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Abstract: Substituent effects of iron porphyrin complexes on the structures and kinetic processes have been examined for the first time. Basing on the premise that iron porphyrin is functional analogous to heme, a series of iron porphyrin derivatives bearing different substituents at the meso positions of the corrole ring are investigated as to their electrochemistry, the relationships among the electron transfer (ET) processes, their structures, and orbital energies. The good coherence between the experiment and theory indicates that the ET rate can be accelerated when electron-donating substituents are introduced to the iron porphyrin ring. Finally, the implications of the results are discussed in the influence of stability of iron porphyrin complexes on the ability to carry molecular oxygen, which may suggest it possible to dominate the biological activity of heme by selecting the appropriate substituents to iron porphyrin ring. [Copyright &y& Elsevier]

Abstract: Multilayers film of nanostructured gold nanoparticles (AuNPs) has been fabricated based on the layer-by-layer (LBL) technique using a self-assembled monolayer of 5,15-di-[p-(6-mercaptohexyl)-phenyl]-10,20-diphenylporphyrin (trans-PPS2). AuNPs act as physical cross-link points in the multilayers. Electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM) are applied to study the formation of the organic–inorganic multilayers film and have determined the electrochemical parameters, i.e., the heterogeneous electron transfer rate constant (K et). The observed phenomena indicate that the electron transfer (ET) process is affected by material properties and the molecular structure of self-assembled monolayers (SAMs). Using the high sensitivity of ET of ferricyanide to the modification of the gold surface with multilayers film, we select this reaction as a probe to study the different modification stages at this modified electrode. ET is retarded on the trans-PPS2 alternative deposition of layers on the electrode surface and is accelerated on the AuNPs’ layers. SECM images are used to collect surface information in the course of the successive modification process. SECM images obtained from bare and different modification stages show very high resolution with different topographies. [Copyright &y& Elsevier]

• A hand-torn bread-like 3D porous structure anode was firstly proposed in MFCs. • A new mode of accelerating electronic transfer was explored. • PANI-PPy-Ag NWs/CF hydrogel anodes are hydrophilic and biocompatible. • It has high COD removal rate (96.69 %) and power density output (2196.61 mW/m3). • The two direct electron transfer pathways were achieved simultaneously. Microbial fuel cell (MFC) can generate electrons through microbial metabolism of organic matter in sewage. In this paper, carbon felt as base material, the conductive polymers polyaniline and polypyrrole combined with silver nanowires were doped in hydrogel, a super hydrophilicity, low electron transfer resistance, good biocompatibility hydrogel MFC anode (PANI-PPy-Ag NWs/CF) were prepared. It showed a hand-torn bread structure, this three-dimensional (3D) porous structure increased microbial attachment amount. The anode could reach a maximum voltage output of 0.66 V in only 5.5 h, and produce a maximum power density of 2196.61 mW/m3. Due to the doping of silver nanowire, a new electronic mode was explored, coulomb efficiency of 31.01 % and an ultra-high COD removal rate (96.69 %) was obtained. This study introduces a conductive composite hydrogel MFC anode, which provides a new idea for the material diversity, electrical production and sewage removal performance of MFC anode. [ABSTRACT FROM AUTHOR]

Abstract: The rate constant of electron transfer reaction between ferrous ion in aqueous phase and decamethyferrocene located on the adjacent aqueous phase was measured by thin layer method, a simple protocol reported recently for studying electron transfer reaction at liquid/liquid interface. Despite this large increase in overall driving force, the rate constants decrease by less than an order of magnitude compared the two reaction systems of Fe3+–DMFe and Fe(CN)6 3−–DMFe. The results demonstrate that reorganization energy may be a dominating factor on the rate of electron transfer across the interface due to the effect of the size and symmetry of reactants in aqueous. In addition, the effect of thickness of the thin layers is investigated further. [Copyright &y& Elsevier]