Bimetallic PtRu Nanoparticles Supported on Functionalized Multiwall Carbon Nanotubes as High Performance Electrocatalyst for Direct Methanol Fuel Cells

Chunhui Tan,Juhui Sa,Feipeng Cai,Bo Jiang,Gai Yang,Bo Wang,Jinhua Gao,Hua Chen,Xianzhong Qin 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.2

PtRu nanoparticles (NPs) supported on acid treated multiwall carbon nanotubes (Pt1Ru1/ MWCNTs) were prepared by a modified polyol method without adding any other surfactant or protective agent. The structural and compositional properties of the as-obtained samples were characterized by transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and X-ray photoelectron (XPS) spectroscopy. The electrocatalytic performance of the catalyst was evaluated by cyclic voltammetry (CV), CO stripping voltammetry and chronoamperometry, indicating a high catalytic activity, excellent CO tolerance and stability for methanol oxidation. Interestingly, a series of accurate controllable experiments have been designed to explore the enhancement mechanism of Pt1Ru1/MWCNTs for methanol oxidation reaction. Most importantly, Pt1Ru1/MWCNTs composites were used as an anode catalyst in the direct methanol fuel cells (DMFCs) exhibiting outstanding power density (126.1 mW/cm2) 1.7 times higher than that of the commercial catalyst of Pt1Ru1/C (74.1 mW/cm2Þ)(E-TEK).

Crosslinked Proton Exchange Membranes with a Wider Working Temperature Based on Phosphonic Acid Functionalized Siloxane and PPO

Zhihui Wu,Chunhui Shen,Shanjun Gao,Xi Zhu,Mingliang Zhang,Ao Ding 한국고분자학회 2021 Macromolecular Research Vol.29 No.3

A series of proton exchange membranes were prepared by incorporating phosphonic functionalized siloxane into sulfonic poly(2,6-dimethyl-1,4-phenyleneoxide) (SPPO) and imidazole functionalized poly(2,6-dimethyl-1,4-phenyleneoxide) grafted with siloxane (IPPO-Si). Phosphonic acid functionalized siloxane was synthesized from amino trimethyl phosphonic acid (ATMP) and (3-aminopropyl)triethoxysilane (APTES). FTIR results showed that 1-methylimidazole and APTES were successfully grafted onto polyphenylene oxide, and APTES successfully formed Si-O-Si crosslinked networks through hydrolytic crosslinking. The membranes were thermally stable up to 220 °C and exhibited excellent oxidative stability and mechanical performance. We also measured the proton conductivity of the membranes. The results showed that the proton conductivities of the composite membranes increased with the increasing of SPPO content at different degrees under high (100 °C-160 °C) and low (25 °C-80 °C) temperature conditions. Furthermore, the IPPO-SI-P/SPPO-30 has the best conductivity, reaching to 0.1131 S cm-1 at 80 °C, 100%RH and 0.1049 S cm-1 at 160 °C, 5%RH, respectively. Therefore, this novel membrane acts as a potential candidate for proton exchange membranes with a wider applicable temperature (25 °C-160 °C).

Proton Exchange Membrane with Enlarged Operating Temperature by Incorporating Phosphonic Acid Functionalized and Crosslinked Siloxane in Sulfonated Poly(ether ether ketone) (SPEEK) Matrix

Xuechao Ren,Chunhui Shen,Shanjun Gao,Yuan Yuan,Jiqin Chen 한국고분자학회 2018 Macromolecular Research Vol.26 No.2

A novel proton exchange membrane which can be applied in the range of 25-140°C is prepared by incorporating phosphonic acid functionalized crosslinked siloxane in sulfonated poly(ether ether ketone) matrix from amino trimethylene phosphonic acid (ATMP), epoxycyclohexylethyltrimethoxysilane (EHTMS), and sulfonated poly(ether ether ketone) (SPEEK). EHTMS is introduced to chemically fix free ATMP as well as a cross-linker. And, the obtained membranes are immersed in deionized water to remove free ATMP. Fourier transform infrared and X-ray diffraction patterns suggest that ATMP is anchored into EHTMS and Si-O-Si network forms successfully. These membranes are thermally stable up to 220 °C and exhibit excellent dimensional stability and mechanical performance. The addition of ATMP not only increases the amount of proton transfer sites, but also provides proton transport units for membranes at elevated temperature and low relative humidity (RH) condition. The proton conductivity of AES-4 membrane reaches 0.114S cm-1 at 80 °C and 100%RH and 0.056 Scm-1 at 140 °C and 20%RH, respectively.

A Multi-Mechanisms Composite Frequency Up-Conversion Energy Harvester

Ping Li,Nuo Xu,Chunhui Gao 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.9

In this paper, a novel broadband hybrid piezoelectric-electromagnetic-electrostatic energy harvester with frequency up conversion is proposed to improve the harvesting bandwidth and energy conversion efficiency. The designed device generates vibration energy with much higher frequency than ambient vibration frequency, which uses the magnet to impact periodically on the piezoelectric cantilever with the top electrode of electrostatic element. The dynamic model of the hybrid energy harvester is established, and performances are experimental tested under the sinusoidal excitation and practical application environment. The results show that multi-mechanisms composite structure can realize the complementary advantages of electrostatic-piezoelectric-electromagnetic mechanisms and improve the energy conversion efficiency effectively compared with a single harvesting mechanism. The fabricated harvester can output electric energy in the frequency range of 1–38 Hz, which significantly reduces frequency dependence, and the maximum power is measured to be 11.7 mW and 12 mW during cycling and walking respectively, which is the sum of the power generated by three different elements. Furthermore, the fabricated prototype can also light up six light-emitting diodes (LEDs) simultaneously when handy shaking.

Numerical modeling and global performance analysis of a 15-MW Semisubmersible Floating Offshore Wind Turbine (FOWT)

Da Li,Ikjae Lee,Cong Yi,Wei Gao,Chunhui Song,Shenglei Fu,Moohyun Kim,Alex Ran,Tuanjie Liu Techno-Press 2023 Ocean systems engineering Vol.13 No.3

The global performance of a 15 MW floating offshore wind turbine, a newly designed semisubmersible floating foundation with multiple heave plates by CNOOC, is investigated with two independent turbine-floater-mooring coupled dynamic analysis programs CHARM3D-FAST and OrcaFlex. The semisubmersible platform hosts IEA 15 MW reference wind turbine modulated for VolturnUS-S and hybrid type (chain-wire-chain with clumps) 3×2 mooring lines targeting the water depth of 100 m. The numerical free-decay simulation results are compared with physical experiments with 1:64 scaled model in 3D wave basin, from which appropriate drag coefficients for heave plates were estimated. The tuned numerical simulation tools were then used for the feasibility and global performance analysis of the FOWT considering the 50-yr-storm condition and maximum operational condition. The effect of tower flexibility was investigated by comparing tower-base fore-aft bending moment and nacelle translational accelerations. It is found that the tower-base bending moment and nacelle accelerations can be appreciably increased due to the tower flexibility.

Objectives, challenges, and prospects of batch processes: Arising from injection molding applications

Yuanqiang Zhou,Zhixing Cao,Jingyi Lu,Chunhui Zhao,Dewei Li,Furong Gao 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.12

Injection molding, a polymer processing technique that converts thermoplastics into a variety of plasticproducts, is a complicated nonlinear dynamic process that interacts with a different group of variables, including themachine, the mold, the material, and the process parameters. As injection molding process operates sequentially inphases, we treat it as a batch process. The review paper discusses the batch nature of injection molding and identifies thethree main objectives for future development of injection molding: higher efficiency, greater profitability, and longer sustainability. From the perspective of system engineering, our discussion centers on the primary challenges for the batchoperation of injection molding systems: 1) Model development in face of product changes, 2) Control strategies in face ofdynamic changes, 3) Data analysis and process monitoring, and 4) Safety assurance and quality improvement, and thecurrent progress that has been made in addressing these challenges. In light of the advancement of new informationtechnologies, this paper provides several opportunities and encourages further research that may break existing capabilitylimits and develop the next generation of automation solutions to bring about a revolution in this area.

Trimethyl-Ammonium Alkaline Anion Exchange Membranes with the Vinylbenzyl Chloride/Acrylonitrile Main Chain

Zhenghan Li,Junjie Chen,JinYue Zhou,YiWen Nie,Chunhui Shen,Shanjun Gao 한국고분자학회 2021 Macromolecular Research Vol.29 No.7

The main chain of polyolefin was synthesized by copolymerization of 4 - vinylbenzyl chloride (VBC) and acrylonitrile (AN), and trimethylamine is used for quaternization to prepare heterogeneous benzyl trimethyl-ammonium anion exchange membranes (Heter-X) and homogeneous benzyl trimethyl-ammonium anion exchange membrane (Homo-X). The results of Fourier-transform infrared (FT-IR), gel permeation chromatography (GPC), and 1H nuclear magnetic resonance (NMR) showed that VBC and AN were successfully copolymerized to form a polymer with a certain molecular weight, and trimethylamine was successfully quaternized. The prepared membranes exhibited good thermal stability and mechanical properties. The theoretical ion exchange capacity (IEC) values of Homo-3 and Heter-3 are the same, but the conductivity at 80 °C were 0.0572 S cm-1 and 0.0505 S cm-1. The results showed that the homogeneous method has a higher degree of quaternization and a more uniform distribution of quaternary ammonium groups, forming a more obvious microphase separation structure, which can also be seen in the atomic force microscopy (AFM) diagram. After being soaked in 1M KOH solution for 480 h, the ionic conductivity of Homo-6 and Heter-6 can still remain 91.4% and 85.5%, and the IEC loss rates were 17.21% and 24.34%. These results indicate that the prepared membranes are promising materials for application in fuel cells.