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Simultaneous densification and nitrogen doping of laser-induced graphene by duplicated pyrolysis for supercapacitor applications
摘要： Laser pyrolysis of polyimide is a facile and cost-effective method to fabricate high performance supercapacitor electrodes. This study proposes a duplicated laser pyrolysis method to densify pyrolyzed carbon electrodes and hence improve electrochemical performance. The initial laser pyrolysis of polyimide generates a graphene-like carbon, called laser-induced graphene (LIG). This LIG is then coated with an additional polyimide layer, and the second laser pyrolysis is applied, producing densified LIG. Laser power effects on densified LIG morphology and electrochemical characteristics are investigated, confirming remarkable density increase. Increased nitrogen content is also observed, signifying significant nitrogen doping. The densified electrode achieves 49.0 mF cm?2 specific capacitance at 0.2 mA cm?2 current density in a standard three-electrode system, approximately 6-fold that for singly pyrolyzed LIG electrodes. A solid-state flexible supercapacitor with densified LIG electrodes is fabricated using a gel electrolyte (PVA-H2SO4), achieving 19.8 mF cm?2 capacitance at 0.05 mA cm?2 current density, with outstanding cyclic charge-discharge stability and mechanical flexibility.
关键词： Nitrogen-doped carbon,Laser pyrolysis,Densification,Laser-induced graphene,Flexible supercapacitors
更新于2025-09-11 14:15:04
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High-performance nitrogen doped carbon quantum dots: Facile green synthesis from waste paper and broadband photodetection by coupling with ZnO nanorods
摘要： High-performance N-doped carbon quantum dots (NCQDs) were synthesized by a proposed green route based on hydrothermal treatments using waste paper and urea as C and N sources. The single-crystalline NCQDs demonstrated strong blue-green luminescence with the maximum intensity enhancement of 6.5 times when compared with undoped CQDs under UV and visible light excitations. XPS spectra results suggested that the enhanced photoluminescence might be attributed to pyridinic N, which could be controlled by adjusting hydrothermal temperature, time, and urea concentration. The NCQDs having excellent optoelectronic properties were fabricated into broadband photodetectors by incorporating ZnO nanorod arrays. Owing to the NCQDs, the detectors demonstrated broadband photoresponse with significantly enhanced photoresponsivity, faster response, and better sensitivity in visible range. The work provides a low-cost, environment friendly route to fabricate excellent NCQD-based broadband photodetectors for various technological applications.
关键词： Photodetection,ZnO,Broadband,Nitrogen,Carbon quantum dot
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Toward Coupling Color Centers in Single Crystal Diamond to Two-Dimensional Materials
摘要： Individual nitrogen vacancy (NV) color centers in diamond are bright, photo-stable, atomic-sized dipole emitters [1]. Consequently, they represent optimal candidates for novel scanning near field microscopy techniques [2]. Here, NV centers form one member of a F¨orster Resonance Energy Transfer (FRET) pair. Due to their broadband emission (> 100 nm), NVs are versatile donors for FRET to systems absorbing in the near infrared spectral range. Highly-promising applications include, e.g., nanoscale imaging of fluorescent molecules or nanomaterials like graphene [2]. Critical parameters for FRET are the NV’s quantum efficiency, charge state stability and NV-sample-distance. Previous experiments used NVs in nanodiamond for FRET [2], however these NVs might suffer from quenching, instability and badly controlled surface termination. We here address this issue by using shallowly implanted NV centers in optimized cylindrical nanostructures [3] used as scanning probes in our homebuilt combination of a confocal and an atomic force microscope. In recent years, two-dimensional materials especially monolayers of semiconducting materials are of major interest in research. Particularly, dichalcogenides like, e.g., tungsten diselenide (WSe2) are promising candidates for a varity of applications [4]. WSe2 emits photons at a wavelength of around 750 nm while absorbing photons below 700 nm [4] which renders WSe2 as a promising FRET partner for NV centers. Here, we present first results towards demonstrating the interaction of NV color centers in single crystal diamond with WSe2. We envisage using quenching of the NV center sued as a donor in FRET in close proximity to the 2D material as a valuable sensing ressource.
关键词： F¨orster Resonance Energy Transfer (FRET),tungsten diselenide (WSe2),nitrogen vacancy (NV) color centers,diamond,two-dimensional materials
更新于2025-09-11 14:15:04
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Nitrogen donor ligand for capping ZnS quantum dots: a quantum chemical and toxicological insight
摘要： Nanoparticles having strong optical and electronic properties are the most widely used materials in sensor development. Since the target analyte interacts directly with the surface of the material, the choice of ligand for functionalizing the surface of the material is the key for its further applications. The functionalized surface of the material makes it suitable for required applications as it controls the size of the particle during its growth from the solution phase. Biomolecule capped nanomaterials are favourable for various applications in bio-sensing. In the present work, an attempt has been made to explore the biologically active molecule imidazole as capping agent for ZnS semiconductor nanoparticles or quantum dots (QDs). This work explores the possibility of replacing conventional thiol-zinc bonding and hence paves new pathways for biomolecules having the possibility of being efficient capping agents. Computational chemistry has been used to study the mechanism of bonding between one of the nitrogen atoms of imidazole and the zinc ion of the ZnS QDs. The quantum chemical insight not only explores the most spontaneous interaction of zinc ion and imidazole molecule so as to act as an efficient capping agent but also explains the probable bonding site for nitrogen–zinc chemistry. The tailormade Mn doped ZnS QDs are one of the most promising materials for probe and sensor development. The ZnS core having non-toxicity and the emission in longer wavelength due to manganese makes this material highly useful biologically. The aqueous route of synthesis has been employed to obtain a highly homogeneous and pure material which was further characterized by UV (Ultra Violet spectroscopy), Spectrofluorometer, Transmission Electron Microscope and X-ray Diffraction. The toxicity at the cellular and genetic levels was also investigated to prove the potential of the imidazole capped Mn doped ZnS QD as a biocompatible material.
关键词： quantum chemical,Nitrogen donor ligand,biocompatibility,capping agent,toxicological insight,ZnS quantum dots,Mn doped ZnS QDs,aqueous synthesis,imidazole
更新于2025-09-11 14:15:04
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Simultaneous Photoreduction and Nitrogen Doping of Graphene Oxide for Supercapacitors by Direct Laser Writing
摘要： Graphene-based supercapacitors have attracted tremendous attention owing to their outstanding electrochemical performance. In terms of material, nitrogen(N)-doped graphene(NDG) displays enhanced specific capacitance and rate performance compared with bare graphene used as a supercapacitor electrode. However, it still remains a challenge to develop a facile and simple method of NDG in cost-effective manner. Here, we used a simple direct laser writing technique to accomplish the simultaneous photoreduction and N-doping of graphene oxide(GO) using urea as a N source. The N content of the resultant reduced N-doped graphene oxide(NGO) reached a maximum value of 6.37%. All reduced NGO(NRGO)-based supercapacitors exhibited a higher specific capacitance than those based on pure reduced GO(RGO). Interestingly, the electrochemical performance of NRGO-based supercapacitors varied with different contents of N species. Therefore, we can control the properties of the obtained NRGOs by adjusting the doping ratios, an important step in developing effective graphene-based energy storage devices.
关键词： Simultaneous photoreduction and nitrogen-doping,Direct laser writing,Graphene based supercapacitor
更新于2025-09-11 14:15:04
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Nitrogen-Doped Cu2O Thin Films for Photovoltaic Applications
摘要： Cuprous oxide (Cu2O) is a p-type semiconductor with high optical absorption and a direct bandgap of about 2.1 eV, making it an attractive material for photovoltaic applications. For a high-performance photovoltaic device, the formation of low-resistivity contacts on Cu2O thin films is a prerequisite, which can be achieved by, for instance, nitrogen doping of Cu2O in order to increase the carrier concentration. In this work, nitrogen-doped p-type Cu2O thin films were prepared on quartz substrates by magnetron sputter deposition. By adding N2 gas during the deposition process, a nitrogen concentration of up to 2.3 × 1021 atoms/cm3 in the Cu2O thin films was achieved, as determined from secondary ion mass spectroscopy measurements. The effect of nitrogen doping on the structural, optical, and electrical properties of the Cu2O thin films was investigated. X-ray diffraction measurements suggest a preservation of the Cu2O phase for the nitrogen doped thin films, whereas spectrophotometric measurements show that the optical properties were not significantly altered by incorporation of nitrogen into the Cu2O matrix. A significant conductivity enhancement was achieved for the nitrogen-doped Cu2O thin films, based on Hall effect measurements, i.e., the hole concentration was increased from 4 × 1015 to 3 × 1019 cm?3 and the resistivity was reduced from 190 to 1.9 ?·cm by adding nitrogen to the Cu2O thin films.
关键词： magnetron sputtering,thin film,nitrogen,cuprous oxide,doping
更新于2025-09-11 14:15:04
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Single-step formation of Cr 2 N nanoparticles by pulsed laser irradiation
摘要： Chromium nitride nanoparticles with mean diameter distribution between 0.8 nm and 30 nm were produced by laser irradiation of a chromium target immersed in liquid nitrogen. Cr was directly converted to chromium nitride nanoparticles according to selected-area electron diffraction analyses using the transmission electron microscopy technique. Crystalline nanoparticles mostly consist of Cr2N, which is commonly reported together with the conversion of Cr2N to CrN and the mixture of chromium oxides. In addition, there is no evidence of oxidation by storage or photodegradation of the nanoparticles in isopropyl alcohol suspensions. The intensity profile of small-angle X-ray scattering indicates that the geometrical shape of the nanoparticles is not spherical but cylindrical with aspect ratio (height-to-radius) of 0:35–0:05. UV-Vis absorption spectroscopy reveals the presence of surface plasmon absorption at the ultraviolet region at wavelengths of 350, 372, and 397 nm. First-principles calculations of density of states, dielectric function, and optical conductivity performed within the theoretical framework of density functional theory for Cr2N with a hexagonal structure corroborate the formation of surface plasmons.
关键词： transmission electron microscopy,liquid nitrogen,chromium nitride nanoparticles,density functional theory,laser irradiation,UV-Vis absorption spectroscopy
更新于2025-09-11 14:15:04
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Optomagnetic plasmonic nanocircuits
摘要： The coupling between solid-state quantum emitters and nanoplasmonic waveguides is essential for the realization of integrated circuits for various quantum information processing protocols, communication, and sensing. Such applications benefit from a feasible, scalable and low loss fabrication method as well as efficient coupling to nanoscale waveguides. Here, we demonstrate optomagnetic plasmonic nanocircuitry for guiding, routing and processing the readout of electron spins of nitrogen vacancy centres. This optimized method for the realization of highly efficient and ultracompact plasmonic circuitry is based on enhancing the plasmon propagation length and improving the coupling efficiency. Our results show 5 times enhancement in the plasmon propagation length using (3-mercaptopropyl) trimethoxysilane (MPTMS) and 5.2 times improvement in the coupling efficiency by introducing a grating coupler, and these enable the design of more complicated nanoplasmonic circuitries for quantum information processing. The integration of efficient plasmonic circuitry with the excellent spin properties of nitrogen vacancy centres can potentially be utilized to extend the applications of nanodiamonds and yield a great platform for the realization of on-chip quantum information networks.
关键词： nitrogen vacancy centres,plasmon propagation length,nanoplasmonic waveguides,quantum information processing,coupling efficiency
更新于2025-09-11 14:15:04
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Synthesis and luminescence properties of a novel dazzling red-emitting phosphor NaSr <sub/>3</sub> SbO <sub/>6</sub> :Mn <sup>4+</sup> for UV/n-UV w-LEDs
摘要： High-loading atomic cobalt (12.8 wt%) dispersed on nitrogen-doped graphene was successfully synthesized via considerably low temperature pyrolysis. The catalyst exhibits excellent electrocatalytic performance towards the oxygen reduction reaction with a large limiting diffusion current density of 5.60 mA cm?2 (10% higher than that of commercial Pt/C), and when acting as the air catalyst of Zn–air batteries, a high open-circuit voltage of 41.40 V and excellent power density are also achieved.
关键词： low-temperature pyrolysis,atomic cobalt,nitrogen-doped graphene,Zn–air batteries,oxygen reduction reaction
更新于2025-09-11 14:15:04
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Plasmonic W18O49/attapulgite nanocomposite with enhanced photofixation of nitrogen under full-spectrum light
摘要： Ammonia (NH3) obtained by traditional Haber–Bosch technique under extreme conditions stimulates the exploration of sustainable approach via nitrogen photofixation process, however, efficient utilization of solar energy remains a great challenge. Herein, a novel plasmonic W18O49 supported on acid modified attapulgite (H-ATP) composite was prepared by microwave hydrothermal method. The impact of the loading fraction of W18O49 on the ammonia production rate was investigated. Results indicate that ATP possesses abundant adsorption sites after modified by phosphoric acid which facilitates the immobilization of W18O49. The 40% W18O49/H-ATP achieves the highest ammonia production rate of 138.76 μmol g?1 h?1 under solar light irradiation, even 78.76 μmol g?1 h?1 under NIR light (λ > 780 nm). The formed Z-scheme heterostructure improves the separation of charge-carriers, and the localized surface plasmon resonance (LSPR) effect of W18O49 broadens the light response range, both of which contribute to the enhanced nitrogen photofixation performance.
关键词： attapulgite,nitrogen,photofixation,W18O49,full-spectrum light,Plasmonic
更新于2025-09-11 14:15:04