Iron phthalocyanine with coordination induced electronic localization to boost oxygen reduction reaction.

Iron phthalocyanine (FePc) is a promising non-precious catalyst for the oxygen reduction reaction (ORR). Unfortunately, FePc with plane-symmetric FeN4 site usually exhibits an unsatisfactory ORR activity due to its poor O2 adsorption and activation. Here, we report an axial Fe-O coordination induced electronic localization strategy to improve its O2 adsorption, activation and thus the ORR performance. Theoretical calculations indicate that the Fe-O coordination evokes the electronic localization among the axial direction of O-FeN4 sites to enhance O2 adsorption and activation. To realize this speculation, FePc is coordinated with an oxidized carbon. Synchrotron X-ray absorption and Mössbauer spectra validate Fe-O coordination between FePc and carbon. The obtained catalyst exhibits fast kinetics for O2 adsorption and activation with an ultralow Tafel slope of 27.5 mV dec-1 and a remarkable half-wave potential of 0.90 V. This work offers a new strategy to regulate catalytic sites for better performance.

Fabrication of Cobalt-Nickel-Zinc Ternary Oxide Nanosheet and Applications for Supercapacitor Electrode.

Mesoporous cobalt-nickel-zinc ternary oxide (CNZO) nanosheets grown on the nickel foam are prepared by a simple hydrothermal treatment and subsequent calcination process. The physical characterizations show that the as-obtained CNZO nanosheets possess the mesoporous structure and a high specific surface of 75.4 m2 g-1 has been achieved. When directly applied for the binder-free supercapacitor electrode for the first time, the nickel foam supported mesoporous CNZO nanosheet electrode exhibits an ultrahigh specific capacity about 1172.2 C g-1 at 1 A g-1. More significantly, an asymmetric supercapacitor based on the as-obtained CNZO positive electrode and an activated carbon negative electrode shows a high energy density of 84.2 Wh kg-1 at a power density of 374.8 W kg-1, with excellent cycle stability (keeps 78.8% capacitance retention and 100% coulombic efficiency after 2,500 cycles). The excellent supercapacitive properties suggest that the nickel foam supported CNZO nanosheet electrodes are promising for application as high-performance supercapacitor.

Nanostructured Three-Dimensional Percolative Channels for Separation of Oil-in-Water Emulsions.

Separation of oil/water mixtures has been one of the leading green technologies for applications such as oil recovery and water purification. Conventional methods to separate oil from water are based on phase separation via physical settlement or distillation. However, challenges still remain in the effective extraction of micron-sized oil droplets dispersed in water, in which case gravity fails to work as separating force. Here, we conformably decorate porous titanium (average pore size 30 µm) with superhydrophilic nanotubes. The resulting three-dimensional superhydrophilic micro channels thus provide a driving force for oil-water separation at the nanotube/emulsion interface, enhancing significantly the water infiltration rate. The high efficiency (>99.95%, with oil droplets of average diameter 10 µm) and strong mechanical durability make the structure a reusable oil/water separator. Our findings pave the way for future applications of oil-in-water emulsion separation, which can be readily scaled up for massive demulsification.