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▲ Vol 01 Issue 04 | October, 2022
Towards understanding metallurgical defect formation of selective laser melted wrought aluminum alloys
Jinliang Zhang, Weihao Yuan, BoSong, ShuoYin, Xiaobo Wang, Qingsong Wei, Yusheng Shi
The formation of balling, porosity and cracking defects is a vital obstacle in selective laser melting of wrought Al alloys. However, it lacks systematic research on the origins of these imperfections. Herein, the formation mechanisms and avoidance methods of metallurgical defects in slective laser melting (SLM)-processed Al–Cu–Mg alloy were investigated by numerical simulation and microstructure characterization. Process optimization by altering laser energy density can effectively suppress balling and porosity, thus enhancing relative density. Cracking results from the stress concentration and columnar grains arise due to the rapid cooling process during SLM. The methods that promote the columnar-to-equiaxed grain transition, such as microalloying by Sc/Zr/Ti elements, co-incorporation of ceramic particles and introducing ultrasound, can effectively enhance the cracking resistance and mechanical properties of wrought Al alloys.
https://www.sciencedirect.com/science/article/pii/S2772834X22000185#
▲ Vol 03 Issue 10 | October, 2022
Design of Bifunctional Nb/V Interfaces for Improving Reversible Hydrogen Storage Performance of MgH2
Yang Meng, Shunlong Ju, Wei Chen, Xiaowei Chen, Guanglin Xia, Dalin Sun, Xuebin Yu
Solid-State Hydrogen Storage
In article number 2200119, Xuebin Yu, Guanglin Xia, and co-workers realized uniform formation of Nb/V interfaces based on a molecular scale to promote H2 storage performance of MgH2. The onset H2 desorption temperature of MgH2 of 165 °C and the reversible hydrogenation of Mg at room temperature could be realized.
https://onlinelibrary.wiley.com/doi/10.1002/sstr.202270030
▲ Vol 01 Issue 04 | October, 2022
Electrocatalytic hydrogen evolution performance of modified Ti3C2O2 doped with non-metal elements: A DFT study
Zhongxiao Wang, Haoxiang Di, Rui Sun, Yuting Zhu, Longwei Yin, Zhiwei Zhang, Chengxiang Wang
Developing highly conductive, stable, and active hydrogen evolution reaction (HER) catalysts is a critical step towards establishing the hydrogen economy. However, there are few catalysts, except for noble metals, that can meet all the requirements. Recently, two-dimensional (2D) transition metal carbon/nitride (MXene) materials have shown excellent performance in catalysis, and have attracted wide attention from researchers. In this study, the effectiveness of non-metal element (B, C, N, P, and S)-doped Ti3C2O2 MXene in the electrocatalytic hydrogen evolution reaction was investigated using density functional theory (DFT) calculations. Non-metal atoms as electron donors can provide additional electrons to the O functional group on the catalyst surface, thereby reducing charge transfer from H to O and the interaction between H and O. The Gibbs free energy (∆GH) of non-metal element-doped Ti3C2O2 is closer to 0 than that of pristine Ti3C2O2, demonstrating better hydrogen evolution performance. Furthermore, in the hydrogen evolution path, the desorption process is more inclined to the Heyrovsky mechanism, and doping greatly reduces the energy barrier of the reaction, thereby improving the catalytic efficiency. The present results prove that doping with non-metallic elements is an effective means of improving the catalytic activity of Ti3C2O2 for hydrogen evolution.
https://www.sciencedirect.com/science/article/pii/S2772571522000249
▲ Vol 01 Issue 04 | October, 2022
Density and porosity optimization of graphene monoliths with high mass-loading for high-volumetric-capacitance electrodes
Dongliang Wang, Lizhi Sheng, Meihui Jiang, Xin Jin, Xinru Lin, Sang-Young Lee, Junyou Shi, Wenshuai Chen
Improving the volumetric capacitance of graphene materials for supercapacitors without sacrificing their rate capability, especially at high mass-loading, is a challenge because of the sluggish electrochemical kinetics of compact graphene electrodes. Here, a compact graphene monolith (dense graphene ribbons [DGRs]-0.6) was fabricated by using graphene oxide ribbons as building blocks and deliberately harmonizing the graphene primitive unit structure and interlayer spacing. The DGRs-0.6 contained abundant oxygen-containing functional groups and a highly interconnected pore structure, resulting in a large ion-accessible surface area, a high packing density, and fast electron/ion transport pathways. The DGRs-0.6 electrode exhibited a volumetric capacitance of 316 F cm–3, a rate capability of 220 F cm–3 at 100 A g–1, and ultralong cycling stability. For a mass loading of 11 mg cm−2, the DGRs-0.6 delivered volumetric capacitances of 150 F cm−3 at 1 A g−1 and 109 F cm−3 at 50 A g−1. The good rate capability and volumetric capacitance of DGRs-0.6 under high mass loading demonstrate its potential as a supercapacitor electrode for practical applications.
https://onlinelibrary.wiley.com/doi/10.1002/bte2.20220017
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静远嘲风(MY Scimage) 成立于2007年,嘲风取自中国传统文化中龙生九子,子子不同的传说,嘲风为守护屋脊之瑞兽,喜登高望远;静远取自成语“宁静致远”,登高莫忘初心,远观而不可务远。
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