查看更多>>摘要：Non-precious molecular cobalt phthalocyanine (CoPc) complexes have been considered to be promising electrocatalysts due to diversity of substituents and carbon supporting matrixes. Here, we report a highly dispersed fluorinated CoPc (CoPcF16) molecule electrocatalyst immobilized in ordered mesoporous carbon CMK-3 (CMK-3-CoPcF16) via pi-pi interaction. The molecular electrocatalyst is characterized by X-ray photoelectron spectroscopy, Raman spectrum, electronic paramagnetic resonance, scanning electron microscopy, transmission electron microscopy and electrochemical impedance spectroscopy. The combination of fluorine substituents and high loading capability of CMK-3 increase the solubility of CoPc, suppress aggregation, and thereby enhance the electrocatalytic performance. As a result, the CMK-3-CoPcF16 modified electrode shows high electrocatalytic activity towards the oxidation of hydrogen peroxide and hydrazine. CMK-3-CoPcF16 hybrid is successfully presented as an electrochemical sensing platform for sensitive detection of H2O2 and hydrazine with a detection limit of 0.03 and 0.2 mu M, respectively.
查看更多>>摘要：One new electrocatalyst for both water reduction and oxidation, based on an iron(III) complex, Fe-III(TAMP)Cl, is formed by the reaction of anhydrous FeCl3 with thiobis(2,1-phenylene)-bis(azanylyidene)-bis(methanylylidene)-bis-phenol (H(2)TAMP). Its structure has been determined by X-ray diffraction. A Bond-Valence Sum (BVS) model calculation was performed to assign the oxidation state of the iron center in Fe-III(TAMP)Cl. Fe-III(TAMP)Cl can electrocatalyze hydrogen evolution from a neutral electrolyte solution (pH 7.0) with a turnover frequency (TOF) of 2.43 mol of hydrogen per mole of catalyst per second (mol (mol cat)(-1) s(-1)) at an overpotential (OP) of 837 mV. Water oxidation occurs at an overpotential of 791 mV to give O-2 with a TOF of similar to 124.06 mol O-2 (mol cat)(-1) s(-1). Sustained proton reduction catalysis occurs at glassy carbon to afford H-2 over a 5 h electrolysis period with 92% Faradaic yield and no observable decomposition of Fe-III(TAMP)Cl. We hope these findings can afford a new method for the design of electrocatalysts for both water reduction and oxidation.
查看更多>>摘要：Two-dimensional (2D) MoSe2 is a promising catalyst for hydrogen evolution reaction (HER). However, the activity of MoSe2 needs to be enhanced further because of the limited exposed edge sites and low conductivity of pure MoSe2. Herein, a monolayer MoSe2-Mo2C heterojunction intercalated into N-doped carbon nanobelt layers (MoSe 2 -Mo2C/NC) is synthesized by in situ carbonizations of dodecylamine (DDA) inserted MoO3 nanobelts and followed by a selenylation treatment. Structural analysis revealed the presence of Mo2C broke the continuity of MoSe2, causing more edge sites for HER. Therefore, MoSe2-Mo2C/NC with high conducive NC layers and huge edge active sites of MoSe2 -Mo2C layers exhibits considerable HER activities in acidic and alkaline environments, including low overpotentials and low Tafel slopes of 174/214 mV (at 10 mA cm(-2)), and 55/67 mV dec(-1) in acid and alkaline solution, respectively, which are more active than the pure MoSe2/NC nanobelts and Mo2C/NC nanobelts. In addition, the MoSe2-Mo2C/NC has high stability with 3% current decrease during 10 h in 0.5 M H2SO4.
查看更多>>摘要：Co based catalysts are the promising substitutes for PVC catalysts in oxygen reduction reaction (ORR). However, designing efficient Co based catalysts still remains a challenge due to many restrictions including charge transfer, mass transport and utilization of active sites, etc. Herein, Co nanoparticles embedded 3D-interconnected hierarchical porous (macro/meso/microporous) carbon matrixes with carbon nanotubes as building blocks (marked as Co@h-ZIF-800) were prepared. The prepared Co@h-ZIF-800 showed fast charge transfer and maintained the channels for continuous O-2 transport. High surface area and efficient utilization of active sites also made Co@h-ZIF-800 exhibited excellent ORR performance with half-wave potential of 0.906 V (vs. RHE), 26 mV positive than commercial Pt/C. Our work can provide an effective strategy to explore efficient Co based electrocatalysts with hierarchical structure.
Yang, LiuqingAdsetts, Jonathan R.Zhang, RuizhongBalonova, Barbora...
8页
查看更多>>摘要：This work reports absolute electrochemiluminescence (ECL) quantum efficiencies (QEs) of two iridium(III) complexes, fac-Ir(ppy) 3 (Ir-1) and [Ir(ppy)(2) (dtbubpy)] ( [Ir-2](+)) in annihilation and coreactant pathways. With potentiodynamic scans and potential pulsing, ECL mechanisms were investigated by means of ECL-voltage curves, ECL-time curves and ECL spectroscopy. It was demonstrated that the radical stability and reactivity are the two main factors affecting ECL efficiencies in various processes, while intermediate charges have little effect. Considering the difference of such radical behaviors between [Ru(bpy)(3)](2+) and other luminophores, absolute ECL QEs are more applicable compared with the ones relative to [Ru(bpy)(3)](2+) as a standard.
查看更多>>摘要：The anode materials play a key role in the electrochemical oxidation process. In this work, a new type of Ti/Sn-SbOx/alpha-PbO2/La-In-beta-PbO2 electrode has been prepared through electrodeposition and applied to the degradation of high concentration aqueous solution of hydrolyzed polyacrylamide (HPAM). Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Energy-dispersive spectroscopy (EDS) were employed to characterize the surface morphological and structural properties of the electrodes, which indicated that the La-In-PbO2 electrode had smaller grain size, denser surface and larger active surface area compared with undoped and single-doped PbO2 electrode. Cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) were also utilized to investigate the electrochemical performance of electrodes. The results showed that the La-In-PbO2 electrode exhibited higher oxidation peak current, oxygen evolution potential (2.22 V) and lower charge transfer resistance. The La-In-PbO2 electrodes were used as anode to degrade HPAM solution under different conditions. The results revealed that the viscosity reduction rate of HPAM reached to 97.63 % after 60 min under the condition of electrolyte concentration, initial concentration of HPAM, initial pH and current density were 0.05 M, 3 g.L-1, 7 and 20 mA.cm(-2), respectively. The kinetic behavior of HPAM degradation was analyzed by the viscosity reduction experiment. The intermediates in the electrochemical oxidation process were identified by GC-MS and the possible degradation mechanism of HPAM was explored by UV-visible absorption spectra and the Fourier Transform Infrared (FT-IR) spectra.
查看更多>>摘要：Developing highly specific, rapid, and cost-effective electrochemiluminescence (ECL) methods capable of detecting multiple analytes remains a compelling research goal but it is still a substantial challenge due to narrow choice of ECL systems. In this study, efficient ECL detections were achieved by using anodic Ru(bpy)(3)(2+)-acridine orange (AO) ECL system. In present system, dimethylamino substituent on acridine ring acts as active sites for strong ECL generation, while heterocyclic nitrogen atom (-N-) contributes to specific complex formation with metal ion. Accordingly, this anodic ECL method was exploited for highly sensitive detection of both mercury (II) (Hg2+) and dopamine (DA), with detection limits as low as 0.36 nM (linear range 0.01-50 mu M) and 1.0 nM (linear range 0.01-10 mu M), respectively. The mechanism of Hg2+ detection was supported by density functional theory (DFT) calculations. Notably, the ECL method exhibit superior selectivity over numerous competing interfering agents. Moreover, the method achieved the detection of both targets in practical media with excellent recoveries (96.0-103.8%). Importantly, the method demonstrates potential advantages in terms of selectivity, sensitivity, rapidity, simplicity, and low cost. This work realizes a successful attempt to further expand the analytical applications of ECL systems and may initiate new thoughts in utilizing acridines in diverse ECL-based sensing and imaging applications.
NSTL
Elsevier