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High mechanical strength Si anode synthesis with interlayer bonded expanded graphite structure for lithium-ion batteries

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Journal of Energy Chemistry 2024年第6期93卷 253-263,I0007页

作者： Wenhui Lai Jong Hak Lee Lu Shi Yuqing Liu Yanhui Pu Yong Kang Ong Carlos Limpo Ting Xiong Yifan Rao chorng haur sow Barbaros Ozyilmaz Department of Material Science&Engineering National University of SingaporeSingapore 117575Singapore Center for Advanced 2D Materials National University of SingaporeSingapore 117546Singapore Department of Physics National University of SingaporeSingapore 117551Singapore Institute forFunctional Intelligent Materials National University of SingaporeSingapore 117544Singapore

Despite advancements in silicon-based anodes for high-capacity lithium-ion batteries,their widespread commercial adoption is still hindered by significant volume expansion during cycling,especially at high active mass loadings crucial for practical *** root of these challenges lies in the mechanical instability of the material,which subsequently leads to the structural failure of the ***,we present a novel synthesis of a composite combining expanded graphite and silicon *** composite features a unique interlayer-bonded graphite structure,achieved through the application of a modified spark plasma sintering ***,this innovative structure not only facilitates efficient ion and electron transport but also provides exceptional mechanical strength(Vickers hardness:up to658 MPa,Young's modulus:11.6 GPa).This strength effectively accommodates silicon expansion,resulting in an impressive areal capacity of 2.9 mA h cm^(-2)(736 mA h g^(-1)) and a steady cycle life(93% after 100cycles).Such outsta nding performance is paired with features appropriate for large-scale industrial production of silicon batteries,such as active mass loading of at least 3.9 mg cm^(-2),a high-tap density electrode material of 1.68 g cm^(-3)(secondary clusters:1.12 g cm^(-3)),and a production yield of up to 1 kg per day.

关键词： Lithium-ion battery Silicon anode Spark plasma sintering Interlayer bonding Mechanical strength Tap density

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A Focused Laser Beam:A Useful and Versatile Tool for 1D Nanomaterials Research:A Review

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Journal of Materials Science & Technology 2015年第6期31卷 616-629页

作者： Junpeng Lu Sharon Xiaodai Lim chorng haur sow Department of Physics National University of Singapore Department of Science Drive National University of Singapore National University of Singapore

One-dimensional(1D) nanomaterials have generated considerable interest amongst researchers because of their potential as fundamental building block in future nano- and micro-electronic *** this article,we present a review of a focused laser beam system as a versatile tool for the manipulation,structural transformation,micropatterning and chemical modification of 1D *** tool was found to be effective in patterning and modifying various physical and chemical properties of the pristine1 D *** also aids in the fabrication process of heterostructures and 1D nanomaterial based ***,we present the implementation of the focused laser beam setup as a valuable tool in the study of the origins and photoresponse mechanism of the 1D nanomaterial devices.

关键词： Laser Nanomaterials Composite Optoelectronic Elect

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Bolstering functionality in multilayer and bilayer WS2 via focused laser micro-engraving

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Science China(Information Sciences) 2023年第6期66卷 94-101页

作者： Si Min CHAN Eng Tuan POH Jin Feng LEONG Kuan Eng Johnson GOH chorng haur sow Department of Physics National University of Singapore Institute of Materials Research and Engineering Agency for ScienceTechnology and Research (A~*STAR) Division of Physics and Applied Physics School of Physical and Mathematical SciencesNanyang Technological University

Laser thinning of multilayer transition metal dichalcogenide(TMD)crystals has long been explored for its potential to produce localized domains of optically functional monolayers. Despite the high spatial control and resolution of the laser, the range of appropriate applications for these laser-thinned domains is still limited by the peripheral regions of unaltered thick multilayers. Herein, we report a newfound property of the laser-thinned regions to adhere strongly to the underlying substrate when lasered down to the monolayer limit. Upon a brief sonication in various solvents, the surrounding pristine multilayers can be lifted off, solely leaving behind the post-lasered monolayer patterns. Coupled with the flexible maneuver of the laser, various monolayer designs can be achieved, including micro-antenna, waveguide, and electrode geometries with lateral line widths at 1.5 μm resolution. Furthermore, we also detail the optical properties of the monolayers obtained from laser thinning, with those acquired from multilayers containing more defectbound excitons, whereas those lasered from bilayers presenting a trion-dominated profile similar to as-grown monolayers. Together, these findings allow for faster and more efficient multilayer removal and areal shaping of optically active monolayer domains, in comparison to multistep and complex standard lithographic etching(lithography–etch–develop)procedures.

关键词： WS$_2$ monolayer micro-patterning focused laser sonication lift-off

Selective enriching of trionic emission in a WS2-ZnO hybrid through type-Ⅱ band alignment

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Science China(Information Sciences) 2023年第6期66卷 63-70页

作者： Jin Feng LEONG Kim Yong LIM Xiao WU Qinghua XU chorng haur sow Eng Tuan POH Department of Physics National University of Singapore Department of Chemistry National University of Singapore

Strategies to modulate the exciton dynamics in ultrathin two-dimensional(2D)semiconductors have always been an integral component in the bid towards improved optoelectronics and quantum photonic devices. The capability to non-destructively tune the relaxation dynamics, valley polarization, binding energies, and population ratio of various excitonic species has been well-sought for advanced *** the rationale design of a WS2-ZnO hybrid platform, we present a distinct increment in the trion-toexciton ratio for WS2emission across a patterned heterostructure. The shift in dominant excitonic species arose due to the efficient charge segregation at the spatially confined interface of the type-Ⅱ *** to the charge transfer process, the resultant emission profile presents up to four times amplification in the trion-to-exciton ratio, with temperature variable trion binding energies up to 59 meV. Since trions possess non-zero charge and spin degrees of freedom, the provision of a higher density of trions with increased binding stability would encourage new opportunities for reproducible optoelectronics and quantum emitters.

关键词： heterostructure trions type-II band alignment

Composition-dependent ultra-high photoconductivity in ternary CdSxSe1-x nanobelts as measured by optical pump-terahertz probe spectroscopy

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Nano Research 2013年第11期6卷 808-821页

作者： Hongwei Liu Junpeng Lu Minrui Zheng Sing Hai Tang Xinhai Zhang chorng haur sow Department of Physics 2 Science Drive 3 National University of Singapore 117542 Singapore Institute of Materials Research and Engineering Agency for Science Technology and Research (A'STAR) 3 Research Link 117502 Singapore

We employ optical pump-terahertz probe spectroscopy to investigate the composition-dependent photoconductivity in ternary CdSxSel_x nanobelts. The observed carrier dynamics of CdS nanobelts display much shorter lifetime than those of ternary CdSKSel_K nanobelts. This indicates the implementation of CdS nanobelts as ultrafast switching devices with a switching speed potentially up to 46.7 GHz. Surprisingly, ternary CdS,-Sel_x nanobelts are found to exhibit much higher photoconductivity than binary CdS and CdSe. This is attributed to the higher photocarrier densities in ternary compounds. In addition, the presence of Se in samples resulted in prominent CdSe-like transverse optical （TO） phonon modes due to electron-phonon interactions. The strength of this mode shows a large drop upon photoexcitation but recovers gradually with time. These results demonstrated that growth of ternary nanostructures can be utilized to alleviate the high surface defect density in nanostructures and improve their photoconductivity.

关键词： nanomaterials andnanostructures optical materials photoconductivity ternary alloys THz spectroscopy

Polychromic carbon black: Laser galvanized multicolour fluorescence display

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Nano Research 2019年第4期12卷 733-740页

作者： Sharon Xiaodai Lim Kae Lin Wong Zheng Zhang Antonio H. Castro Neto chorng-haur sow Department of Physics National University of Singapore 2 Science Drive 3 Singapore 117542 Singapore Department of Electrical and Electronic Engineering Universiti Tunku Abdul Rahman Sungai Long Campus Jalan Sungai Long Bandar Sungai Long Cheras Kajang 43000 Selangor Malaysia Institute of Materials Research Engineering A*Star (Agency for Science Technology and Research) 2 Fusionopolis Way Innovis Singapore 138634 Singapore Center for Advanced 2D Materials and Graphene Research Center National University of Singapore 6 Science Drive 2 Singapore 117546 Singapore

Recovered carbon black (rCB),a very economical and abundance source of material,is transformed into dazzling multicolour fluorescence and visual display for the first time by way of a scanning focused laser *** laser-initiated process is both straightforward and versatile,catering to both micro-and macro-scopic patterning with the sample in ambient or helium *** observed phenomenon is attributed to both chemical and structural induced colouration of rCB ***,carbon infusion of oxidised metal occurs when photothermal reaction takes place in *** laser modification with the sample in helium environment,the powder not only fluoresces due to sulphur impurities,control annealing of these powders results in formation of periodic arrangements of carbon *** periodicity of these arrangement falls within the range of visible wavelength,hence contributing to the visually observable rainbow coloured rCB *** patterned sample is also transferrable using PDMS *** in turn broadens the application of this material in flexible electronic devices/*** measurements show most significant enhancement under yellow light ***,in the presence of an applied potential,the fluorescence detected from the sample can easily be switched *** in all,we present a simple process to add multiple functionalities to a material that is both inexpensive and sustainable.

关键词： recovered carbon black laser modification fluorescence emission photocurrent flexible

Multifaceted Approaches to Engineer Fluorescence in Nanomaterials via a Focused Laser Beam

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Light(Advanced Manufacturing) 2022年第1期3卷 51-70页

作者： Eng Tuan Poh Sharon Xiaodai Lim chorng haur sow Department of Physics National University of Singapore2 Science Drive 3Singapore 117551Singapore

Fluorescent nanomaterials have long been recognized as essential contributors to the advancement of material *** the years,the rapid expansion in this massive selection of materials has led to the emergence of systems with tunable and unique fluorescent properties,occupying pivotal roles across niche areas in imaging,photonics,micro-encryption,and steganographic *** recent years,research interest in the translation of laser-based operations towards the production and modulation of nanomaterial fluorescence has been reignited,owing to its ease of operation and low *** this paper,we summarize the assortment of laser operations for the fabrication,modification,and spatial positioning of various fluorescent nanomaterials,ranging from metallic nanoparticles,carbon dots,2D ultrathin films to wide-bandgap nanomaterials,and upconversion *** addition,we evaluate the importance of laser-modified fluorescence for various applications and offer our perspective on the role of laser-based techniques in the forthcoming advancement of nanomaterials.

关键词： Multifaceted Approaches Engineering Fluorescences Nanomaterials Focused

Emergence of photoluminescence on bulk MoS2 by laser thinning and gold particle decoration

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Nano Research 2018年第9期11卷 4574-4586页

作者： Lili Gong Qi Zhang Liangjun Wang Jianfeng Wu Cheng Han Bo Lei Wei Chen Goki Eda Kuan Eng Johnson Goh chorng haur sow Department of Physics National University of Singapore Singapore 117542 Singapore Department of Chemistry National University of Singapore Singapore 117542 Singapore Centre for Advanced 2D Materials and Graphene Research Centre National University of Singapore 6 Science Drive 2 Singapore 117546 Singapore Institute of Materials Research and Engineering Agency for Science Technology and Research (A＊STAR) 2 Fusionopolis Way Innovis #08-03 Singapore 138634 Singapore

We demonstrate a facile and effective approach to significantly improve the photoluminescence of bulk MoS2 via laser thinning followed by gold particle decoration. Upon laser thinning of exfoliated bulk MoSz photoluminescence emerges from the laser-thinned region. After further treatment with an AuCl3 solution, gold particles self-assemble on the laser-thinned region and thick edges, further increasing the fluorescence of bulk MoS2 28 times and the Raman response 3 times. Such fluorescence enhancement can be attributed to both surface plasmon resonance and p-type doping induced by gold particles. The combination of laser thinning and AuCl3 treatment enables the functionalization of bulk MoS2 for optoelectronic applications. It can also provide a viable strategy for mask-free and area-selective p-type doping on single MoS2 flakes.

关键词： bulk MoS photoluminescence laser thinning gold particle plasmonic effect doping