TiO is the most investigated photocatalyst because of its nontoxicity, low cost, chemical stability, and strong photooxidative ability. Because of the morphology- and structure-dependent photocatalytic properties of TiO, accurate characterization of the crystal and electronic structures of TiO-based materials and their performance during the photocatalytic process is crucial not only for understanding the photocatalytic mechanism but also for providing experimental guidelines as well as a theoretical framework for the synthesis of high performance photocatalysts. In this review, we focused on the advanced characterization techniques that are utilized in the studies on the TiO structures and photocatalytic performance of TiO and TiO-based materials. It is therefore anticipated that this review can provide a novel perspective to understand the fundamental aspects of photocatalysis and inspire the development of new photocatalysts with superior performances.

In this review, we provide an overview of our work in resistive switching mechanisms on oxide-based resistance random access memory (RRAM) devices. Based on the investigation of physical and chemical mechanisms, we focus on its materials, device structures, and treatment methods so as to provide an in-depth perspective of state-of-the-art oxide-based RRAM. The critical voltage and constant reaction energy properties were found, which can be used to prospectively modulate voltage and operation time to control RRAM device working performance and forecast material composition. The quantized switching phenomena in RRAM devices were demonstrated at ultra-cryogenic temperature (4K), which is attributed to the atomic-level reaction in metallic filament. In the aspect of chemical mechanisms, we use the Coulomb Faraday theorem to investigate the chemical reaction equations of RRAM for the first time. We can clearly observe that the first-order reaction series is the basis for chemical reaction during reset process in the study. Furthermore, the activation energy of chemical reactions can be extracted by changing temperature during the reset process, from which the oxygen ion reaction process can be found in the RRAM device. As for its materials, silicon oxide is compatible to semiconductor fabrication lines. It is especially promising for the silicon oxide-doped metal technology to be introduced into the industry. Based on that, double-ended graphene oxide-doped silicon oxide based via-structure RRAM with filament self-aligning formation, and self-current limiting operation ability is demonstrated. The outstanding device characteristics are attributed to the oxidation and reduction of graphene oxide flakes formed during the sputter process. Besides, we have also adopted a new concept of supercritical CO2 fluid treatment to efficiently reduce the operation current of RRAM devices for portable electronic applications.

Solid carbon nanofibers (CNFs) made from ethanol flames were used to prepare supercapacitors. Their microstructure, crystallinity, porosity, chemical properties, and electrochemical activity were compared with the multiwalled carbon nanotubes (MWCNTs) synthesized by chemical vapor deposition. The produced CNFs have a unique microstructure with a solid core and porous surface. The specific surface area of CNFs was comparable to that of MWCNTs because of their larger amount of micropores on the surface. The synthesis environment also resulted in abundant functional groups absorbed on the surface of the CNFs. Electrochemical characterization shows that CNFs have much larger capacitance than that of MWCNTs. The capacitance of CNFs consists of both double-layer capacitance contributed by micropores and pseudo-capacitance produced from redox reactions of the absorbed oxygen functional groups. In comparison to the reported MWCNTs-based supercapacitors, the CNF demonstrates more promising potential in energy storage applications because of its larger electrochemical capacitance.