin (H2TAPP) derivatives and various aldehyde compounds. The porphyrin‐ferrocene imine gels based on MTAPP (M=H2, Ni2+, Co2+, Pd2+ and Zn2+) and ferrocene‐1,1′‐dicarbaldehyde (NA) display efficient HER, OER and ORR activities in alkaline media. Among the gels, CoTAPP‐NA shows an HER current density of 10 mA cm?2 at low overpotential of 470 mV and small Tafel slope of 110 mV decade?1 in alkaline media. CoTAPP‐NA also exhibits OER catalytic activity with low overpotential (416 mV for 10 mA cm?2). CoTAPP‐NA shows ability in overall water splitting in alkaline media. In addition, CoTAPP‐NA exhibits onset potential (Ep) of 0.95 V and half‐wave potential (E1/2) of 0.84 V in 1.0 mol L?1 KOH solution for oxygen reduction. Moreover, the gel catalyst shows good stability. 相似文献
92.
In‐depth understanding of the catalytic active sites is of paramount importance for the design of efficient electrocatalysts for CO2 conversion. Here we highlight the structural evolution of SnO2 nanosheets for electrocatalytic CO2 reduction. The transformation of SnO2 into metallic Sn would occur on the surface of catalyst during the catalytic process, followed by enhanced selectivity and activity for the conversion of CO2 to HCOOH. Electrocatalytic characterization and structural analysis demonstrate that the metallic Sn derived from structural evolution plays a dominant role in the CO2 reduction to HCOOH. This work deepens the understanding of the catalytic mechanism and provides a new pathway for the rational design of advanced electrocatalysts for CO2 reduction. 相似文献
93.
94.
Dr. Hongjing Wang Shiqian Jiao Songliang Liu Hugang Zhang Dr. You Xu Prof. Xiaonian Li Dr. Ziqiang Wang Prof. Liang Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(58):14472-14477
The optimization of structure and composition is essential to improve the performance of catalysts. Herein, mesoporous nanoparticles assembled PdNi/Ni nanotubes (mPdNi/Ni NTs) are successfully fabricated using nickel nanowires as sacrificial template. The combination of nanotubular structure with mesoporous nanoparticle morphology can provide facilitated transfer channels and sufficient active sites, allowing the full contact and reaction between catalysts and reactants. Therefore, the synthesized mPdNi/Ni NTs exhibite superior ethanol oxidation performance to mesoporous Pd nanotubes and commercial Pd black. This study proposes a rational strategy for the development of nanoparticle assembled nanotubes with surface mesoporous morphology, which can greatly improve catalytic performance in various electrocatalytic fields. 相似文献
95.
96.
Results on the paper's theme are reviewed. Attention is focused mainly on the use of transients of current and open-circuit potential for elucidating changes in the structure of the electrical double layer (EDL) caused by the CO adsorption. It is shown that the high binding energy of CO with surfaces of platinum metals leads to a strong suppression of the total differential capacitance of the electrode, the recharge of the surface, the displacement of strongly adsorbed atoms formed during the adsorption of ions with a total charge transfer, and to other alterations in the EDL plates facing both solution and metal. The importance of allowing for double-layer effects when solving problems of electrocatalysis on platinum metals is emphasized. 相似文献
97.
Christopher A. Paddon Farrah L. Bhatti Timothy J. Donohoe Richard G. Compton 《Journal of Physical Organic Chemistry》2007,20(2):115-121
Recent interest in the electrocatalytic activity of silver towards the reduction of alkyl iodides has led us to investigate whether the effect is observed in tetrahydrofuran (THF) at room temperature. Using platinum electrodes in THF for the reduction of alkyl halides at 298 K has been hampered by the solvent window, which ‘obscures’ the voltammetric signals of interest. In order to overcome these problems, voltammetry has been performed at low temperature and was shown to extend the voltammetric window, leading to accurate electrochemical analyses and even novel changes in mechanism(s) of the reactive species following electron‐transfer (ET). Herein, it is shown that for a primary and tertiary alkyl iodide in THF, electroreduction at silver leads to a significant shift in the reduction potential to more positive values compared to platinum. In addition, following reduction, a characteristic series of oxidation peaks are observed and are shown to be due to the specific activity of iodide ions towards silver following reductive cleavage of the parent alkyl iodide. This characteristic feature is not observed with other halide ions: bromide and chloride. Preparative electrolyses at controlled‐potential have suggested that the reduction of the above alkyl iodides is a one‐electron concerted process. The ‘free’ iodide ions act as a monitor of reaction progression, and the carbon‐centred radical either dimerises and/or abstracts a hydrogen atom from the electrolyte/solvent; 1‐iodoadamantane giving percentage yields of 58% adamantane and 39% 1,1'‐biadamantane, the primary alkyl iodide, prepared in‐house, giving 67% R‐H and 25% R‐R. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
98.
Jianghua Zeng Dingsheng Yuan Yingliang Liu Jingxing Chen Sanxiang Tan 《Frontiers of Chemistry in China》2009,4(2):127-131
Tungsten carbide (WC) nanocrystals have been prepared by a solvothermal method with Mg as the reductant and WO3 and anhydrous ethanol as the precursors. The effects of time and temperature on the synthesis of WC were investigated and
a probable formation mechanism was discussed. The obtained WC nanocrystals were characterized by X-ray diffraction, transmission
electron microscopy, energy dispersive spectroscopy and electrochemical methods. Hexagonal closepacked WC was successfully
synthesized when the temperature was as low as 500°C. The content of carbon was more than that of W, indicating that the composition
of the treated sample was C and WC only. The diameters of WC nanocrystals were ranged from 40 nm to 70 nm and the nanocrystals
were dispersed on carbon films. The electrochemical measurements reveal that WC nanocrystals obviously promote Pt/C electrocatalytic
ability for the oxygen reduction reaction.
__________
Translated from Chinese Journal of Catalysis, 2008, 29(7) (in Chinese) 相似文献
99.
100.
As an alternative selection of electrocatalytic surface modifier, the electrochemically generated copper oxides is re‐ investigated by using cyclic voltammetry (CV), scanning electron microscopy (SEM) and X‐ray photoelectron spectroscopy (XPS). Interesting phenomena have been found, which indicate that the electrodeposition from the Cu2+ solution under cyclic voltammetric conditions can generate a transparent Cu(OH)2 crystalline on the surface of glassy carbon electrodes, and this crystalline can be further transferred to a novel cubic opaque CuO crystalline of about 300 nm in size by second step of cyclic voltammetry in pH 12 NaOH solution. The final electrode (denoted as nano‐CuO/GCE) can catalyze the oxidation (as well as the reduction) of H2O2 in basic solutions. It shows pH dependent three‐part catalytic mechanism in the range from pH 7 to pH 14. In 0.10 mol/L NaOH solution, the amperometric response at 0.15 V (vs. SCE) can give a current sensitivity as high as 139 mA/(mol·L?1) in the rage of 5.0×10?7?6.0×10?4 mol/L with a lower detection limit (s/n=3) of 2.5×10?8 mol/L, and a current sensitivity of 78.4 mA/(mol·L?1) in the rage of 6.0×10?4–2.0×10?3 mol/L. This electrode also has excellent reproducibility and stability. The mechanisms for the two steps of preparation and the catalytic reactions are proposed. The nano‐CuO crystalline modified electrode may have more applications in the field of electrochemical sensing. 相似文献