Electrode modification using nanocomposites of electropolymerised cobalt phthalocyanines supported on multiwalled carbon nanotubes

A polymer of tetra(4)-(4,6-diaminopyrimidin-2-ylthio) phthalocyaninatocobalt(II) (CoPyPc) has been deposited over a multiwalled carbon nanotube (MWCNT) platform and its electrocatalytic properties investigated side by side with polymerized cobalt tetraamino phthalocyanine (CoTAPc). X-ray photoelectron spectroscopy, scanning electron microscopy and cyclic voltammetry studies were used for characterization of the prepared polymers of cobalt phthalocyanine derivatives and their nanocomposites. L-Cysteine was used as a test analyte for the electrocatalytic activity of the nanocomposites of polymerized cobalt phthalocyanines and multiwalled carbon nanotubes. The electrocatalytic activity of both polymerized cobalt phthalocyanines was found to be superior when polymerization was done on top of MWCNTs compared to bare glassy carbon electrode. A higher sensitivity for L-cysteine detection was obtained on CoTAPc compared to CoPyPc

Self-assembled monolayers of cobalt and iron phthalocyanine complexes on gold electrodes: Comparative surface electrochemistry and electrocatalytic interaction with thiols and thiocyanate

The self-assembling of the octa(hydroxyethylthio)-metallophthalocyanine {MOHETPc (M=Co and Fe)} complexes and their similar analogues, octabutylthiometallophthalocyanine {MOBTPc (M=Co and Fe)} complexes on gold electrodes are investigated. Comparative surface voltammetric insights into their distinct self-assembling properties with respect to the passivation of Faradaic processes and surface coverages, including their solution electrochemistry, suggest different orientations and non-cleavage of their CS bonds. In the pH 2−9 range, the reversible [M(III)Pc(−2)]+ / [M(II)Pc(−2)] redox couples show potential shifts close to −59 mV / pH. The gold electrodes modified with the SAMs of these species show electrocatalytic activity towards the oxidation of thiols (L-cysteine, homocysteine and penicillamine) and thiocyanate in acidic media with detection limits in the region of 10−7–10−6 mol dm−3. These monolayers are stable and easily reproducible

Rational Design of 2D Manganese Phosphate Hydrate Nanosheets as Pseudocapacitive Electrodes

A new class of 2D nanosheets of nitrogen-integrated phosphate-rich ammonium manganese phosphate hydrate, (NH4MnPO4·H2O) (AMP), has been developed as pseudocapacitive electrode materials. The optimized electrodes exhibited device capacitances of 48.4 and 65.4 F/g for symmetric and asymmetric configurations, respectively. The devices showed excellent energy and power (e.g., 29.4 Wh/kg and 133 kW/kg for asymmetric cells) with extraordinary capacitance retention (e.g., >93%, 100 000 cycles at 5 A/g for asymmetric cells) that surpass those of most of the reported values. The huge pseudocapacitance of AMP is attributed to several factors, including the electroactive sites containing NH4+ ions, the conductive inorganic layers, intercalated water interactions of Mn2+···H2O, redox-active phosphate ions, and the 2D nanosheets. AMP-based all-solid-state flexible asymmetric devices exhibited >95% capacitance retention upon 1000 repetitive charge-discharge cycles. This study opens doors to elegant strategies of unlocking the rich physicoelectrochemical properties of 2D AMP for next-generation pseudocapacitors

Platinum supported on pristine and nitrogen-doped bowl-like broken hollow carbon spheres as oxygen reduction reaction catalysts

The development of active and durable proton exchange membrane fuel cell catalysts with high loading (ca. 40%) is critical for the commercialization of hydrogen fuel cells. Herein we report on the synthesis of a novel Pt/C catalyst using a novel bowl-like broken hollow carbon sphere (and N-doped sphere) support (carbon shell thickness ~ 4.6 nm). Highly dispersed Pt nanoparticles (dPt ~ 4 nm) were deposited on both supports and within the carbon shell. The Pt particles in the pores were exposed on both sides of the shell, while the shell porosity ensured pore confinement of the Pt. Both catalysts exhibited high electrochemical surface areas (60–65 m2 g−1) and cycling durability (6000 cycles) that was superior to a commercial benchmark Pt/C catalyst. These studies indicate that high loadings of confined small Pt particles on both sides of thin interconnected carbons can lead to high oxygen reduction reaction activities and durability