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Portable power supplies, particularly lithium‐ion batteries (LIBs), will play a key role in achieving sustainable development goals, and electrode active materials for the next generation of LIBs with higher energy density and longer life time is highly demanded. For this, in situ visualization of Li behavior during the charge/discharge process is essential, and transmission electron microscopy (TEM) will be promising for this purpose. Here, a quite simple experimental setup consisting of a newly developed Li–C nanocomposite film sputter‐deposited onto Au nanoprotrusions at room temperature and graphene synthesized on a W probe at 500 °C for the in situ TEM observation of the battery reaction is proposed. The preservation of the metallic Li in the Li–C film that is transferred to TEM without using any transfer vessels under atmospheric conditions is confirmed by high resolution TEM before the in situ electrochemical process in TEM. After the one cycle of the in situ electrochemical process, the intercalation of Li ions into graphene (lithiation) is clearly observed. Thus, it is concluded that the metallic Li stored in the Li–C film works well as the anode active material in the electrochemical process for solid state LIBs, implying the developed in situ experimental system is promising.

Portable power supplies, particularly lithium‐ion batteries (LIBs), will play a key role in achieving sustainable development goals, and electrode active materials for the next generation of LIBs with higher energy density and longer life time is highly demanded. For this, in situ visualization of Li behavior during the charge/discharge process is essential, and transmission electron microscopy (TEM) will be promising for this purpose. Here, a quite simple experimental setup consisting of a newly developed Li–C nanocomposite film sputter‐deposited onto Au nanoprotrusions at room temperature and graphene synthesized on a W probe at 500 °C for the in situ TEM observation of the battery reaction is proposed. The preservation of the metallic Li in the Li–C film that is transferred to TEM without using any transfer vessels under atmospheric conditions is confirmed by high resolution TEM before the in situ electrochemical process in TEM. After the one cycle of the in situ electrochemical process, the intercalation of Li ions into graphene (lithiation) is clearly observed. Thus, it is concluded that the metallic Li stored in the Li–C film works well as the anode active material in the electrochemical process for solid state LIBs, implying the developed in situ experimental system is promising.

We present the device properties of a nickel (Ni)- gallium oxide (Ga2O3) Schottky junction with an interfacial hexagonal boron nitride (hBN) layer. A vertical Schottky junction with the configuration Ni/hBN/Ga2O3/In was created using a chemical vapor-deposited hBN film on a Ga(2)O(3 )substrate. The current-voltage characteristics of the Schottky junction were investigated with and without the hBN interfacial layer. We observed that the turn-on voltage for the forward current of the Schottky junction was significantly enhanced with the hBN interfacial film. Furthermore, the Schottky junction was analyzed under the illumination of deep ultraviolet light (254 nm), obtaining a photoresponsivity of 95.11 mA/W under an applied bias voltage (-7.2 V). The hBN interfacial layer for the Ga2O3-based Schottky junction can serve as a barrier layer to control the turn-on voltage and optimize the device properties for deep-UV photosensor applications. Furthermore, the demonstrated vertical heterojunction with an hBN layer has the potential to be significant for temperature management at the junction interface to develop reliable Ga2O3-based Schottky junction devices.

We present the device properties of a nickel (Ni)- gallium oxide (Ga2O3) Schottky junction with an interfacial hexagonal boron nitride (hBN) layer. A vertical Schottky junction with the configuration Ni/hBN/Ga2O3/In was created using a chemical vapor-deposited hBN film on a Ga(2)O(3 )substrate. The current-voltage characteristics of the Schottky junction were investigated with and without the hBN interfacial layer. We observed that the turn-on voltage for the forward current of the Schottky junction was significantly enhanced with the hBN interfacial film. Furthermore, the Schottky junction was analyzed under the illumination of deep ultraviolet light (254 nm), obtaining a photoresponsivity of 95.11 mA/W under an applied bias voltage (-7.2 V). The hBN interfacial layer for the Ga2O3-based Schottky junction can serve as a barrier layer to control the turn-on voltage and optimize the device properties for deep-UV photosensor applications. Furthermore, the demonstrated vertical heterojunction with an hBN layer has the potential to be significant for temperature management at the junction interface to develop reliable Ga2O3-based Schottky junction devices.

Novel glass-ceramic composites with optical bandgap tunability were synthesised. Zinc silicate powder (ZS) was mixed with multi-walled carbon nanotubes (MWCNTs) at various mass fractions (0, 1, 2, and 3 wt %), followed by argon sintering. X-ray diffraction (XRD) analysis revealed the structural change from an amorphous ZS phase to a crystalline willemite phase (Zn2SiO4) by adding MWCNTs, and the largest crystallite size was obtained for ZS with 2.0 wt% MWCNTs. Although the agglomeration of ZS and MWCNTs was observed by field emission scanning electron microscopy (FESEM), there was no chemical interaction between ZS and MWCNTs as confirmed by Fourier transform infrared spectroscopy (FTIR). MWCNTs enhanced the crystallisation, which led to the green emission of Zn2SiO4 blue-shifting from 572 nm to 557 nm. The narrowed optical bandgap of Zn2SiO4 was attributed to the MWCNT-induced exciton localised between the valence band and conduction band of Zn2SiO4. The bandgap tuning effect of MWCNTs potentially paved new ways to mass fabricate zinc silicate-based semiconductors with desirable optical bandgap energy Eg, which significantly benefits the sensor and laser-related industry.

Novel glass-ceramic composites with optical bandgap tunability were synthesised. Zinc silicate powder (ZS) was mixed with multi-walled carbon nanotubes (MWCNTs) at various mass fractions (0, 1, 2, and 3 wt %), followed by argon sintering. X-ray diffraction (XRD) analysis revealed the structural change from an amorphous ZS phase to a crystalline willemite phase (Zn2SiO4) by adding MWCNTs, and the largest crystallite size was obtained for ZS with 2.0 wt% MWCNTs. Although the agglomeration of ZS and MWCNTs was observed by field emission scanning electron microscopy (FESEM), there was no chemical interaction between ZS and MWCNTs as confirmed by Fourier transform infrared spectroscopy (FTIR). MWCNTs enhanced the crystallisation, which led to the green emission of Zn2SiO4 blue-shifting from 572 nm to 557 nm. The narrowed optical bandgap of Zn2SiO4 was attributed to the MWCNT-induced exciton localised between the valence band and conduction band of Zn2SiO4. The bandgap tuning effect of MWCNTs potentially paved new ways to mass fabricate zinc silicate-based semiconductors with desirable optical bandgap energy Eg, which significantly benefits the sensor and laser-related industry.

In this work, the potential of utilizing a waste latex-based precursor (i.e., natural rubber glove (NRG)) as a carbon source for carbon nanotube (CNT) fabrication via chemical vapor deposition has been demonstrated. Gas chromatography-mass spectroscopy (GC-MS) analysis reveals that the separation of the lightweight hydrocarbon chain from the heavier long chain differs in hydrocarbon contents in the NRG fraction (NRG-L). Both solid NRG (NRG-S) and NRG-L samples contain >63% carbon, <0.6% sulfur and <0.08% nitrogen content, respectively, as per carbon-nitrogen-sulfur (CNS) analysis. Growth of CNTs on the samples was confirmed by Raman spectra, SEM and TEM images, whereby it was shown that NRG-S is better than NRG-L in terms of synthesized CNTs yield percentage with similar quality. The optimum vaporization and reaction temperatures were 350 and 800 °C, respectively, considering the balance of good yield percentage (26.7%) and quality of CNTs (ID/IG = 0.84 ± 0.08, diameter ≈ 122 nm) produced. Thus, utilization of waste NRG as a candidate for carbon feedstock to produce value-added CNTs products could be a significant approach for eco-technology.

In this work, the potential of utilizing a waste latex-based precursor (i.e., natural rubber glove (NRG)) as a carbon source for carbon nanotube (CNT) fabrication via chemical vapor deposition has been demonstrated. Gas chromatography-mass spectroscopy (GC-MS) analysis reveals that the separation of the lightweight hydrocarbon chain from the heavier long chain differs in hydrocarbon contents in the NRG fraction (NRG-L). Both solid NRG (NRG-S) and NRG-L samples contain >63% carbon, <0.6% sulfur and <0.08% nitrogen content, respectively, as per carbon-nitrogen-sulfur (CNS) analysis. Growth of CNTs on the samples was confirmed by Raman spectra, SEM and TEM images, whereby it was shown that NRG-S is better than NRG-L in terms of synthesized CNTs yield percentage with similar quality. The optimum vaporization and reaction temperatures were 350 and 800 °C, respectively, considering the balance of good yield percentage (26.7%) and quality of CNTs (ID/IG = 0.84 ± 0.08, diameter ≈ 122 nm) produced. Thus, utilization of waste NRG as a candidate for carbon feedstock to produce value-added CNTs products could be a significant approach for eco-technology.

This study demonstrates graphitization directly through the amorphous carbon under the catalysis of a low-melting-point metal, gallium (Ga), by heating in a vacuum heater as well as by Joule heating during in situ transmission electron microscopy (TEM) operation. For the material system of the mixture of Ga nanoparticles (NPs) and amorphous carbon matrix, the graphitization temperature is determined to be about 600 °C for the first time. With increasing the temperature, evaporation and agglomeration of small Ga NPs start to occur together with the graphitization at around the places where Ga NPs would have been located at the surface region. In situ TEM experiment reveals the accelerated increase in electrical conductivity with structural change from amorphous to graphitization. Thus, the combination of the in situ and ex situ TEM observations is believed to be a lead step to understand deeper the graphitization process and provide information in nanoscale.

This study demonstrates graphitization directly through the amorphous carbon under the catalysis of a low-melting-point metal, gallium (Ga), by heating in a vacuum heater as well as by Joule heating during in situ transmission electron microscopy (TEM) operation. For the material system of the mixture of Ga nanoparticles (NPs) and amorphous carbon matrix, the graphitization temperature is determined to be about 600 °C for the first time. With increasing the temperature, evaporation and agglomeration of small Ga NPs start to occur together with the graphitization at around the places where Ga NPs would have been located at the surface region. In situ TEM experiment reveals the accelerated increase in electrical conductivity with structural change from amorphous to graphitization. Thus, the combination of the in situ and ex situ TEM observations is believed to be a lead step to understand deeper the graphitization process and provide information in nanoscale.

In this work, CNS were successfully synthesized using waste latex from natural rubber gloves as carbon source via chemical vapor deposition. The synthesized process has been done at reaction temperature of 700˚C using iron oxide as catalyst. The CNS characterization were investigated by atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS) and Raman spectrum techniques. It was found that the obtained carbon material existed in the form of nanotubes, fibers and nanocapsules with diameter of 5 - 20 nm. The IG/ID value was found to be approximately 0.84, indicating CNS in the samples were not well crystalline and contain defects. HRTEM images and EDS results reveal non-uniform of large catalyst size and impurities of carbon source might lead to less population of grown CNTs. This study demonstrates that waste latex can be an alternative and inexpensive carbon source for CNS production and promotes green technology.

In this work, CNS were successfully synthesized using waste latex from natural rubber gloves as carbon source via chemical vapor deposition. The synthesized process has been done at reaction temperature of 700˚C using iron oxide as catalyst. The CNS characterization were investigated by atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS) and Raman spectrum techniques. It was found that the obtained carbon material existed in the form of nanotubes, fibers and nanocapsules with diameter of 5 - 20 nm. The IG/ID value was found to be approximately 0.84, indicating CNS in the samples were not well crystalline and contain defects. HRTEM images and EDS results reveal non-uniform of large catalyst size and impurities of carbon source might lead to less population of grown CNTs. This study demonstrates that waste latex can be an alternative and inexpensive carbon source for CNS production and promotes green technology.

Synthesis of hexagonal boron nitride (hBN) crystals with a controlled morphology is a major challenge due to various kinetic and thermodynamic factors at the edge. Supplying BN building blocks by heating precursor ammonia borane at a temperature of 90 °C produced triangular crystals, whereas, at higher heating (130 °C), hBN crystals with a hexagonal morphology were observed. The shape of crystals could also be modulated from hexagonal to triangular under a continuous reduced supply of BN building blocks. We attributed these phenomena to a different growth mechanism dependent on the concentration of BN radicals in the growth region. With a low supply of BN building blocks, crystal growth is the edge attachment limited, producing triangles, whereas, under higher concentration of BN building blocks, crystal growth is limited by diffusion producing hexagons. The presence of alternating B and N terminated vertices in hexagonal hBN crystals offers the possibility of hBN/graphene in-plane heterostructure synthesis with B–C and N–C bonding at the interface, which is not possible with N terminated triangular crystals. Supplying the controlled amount of BN building blocks to synthesize triangular and hexagonal crystals and modulation from hexagons to triangles is a major achievement (in the present work) due to single parameter control over the experiment.

Here, we demonstrate the synthesis of nitrogen-doped (N-doped) graphene using imidazole and melamine as two different nitrogen containing aromatic rings carbon precursors. Structure of N-doped graphene was investigated at different temperature (800–1020 °C) without changing the precursor quantity. It is observed that higher crystalline N-doped graphene can be obtained from the solid precursors at 1020 °C on Cu foil. X-ray photoelectron spectroscopy (XPS) analysis shows interesting features for the N-doped graphene synthesized from mixture of imidazole and melamine. Overall graphitic nitrogen content is enhanced in the graphene layers using the mixture of precursors, attributing better coordination of carbon and nitrogen atoms on Cu catalyst. Our finding shows that the graphitic and pyridinic nitrogen content in graphene lattice can be tuned by combination of two different nitrogen containing organic molecules.

Here, we demonstrate the synthesis of nitrogen-doped (N-doped) graphene using imidazole and melamine as two different nitrogen containing aromatic rings carbon precursors. Structure of N-doped graphene was investigated at different temperature (800–1020 °C) without changing the precursor quantity. It is observed that higher crystalline N-doped graphene can be obtained from the solid precursors at 1020 °C on Cu foil. X-ray photoelectron spectroscopy (XPS) analysis shows interesting features for the N-doped graphene synthesized from mixture of imidazole and melamine. Overall graphitic nitrogen content is enhanced in the graphene layers using the mixture of precursors, attributing better coordination of carbon and nitrogen atoms on Cu catalyst. Our finding shows that the graphitic and pyridinic nitrogen content in graphene lattice can be tuned by combination of two different nitrogen containing organic molecules.

Synthesis of hexagonal boron nitride (hBN) crystals with a controlled morphology is a major challenge due to various kinetic and thermodynamic factors at the edge. Supplying BN building blocks by heating precursor ammonia borane at a temperature of 90 °C produced triangular crystals, whereas, at higher heating (130 °C), hBN crystals with a hexagonal morphology were observed. The shape of crystals could also be modulated from hexagonal to triangular under a continuous reduced supply of BN building blocks. We attributed these phenomena to a different growth mechanism dependent on the concentration of BN radicals in the growth region. With a low supply of BN building blocks, crystal growth is the edge attachment limited, producing triangles, whereas, under higher concentration of BN building blocks, crystal growth is limited by diffusion producing hexagons. The presence of alternating B and N terminated vertices in hexagonal hBN crystals offers the possibility of hBN/graphene in-plane heterostructure synthesis with B–C and N–C bonding at the interface, which is not possible with N terminated triangular crystals. Supplying the controlled amount of BN building blocks to synthesize triangular and hexagonal crystals and modulation from hexagons to triangles is a major achievement (in the present work) due to single parameter control over the experiment.

Many nanofabrication methods based on scanning probe microscopy have been developed during the last decades. Local anodic oxidation (LAO) is one of such methods: Upon application of an electric field between tip and surface under ambient conditions, oxide patterning with nanometer-scale resolution can be performed with good control of dimensions and placement. LAO through the non-contact mode of atomic force microscopy (AFM) has proven to yield a better resolution and tip preservation than the contact mode and it can be effectively performed in the dynamic mode of AFM. The tip plays a crucial role for the LAO-AFM, because it regulates the minimum feature size and the electric field. For instance, the feasibility of carbon nanotube (CNT)-functionalized tips showed great promise for LAO-AFM, yet, the fabrication of CNT tips presents difficulties. Here, we explore the use of a carbon nanofiber (CNF) as the tip apex of AFM probes for the application of LAO on silicon substrates in the AFM amplitude modulation dynamic mode of operation. We show the good performance of CNF-AFM probes in terms of resolution and reproducibility, as well as demonstration that the CNF apex provides enhanced conditions in terms of field-induced, chemical process efficiency.

Surface and bulk plasmon resonance of noble metal particles play an essential role in the multicolor photochromism of semiconductor systems containing noble metal particles, Here we examined several key parameters affecting surface plasmon resonance wavelength (SPRW) of Ag particles and investigated the relation between surface plasmon and photochromic reaction wavelength. From the transmission spectra of sandwiched (TiO2/Ag/TiO2) and overcoated (Ag/TiO2) films deposited on quartz substrates at room temperature by rf helicon magnetron sputtering, we demonstrated that the SPRW can be made tunable by changing the surrounding media and thickness of the metal layer. The coloration and bleaching in visible light region due to photochromism were clearly observed for the films inserted with a 0.55 nm Ag layer.