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A novel ICP-OES method has been developed for the determination of Si concentration, originating from polyorganophosphosilanes, in biological specimens that also contain metal ions. The method is free of hazardous hydrofluoric acid (HF) and involves digestion with HNO3/H2O2 prior to the analysis by ICP-OES. High and reproducible spike recovery was obtained from the controls.

A novel ICP-OES method has been developed for the determination of Si concentration, originating from polyorganophosphosilanes, in biological specimens that also contain metal ions. The method is free of hazardous hydrofluoric acid (HF) and involves digestion with HNO3/H2O2 prior to the analysis by ICP-OES. High and reproducible spike recovery was obtained from the controls. [ABSTRACT FROM AUTHOR]

The preparation of titanium carbide (Ti3C2Tx) thin sheets (T represents surface termination), an emerging class of two-dimensional materials, heavily relies on the etching of interlayered aluminum (Al) of MAX (M, A, and X represent transition metals, Al, and carbon, respectively) using concentrated hydrofluoric acid (HF). However, HF is an acutely toxic chemical. Herein, for the first time, we propose a dissolution-driven delamination method to prepare Ti3C2Tx MXene thin sheets using an HF-free solvent to remove the interlayers of Al. Bis-(trifluoromethanesulfonyl)-imide (TFSI) is a delaminating agent that can directly and effectively dissolve the Al interlayers of MAX. The role of TFSI in this delamination process, i.e., the preferential formation of the surface of a Ti3C2Tx thin sheet, is a key parameter for superior supercapacitor application. The prepared Ti3C2Tx sheets were loaded on Ni foam (NF) via a hydrothermal reaction to form a Ti3C2Tx MXene/NF-4 h composite electrode. This Ti3C2Tx MXene/NF-4 h composite electrode exhibits the highest unprecedented capacitance of 3090 F/g at a current density of 10 A/g in a 1 M KOH electrolyte. It also exhibits excellent rate capabilities at different current densities (from 10 to 30 A/g) while maintaining 76.4% capacity retention after long life cycles. This study provides fundamental insights into the effect of the dissolution of interlayered Al of Ti3AlC2 on the preparation of Ti3C2Tx thin sheets as well as sheds light on the development of next-generation flexible and simple integrated supercapacitors with excellent gravimetric performance. [ABSTRACT FROM AUTHOR]

The development of an HF-free and environmentally benign method for etching the middle aluminum layer (Al) from the Ti 3 AlC 2 -MAX phase is a challenging task in titanium carbide (Ti 3 C 2 Tx) MXene synthesis. Herein, we designed a diazonium salt-based ultrasonic method to prepare MXene. We have explored 4-carboxy benzene diazonium tetrafluoroborate (4-CBDF) as a delaminating agent, which can dissolve the Al layer directly from the MAX phase. 4-carboxy benzene diazonium (4-CBD+) ion promotes the intercalation as well as exfoliation simultaneously during the etching of the MAX phase and directly results in Ti3C2Txnanosheets without undergoing any additional delamination process. Synthesized MXene nanosheets show excellent photothermal performance with a conversion efficiency of 59 %. This MXene-coated GC electrode exhibits the highest capacitance of 1133 F/g at a current density 1 A/g, which maintains a retention capacitance of 91% even after 10,000 GCD cycles. The present method provides a fundamental insight into the development of MXene-based next-generation photothermal materials and supercapacitors. [Display omitted] [ABSTRACT FROM AUTHOR]

Porous silicon-based anode materials have gained much interest because the porous structure can effectively accommodate volume changes and release mechanical stress, leading to improved cycling performance. Magnesiothermic reduction has emerged as an effective way to convert silica into porous silicon with a good electrochemical performance. However, corrosive HF etching is normally a mandatory step to improve the electrochemical performance of the as-synthesized silicon, which significantly increases the safety risk. This has become one of the major issues that impedes practical application of the magnesiothermic reduction synthesis of the porous silicon anode. Here, a facile HF-free method is reported to synthesize macro-/mesoporous silicon with good cyclic and rate performance by simply increasing the reduction temperature from 700 °C to 800 °C and 900 °C. The mechanism for the structure change resulting from the increased temperature is elaborated. A finite element simulation indicated that the 3D continuous structure formed by the magnesiothermic reduction at 800 °C and 900 °C could undertake the mechanical stress effectively and was responsible for an improved cyclic stability compared to the silicon synthesized at 700 °C. [ABSTRACT FROM AUTHOR]

A novel two-dimensional nanolayered Ti 3 C 2 Cl 2 MXene material derived from MAX phase was synthesized through a HF-free method based on elemental replacement reaction in the A atom of traditional Ti 3 AlC 2 MAX phase and ZnCl 2 molten salts, which possess large specific surface areas, excellent electric conductivity and reducing property. Then the Au/Pt bimetallic nanoparticles decorated Ti 3 C 2 Cl 2 nanoflakes were synthesized by a self-reduction method with Ti 3 C 2 Cl 2 as a natural reducing agent and supporter, which possess peroxidase mimic activity and oxidase mimic activity, simultaneously. Based on the prominent catalytic activity of Au/Pt/Ti 3 C 2 Cl 2 nanocomposite, a novel colorimetric platform was developed for in situ sensing of hydrogen peroxide (H 2 O 2) released from live HeLa cells and colorimetric detection of glutathione (GSH), with the detection ranges of 50–10000 μM and 0.1–20 μM, the detection limits were 10.24 μM and 0.07 μM, respectively. These results allow utilization of the easily accessible 2D surface for the design and application of 2D layered material-supported MXene nanocomposites catalysts in intracellular biosensing. Preparation of Au/Pt/Ti 3 C 2 Cl 2 nanoflakes with a HF-free and self-reduction method for in-situ detection of hydrogen peroxide released from live HeLa cells and colorimetric detection of glutathione. [Display omitted] [ABSTRACT FROM AUTHOR]

Pure silica ITH zeolite is normally synthesized under neutral or acidic conditions in the presence of HF, but it is challenging for synthesis of this zeolite under alkaline conditions. In this work, it is successful for alkaline synthesis of pure silica ITH in the absence of HF using a designed organic template containing F species, showing that the sample obtained has high crystallinity associated with ITH structure, nanosheet morphology, and rich silanol nests. Very importantly, this ITH zeolite exhibited better performance in vapor phase Beckmann rearrangement of cyclohexanone oxime than that of Silicalite-1 zeolite, one of the best catalysts for this reaction. This work might offer a new opportunity for preparation of pure silica zeolites as efficient catalysts in the Beckmann rearrangement in the future., (© 2024 Wiley-VCH GmbH.)

Porous silicon-based anode materials have gained much interest because the porous structure can effectively accommodate volume changes and release mechanical stress, leading to improved cycling performance. Magnesiothermic reduction has emerged as an effective way to convert silica into porous silicon with a good electrochemical performance. However, corrosive HF etching is normally a mandatory step to improve the electrochemical performance of the as-synthesized silicon, which significantly increases the safety risk. This has become one of the major issues that impedes practical application of the magnesiothermic reduction synthesis of the porous silicon anode. Here, a facile HF-free method is reported to synthesize macro-/mesoporous silicon with good cyclic and rate performance by simply increasing the reduction temperature from 700 °C to 800 °C and 900 °C. The mechanism for the structure change resulting from the increased temperature is elaborated. A finite element simulation indicated that the 3D continuous structure formed by the magnesiothermic reduction at 800 °C and 900 °C could undertake the mechanical stress effectively and was responsible for an improved cyclic stability compared to the silicon synthesized at 700 °C.

Narrow‐band red‐emitting fluoride phosphors with Mn4+‐doped are used as WLED backlight display source with its unique advantages. Its synthesis involving HF and its humidity‐sensitive feature hinder the application in white LED. Here, we synthesized the fluoride phosphors K2SiF6:Mn4+ in a HF‐free environment and improved the chemical stability. Soaked in water for 6 h, the emission intensity of modified phosphor was measured to maintain 86% of the original state compared with that of K2SiF6:Mn4+ which was kept at 72%. The as‐synthesized phosphor has an excellent color stability and thermal quenching behavior within the temperature range of 298–498 K. The white light‐emitting devices fabricated with encapsulated KSFM phosphor demonstrated the correlated color temperature (CCT) of 3334 K, color render index (CRI) of 88.91, chromaticity coordinates of (0.4176, 0.402). These considerable capabilities exhibit that this phosphor qualifies excellent performance for application in warm white LED. We synthesized the K2SiF6:Mn4+ phosphors in a HF‐free environment, of which the particle size and the emission intensity are silicon source‐dependent and improved its water resistance by surface modification with a silane. The experimental results illustrate that as‐prepared phosphor shows excellent performance for application in warm white LED. [ABSTRACT FROM AUTHOR]

Abstract Limited information exists on the movement and partitioning of 235U series radionuclides following their release to the environment from activities associated with the nuclear fuel cycle. Only three isotopes in the series, 235U, 231Pa and 227Ac, have half-lives greater than a month. The extent to which the radiologically-significant isotopes of the 235U series differentiate and fractionate in the environment, and then accumulate in biota, is largely controlled by the chemical properties of these three elements and by their biological uptake. This is particularly the case for biota with life cycles in the order of years. There is therefore potential for changes in the radiation dose received by humans and the environment during, for example, the operational and post-remediation phases of uranium mining practices, particularly where mine sites revert to traditional land uses such as hunting, fishing and camping. Natural activity concentrations of 235U are ∼20 times lower than for 238U. In an environmental context, however, the radiation dose that arises from subsequent members of the 235U decay chain will be determined by their abundance distribution and can exceed that from the 238U series. The half-lives of the protactinium isotopes allow only 231Pa to accumulate independently of its parent radionuclide along the transport pathways and/or through preferential uptake by biota. In particular, 231Pa could make a disproportionately high contribution to the dose if it is preferentially transported and/or taken up. The AMS technique is capable of assessing accumulation of 231Pa in natural environmental samples. We report on a new, safer radiochemical extraction method to prepare the 233Pa isotopic tracer (one that does not use hydrofluoric acid), and on the development of 231Pa AMS measurements at the Australian National University. [ABSTRACT FROM AUTHOR]

The K 2 SiF 6 :Mn4+ red phosphor has caused widespread concern in warm white light-emitting diodes (WLEDs) due to its unique broadband blue light absorption and narrow-band red emission. However, commercial K 2 SiF 6 :Mn4+ red phosphor inevitably needs to use extremely corrosive HF as a raw material, which will cause great harm to the environment and human beings. In this work, the K 2 SiF 6 :Mn4+ phosphor with highly uniform particle shape and size was successfully synthesized without using HF solution through microfluidic technology. The structure, morphology and photoluminescence properties of the K 2 SiF 6 :Mn4+ phosphors prepared in this work were systematically investigated and analyzed. The K 2 SiF 6 :Mn4+ phosphors synthesized by microfluidic technology are all cubic particles. The sample was the most uniform with a particle size of about 4.14 μm when the pipe diameter was 4 mm and the injection speed was 1000 μL/min, and the number of active Mn4+ in this sample is the largest according to the calculation results, resulting in its maximum luminous intensity. Finally, a warm WLED with low CCT (3379 K) and high CRI (R a = 89.7) was fabricated by combining the as-prepared red K 2 SiF 6 :Mn4+ phosphor with yellow phosphor YAG:Ce3+ and blue LED chip. The results indicate that the K 2 SiF 6 :Mn4+ phosphor prepared by the proposed green continuous route is suitable for WLEDs. • K 2 SiF 6 :Mn4+ red phosphor was successfully synthesized without using HF solution. • The morphology and size of the sample particles synthesized by the microfluidic technology are highly uniform. • By using the prepared K 2 SiF 6 :Mn4+ red phosphor, a warm WLED with low CCT (3379 K) and high CRI (R a = 89.7) was obtained. [ABSTRACT FROM AUTHOR]

The direct preparation of tetrabutylammonium trifluoroborates from boronic acids without using HF or the corresponding potassium salt is described. The method is highly efficient for aromatic and aliphatic boronic acids. This protocol, however, was less efficient for boronic acids that were sensitive to protiodeboronation. [ABSTRACT FROM AUTHOR]

Hf-free n -type half-Heusler with a nominal composition of Ti 0.5 Zr 0.5 NiSn 0.98 Sb 0.02 has been reported to have a high ZT value of almost 1.2. However, the synthesis process requires a long annealing time to achieve single-phase structure, which contributes to high product costs due to energy and time consumption. Here we introduce a new route to prepare (Ti 0.5 Zr 0.5) 1−x Nb x NiSn (x = 0, 0.0050, 0.0075, 0.0100, 0.0125, 0.0150, 0.0175 and 0.0200) compounds for high thermoelectric (TE) performance along with shortening time for sample preparation. The samples were prepared by a combination of arc-melting (AM) and melt-spinning (MS) followed by spark plasma sintering process (SPS). The combination of these synthetic methods produced (Ti 0.5 Zr 0.5) 1−x Nb x NiSn samples with high chemical homogeneity, single-phase structure, and fine grain about 300 nm in size, which are preferred for both charge and phonon transport properties. As a result, a maximum power factor of 44.5 µW cm−1 K−2 at 817 K and a maximum ZT of 1.19 at 874 K were achieved for the sample with x = 0.015, which are comparable to the highest ZT value reported so far for the Hf-free n -type MNiSn (M = Ti, Zr) compounds. The calculated output power density P d and efficiency η based on a single-leg device showed an excellent performance, which yields the maximum P d of 16.2 W cm−2 and η of 12.08% at the cold side temperature T C ≈ 305 K and the hot side temperature T H ≈ 875 K for the optimized composition with x = 0.0125. Furthermore, it is noted that the synthetic process here does not require a long-annealing time and it can be easily applied to mass production. • Hf-free n -type (Ti 0.5 Zr 0.5) 1-x NbxNiSn was synthesized via highly fast process. • A single-phase half-Heusler with a grain refinement was achieved for the optimization of charge and phonon transport properties. • High PF of 44.5 µWcm-1K-2 at 817 K and a peak ZT ~ 1.19 at 874 K were achieved for (Ti 0.5 Zr 0.5) 0.985 Nb 0.015 NiSn. • The calculated power density Pd and efficiency η showed an excellence performance (P d ~ 16.2 Wcm-2, η ~ 12.08%) for the 1.25 at% Nb doped sample. [ABSTRACT FROM AUTHOR]

• K 2 SiF 6 and BaSiF 6 nanoparticles were synthesized for the first time by thermal decomposition method. • This synthesis process does not require the use of highly toxic hydrofluoric acid as fluorine source. • The as-obtained particles are coated with OA molecules, which is an asset for moisture resistance. K 2 SiF 6 and BaSiF 6 nanoparticles are synthesized for the first time by thermal decomposition of a mixture consisting of oleic acid and 1-octadecene using ammonium fluoride as fluorine source instead of highly toxic hydrofluoric acid. The structural and morphological properties of the as-obtained nanocrystals are investigated. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A HNO 3 assisted MIL-101(Cr) was successfully synthesized. • Higher surface area (3841 m2/g) and pore volume (1.72 cm3/g) were obtained. • MIL-101-HNO 3 exhibited higher H 2 S and CO 2 uptake than MIL-101-HF. • The CO 2 /CH 4 , H 2 S/CH 4 and CO 2 /N 2 selectivies of MIL-101-HNO 3 were higher than those of MIL-101-HF. Abstract Despite worldwide attention toward MIL-101(Cr) as a superior adsorbent during past decade, it is still failed to be commercialized. The main barrier can be addressed to the poisonous and expensive synthesis procedure of MIL-101(Cr). In this study, nitric acid (HNO 3) was introduced as a premier, inexpensive and non-poisonous substitute for typical hydrofluoric acid (HF) in the hydrothermal synthesis of MIL-101(Cr). A series of MIL-101-HNO 3 nanoadsorbents, with different amounts of HNO 3 , were synthesized and characterized by different techniques. For the first time, the H 2 S, CO 2 , CH 4 , and N 2 isotherms on the MIL-101-HNO 3 samples were measured in a wide pressure region (1–35 bar) and different temperatures (273, 283, and 293 K) using an in-house made volumetric setup. The results indicated that the MIL-101-HNO 3 -1 possessed the maximum surface area (3841 m2/g), pore volume (1.72 cm3/g), and as a consequence, the highest H 2 S (8.80 mmol/g at 1 bar and 27.16 mmol/g at 35 bar) and CO 2 uptake (5.86 mmol/g at 1 bar and 21.98 mmol/g at 35 bar) among all synthesized samples. More importantly, ideal adsorbed solution theory (IAST) indicated that H 2 S/CH 4 , CO 2 /CH 4, and CO 2 /N 2 adsorption selectivity elevated up to 166.9%, 21.8%, and 13.6% at 1 bar compared to the conventional MIL-101-HF-1. These advantageous were all ascribed to the additional open Cr3+ metal sites and more electrostatic adsorptive behavior of MIL-101-HNO 3 -1. The impressive preferential gas adsorption, along with excellent cyclic performance, thermal and water stability, made the MIL-101-HNO 3 -1 a promising replacement for hazardous MIL-101-HF-1 and other commercial adsorbents. [ABSTRACT FROM AUTHOR]