Supramolecular chirality has been optically induced in an achiral epoxy‐based polymer containing photoresponsive azobenzene groups. The origin of this effect is the long‐range helical arrangement of the azobenzenes, which extends through the entire thickness of the film. The helicity induced by the handedness of the laser can be reversibly switched by alternately exposing the film to a 488 nm laser with right‐ and left‐handed elliptical polarization. The chiral properties of these films have been characterized by circular dichroism spectroscopy and optical rotation. After five switching cycles, the fatigue resistance is seen to depend on the absorption wavelength of the film, probably due to differences in the photoresponsive speed of the azobenzenes and the polymeric segments.

Exploring cheap and active non-precious metal catalyst for the oxygen reduction reaction (ORR) is a recent major effort in fuel cells for large-scale applications. Herein, we report electrospun cobalt-carbon nanofiber (Co-CNF) as an efficient catalyst for the ORR together with systematic study on active site formation. The ORR activity of Co-CNF increases with increasing Co content up to approximately 30 wt. %, which exhibits high ORR activity comparable with a commercial Pt/C catalyst in alkaline media. XPS and structural analysis reveals a Co-pyridinic N x bond at the edge plane and Co nanoparticles in the Co-CNFs also increase with increasing Co contents. These sites can behave as the primary and the secondary active site for the ORR according to a dual-site mechanism. The ORR activity of Co-CNF may deteriorate even if only one of these sites is limited. The high ORR activity of the Co-CNF catalysts results from the synergetic effect of dual site formation for the ORR. Figure 4. (a) The ORR activity of Co-CNF catalysts with various Co contents and the commercial Pt/C catalysts. (b) H2O2 yield and the electron transfer number of the 32.2 wt. % Co-CNF catalyst in O2-saturated 0.1 M KOH solution at rotating speed of 1600 rpm. ORR activity of (c) 32.2 wt % Co-CNF and (d) 20 wt% Pt/C measured before and after 10,000 voltage cycling from 0.6 to 1.0 V.

We propose a method to enhance the fuel cell efficiency with the simultaneous removal of toxic heavy metal ions. Carbon monoxide (CO), an intermediate of methanol oxidation that is primarily responsible for Pt catalyst deactivation, can be used as an in-situ reducing agent for hexavalent chromium (Cr (VI)) with reactivating the CO-poisoned Pt catalyst. Using electro-oxidation measurements, the oxidation of adsorbed CO molecules coupled with the concurrent conversion of Cr (VI) to Cr (III) was confirmed. This concept was also successfully applied to a methanol fuel cell to enhance its performance efficiency and to remove toxic Cr (VI) at the same time.