Formation of a polycrystalline film of donor material on PEDOT:PSS buffer induced by crystal nucleation

Unusual bromine enrichment in the gastric mill and setae of the hadal amphipod Hirondellea gigas

The hadal amphipod Hirondellea gigas is an emblematic animal of the Pacific trenches, and has a number of special adaptations to thrive in this ‘extreme’ environment, which includes the deepest part of the Earth’s ocean. One such adaptation that has been suggested is the presence of an ‘aluminum gel shield’ on the surface of its body in order to prevent the dissolution of calcitic exoskeleton below the carbonate compensation depth. However, this has not been investigated under experimental conditions that sufficiently prevent aluminum artefacts, and the possibility of other elements with similar characteristic X-ray energy as aluminum (such as bromine) has not been considered. Here, we show with new electron microscopy data gathered under optimized conditions to minimize aluminum artefacts that H. gigas actually does not have an aluminum shield–instead many parts of its body are enriched in bromine, particularly gastric ossicles and setae. Results from elemental analyses pointed to the use of calcite partially substituted with magnesium by H. gigas in its exoskeleton, in order to suppress dissolution. Our results exemplify the necessity of careful sample preparation and analysis of the signals in energy-dispersive X-ray spectroscopic analysis, and the importance of analyses at different electron energies.

Voltammetric sensing performances of a carbon ionic liquid electrode modified with black phosphorene and hemin

A black phosphorene (BPE) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) hybrid was used for the immobilization of hemin on a carbon ionic liquid electrode (CILE). BPE inside the PEDOT:PSS film was stable without adverse effects of water and oxygen. The hemin-modified electrode facilitates electrochemical communication with a couple of well-shaped and enhanced redox waves. Therefore BPE exhibits an accelerating function to the electron movement. This sensor exhibits excellent electrocatalytic effects on the reduction of various substrates including trichloroacetic acid (TCA), nitrite and H₂O₂. As for TCA, the reduction current at -0.36 V (vs. Ag/AgCl) increases linearly in the concentration range from 2.0 to 180 mmol·L^-1 with a detection limit of 0.67 mmol·L^-1 (at 3σ). As for nitrite, the reduction current at -0.59 Vis linear in the 1.0 to 10.5 mmol·L^-1 concentration range, and the detection limit is 0.33 mmol·L^-1 (at 3σ). As for H₂O₂, the reduction current at -0.033 V (vs. Ag/AgCl) is linear in the concentration range from 4.0 to 35.0 mmol·L^-1 and the detection limit is 1.3 mmol·L^-1 (at 3σ). The real sample was analyzed with satisfactory results, which indicated that BPE had potential applications in the field of electrochemical biosensor. Graphical abstract Photos of (a) black phosphorene (BPE) solution, (b) poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), (c) BPE-PEDOT:PSS (1:5) dispersion, and the fabrication procedure of this electrochemical sensor. It was applied to the determination of trichloroacetic acid, nitrite and hydrogen peroxide.

Acid-Responsive Conductive Nanofiber of Tetrabenzoporphyrin Made by Solution Processing

While cofacial one-dimensional (1-D) π stacking of a planar aromatic molecule is ideal for the construction of conduction systems, such molecules, including tetrabenzoporphyrin (BP), prefer to form edge-to-face stacking through CH-π interactions. We report here that the BP molecules spontaneously form a 1-D cofacial stack in chloroform containing 1% trifluoroacetic acid (TFA) and that a bundle of the formed nanofiber shows acid-responsive 1-D conductivity as high as 1904 S m^-1. A small fraction (2.7%) of BP in the fiber exists in a cation radical state, and 1.5 equiv of TFA is located in an intercolumnar void. Dedoping and redoping of TFA with trimethylamine vapor results in 1300-2700-fold decreases and increases, respectively, in the conductivity and also the amount of the radical cation. The conductivity of the fiber also shows a correlation with the pK_a of acid dopants.