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In order to accurately simulate the actual road driving resistance of four-wheel drive motor vehicles based on the chassis dynamometer and efficiently test the vehicle performance, it is necessary to analyze the influencing factors of the additional loss resistance and the loading resistance of the chassis dynamometer bench system. In this paper, the effects of the drum speed, the sampling speed interval, and basic inertia on the test results of the additional loss resistance are tested and analyzed based on the self-developed chassis dynamometer of a four-wheel drive motor vehicle. The static and dynamic components of the additional loss resistance are defined by linear regression through ordinary least squares, and the additional loss resistance of the four-axis eight-drum chassis dynamometer and mainstream chassis dynamometer system for four-wheel drive motor vehicles are compared. In addition, the effects of the dynamometer type and the control strategy on the loading resistance are discussed, and the transient condition, steady-state condition, and overall operating condition deviation coefficient of loading force are defined, according to which the advantages and disadvantages of the control strategy of the chassis dynamometer system for four-wheel drive motor vehicles are evaluated. The analysis of the influencing factors and laws of the resistance of the four-wheel drive motor vehicle chassis dynamometer bench system can provide a reference basis for accurately simulating the resistance of vehicle road driving based on the bench testing. [ABSTRACT FROM AUTHOR]

Bimetallic NiCo functional graphene (NiCo/rGO) was synthesized by a facile one-pot method. During the coreduction process, the as-synthesized ultrafine NiCo nanoparticles (NPs), with a typical size of 4-6 nm, were uniformly anchored onto the surface of reduced graphene oxide (rGO). The NiCo bimetal-supported graphene was found to be more efficient than their single metals. Synergetic catalysis of NiCo NPs and rGO was confirmed, which can significantly improve the hydrogen-storage properties of MgH2. The apparent activation energy (Ea) of the MgH2-NiCo/rGO sample decreases to 105 kJ mol-1, which is 40.7% lower than that of pure MgH2. More importantly, the as-prepared MgH2-NiCo/rGO sample can absorb 5.5 and 6.1 wt% hydrogen within 100 and 350 s, respectively, at 300 °C under 0.9 MPa H2 pressure. Further cyclic kinetics investigation indicates that MgH2-NiCo/rGO nanocomposites have excellent cycle stability. [ABSTRACT FROM AUTHOR]

Size-controlled Ag0.04@Co0.48@Ni0.48 core-shell nanoparticles (NPs) were synthesized by employing graphene (rGO) with different reduction degrees as supports. The number of CO and CO functional groups on the surface of rGO might play a major role in controlling the particle size. The strong steric-hindrance effect of CO resulted in the growth of large particles, whereas CO contributed to the formation of small particles. The particle size of Ag0.04@Co0.48@Ni0.48 NPs supported on rGO with different reduction degrees decreased as the number of CO functional groups decreased. The decrease in the particle size probably led to the increase in the catalytic activity towards the hydrolysis of ammonia borane (AB). The enhanced catalytic activity largely stemmed from the increasing active sites on the surface of catalysts owing to the decreasing particle size. [ABSTRACT FROM AUTHOR]

Triple-layered Ag@Co@Ni core-shell nanoparticles (NPs) containing a silver core, a cobalt inner shell, and a nickel outer shell were formed by an in situ chemical reduction method. The thickness of the double shells varied with different cobalt and nickel contents. Ag0.04@Co0.48@Ni0.48 showed the most distinct core-shell structure. Compared with its bimetallic core-shell counterparts, this catalyst showed higher catalytic activity for the hydrolysis of NH3BH3 (AB). The synergetic interaction between Co and Ni in Ag0.04@Co0.48@Ni0.48 NPs may play a critical role in the enhanced catalytic activity. Furthermore, cobalt-nickel double shells surrounding the silver core in the special triple-layered core-shell structure provided increasing amounts of active sites on the surface to facilitate the catalytic reaction. These promising catalysts may lead to applications for AB in the field of fuel cells. [ABSTRACT FROM AUTHOR]

Abstract: Well-dispersed Fe0.3Co0.7/rGO nanocatalysts have been synthesized utilizing the two-step reduction method and successfully employed in the hydrolysis of ammonia borane (NH3BH3 AB) at room temperature. The mass percent of the supported Fe0.3Co0.7 nanoparticles (NPs) on graphene (rGO) sheets can reach to the maximum value of 50 wt%. The as-synthesized catalysts exerted satisfying activity and reusability for the hydrolytic dehydrogenation of AB at 298 K, especially for the specimen of 50 wt% Fe0.3Co0.7/rGO NPs. The catalytic hydrolysis reaction was rapidly completed within 1 min. [Copyright &y& Elsevier]

Abstract: The hydrogen storage properties of LiAlH4 doped efficient TiN catalyst were systematically investigated. We observe that TiN catalyst enhances the dehydrogenation kinetics and decreases the dehydrogenation temperature of LiAlH4. The dehydrogenation behaviors of 2%TiN–LiAlH4 are investigated using temperature programmed desorption (TPD), differential scanning calorimetry (DSC) and fourier transform infrared spectroscopy (FTIR). Interestingly, the onset hydrogen desorption temperature of 2%TiN–LiAlH4 sample gets lowered from 151.0 °C to 90.0 °C with a faster kinetics, and the dehydrogenation rate reached a maximum value at 137.2 °C. By adding a small amount of as-prepared TiN, approximately 7.1 wt% of hydrogen can be released from the LiAlH4 at 130 °C. Interestingly, the result of the FTIR indicates that the 2%TiN–LiAlH4 maybe restore hydrogen under 5.5 MPa hydrogen. Moreover, 2%TiN–LiAlH4 displayed a substantially reduced activation energy for LiAlH4 dehydrogenation. [Copyright &y& Elsevier]

Abstract: A systematic investigation is performed on the dehydrogenation performance of TiB2-doped NaAlH4. A dramatic enhancement in the dehydrogenation kinetics of NaAlH4 is achieved by adding as-prepared TiB2 catalyst based on a low temperature solid phase reaction, whereas pure NaAlH4 exhibits a poor desorption kinetics. Thermodynamic analyses show that the onset dehydrogenation temperature of as-prepared TiB2-doped NaAlH4 is lowered to about 75 °C. In addition, the experimental results show that as-prepared TiB2-doped NaAlH4 after milling releases 3.60 wt.% H2 for 1 h and 5.21 wt % H2 for 4 h at 190 °C with a excellent dehydriding rate and capacity. [Copyright &y& Elsevier]