Emission Of Nanoparticles Research Articles

Novel turn-on fluorescent biosensors for selective detection of cellular Fe3+ in lysosomes: Thiophene as a selectivity-tuning handle for Fe3+ sensors

Iron-selective turn-on sensors are indispensable tools for understanding iron-related cell death processes and human diseases. In this study, we report a novel class of fluorescent sensors derived from an indolizino[3,2-c]quinoline scaffold that exhibit high selectivity for Fe3+ over other biologically abundant cations in cells, including Fe2+, Al3+, Zn2+, and Mn2+. IQ18 works as a ratiometric sensor with a Kd value of 7.1 × 10 −7 M and a detection limit of 5.2 nM in ethanol, whereas IQ44 displays fluorescence enhancement upon binding with Fe3+ in both ethanol and water. In aqueous solution, IQ44 exists as 150-nm nanoparticles. The suppressed fluorescent emission of IQ44 nanoparticles in water is switched on in response to Fe3+, working as a turn-on nanoparticle sensor. Structure-property relationship analysis with IQ derivatives revealed that the thiophene ring confers selectivity for Fe3+. By installing thiophene in IQ44 as a selectivity-tuning handle, fluorescence in the presence of Fe3+ resulting from restriction of intramolecular rotation (RIR) and increased torsion angle induced by iron demonstrated that IQ44 is specifically localized in lysosomes, where it recognizes cellular Fe3+ in live cells, as determined using confocal microscopy. In addition, the increased fluorescent puncta of IQ44 in the presence of Fe3+ colocalized well with the RFP-tagged LC3 proteins (pmRFP-LC3), enabling the detection of the autophagy process.

Impacts of gasoline aromatic and ethanol levels on the emissions from GDI vehicles: Part 2. Influence on particulate matter, black carbon, and nanoparticle emissions

Fuel composition plays an important role on the particulate matter (PM) emissions formation from gasoline direct injection (GDI) engines. In this study, the impacts of gasoline chemical structure and physical properties on the particulate emissions were assessed for a fleet of five Tier 3 compliant GDI vehicles. All vehicles were tested on eight fuels with varying aromatic and ethanol levels, as well as varying PM indices (PMIs) over the LA92 test cycle in at least duplicate on each of the test fuels. Our results showed strong, statistically significant fuel differences for the weighted PM mass emissions and all three phases of the LA92 cycle. The higher aromatic content fuels showed increases in PM mass and black carbon emissions that were statistically significant compared to the lower aromatic fuels. The fuels with higher PMIs showed an upward, but not statistically significant, trend for PM mass emissions with increasing ethanol content likely due to ethanol’s evaporative charge cooling effect. This observation does not hold true for the lower PMI fuels. Similar trends to the weighted PM mass emissions were also seen for the cold-start and hot-running PM mass emissions, as well as for the weighted black carbon emissions, indicating a possible ethanol reinforcing effect on PM formation for the high PMI fuels. Total and solid particle number emissions also showed increases with the higher aromatic fuels compared to the lower aromatic fuels. Similar to PM mass, both total and solid particle number emissions demonstrated an upward trend for the high PMI fuels with an increase in ethanol content. While the study is consistent with other studies showing that increasing aromatics and PMI values lead to higher PM emissions, the results also suggest that this relationship is complicated by the presence of varying levels of ethanol in high aromatic and PMI fuels, where increasing levels of ethanol in these fuels can also lead to PM increases. High molecular weight and low volatility hydrocarbon species (especially aromatics) also strongly impacted particulate emissions formation in GDI vehicles.

Modeling of High Nanoparticle Exposure in an Indoor Industrial Scenario with a One-Box Model.

Mass balance models have proved to be effective tools for exposure prediction in occupational settings. However, they are still not extensively tested in real-world scenarios, or for particle number concentrations. An industrial scenario characterized by high emissions of unintentionally-generated nanoparticles (NP) was selected to assess the performance of a one-box model. Worker exposure to NPs due to thermal spraying was monitored, and two methods were used to calculate emission rates: the convolution theorem, and the cyclic steady state equation. Monitored concentrations ranged between 4.2 × 104–2.5 × 105 cm−3. Estimated emission rates were comparable with both methods: 1.4 × 1011–1.2 × 1013 min−1 (convolution) and 1.3 × 1012–1.4 × 1013 min−1 (cyclic steady state). Modeled concentrations were 1.4-6 × 104 cm−3 (convolution) and 1.7–7.1 × 104 cm−3 (cyclic steady state). Results indicated a clear underestimation of measured particle concentrations, with ratios modeled/measured between 0.2–0.7. While both model parametrizations provided similar results on average, using convolution emission rates improved performance on a case-by-case basis. Thus, using cyclic steady state emission rates would be advisable for preliminary risk assessment, while for more precise results, the convolution theorem would be a better option. Results show that one-box models may be useful tools for preliminary risk assessment in occupational settings when room air is well mixed.

Synthesis and Characterization of PVP-Stabilized Palladium Nanoparticles by XRD, SAXS, SP-ICP-MS, and SEM

Due to increased emissions of palladium nanoparticles in recent years, it is important to develop analytical techniques to characterize these particles. The synthesis of defined and stable particles plays a key role in this process, as there are not many materials commercially available yet which could act as reference materials. Polyvinylpyrrolidone- (PVP-) stabilized palladium nanoparticles were synthesized through the reduction of palladium chloride by tetraethylene glycol (TEG) in the presence of KOH. Four different methods were used for particle size analysis of the palladium nanoparticles. Palladium suspensions were analyzed by scanning electron microscopy (SEM), small angle X-ray scattering (SAXS), single-particle ICP-MS (SP-ICP-MS), and X-ray diffraction (XRD). Secondary particles between 30 nm and 130 nm were detected in great compliance with SAXS and SP-ICP-MS. SEM analysis showed that the small particulates tend to form agglomerates.

Nanoparticle Emissions From Metal-Assisted Chemical Etching of Silicon Nanowires for Lithium Ion Batteries

As one of the most promising anode materials for high-capacity lithium ion batteries (LIBs), silicon nanowires (SiNWs) have been studied extensively. The metal-assisted chemical etching (MACE) is a low-cost and scalable method for SiNW synthesis. Nanoparticle emissions from the MACE process, however, are of grave concerns due to their hazardous effects on both occupational and public health. In this study, both airborne and aqueous nanoparticle emissions from the MACE process for SiNWs with three sizes of 90 nm, 120 nm, and 140 nm are experimentally investigated. The prepared SiNWs are used as anodes of LIB coin cells, and the experimental results reveal that the initial discharge and charge capacities of LIB electrodes are 3636 and 2721 mAh g−1 with 90 nm SiNWs, 3779 and 2712 mAh g−1 with 120 nm SiNWs, and 3611 and 2539 mAh g−1 with 140 nm SiNWs. It is found that for 1 kW h of LIB electrodes, the MACE process for 140 nm SiNWs produces a high concentration of airborne nanoparticle emissions of 2.48 × 109 particles/cm3; the process for 120 nm SiNWs produces a high mass concentration of aqueous particle emissions, with a value of 9.95 × 105 mg/L. The findings in this study can provide experimental data of nanoparticle emissions from the MACE process for SiNWs for LIB applications and can help the environmental impact assessment and life cycle assessment of the technology in the future.

Tunable bandgap and blue emission of ZnS nanoparticles induced by controlled S vacancies

Poly(vinylpyrrolidone) capped ZnS semiconductor nanoparticles with a controlled amount of S vacancies have been synthesized through the one step hydrothermal method at low temperatures by varying the concentration of thiourea, the sulfur reagent. The hexagonal wurtzite structure of ZnS with particle like morphology has been identified from powder X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. The formation of compound ZnS and elemental purity has been studied from energy dispersive spectra. The role of S vacancy, the influence of lattice strain and surface defect on the emission, as well as the variation of emission intensity with different excitation wavelengths have been studied using a photoluminescence spectrometer. With an increase in the excitation wavelength, a variation intensity and a red shift in the peak position due to different contributions of free excitonic emissions and its phonon replicas have been noticed and discussed in detail. Raman spectroscopy confirms the formation of ZnS nanoparticles; the shift and broadening in Raman spectra have been studied in detail. The spectral shift and the tunable bandgap of ZnS with S vacancy have been explained on the basis of crystallinity, crystallite size, particle size, lattice strain, and defects on the surface.

Surface Chemistry-Mediated Near-Infrared Emission of Small Coinage Metal Nanoparticles.

From size-dependent luminescence to localized surface plasmon resonances, the optical properties that emerge from common materials with nanoscale dimensions have been revolutionary. As nanomaterials get smaller, they approach molecular electronic structures, and this transition from bulk to molecular electronic propertiesis a subject of far-reaching impact. One class of nanomaterials that exhibit particularly interesting optoelectronic features at this size transition are coinage metal (i.e., group 11 elements copper, silver, and gold) nanoparticles with core diameters between approximately 1 to 3 nm (∼25-200 atoms). Coinage metal nanoparticles can exhibit red or near-infrared photoluminescence features that are not seen in either their molecular or larger nanoscale counterparts. This emission has been exploited both as a probe of electronic behavior at the nanoscale as well as in critical applications such as biological imaging and chemical sensing. Interestingly, it has been demonstrated that theirphotoluminescence figures of merit such as emission quantum yield, energy, and lifetimeare largely independent of particle diameter. Instead, emission from particles at this size range depends heavily on the particle surface chemistry, which includes both its metallic composition and the capping ligand architecture. The strong influence of surface chemistry on these emergent optoelectronic phenomena has powerful implications for both the study and use of these particles, primarily due to the theoretically limitlesspossible surface ligand architectures and metallic compositions. In this Account, we highlight recent work that studies and uses surface chemistry-mediated photoluminescence from coinage metal nanoparticles. Specifically, we emphasize the distinct, as well as synergistic, roles of the nanoparticle capping ligand and the nanoparticle corefor controlling and/or enhancing theirnear-infrared photoluminescence. We then discuss the implications of surface chemistry-mediated photoluminescence as it relates to downstream applications such as energy transfer, sensing, and biological imaging. We conclude by discussing current challenges that remain in the field, including opportunities to develop new particle synthetic routes, analytical tools, and physical frameworks with which to understand small nanoparticle emission. Taken together, we anticipate that these materials will be foundational both in understanding the unique transition from molecular to bulk electronic structures and in the development of nanomaterials that leverage this transition.

Difference in the Tailpipe Particle Number by Consideration of Sub-23-nm Particles for Different Injection Settings of a GDI Engine

The purpose of this study was to investigate the characteristic of nanoparticles under consideration of sub-23-nm particles from a 1.8-l direct injection (DI) gasoline engine under stoichiometric air/fuel conditions in the exhaust gas system. For future CO2 challenges, the usage of DI—instead of port fuel injection (PFI)—gasoline engines is unavoidable. Therefore, a state of the art particle management program-particle number (PN) system, the Horiba SPCS (2100) with an integrated CPC (condensation particle counter), was recalibrated from a 50% cutoff (D50%) at 23 nm down to a cutoff at 10 nm and the PCRF (particle concentration reduction factor) for sizes smaller than 23 nm was checked. Two different modal points, out of a representative Real Driving Emission (RDE) cycle, were investigated with both calibrations, D50% = 10 nm and D50% = 23 nm. For these different load points, the fuel pressure (FUP) and the start of injection (SOI) were varied, to represent the difference in the structure and the ratio conc(10 nm)/conc(23 nm) of the nanoparticle emissions. The particle characterization includes the particle number (PN), the particle size distribution (PSD), and the particle mass (PM). The particle number was measured with Horiba SPCS (2100). The particle size distribution was analyzed with a Grimm differential mobility analyzer (DMA) in combination with a Faraday cup electrometer (FCE). Micro Soot and Pegasor were used to determine the PM, and an optical characterization was done with a 120-kV Phillips CM12 transmission electron microscope (TEM). The position of all particle measurement systems was downstream the three-way catalyst (TWC). The results of this investigation showed that a higher injection pressure decreases the PN (without consideration of sub-23-nm particles) in general. The ratio conc(10 nm)/conc(23 nm) was therefore higher, because smaller particles, especially ash particles, were less reduced from the FUP. This means higher FUP tends to a higher ratio. For the SOI, the main reasons of the ratio differences were explained by an encroachment between the injection jet and the piston, the valve and the wall.

Thermionic emission in gold nanoparticles under femtosecond laser irradiation observed with photoemission electron microscopy

This study reports that thermionic emission can dominate over multi-photon ionization in gold nanoparticles under femtosecond laser irradiation. The brightness of individual particles observed with photoemission electron microscopy increased steeply for laser power above 200 mW, which is reproduced well by the Richardson–Dushman equation. The temperature estimated by fitting the equation is about 1 eV. This high temperature suggests that the laser is absorbed by defects. The difference in brightness among the nanoparticles as large as a few orders of magnitude is attributed to variation in the defect density. The particles having a similar temperature despite exhibiting largely varying brightness levels can be explained by slow energy transfer from the defects to the ambient electron gas. Discussions for interpreting the observed results suggest that thermionic emission can be a useful diagnostic tool for characterizing nanoparticles.

A simple synthesis route for preparation and optical properties of PMMA-g-ZnO nanocomposites through surface-initiated radical polymerization

An effortless chemisorption access for the planning of nanocomposites containing a semiconductor ZnO nanoparticles and poly(methyl methacrylate) (PMMA) is demonstrated. First, thiol-functionalized ZnO (ZnO-SH) were prepared by a silanization reaction between ZnO nanoparticles and (3-mercaptopropyl) trimethoxysilane. Then, a reserved radical polymerization of methyl methacrylate in the attendance of Zinc oxide-thiol (ZnO-SH) and butyrolactam produced PMMA-g-ZnO nanocomposites. DSC were used to examine the weight decline of glass transition temperature of nanocomposites. The ocular characteristics of the nanocomposites were studied by Ultraviolet-visible (UV–vis) absorption spectroscopy and photoluminescence spectroscopy (PL). The results accentuate the role of the grafted PMMA polymer segments in augmenting the strength of dispersal and near-band edge (NBE) emission of ZnO nanoparticles.

Fe3+-sensing by 3,3′,5,5′-tetramethylbenzidine-functionalized upconversion nanoparticles

Detection of Fe3+ ion is essential for human health because it is an important element of hemoglobin, which carries oxygen to cells in the body. Here, a 3,3′,5,5′-tetramethylbenzidine (TMB) functionalized NaYF4: Yb3+, Er3+@NaYF4 composite upconversion probe was developed, and demonstrated Fe3+ sensing ability with high sensitivity and selectivity. The red emission of upconversion nanoparticles (UCNPs) has a higher penetration depth in tissue than green light and works within the biological window. The obtained hydrophobic NaYF4: Yb3+, Er3+@NaYF4 nanoparticles were treated with HCl to achieve hydrophilic ligand-free nanoparticles with non-saturated metal ions on their surface. Then, a Fe3+ responsive TMB-UNCPs composite luminescence probe was formed through linking TMB onto the ligand-free UCNPs by a coordination bond between the NH2 groups in TMB and the metal ions on the UCNPs. Due to the efficient fluorescence resonance energy transfer from UCNPs to Fe3+-TMB, the obtained probe shows high sensitivity for detecting Fe3+ in the range of 0–100 μM with a detection limit of 0.217 μM. And the color change of the detection system can also be easily recognized by the naked eye. The 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) experiments and the bioimaging experiments show promising prospects in tissue imaging.

Experimental investigation on a 3000 bar fuel injection system for a SCR-free non-road diesel engine

The upcoming Stage V emissions regulation for Non-Road Heavy Duty Diesel Engines will force OEMs to adopt Diesel Particulate Filters, adding a further degree of complexity to the aftertreatment system, which in several cases already includes specific devices for NOx reduction. Since complex aftertreatment systems can rise packaging problems as well as reliability issues, the authors evaluated the performance of a Stage V compliant engine layout which can avoid dedicated aftertreatment devices for NOx. This engine features a low pressure exhaust gas recirculation system, a two-stage turbocharger and a 3000 bar injection pressure-capable fuel injection system. This paper focus on the experimental assessment of the performance of the fuel injection system, demonstrating how increasing the rail pressure from 2000 to 3000 bar can dramatically improve the NOx-Soot and NOx-Particulate Number trade-off, together with the engine efficiency, without adversely affecting the emission of nanoparticles. In particular, extremely high injection pressures in conjunction with the use of after injection as a soot reduction technique, was found to be capable of achieving a 50% smoke reduction with a more than acceptable engine efficiency degradation.

FRET-Based Upconversion Nanoprobe Sensitized by Nd3+ for the Ratiometric Detection of Hydrogen Peroxide in Vivo.

The exorbitant level of hydrogen peroxide is closely related to many human diseases. The development of novel probes for H2O2 detection will be beneficial to disease diagnosis. In this study, a novel Nd3+-sensitized upconversion nanoprobe based on Förster resonance energy transfer was first developed for sensing H2O2. This nanosystem was made of core-shell upconversion nanoparticles (emission at 540 and 660 nm), dicyanomethylene-4 H-pyran (DCM)-H2O2, and poly acrylic acid (PAA)-octylamine. Obviously, upconversion nanoparticles (UCNPs) doped with Nd3+ acted as an energy donor, and DCM-H2O2, transferring to DCM-OH with the reaction of H2O2, acted as an energy acceptor. The ratiometric upconversion luminescence (540 nm/660 nm) signal could be utilized to visualize the H2O2 level, and the LOD of the nanoprobe for H2O2 was quantified to be 0.168 μM. Meanwhile, owing to the dope of Nd3+, the nanoprobe would not induce the overheating effect in biological samples and could possess deeper tissue penetration depth, compared with the UCNPs excited by 980 nm light during bioimaging. The nanoprobe could also play an important role in detecting the exogenous and endogenous H2O2 in living cells with ratiometric UCL (upconversion luminescence) imaging. Furthermore, our nanoprobe could function in detecting the H2O2 in a tumor-bearing mouse model. Therefore, this novel nanoprobe along with the ratiometric method for responding and bioimaging H2O2 could serve as a new model that promotes the emergence of novel probes for H2O2 detection.

Fighting Aggregation-Caused Quenching and Leakage of Dyes in Fluorescent Polymer Nanoparticles: Universal Role of Counterion.

Dye-loaded polymer nanoparticles (NPs) emerge as a powerful tool for bioimaging applications, owing to their exceptional brightness and controlled small size. However, aggregation-caused quenching (ACQ) and leakage of dyes at high loading remain important challenges of these nanomaterials. The use of bulky hydrophobic counterions has been recently proposed as an effective approach to minimize ACQ and dye leakage, but the role of counterion structure is still poorly understood. Here, a systematic study based on ten counterions, ranging from small hydrophilic perchlorate up to large hydrophobic tetraphenylborate derivatives, reveals how counterion nature can control encapsulation and emission of a cationic dye (rhodamine B octadecyl ester) in NPs prepared by nanoprecipitation of a biodegradable polymer, poly-lactide-co-glycolide (PLGA). We found that increase in counterion hydrophobicity enhances dye encapsulation efficiency and prevents dye adsorption at the particle surface. Cellular imaging studies revealed that ≥95 % encapsulation efficiency, achieved with most hydrophobic counterions (fluorinated tetraphenylborates), is absolutely required because non-encapsulated dye species at the surface of NPs are the origin of dye leakage and strong fluorescence background in cells. The size of counterions is found to be essential to prevent ACQ, where the largest species, serving as effective spacer between dyes, provide the highest fluorescence quantum yield. Moreover, we found that the most hydrophobic counterions favor dye-dye coupling inside NPs, leading to ON/OFF fluorescence switching of single particles. By contrast, less hydrophobic counterions tend to disperse dyes in the polymer matrix favoring stable emission of NPs. The obtained structure-property relationships validate the counterion-based approach as a mature concept to fight ACQ and dye leakage in the development of advanced polymeric nanomaterials with controlled optical properties.

Assembly-Induced Emission and Stability Enhancement of Cu Nanoparticles

Assembly-Induced Emission and Stability Enhancement of Cu Nanoparticles

Size-dependent ion emission asymmetry of free NaCl nanoparticles excited by intense femtosecond laser pulses.

We report on asymmetric ion emission of size-selected NaCl nanoparticles (d = 100-600 nm) ionized by intense femtosecond laser pulses (λ = 800 nm, peak intensity ∼1013 W cm-2). Velocity map imaging indicates that a higher ion yield is observed in the propagation direction of the laser pulses than in the opposite direction. This asymmetric ion emission is found to be size-dependent and increases with particle size. This pronounced size dependence is interpreted in terms of discrete dipole simulations of the internal electric field in the nanoparticles, which reveal that the internal field is enhanced in the forward propagation direction of the laser pulses, occurring for nanoparticles >100 nm. The ion emission asymmetry is further found to depend on the peak intensity of the laser radiation. Nanoparticles of 100 nm show a symmetric distribution of ion emission, while the ion emission for 600 nm particles is found to become increasingly symmetric as the peak intensity is increased. In addition to single pulse ionization experiments, we explore the angular distribution of ion emission of resonantly heated NaCl nanoparticles using a pump-probe setup. Here, ion emission is found to be more symmetric for resonantly heated nanoparticles than for single pulse excitation. These differences are explained by the absorption mechanism, where the probe pulse in a dual pulse experiment can be efficiently absorbed by plasmonic excitation for suitable delays between both laser pulses.

Orthogonal shortwave infrared emission based on rare earth nanoparticles for interference-free logical codes and bio-imaging.

Shortwave infrared (SWIR) photoluminescence has received intense interest in many fields in recent years thanks to the advantages of its wide wavelength range and high tissue imaging ability and it is invisible to the naked eye. However, achieving orthogonal SWIR emission still remains a challenge. In the present study, synthesized NaErF4@NaLuF4 (Er@Lu) and NaYF4:Nd@NaLuF4 (Y:Nd@Lu) nanoparticles emitted atom-like SWIR emission, and the separation distance between the SWIR emission was beyond 50 nm, which permitted orthogonal SWIR signal acquirement with optical filters. Furthermore, an invisible logical code was designed by manipulating the orthogonal SWIR emission of the lanthanide fluoride nanoparticles, and was further operated by basic logical operations and applied in information encryption and anti-counterfeit fields. In addition, the emission between these two hydrophilic nanoparticles could also be separated in vivo without signal interference and the orthogonal SWIR imaging mode was achieved, which was demonstrated in a bio-imaging experiment in vivo. This demonstration extended the orthogonal SWIR emission capacity by controlling the orthogonal emission, opening new opportunities in the fields of data security, disease diagnosis and non-interference label in vivo.

Characteristics of nanoparticle formation and hazardous air pollutants emitted by 3D printer operations: from emission to inhalation.

This study examined the emissions of nanoparticles and hazardous air pollutants (HAPs) by 3D printer operations and evaluated nanoparticle deposition behavior using a prediction model. Nanoparticles and HAPs were sampled at the Inha University 3D printing center with five fused filament fabrication (FFF)-type 3D printers. The number size distribution of the nanoparticles exhibited a bimodal distribution with dominant peaks over a large size range between 70 and 100 nm and a smaller size range between 10 and 20 nm. With increasing 3D printer operation, the number concentration of 10 nm particles increased, and the final number concentration was 3.6 times higher than that of the background concentration. Nanoparticle formation and agglomeration were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Model calculations revealed that a large number of nanoparticles between 10 and 30 nm in size are deposited in the lower human respiratory tract (generation number: 16–22). A total of 14 HAPs species were detected, among which hexane, acrylonitrile, and benzene concentrations were the highest.

Upconversion luminescence in sub-10 nm β-NaGdF4:Yb3+,Er3+ nanoparticles: an improved synthesis in anhydrous ionic liquids.

Sub-10 nm β-NaGdF4:18% Yb3+,2% Er3+ nanoparticles were synthesized in ethylene glycol and various ionic liquids under microwave heating. The products were characterized by powder X-ray diffraction, electron microscopy, and upconversion (UC) luminescence spectroscopy. After Yb3+ excitation at 970 nm, Er3+ ions are excited by energy transfer upconversion and show the typical green and red emission bands. The UC luminescence intensity was optimized with respect to reactant concentrations, solvents, and reaction temperature and time. The strongest UC emission was achieved for sub-20 nm core–shell nanoparticles which were obtained in the ionic liquid diallyldimethylammonium bis(trifluoromethanesulfonyl)amide from a two-step synthesis without intermediate separation. Strictly anhydrous reaction conditions, a high fluoride/rare earth ion ratio, and a core–shell structure are important parameters to obtain highly luminescent nanoparticles. These conditions reduce non-radiative losses due to defects and high energy acceptor modes of surface ligands. A low power excitation of the core–shell particles by 70 mW at 970 nm results in an impressive UC emission intensity of 0.12% compared to the bulk sample.

Experimental Methods to Study Environmental Sustainability of Silicon-based Lithium Ion Battery Manufacturing

Abstract Next-generation lithium ion batteries (LIBs) are under rapid development using various nano-structured materials. Among them, silicon nanowires (SiNWs) and silicon nanotubes (SiNTs) are two promising anode materials due to their high specific capacities. However, fabrication processes of SiNWs and SiNTs involve a large amount of toxic chemicals and generate significant potential impacts on the environment. In this study, both in-situ and ex-situ measurements were proposed for investigating the process emissions, including gas, aerosol nanoparticle, and aqueous nanoparticle emissions, from chemical etching processes for producing SiNWs and SiNTs for use as anode materials for LIBs. The feasibilities of the measurements were verified by the preliminary results of the emissions from the SiNTs synthesis process. This study provides insight into experimental measurements of and supports the gathering of process data on emissions from synthesis processes for SiNWs and SiNTs as anode materials for LIBs, which can be useful for future assessment of the sustainability performance of silicon-based LIB technology.