No abstract

Atomic level engineering of graphene-based materials is in high demand to enable customize structures and properties for different applications. Unzipping of the graphene plane is a potential means to this end, but uncontrollable damage of the two-dimensional crystalline framework during harsh unzipping reaction has remained a key challenge. Here we present heteroatom dopant-specific unzipping of carbon nanotubes as a reliable and controllable route to customized intact crystalline graphene-based nanostructures. Substitutional pyridinic nitrogen dopant sites at carbon nanotubes can selectively initiate the unzipping of graphene side walls at a relatively low electrochemical potential (0.6 V). The resultant nanostructures consisting of unzipped graphene nanoribbons wrapping around carbon nanotube cores maintain the intact two-dimensional crystallinity with well-defined atomic configuration at the unzipped edges. Large surface area and robust electrical connectivity of the synergistic nanostructure demonstrate ultrahigh-power supercapacitor performance, which can serve for AC filtering with the record high rate capability of −85° of phase angle at 120 Hz.

Linker-free spontaneous binding of Co4POMs on NCNTs are presented via electrostatic hybridization for efficient water oxidation at neutral pH. Co4POM/NCNT hybrids exhibited outstanding catalytic activities for water oxidation under neutral conditions.

Stoichiometric crystalline binary metal oxide thin films can be used as channel materials for transparent thin film transistors. However, the nature of the process used to fabricate these films causes most binary metal oxide thin films to be highly conductive, making them unsuitable for channel materials. We overcame this hurdle by forming stoichiometric ultra-thin (5 nm) crystalline In2O3 films by using a thermal atomic layer deposition method. Specifically, (3-(dimethylamino)propyl)dimethylindium was used as a liquid precursor and ozone as an oxygen source to grow In2O3 thin films at a high growth rate of 0.06 nm/cycle. Adjustment of the deposition processing temperature followed by annealing in an oxygen atmosphere enabled us to fully crystallize the film into a cubic bixbyite structure with the retained stoichiometry. The transparent crystalline ultra-thin In2O3-based bottom-gate thin film transistors showed excellent and statistically uniform switching characteristics such as a high Ion/Ioff ratio exceeding 107, a high linear mobility of 41.8 cm2/V s, a small subthreshold swing of 100 mV/dec, and a low hysteresis of 0.05 V. Our approach offers a straightforward scheme, which is compatible with oxide electronics, for fabricating a transparent metal oxide device without resorting to complicated oxide compositional strategies.

In all-solid-state batteries, the electrode has been generally fabricated as a composite of active material and solid electrolyte to imitate the electrode of lithium-ion batteries employing liquid electrolytes. Therefore, an efficient protocol to spatially arrange the two components with a scalable method is critical for high-performance all-solid-state batteries. Herein, a design of the all-solid-state electrode is presented for all-solid-state batteries with higher energy density than the typical composite-type electrode. The proposed electrode, composed mostly of the active materials, has a seamless interface between the active materials, which allows interparticle lithium-ion diffusion. Thus, the solid electrolyte can be completely excluded during the electrode manufacturing process, which enables higher flexibility for fabrication protocol by relieving the concerns about (electro)­chemistry related to solid electrolytes. Furthermore, it can dramatically enhance the normalized energy density by increasing the content of the active material in the electrode. This electrode concept provides a meaningful advance toward high-performance all-solid-state batteries.