Purity Chemicals Research Articles

Electric Field-Assisted Agglomeration of Trace Nanoparticle Impurities for Ultrahigh Purity Chemicals.

With the advancement of semiconductor manufacturing technology, the effects of trace impurities in industrial chemicals have grown significantly. In industrial processes, conventional purification methods, such as filtration and distillation, have reached their limits for removing nanoparticles from aqueous and acidic solutions. Especially, silicon and silicate are two fundamental byproducts in semiconductor fabrication processes. Assembly and subsequent removal of these materials at the nanoparticle level have been confronted with significant challenges. Therefore, it is imperative to develop technologies to effectively control and remove these impurities for next-generation manufacturing processes. In this study, we explored the use of electric field-assisted assembly to agglomerate silicate and silicon nanoparticles in industry-standard aqueous and acidic solutions. By applying an alternating current electric field, we induced dipole moments in the nanoparticles, which led to their agglomeration. Notably, nanoparticles smaller than 4 nm grew into significantly larger ones, with submicroparticle sizes exceeding 87 nm for silicate and reaching 130 nm for silicon. Through systematic analysis of the size distribution changes, we identified optimal agglomeration times of 10 min for silicate and 20 min for silicon, revealing effective agglomeration within the frequency range of 1-1000 kHz. The agglomerated particles were stable for 5 days. Our electric field-assisted approach to obtain assembled nanoparticles that can be subsequently removed by conventional purification processes holds promise for enhancing future microfabrication processes, such as semiconductor manufacturing, potentially improving the manufacturing yield and uniformity by reducing the number of trace particles that can act as defective sites.

Optical properties and radiation shielding performance of tellurite glassy composites: Role of rare earth oxides

In this research, the synthesis, optical parameters, and radiation absorption quantities of 50TeO2–15Na2O—(20-x)PbO—15ZnO—xEu2O3 glasses were reported. The glasses were prepared by the well-known melting and quenching method using high purity chemicals. The glasses were coded as TPEu-0, TPEu-1, TPEu-2, and TPEu-3 for glasses containing 0, 1, 2, and 3 mol% of Eu2O3, respectively. The density of the glasses was determined by the Archimedes method. The optical parameters of the glasses, such as the refractive index n, molar refractivity Rm, molar polarizability αm, reflection loss RL, optical transmission T, metallization criterion M, static dielectric constant εstatic, and optical dielectric constant εoptical were estimated by theoretical methods. The stopping powers and range of electrons, protons, α-particles, and carbon ions in the TPEu-X glasses for particle kinetic energies between 15 keV and 15 MeV were computed using the ESTAR, PSTAR, ASTAR, and STRIM software. In addition, the fast neutron (FN) removal cross section (FNRCS), thermal neutron (TN), and total cross-section (σtot) for the prepared glasses were evaluated theoretically using established models. The estimated optical parameters showed strong relationship with the chemical content of the glasses. Glass density and molar volume increased as Eu2O3 content increased. The Rm, αm, RL, εstatic, and εoptical vary from 16.24 to 17.20 cm3/mol, 6.44 × 10−24 cm3‒17.20 × 10−24 cm3, 0.17–0.19, 5.71–6.55, and 4.71–5.55 respectively, with TPEu-0 and TPEu-1 having the maximum and minimum values, respectively. Generally, the increase in Eu2O3 concentration increased the charged radiation shielding ability of the glasses. The increment in the Eu2O3 content of the glasses brought about an improvement in the thermal and fast neutron absorption probabilities of the glasses.

Towards sustainable production of minerals and chemicals through seawater brine treatment using Eutectic freeze crystallization and Electrodialysis with bipolar membranes

European policy encourages the adoption of sustainable systems that promote the efficient use and recovery of minerals and chemicals. In this respect, desalination brines do contain a dramatic amount of valuable minerals and can be valorized through appropriate treatments rather than releasing them into the environment. This paper proposes an innovative brine recovery system for obtaining high purity chemicals through the integration of Eutectic Freeze Crystallization (EFC) and Electrodialysis with Bipolar Membrane (EDBM) technologies. Two separate laboratory-scale experimental campaigns were carried out to validate the potential integration of the two processes. Mirabilite (Na2SO4∙10H2O) has been recovered with a purity of 99.9% using the EFC, and a feed rich in NaCl with low impurities has been further processed in an EDBM unit. EDBM tests with feed solutions simulating EFC effluents have shown that it is possible to produce acidic and basic solutions with high purity (>99%), despite the presence of impurities in the feed. Interestingly, the low EDBM specific consumptions of 0.9–1.1 kWh kg−1NaOH at 100 A m−2 and 1.3–1.6 kWh kg−1NaOH at 300 A m−2 were comparable with and without impurities. In the context of the circular economy strategy promoted by the EU-H2020 Water Mining project, the current study demonstrates that this integrated system effectively minimizes waste, promoting sustainability while providing a potential economic return.

Purification Method for Achieving Low Trace Metals in Ultra-High Purity Chemicals

The high purity requirements of materials used in semiconductor manufacturing are being pushed to unprecedented levels as demand for reliability in computer processors over increasingly longer lifetimes continues to rise. The production of these high purity chemicals requires new purification methods and technologies where the metal concentrations of low parts per billion (ppb) were effectively reduced to low parts per trillion (ppt). The new approach discussed in this paper would present a method for dividing the fluid through micro-channels that form tortuous pathways. These micro-channels allow for further dividing and converging of the fluid thereby presenting the metal species to the purifying surfaces throughout the porous matrix. The ion exchange capability was a function of the concentration and the presence of the species in the solution. Two ion exchange chemistries of strong acid and chelating were made into these structures and their purification performances were assessed and compared in terms of removal efficiencies. Furthermore, these two chemistries were evaluated in series to demonstrate the overall synergistic purification capabilities.

Graphite furnace atomic absorption spectrometric studies for the quantification of trace and ultratrace impurities in the semiconductor grade organic chemicals such as triethylborate, tetraethylorthosilicate and trimethylphosphate

The paper describes the direct determination of impurities by graphite furnace atomic absorption spectrometry (GF AAS) in high (7 N, i.e. 99.99999%) purity organic compounds used as precursors for the deposition of dielectric films by chemical vapour deposition (CVD). The impurity analysis is required to assess the suitability of the compounds that include triethyl borate (TEB), tetraethyl orthosilicate (TEOS) and trimethyl phosphate (TMPO), used as precursors for the deposition of compositionally good quality films. Such features as high sensitivity and limits of detection of GFAAS are exploited for the direct determination of twenty elements (Ag, Al, Bi, Ca, Cd, Cr, Co, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Sn, Sb, Zn) in μg L−1 levels in the three compounds. The analysis was preceded by a comprehensive study on the quantitative recovery of spiked elements using clean room procedures. Specially designed sample holders made of polytetrafluoroethylene (PTFE) were used for the analysis. The routinely used polystyrene sample holders are attacked by these chemicals and are thus rendered unsuitable for analysis. GFAAS operating parameters such as drying, pyrolysis and atomisation temperatures were optimized for each analyte in each organic sample for the removal of the matrix effects on the analyte and for quantitative recovery of the analytes. A fourth drying step was introduced in the furnace program. The accuracy of the method has been established by spike recovery tests in the absence of certified reference materials for high purity chemicals. The method is free from any interference and has a precision of <10%. Studies on the effect of polypropylene (PP) and perfluoroalkhoxy (PFA) storage containers on the impurities of these chemicals were performed and the results were discussed. The method can be effectively utilized for the quality control and quality assurance of these important class of chemicals used extensively in semiconductor industry.

Investigation on the Electrical Conductivity of PZT Modified by Manganese and Cerium

PZT is a ferroelectric ceramic material that has acquired immense importance in the field of electronics industry. The main focus of this report is to present the electrical conductivity response of manganese and cerium modified lead zirconatetitanate (PZT). The conductivity response has been investigated with respect to frequency of applied ac electric field and temperature. The samples have been prepared by mixing high purity chemicals, through high temperature solid state route. The frequency response of electrical conductivity has been analysed on the basis of Maxwell-Wagner and Koop’s model. The temperature response of electrical conductivity indicated that the compounds exhibit Arrhenius behaviour.

Safety evaluation of different acids in high-density polyethylene container loading

To reduce costs, high-purity chemical suppliers wash and reuse HDPE containers collected from users. To determine the lifetime of a container, the appearance of that container and the manufacturer's recommendations for its lifetime are generally considered. Guidelines for determining the lifetime of an HDPE container have not been clearly defined. The lack of these specifications may result in the leakage of high-purity chemicals in the storage, transportation and use of HDPE containers. To understand the effects of using high-purity chemicals (sulfuric acid (H2SO4) and nitric acid (HNO3)) on HDPE, this study revealed its effects by mechanical and thermal performance tests. According to the mechanical properties test results, the ductility and tensile strength of HDPE soaked H2SO4 and HNO3 decreased. HDPE immersed in HNO3 exhibited the lowest thermal stability by thermal performance testing. In summary, the degradation of HDPE is affected by storage conditions. For this study, HDPE only needs 60 days of immersion in HNO3, and its ductility and tensile strength will decline obviously. This study shows that when these containers are used for long-term storage of high purity chemicals, the mechanical properties (including ductility, ductility, and tensile strength) of HDPE containers tend to decrease. To decrease accidental leakage of chemicals due to aging of HDPE, comprehensive and approved regulations should be established for the loading, transport, and storage of HDPE containers.

Structural investigation of La2SrDyCu2Oy complexities

Abstract The structural complexities in lanthanum cuprates family were revisited with the aim of understanding factors that structurally triggers long-range repulsive Coulomb interactions. In this study, polycrystalline samples of La2SrDyCu2Oy (LSDCO) were prepared via solid-state synthesis using high purity chemicals. The X-ray diffraction experiment revealed an unusual structural anomaly in the [2 0 5] and [2 1 3] planes of the crystal lattice. The lattice system was further probed using the Niggli-reduced cell at gamma = 6.0678. It was observed that grain boundaries leading to electron trapping originates from the CuO2 plane while the mesoscopic phase separation is controlled by the cell type and axial value in the x- and y-axes of the crystal lattice. Although the research partly supports popular findings that the main positive lobes of LSDCO are centered on the z-axis, it observed that the negative lobe is located in a ring-like structure along the X Y plane. This result is particularly interesting because it shows the likely origin of broken symmetry in LSDCO sample. The ion bombardment analysis shows that the LSDCO electron-phonon ratio was 8:5. The microstructural analysis of the LSDCO sample was observed to have magnetic field strength of 1.5 kA/m. LSDCO sample possess enormous structural mystery that may interest further studies beyond superconductivity.

Direct determination of impurities in high purity chemicals by electrolyte cathode discharge atomic emission spectrometry (ELCAD-AES)

An ELCAD-AES method was reported for direct determination of metallic impurities in different high purity chemicals such as ammonium hydroxide, hydrogen peroxide and sulphuric acid. Direct analysis of these chemicals for their impurities was found to be feasible by ELCAD-AES without going for chemical processing/treatment like dilution or evaporation of matrix. 100% solutions of NH4OH and H2O2 chemicals produced stable ELCAD plasma, whereas 0.5% solution produced stable plasma for H2SO4. As standard addition calibration method to quantify impurities in these chemicals could not be useful, an alternative aqueous calibration method was examined and found to be suitable for their quantification by ELCAD-AES. As the certified reference materials for these chemicals were not available, the ELCAD-AES results were validated with the corresponding graphite furnace atomic absorption spectrometer (GF-AAS) results for NH4OH and H2O2 whereas for sulphuric acid they were validated with inductively coupled plasma optical emission spectrometer (ICP-OES) and supplier's results. ELCAD-AES method was free from matrix related problems and did not demand for the dilution of NH4OH and H2O2. The method was found to be useful for direct determination of trace and ultra trace metallic impurities in NH4OH and H2O2 pure chemicals and also for trace impurities in H2SO4 chemicals. Repeatability and accuracy of this method were found to be <10% and between 10 and 20% respectively. Thus ELCAD-AES could be an alternative analytical, rapid and direct analysis technique to check levels of metallic impurities (i.e. metal salts) and quality of these high purity chemicals for various industries.

Heat Transfer in Vacuum Pyrolysis of Decomposing Hazardous Plastic Wastes

Vacuum pyrolysis has been widely used to decompose plastic wastes for obtaining purity chemicals or remove hazardous organic pollutants. The pyrolysis temperature determined the variety of pyrolysis products. The final (highest) temperature was the most investigated factor. However, temperatures used in vacuum pyrolysis were not equally distributed. The lowest temperature also determined the variety of the products. Regrettably, this vital factor has not been researched and reported. In this paper, the heat transfer process of vacuum pyrolysis was fully analyzed. The models for computing the lowest temperature were constructed. The models were certified by the vacuum pyrolysis of novolac epoxy particles collected from crushed waste printed circuit boards. According to the models, we found the heat transfer coefficient of the crucible and the inner diameters of the crucible and alundum tube were the key factors for controlling the lowest temperature. The models can help us to modify and adjust the lowest a...

Impedance of Nickel and Platinum Anodic Dissolution in Anhydrous Hydrogen Fluoride

Liquid anhydrous hydrogen fluoride (aHF) is a widely used solvent for the anodic fluorination of organic and inorganic molecules, electrosynthesis of fluorine containing compounds and electrolytic generation of fluorine. Anhydrous hydrogen fluoride is also used on the industrial scale for the production of most fluorine compounds. In this research we intended to use aHF in electrosynthesis of divalent silver fluoride, AgIIF2, which is the most stable and commonly used divalent silver compound. Currently, the chemical methods of AgIIF2 synthesis involve several steps performed in aHF leading to the formation of a fine graded powders contaminated with amorphous impurities. Strongly aggressive nature and high toxicity of aHF makes this synthesis difficult and time consuming, however by using electrochemical methods one may reduce the number of necessary steps and complexity of the synthesis. It should be noted that in general electrosynthesis is inexpensive, safe and effective method of high purity chemicals preparation. Electrochemical methods usually lead also to the formation of more crystalline products as we have recently observed for silver(II) sulfate obtained in the form of compact crystallites with a few tens of micrometers in size [1]. Electrochemical studies in aHF are seldom reported, Hackerman et al. reported kinetic measurements of anodic dissolution of 24 different materials in aHF [2]. All investigated electrodes have undergone corrosion in aHF particularly during anodic polarization. To date no stable working electrode material has been reported for electrochemical studies in aHF. The most promising materials with the slowest anodic dissolution are platinum and nickel [2]. Here we report the mechanistic studies of platinum and nickel corrosion during anodic polarization in aHF carried out by using Electrochemical Impedance Spectroscopy (EIS). It should be noted that although this method is the most suitable for mechanistic studies it has not been previously reported for electrochemical processes in anhydrous HF. The stability of individual electrodes during anode polarization in aHF was determined. Based on the impedance analysis we report strong passivation of nickel electrode and we discuss the mechanism of platinum oxidation. Pt undergo anodic dissolution with the formation of adsorbed intermediates, furthermore the electrode processes are coupled with chemical reactions leading to the fluorine evolution. The electrosynthesis of AgIIF2 in aHF containing AgF was attempted and possible reaction mechanism will be also discussed. [1] P. Połczyński, T.E. Gilewski, J. Gawraczyński, M. Derzsi, P.J. Leszczyński, W. Gadomski, Z. Mazej, R. Jurczakowski, W. Grochala, Efficient Electrosynthesis of AgIISO4: A Powerful Oxidizer and Narrow Band Gap Semiconductor, European Journal of Inorganic Chemistry, 2016 (2016) 5401-5404. [2] N. Hackerman, E. Snavely, L. Fiel, The anodic polarization behaviour of metals in hydrogen fluoride, Corrosion Science, 7 (1967) 39-50.

P11. Dose verification for high-dose bulk industrial 60Co irradiators with chemical dosimeters and gafchromic media

Introduction Dosimetry and dose verification at bulk industrial irradiator facilities is subject to numerous challenges, most notably due to their high volume, high throughput design and operations. Industries such as the Sterile Insect Technique (SIT), a biological control practice for the management of insect pests of agricultural and medical or veterinary significance, rely on annually derived output factors to deliver sterilization doses to organisms within strict parameters. Routine dose verification should therefore constitute an integral part of the quality control system. Materials and methods Two distinct dosimeter types were employed in this study. Firstly a chemical solution, Fricke’s solution made up of 1 mM Fe(NH4)2(SO4)2, 0.8 N H 2 SO 4 , 1 mM NaCl high purity chemicals, decanted in 2 ml ampules, secondly enveloped 1 cm 2 EBT2 radiochromic media sections. Dosimeters were exposed in a reference 60Co field under charged particle equilibrium conditions to incremental doses up to 100 Gy. Dosimeter absorbance measurements were conducted with a diode array spectrophotometer, resolution of 1 nm, at 304 nm and 676 nm for the Fricke and EBT2 dosimeters respectively. Results Dosimeter absorbance unit (AU) readings for the Fricke (0.06–0.35) and EBT2 (0.05–1.36) dosimetry systems were recorded for the dose range 0–100 Gy. Linear dose response relationships were noted for both the Fricke (dose range 20–100 Gy, r 2 = 0.9992 ) and EBT2 (2–100 Gy, r 2 = 0.9868 ) dosimetry systems. The dose–response relationship of the Fricke dosimetry system ( 3.6 × 10 - 3 ± 2.42 × 10 - 5 ) is roughly one order of magnitude lower compared to the EBT2 ( 1.35 × 10 - 2 ± 3.67 × 10 - 4 ) system. Conclusion Both dosimetry systems prove to be reliable dose verification tools for bulk industrial irradiator applications. The Fricke dosimetry system, a primary dosimeter, remains the preferred dosimeter due to its superior linear dose response and higher dose range capabilities.

A Study on Degradation of Ni-YSZ Anode Materials in Terms of Redox Stability for Solid Oxide Fuel Cells

▪ Introduction Solid oxide fuel cells (SOFCs) have lately attracted considerable attention as the source of new energy considering environmental pollution and exhaustion of underground resources. Nickel-yttria stabilized zirconia (Ni-YSZ) cermet has been used as an anode material for SOFCs for more than 20 years. Although Ni-YSZ has various advantages such as high catalytic activity for H2 oxidation and methane reforming, stability in reducing atmosphere, high electrical conductivity, it exhibits various types of degradations such as poor redox stability, sulfur poisoning, carbon deposition. Ni-YSZ anode still suffers from exposure to oxidizing condition caused by sudden interruption of fuel or sealing problem like leakage. When exposed in oxidizing atmosphere, Ni-YSZ experiences significant volume change due to the oxidation of Ni to NiO, which causes internal cracks and consequent destruction of the cell. In this study, the redox stability of Ni-YSZ cermet according to various conditions such as porosity, pore size distribution, and composition has been studied systematically. ▪ Experimental NiO-YSZ composite powders have been prepared by mixing of commercial NiO (High purity chemicals, 99.97%), 8YSZ (TZ-8YS: 8 mol% Y2O3-stabilized ZrO2, 99.9% Tosoh, Japan) and PMMA as a pore former. The NiO-YSZ bulk samples were fabricated by the typical die compaction method and sintering at 1450 °C for 4 h in air. The sintered NiO-YSZ samples were reduced at 800 °C for 3 h in H2 in order to make Ni-YSZ. The phase change was confirmed by the X-ray diffraction (XRD). The morphology of Ni-YSZ was investigated by scanning electron microscopy (SEM). Degree of oxidation (D.o.O) of Ni was calculated from thermogravimetric analysis (TGA) data. The amount of volume change of Ni powders during oxidation was measured using a helium pycnometer. The both porosity and pore size distribution of Ni-YSZ bulk samples were analyzed with mercury porosimeter. The linear length change of Ni-YZ during oxidation was measured using dilatometer. ▪ Results and Discussion If we know both temperature and time of exposure in oxidizing atmosphere, we can predict the D.o.O of Ni at a certain condition using the D.o.O equation obtained from TGA data. The percentage weight gain per specific surface area can explain the oxidation kinetics of the Ni-YSZ anode supports, which obeys a multi-stage parabolic law expressed by Kp. Kp can be expressed by Kp1 and Kp2. Kp1 and Kp2 correspond to fast oxidation reaction at early oxidation stage and slow oxidation reaction at the next oxidation stage, respectively. The volume change of Ni-YSZ caused by oxidation can be the result of two competing factors: expansion caused by NiO formation and shrinkage caused by continuous sintering of both Ni and NiO. Ni-YSZ cermet with high porosity showed higher tolerance to the cumulative length change due to providing the more relaxation space.

PFA 라이닝 볼밸브의 헬륨누설 검출 및 비산배출에 관한 연구

A PFA lined ball valve, which is machined with fluorinated resin PFA to its inner part for improving corrosion resistance, non-stickness, heat-resistance, has been widely used to the chemical/pharmaceutical industries, the semiconductor/LCD manufacturing processes, etc. with the high purity chemicals as working fluid. EPA stated that 60% of all fugitive emissions come from the valve stem packing in a typical petroleum or chemical processing plant. They monitor regulated components for leaks and maintain seal performance at acceptable levels. Korean industrial standards only deals with the bubble test for in-line leakage of valves, which has the detectable leak rate of 10SUP-4/SUP [mbar·L·sSUP-1/SUP], therefore, it is not sufficient to check fugitive emissions. In this study, we conducted Helium leak detection from a PFA lined ball valve and evaluated fugitive emissions according to ISO 15848-1, which has the detectable leak rate of 10SUP-9/SUP [mbar·L·sSUP-1/SUP], for manufacturing the high-reliable PFA lined ball valves against fugitive emissions.

Development of BaO–ZnO–B2O3 glasses as a radiation shielding material

The effects of the BaO on the optical, physical and radiation shielding properties of the xBaO: 20ZnO: (80−x)B2O3, where x=5, 10, 15, 20 and 25mol%, were investigated. The glasses were developed by the conventional melt-quenching technique at 1400°C with high purity chemicals of H3BO3, ZnO, and BaSO4. The optical transparency of the glasses indicated that the glasses samples were high, as observed by visual inspections. The mass attenuation coefficients (µm), the effective atomic numbers (Zeff), and the effective electron densities (Ne) were increased with the increase of BaO concentrations, and the decrease of gamma-ray energy. The developed glass samples were investigated and compared with the shielding concretes and glasses in terms of half value layer (HVL). The overall results demonstrated that the developed glasses had good shielding properties, and highly practical potentials in the environmental friendly radiation shielding materials without an additional of Pb.

Synthesis, structural and dielectric properties of Magnesium calcium titanate (1-x)MgTiO3-xCaTiO3 (x=0, 0.1, 0.2 and 0.3)

Magnesium Titanate-based ceramics is one of the popular microwave dielectric materials. These are widely used as dielectrics in resonators and filters for communication, capacitors and radar systems operating at microwave frequencies. The pure and Calcium doped Magnesium Titanate ceramic materials are synthesised by conventional Solid-state route diffusion method. High purity chemicals of MgO, TiO2 and CaO which are taken in according to their compositions for the preparation of Mg1-xCaxTiO3 (x=0,0.1,0.2 and 0.3) ceramics. They are grounded well for 12h in a Ball Mill. Then the powders are calcined at 1175°C to 1200°C for 36h and are pressed into pellets. These pellets are sintered at 1270°C to 1300°C for 6h. The dielectric constant from room temperature to 350°C is calculated using HIOKI 3532-50 LCR HiTESTER in the frequency range of 100Hz-5MHz. The dielectric constant at room temperature at a frequency of 0.1KHz for pure Magnesium Titanate is found to be 14.13 and as the concentration of Calcium increases dielectric constant increases. The AC conductivity and Dielectric loss of the samples are measured. XRD studies revealed that the compound exhibits major phase of MgTiO3 with Hexagonal structure and space group 148: R-3.

High precision zinc isotopic measurements applied to mouse organs.

We present a procedure to measure with high precision zinc isotope ratios in mouse organs. Zinc is composed of 5 stable isotopes ((64)Zn, (66)Zn, (67)Zn, (68)Zn and (70)Zn) which are naturally fractionated between mouse organs. We first show how to dissolve the different organs in order to free the Zn atoms; this step is realized by a mixture of HNO3 and H2O2. We then purify the zinc atoms from all the other elements, in particular from isobaric interferences (e.g., Ni), by anion-exchange chromatography in a dilute HBr/HNO3 medium. These first two steps are performed in a clean laboratory using high purity chemicals. Finally, the isotope ratios are measured by using a multi-collector inductively-coupled-plasma mass-spectrometer, in low resolution. The samples are injected using a spray chamber and the isotopic fractionation induced by the mass-spectrometer is corrected by comparing the ratio of the samples to the ratio of a standard (standard bracketing technique).This full typicalprocedure produces an isotope ratio with a 50 ppm (2 s.d.) reproducibility.

We manufacture high purity chemicals and deliver them globally.

We manufacture high purity chemicals and deliver them globally.

E. coli-derived carbon with nitrogen and phosphorus dual functionalities for oxygen reduction reaction

Nitrogen and phosphorus dual doped carbon materials have shown competing catalytic activity as metal-free catalysts for oxygen reduction reaction (ORR). Prevailing methods to synthesize such carbon catalysts require high purity chemicals and gases, excessive amount of strong acids and bases, or costly organic precursors. Here, we show that Escherichia coli (E. coli), a common bacterium, can be used as a novel precursor to synthesize heterogeneous carbon materials with nitrogen and phosphorus dual functionalities by direct carbonization. The E. coli derived carbon has a large surface area up to 636m2/g, and is comprised of up to 7.64at% nitrogen and 8.53at% phosphorus. The carbon material obtained at an optimum carbonization condition of 1000°C for 2h shows excellent catalytic performances, comparable to that of a 20wt% Pt-C catalyst, with ∼50% higher limiting current density, for ORR in near four-electron transfer processes and excellent durability. The outstanding electrocatalytic performances are credited to the fine tuning of nitrogen species by carbonization conditions and the synergy between nitrogen and phosphorus dual functionalities. Our work demonstrates the great potential of using bacterial cells as a novel green precursor to synthesize heterogeneous carbon materials with nitrogen and phosphorus dual functionalities as electrocatalytic catalysts for ORR.

We manufacture high purity chemicals and deliver them globally.

We manufacture high purity chemicals and deliver them globally.