Qingdao University

About: Qingdao University is a education organization based out in Qingdao, China. It is known for research contribution in the topics: Cancer & Apoptosis. The organization has 35675 authors who have published 27275 publications receiving 374908 citations. The organization is also known as: Qīngdǎo Dàxué.

Fabrication of mesoporous Co3O4 oxides by acid treatment and their catalytic performances for toluene oxidation

Abstract: Considering the harmful effects of volatile organic compounds (VOCs) on the atmosphere and public health, the search for proper catalytic materials for the effective catalytic elimination of VOCs remains one of the most pressing issues in the environmental field. In this study, a series of mesoporous Co3O4-n (n = 0.00, 0.0001, 0.01, 0.05, 0.10, 1.00, representing the concentration of HNO3 aqueous solution) catalysts were fabricated by the acid treatment of Co3O4 that was previously prepared via a hydroxycarbonate precipitation method (Co3O4-P). The catalytic performances of the prepared catalysts were evaluated for the model reaction of toluene oxidation. An obvious enhancement of catalytic activity in the reaction was achieved over the acid-treated Co3O4 catalysts using lower HNO3 concentrations, with Co3O4-0.01 exhibiting the optimum catalytic activity (T90 = 225 °C, 15 °C lower than that of Co3O4-P), excellent catalytic durability under dry conditions and a high regeneration capability under humid conditions. Benefitting from the dilute acid treatment, the Co3O4-n (n = 0.01, 0.05, 0.10) catalysts presented higher specific surface areas, more weak acidic sites and higher abundances of surface Co2+ and Oads species, which were regarded as the key factors responsible for their enhanced catalytic activities.

Pt-Enhanced Mesoporous Ti3+/TiO2 with Rapid Bulk to Surface Electron Transfer for Photocatalytic Hydrogen Evolution.

Abstract: Pt-doped mesoporous Ti3+ self-doped TiO2 (Pt–Ti3+/TiO2) is in situ synthesized via an ionothermal route, by treating metallic Ti in an ionic liquid containing LiOAc, HOAc, and a H2PtCl6 aqueous solution under mild ionothermal conditions. Such Ti3+-enriched environment, as well as oxygen vacancies, is proven to be effective for allowing the in situ reduction of Pt4+ ions uniformly located in the framework of the TiO2 bulk. The photocatalytic H2 evolution of Pt–Ti3+/TiO2 is significantly higher than that of the photoreduced Pt loaded on the original TiO2 and commercial P25. Such greatly enhanced activity is due to the various valence states of Pt (Ptn+, n = 0, 2, or 3), forming Pt–O bonds embedded in the framework of TiO2 and ultrafine Pt metal nanoparticles on the surface of TiO2. Such Ptn+–O bonds could act as the bridges for facilitating the photogenerated electron transfer from the bulk to the surface of TiO2 with a higher electron carrier density (3.11 × 1020 cm–3), about 2.5 times that (1.25 × 1020 cm...

Combined Speed and Current Terminal Sliding Mode Control With Nonlinear Disturbance Observer for PMSM Drive

Abstract: A terminal sliding mode control (SMC) method based on nonlinear disturbance observer is investigated to realize the speed and the current tracking control for the permanent magnet synchronous motor (PMSM) drive system in this paper. The proposed method adopts the speed-current single-loop control structure instead of the traditional cascade control in the vector control of the PMSM. First, considering the nonlinear and the coupling characteristic, a single-loop terminal sliding mode controller is designed for PMSM drive system through feedback linearization technology. This method can make the motor speed and current reach the reference value in finite time, which can realize the fast transient response. Although the SMC is less sensitive to parameter uncertainties and external disturbance, it may produce a large switching gain, which may cause the undesired chattering. Meanwhile, the SMC cannot keep the property of invariance in the presence of unmatched uncertainties. Then, a nonlinear disturbance observer is proposed to the estimate the lump disturbance, which is used in the feed-forward compensation control. Thus, a composite control scheme is developed for the PMSM drive system. The results show that the motor control system based on the proposed method has good speed and current tracking performance and strong robustness.