Vibrational and electrochemical studies of pectin-a candidate towards environmental friendly lithium-ion battery development.

Pectin polymers are considered for lithium-ion battery electrodes. To understand the performance of pectin as an applied buffer layer, the electrical, magnetic, and optical properties of pectin films are investigated. This work describes a methodology for creating pectin films, including both pristine pectin and Fe-doped pectin, which are optically translucent, and explores their potential for lithium-ion battery application. The transmission response is found extended in optimally Fe-doped pectin, and prominent modes for cation bonding are identified. Fe doping enhances the conductivity observed in electrochemical impedance spectroscopy, and from the magnetic response of pectin evidence for Fe3+ is identified. The Li-ion half-cell prepared with pectin as binder for anode materials such as graphite shows stable charge capacity over long cycle life, and with slightly higher specific capacity compare with the cell prepared using polyvinylidene fluoride (PVDF) as binder. A novel enhanced charging specific capacity at a high C-rate is observed in cells with pectin binder, suggesting that within a certain rate (∼5 C), pectin has higher capacity at faster charge rates. The pectin system is found as a viable base material for organic-inorganic synthesis studies.

Doping-free bandgap tunability in Fe2O3 nanostructured films.

A tunable bandgap without doping is highly desirable for applications in optoelectronic devices. Herein, we develop a new method which can tune the bandgap without any doping. In the present research, the bandgap of Fe2O3 nanostructured films is simply tuned by changing the synthesis temperature. The Fe2O3 nanostructured films are synthesized on ITO/glass substrates at temperatures of 1100, 1150, 1200, and 1250 °C using the hot filament metal oxide vapor deposition (HFMOVD) and thermal oxidation techniques. The Fe2O3 nanostructured films contain two mixtures of Fe2+ and Fe3+ cations and two trigonal (α) and cubic (γ) phases. The increase of the Fe2+ cations and cubic (γ) phase with the elevated synthesis temperatures lifted the valence band edge, indicating a reduction in the bandgap. The linear bandgap reduction of 0.55 eV without any doping makes the Fe2O3 nanostructured films promising materials for applications in bandgap engineering, optoelectronic devices, and energy storage devices.