Electrosynthesis of conducting poly(o-aminophenol) films on Pt substrates: a combined electrochemical and XPS investigation

Electropolymerization of a Carbonyl-Modified Dihydropyrazine Derivative for Aqueous Zinc Batteries with Ultrahigh Cycling Stability

The design of aqueous zinc-ion batteries (ZIBs) that have high specific capacity and long-term stability is essential for future large-scale energy storage systems. Cathode materials with extended π-conjugation and abundant active sites are desirable to enhance the charge storage performance and the cycling stability of the aqueous ZIB. Based on this concept, 6,9-dihydropyrazino[2,3-g]quinoxaline-2,3,7,8(1H,4H)-tetrone was chosen as the monomer to be electropolymerized onto carbon cloth (PDHPQ-Tetrone/CC). When used as the cathode material for aqueous ZIBs, an exceptional cycling life (>20,000 cycles) at a current density of 10 A g-1 was achieved, with the specific capacity maintained at 82.8% and with the Coulombic efficiency at around 100% throughout cycling. At the charge-discharge current density of 0.1 A g-1, the ZIB with PDHPQ-Tetrone/CC achieved a high specific capacity of 248 mAh g-1. Kinetic analyses showed that both surface-capacitive-controlled processes and semi-infinite diffusion-controlled processes contribute to the stored charge. The charge storage mechanism was investigated with ex situ characterizations and involves the redox processes of carbonyl/hydroxyl and amino/imino groups coupled with insertion and extraction of both Zn2+ and H+.

Electrodeposited Poly(5-Amino-2-Naphthalenesulfonic Acid-co-o-Aminophenol) as the Electrode Material for Flexible Supercapacitor

Copolymers of 5-amino-2-naphthalenesulfonic acid (ANS) and o-aminophenol (oAP) are electropolymerized on carbon cloth substrate from aqueous solutions, and the electropolymerization process is investigated using electrochemical quartz-crystal microbalance. The surface of the copolymer (PANS-co-oAP) appears rough and is capable to store charge as the battery-type electrode in 1 m H2 SO4 (102.9 mAh g-1 at 1 A g-1 ) or in 1 m ZnSO4 (79.75 mAh g-1 at 1 A g-1 ) aqueous solutions. Compared with PANS and PoAP, the high specific capacity of the PANS-co-oAP is originated from the increased number of electrochemically active sites and increased diffusion rates of ions. Evidence of amino/imino and hydroxyl/carbonyl groups redox processes and cation insertion and extraction are given by ex situ X-ray photoelectron spectroscopy. When used as the electrode material in the flexible solid-state supercapacitors, the specific capacitance is at 37.9 F g-1 which does not significantly alter with the bending angle. The flexible solid-state supercapacitor shows a specific energy of 5.4 Wh kg-1 and a power density of 250.3 W kg-1 at 0.5 A g-1 , and a high capacitance retention (88.2%) after 3000 cycles at 5 A g-1 is achieved.

Peculiarities of Oxidative Polymerization of Diarylaminodichlorobenzoquinones

New oxidative polymerization monomers-diarylaminodichlorobenzoquinones were synthesised by alkylating aniline, m-phenylenediamine and methanilic acid with chloranil. Oxidative polymerization of diarylaminodichlorobenzoquinones was studied for the first time in relation to the concentration of the monomer, acid, and oxidant/monomer ratio. It was found that the synthesized monomers are highly active in the polymerization reaction, and the oxidation rate grows with the increase in the acid concentration. Only one arylamine group is involved in the polymerization reaction. The optimal oxidant/monomer ratio is stoichiometric for one arylamine group, despite the bifunctionality of the monomers. It was shown that the type of the substituent in the aniline ring (electron donor or electron acceptor) determines the growth of the polymer chain and the structure of the resulting conjugated polymers. A mechanism for the formation of active polymerization centers for diarylaminodichlorobenzoquinones was proposed. FTIR-, NMR-, X-ray photoelectron spectroscopy, and SEM were used to identify the structure of the synthesized monomers and polymers. The obtained polymers have an amorphous structure and a loose globular morphology. The frequency dependence of the electrical conductivity was studied.

On-Surface Driven Formal Michael Addition Produces m-Polyaniline Oligomers on Pt(111)

On-surface synthesis is emerging as a highly rational bottom-up methodology for the synthesis of molecular structures that are unattainable or complex to obtain by wet chemistry. Here, oligomers of meta-polyaniline, a known ferromagnetic polymer, were synthesized from para-aminophenol building-blocks via an unexpected and highly specific on-surface formal 1,4 Michael-type addition at the meta position, driven by the reduction of the aminophenol molecule. We rationalize this dehydrogenation and coupling reaction mechanism with a combination of in situ scanning tunneling and non-contact atomic force microscopies, high-resolution synchrotron-based X-ray photoemission spectroscopy and first-principles calculations. This study demonstrates the capability of surfaces to selectively modify local molecular conditions to redirect well-established synthetic routes, such as Michael coupling, towards the rational synthesis of new covalent nanostructures.

In Situ Electrochemical-AFM and Cluster-Ion-Profiled XPS Characterization of an Insulating Polymeric Membrane as a Substrate for Immobilizing Biomolecules

The electrochemical oxidation of ortho-aminophenol (oAP) by cyclic voltammetry (CV), on platinum substrates in neutral solution, produces a polymeric film (PoAP) that grows to a limiting thickness of about 10 nm. The insulating film has potential use as a bioimmobilizing substrate, with its specificity depending on the orientation of its molecular chains. Prior investigations suggest that the film consists of alternating quinoneimine and oAP units, progressively filling all the platinum sites during the electrosynthesis. This work concerns the evaluation of the growth orientation of PoAP chains, which until now was deduced only from indirect evidence. Atomic force microscopy (AFM) has been used in situ with an electrochemical cell so that PoAP deposition on a specific area can be observed, thus avoiding any surface reorganization during ex situ transport. In parallel with microscopy, XPS experiments have been performed using cluster ion beams to profile this film, which is exceptionally thin, without damage while retaining molecular information.

Ultrasensitive sensing of tris(2,3-dibromopropyl) isocyanurate based on the synergistic effect of amino and hydroxyl groups of a molecularly imprinted poly(o-aminophenol) film

The ultrasensitive sensing of tris(2,3-dibromopropyl) isocyanurate was achieved by the synergistic effect of amino and hydroxyl groups in an imprinted poly(o-aminophenol) film.