Covalent-linked porphyrin/single-walled carbon nanotube nanohybrids: synthesis and influence of porphyrin substituents on nonlinear optical performance

Electron-withdrawing 4-cyanophenyl-, electronically innocent phenyl-, and electron-donating 4-dimethylaminophenyl-functionalized porphyrin/single-walled carbon nanotube (SWCNT) nanohybrids have been synthesized and characterized by ultraviolet–visible absorption, steady-state fluorescence, Fourier transform infrared, and Raman spectroscopies, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and thermogravimetric analysis. Nonlinear optical (NLO) studies using the Z-scan technique revealed that both the cyano (CN) and the dimethylamino (DMA) substituents have a positive effect in optimizing the optical limiting performance of the SWCNT–porphyrin nanohybrids, owing to increased reverse saturable absorption (RSA) of the porphyrin moieties after functionalization by CN or DMA. In comparison with CN, the DMA group has a more positive influence on the porphyrin excited states and thereby the RSA and NLO activity.This research was financially supported by the National Natural Science Foundation of China (Nos. 51432006 and 51172100), the Ministry of Education and the State Administration of Foreign Experts Affairs for the 111 Project (No. B13025), the Ministry of Education of China for the Changjiang Innovation Research Team (No. IRT14R23), 100 Talents Program of CAS, and the Ministry of Science and Technology of China for International Science Linkages Program (2011DFG52970). M.G.H. and C.Z. thank the Australian Research Council for support

Autotrophic denitrification in nitrate-induced marine sediment remediation

published_or_final_versionCivil EngineeringDoctoralDoctor of Philosoph

Integrated electrocatalysts derived from metal organic frameworks for gas-involved reactions

Integrated electrocatalysts (IECs) containing well-defined functional materials directly grown on the current collector have sparked increasing interest in the fields of electrocatalysis owing to efficient activity, high stability and the fact that they are easily assembled into devices. Recently, metal organic frameworks (MOFs) provide a promising platform for constructing advanced IECs because of their properties of low cost, large surface area and efficient structural tunability. In this review, the design principles of state-of-the-art IECs based on MOFs are presented, including by hydrothermal/solvothermal, template-directed, electrospinning, electrodeposition and other methods. The high performance of MOF-derived IECs has also been demonstrated in electrocatalytic gas-involved reactions. This is promising for green energy storage and conversion. The structure-activity relationship and performance improvement mechanism of IECs are uncovered by discussing some in situ technologies for IECs. Finally, we provide an outlook on the challenges and prospects in this booming field

Hydrogen production coupled with water and organic oxidation based on layered double hydroxides

Abstract Hydrogen production via electrochemical water splitting is one of the most green and promising ways to produce clean energy and address resource crisis, but still suffers from low efficiency and high cost mainly due to the sluggish oxygen evolution reaction (OER) process. Alternatively, electrochemical hydrogen‐evolution coupled with alternative oxidation (EHCO) has been proposed as a considerable strategy to improve hydrogen production efficiency combined with the production of high value‐added chemicals. Although with these merits, high‐efficient electrocatalysts are always needed in practical operation. Typically, layered double hydroxides (LDHs) have been developed as a large class of advanced electrocatalysts toward both OER and EHCO with high efficiency and stability. In this review, we have summarized the latest progress of hydrogen production from the perspectives of designing efficient LDHs‐based electrocatalysts for OER and EHCO. Particularly, the influence of structure design and component regulation on the efficiency of their electrocatalytic process have been discussed in detail. Finally, we look forward to the challenges in the field of hydrogen production via electrochemical water splitting coupled with organic oxidation, such as the mechanism, selected oxidation as well as system design, hoping to provide certain inspiration for the development of low‐cost hydrogen production technology

Host-Guest Engineering of Layered Double Hydroxides towards Efficient Oxygen Evolution Reaction: Recent Advances and Perspectives

Electrochemical water splitting has great potential in the storage of intermittent energy from the sun, wind, or other renewable sources for sustainable clean energy applications. However, the anodic oxygen evolution reaction (OER) usually determines the efficiency of practical water electrolysis due to its sluggish four-electron process. Layered double hydroxides (LDHs) have attracted increasing attention as one of the ideal and promising electrocatalysts for water oxidation due to their excellent activity, high stability in basic conditions, as well as their earth-abundant compositions. In this review, we discuss the recent progress on LDH-based OER electrocatalysts in terms of active sites, host-guest engineering, and catalytic performances. Moreover, further developments and challenges in developing promising electrocatalysts based on LDHs are discussed from the viewpoint of molecular design and engineering

Integrated Uncertainty/Disturbance Suppression Based on Improved Adaptive Sliding Mode Controller for PMSM Drives

Permanent magnet synchronous motors (PMSMs) have attracted great attention in the field of electric drive system. However, the disturbances caused by parameter mismatching, model uncertainty, external load and torque ripple seriously weaken the control accuracy. The traditional adaptive sliding mode control (ASMC) methodology can address slow-varying uncertainties/disturbances whose frequencies are located at the bandwidth of the filter used to design the adaptive law well; however, it has been barely discussed with respect to the periodic situation. In this paper, we extend the ASMC arrangement to periodic case to suppress the torque ripple by using a series-structure resonant controller. Firstly, a typical SMC is designed to force the tracking error of speed to converge to zero and obtain a certain capacity to disturbance. Then, the improved adaptive law is incorporated to estimate the lumped disturbance and torque ripple. The improved adaptive law is enhanced by embedding the resonant controller, which can obtain a better estimating result for torque ripple with repetitive feature. Finally, simulation and experimental results with PI, SMC and proposed methods are compared to verify the effectiveness of the developed controller

Torque Ripple Suppression of PMSM Based on Robust Two Degrees-of-Freedom Resonant Controller

This paper concentrates on a robust resonant control strategy of a permanent magnet synchronous motor (PMSM) for electric drivers with model uncertainties and external disturbances to improve the control performance of the current loop. Firstly, to reduce the torque ripple of PMSM, the resonant controller with fractional order (FO) calculus is introduced. Then, a robust two degrees-of-freedom (Robust-TDOF) control strategy was designed based on the modified resonant controller. Finally, by combining the two control methods, this study proposes an enhanced Robust-TDOF regulation method, named as the robust two degrees-of-freedom resonant controller (Robust-TDOFR), to guarantee the robustness of model uncertainty and to further improve the performance with minimized periodic torque ripples. Meanwhile, a tuning method was constructed followed by stability and robust stability analysis. Furthermore, the proposed Robust-TDOFR control method was applied in the current loop of a PMSM to suppress the periodic current harmonics caused by non-ideal factors of inverter and current measurement errors. Finally, simulations and experiments were performed to validate our control strategy. The simulation and experimental results showed that the THDs (total harmonic distortion) of phase current decreased to a level of 0.69% and 5.79% in the two testing environments

Measurement and simulation of carbon nanotube’s piezoresistance property by a micro/nano combined structure

282-286In this paper, the present status of carbon nanotube’s electromechanical properties was reviewed. The relationships among the carbon nanotube’s resistance, gauge factor and the rates of change of the band gaps with strain (dEℊ/dƐ) were analyzed and simulated. Then, a micro/nano combined device and method for measuring the piezoresistance property of carbon nanotube were proposed. The device is consisted of a silicon chip and a printed circuit board which is used for loading and leading wire. The microelectrodes were fabricated on the silicon chip by FIB and a CVD-growth single-wall carbon nanotube was connected with the microelectrodes. The voltage-current characteristic of the carbon nanotube was measured using the proposed device. The relationship between the current and the voltage is basically linear, which demonstrates that the carbon nanotube is metallic. The experimental results show that the micro/nano combined device can be used for measuring the piezoresistance of carbon nanotube in our future work