Activated carbons with extremely high surface area produced from cones, bark and wood using the same procedure

Activated carbons have been previously produced from a huge variety of biomaterials often reporting advantages of using certain precursors. Here we used pine cones, spruce cones, larch cones and a pine bark/wood chip mixture to produce activated carbons in order to verify the influence of the precursor on properties of the final materials. The biochars were converted into activated carbons with extremely high BET surface area up to similar to 3500 m(2) g(-1) (among the highest reported) using identical carbonization and KOH activation procedures. The activated carbons produced from all precursors demonstrated similar specific surface area (SSA), pore size distribution and performance to electrodes in supercapacitors. Activated carbons produced from wood waste appeared to be also very similar to "activated graphene" prepared by the same KOH procedure. Hydrogen sorption of AC follows expected uptake vs. SSA trends and energy storage parameters of supercapacitor electrodes prepared from AC are very similar for all tested precursors. It can be concluded that the type of precursor (biomaterial or reduced graphene oxide) has smaller importance for producing high surface area activated carbons compared to details of carbonization and activation. Nearly all kinds of wood waste provided by the forest industry can possibly be converted into high quality AC suitable for preparation of electrode materials

The Water-Based Synthesis of Platinum Nanoparticles Using KrF Excimer Laser Ablation

Our work presents, for the first time, a comprehensive study of the synthesis of fully metallic platinum nanoparticles (Pt-NPs) involving the ablation process in double distilled water using a KrF excimer laser. To obtain detailed information on Pt-NP morphology and optical properties, prepared colloids were characterized using High Resolution Scanning Transmission Electron Microscopy (HR-STEM) with advanced capabilities for Energy Dispersive X-ray Analysis (EDX), UV/Vis optical spectroscopy, and Direct Analysis in Real Time—Mass Spectrometry (DART-MS). The influence of the applied laser fluence and laser repetition rate (RR) values on the characteristics of the obtained Pt-NPs and the ablation process, respectively, were also analyzed. Spherical and spherical-like nanoparticles exhibiting aggregation were produced. The Pt-NP mean size values were between 2.2 ± 1.2 nm and 4.0 ± 1.0 nm, while their interplanar distance measurements showed a face-centered cubic (FFC) Pt lattice (111), as revealed by HR–STEM measurements, for all investigated samples. The smallest mean size of 2.2 nm of the Pt-NPs was obtained using a 2.3 J cm−2 laser fluence at a 10 Hz RR, and the narrowest size distribution of the NPs was obtained with a 2.3 J cm−2 laser fluence at a 40 Hz RR. A linear dependence of the Pt-NP diameters versus the laser repetition rate was found at a constant fluence of 2.3 J cm−2. The proposed eco-friendly synthesis route of Pt-NPs, because of its relative simplicity, has the potential for use in industrial production

Pulsed Laser Ablation in Liquids for Fabrication of Noble Metal Nanostructures

Pulsed laser ablation in liquids (PLAL) is a physical method that is applied for the fabrication of noble metal nanostructures with different optical and morphological properties. The physical mechanism of laser ablation in liquid environment, the subsequent growth of nanostructures, the essential laser technological parameters that determine the nanostructures’ properties, and the liquid medium’s influence are discussed. The main advantages and disadvantages of the PLAL method are noted. Post-ablation treatment at optimal laser wavelength, fluence and duration of exposure has been indicated as a means of mitigating and overcoming the latter. The aging effect of the colloids and some applications of them are also marked. The most commonly used methods for studying the nanostructures’ characteristics such as UV/vis spectroscopy, high-resolution scanning transmission electron microscopy (HR-STEM), mass spectrometry (MS) and X-ray diffraction (XRD) are commented

Reduced Graphene Oxide Decorated with Dispersed Gold Nanoparticles: Preparation, Characterization and Electrochemical Evaluation for Oxygen Reduction Reaction

The commonly used electrode Pt supported on a carbon (Pt/C) catalyst has demonstrated underperforming electrochemical durability in proton exchange membrane fuel cell (PEMFC) harsh operation conditions, especially in terms of Pt electrochemical instability and carbon corrosion. Gold nanoparticles (AuNPs) are considered one of the best alternative catalysts of PtNPs due to their remarkable selectivity for oxygen reduction reaction (ORR) and electrochemical stability in strong acid conditions, attributes which are ideal for practical PEMFC applications. In this work, we propose a new, facile and low-cost approach to prepare AuNPs supported on reduced graphene oxide nanocompounds (AuNPs/rGO). The morphological and structural properties of the as-prepared AuNPs/rGO were studied using various microscopic and spectroscopic techniques, namely, Raman Spectroscopy, Scanning Electron Microscopy (SEM), Scanning Transmission Electron Microscopy (STEM), X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), specific surface area (Brunauer–Emmett–Teller, BET). A mesoporous structure with narrow pore size distribution centered at 2 nm approximately, where the pores are regular and interconnected was successfully fabricated. The prepared catalyst was exposed to an accelerated stress test (potential cycles between −0.8 and +0.2 in KOH 1 M solution). The voltammetric stability test indicated a slight degradation after 1500 cycles. The electrochemical stability was assigned to the combined effect of AuNPs formed during chemical synthesis and to graphene oxide support

Activated carbons with extremely high surface area produced from cones, bark and wood using the same procedure

Activated carbons have been previously produced from a huge variety of biomaterials often reporting advantages of using certain precursors. Here we used pine cones, spruce cones, larch cones and a pine bark/wood chip mixture to produce activated carbons in order to verify the influence of the precursor on properties of the final materials. The biochars were converted into activated carbons with extremely high BET surface area up to ∼3500 m2 g−1 (among the highest reported) using identical carbonization and KOH activation procedures. The activated carbons produced from all precursors demonstrated similar specific surface area (SSA), pore size distribution and performance to electrodes in supercapacitors. Activated carbons produced from wood waste appeared to be also very similar to “activated graphene” prepared by the same KOH procedure. Hydrogen sorption of AC follows expected uptake vs. SSA trends and energy storage parameters of supercapacitor electrodes prepared from AC are very similar for all tested precursors. It can be concluded that the type of precursor (biomaterial or reduced graphene oxide) has smaller importance for producing high surface area activated carbons compared to details of carbonization and activation. Nearly all kinds of wood waste provided by the forest industry can possibly be converted into high quality AC suitable for preparation of electrode materials

KrF excimer laser for Pt–NPs synthesis by PLAL in isopropanol solution and their use in a SERS application

Pulsed laser ablation in aqueous isopropanol (IPA) solution (PLAL) using KrF excimer laser was employed for the first time to produce platinum nanoparticles (Pt–NPs). The dependence of their optical and morphological properties on the IPA concentration and ablation time at certain values of the laser fluence (LF) and repetition rates (RR), was investigated. The UV/Vis transmission (T) spectra of the Pt–NPs were measured to assess indirectly their type, relative mean size (MS) and standard deviation (SD). Peculiarities of this spectra, related to the presence of a volatile component in the solution are discussed. Morphological properties as shape, MS, SD, and microstructure were studied via High-Resolution Scanning Transmission Electron Microscopy (HR-STEM). The created Pt–NPs show spherical shape with smallest MS value of 1.7 nm using 2.3 Jcm−2 LF, 10 Hz RR and 10 min ablation time in 80% aqueous IPA solution and the narrowest SD of ±0.7 nm with the same technological parameters but using 30% IPA concentration. The Pt nature of the NPs was confirmed by Energy Dispersive X-Ray technique. The crystallographic structure was determined by HR-STEM and X-ray diffraction measurements. An application of the synthesized Pt–NPs is presented using their role as substrate in methylene blue through surface-enhanced Raman spectroscopy method

The Water-Based Synthesis of Platinum Nanoparticles Using KrF Excimer Laser Ablation

Our work presents, for the first time, a comprehensive study of the synthesis of fully metallic platinum nanoparticles (Pt-NPs) involving the ablation process in double distilled water using a KrF excimer laser. To obtain detailed information on Pt-NP morphology and optical properties, prepared colloids were characterized using High Resolution Scanning Transmission Electron Microscopy (HR-STEM) with advanced capabilities for Energy Dispersive X-ray Analysis (EDX), UV/Vis optical spectroscopy, and Direct Analysis in Real Time—Mass Spectrometry (DART-MS). The influence of the applied laser fluence and laser repetition rate (RR) values on the characteristics of the obtained Pt-NPs and the ablation process, respectively, were also analyzed. Spherical and spherical-like nanoparticles exhibiting aggregation were produced. The Pt-NP mean size values were between 2.2 ± 1.2 nm and 4.0 ± 1.0 nm, while their interplanar distance measurements showed a face-centered cubic (FFC) Pt lattice (111), as revealed by HR–STEM measurements, for all investigated samples. The smallest mean size of 2.2 nm of the Pt-NPs was obtained using a 2.3 J cm−2 laser fluence at a 10 Hz RR, and the narrowest size distribution of the NPs was obtained with a 2.3 J cm−2 laser fluence at a 40 Hz RR. A linear dependence of the Pt-NP diameters versus the laser repetition rate was found at a constant fluence of 2.3 J cm−2. The proposed eco-friendly synthesis route of Pt-NPs, because of its relative simplicity, has the potential for use in industrial production

Rapid decline of kidney function in diabetic kidney disease is associated with high soluble Klotho levels

Background: Klotho is found in two forms: a transmembrane form and a soluble form (s-Klotho). In order to be excreted, s-Klotho, that is too large to be filtered, will probably reach the proximal convoluted tubule by a transcytosis process. The aim of our study was to show the relationship between the levels of s-Klotho and tubular injury in patients with diabetic kidney disease (DKD), using as tubular injury marker the kidney injury molecule-1 (KIM-1). Methods: Our study included 63 DKD patients (stages 1–5, mean eGFR 65.15 ± 32.45 ml/min) with a mean age 58.13 ± 12 years. In all patients we determined serum levels of: KIM-1 and s-Klotho using ELISA, urinary albumin/creatinine ratio (UACR) and reduction in the estimated glomerular filtration rate (eGFR) per year. Results: We found a strong statistically significant correlation of s-Klotho with the rate of reduction of eGFR/year (r = 0.714, p = 0.0004) and with the tubular injury marker KIM-1 (r = 0.758, p = 0.005) and strong correlations of UACR with the rate of reduction of eGFR/year (r = 0.53, p < 0.01), KIM-1 (r = 0.49, p < 0.05) and s-Klotho (r = 0.52, p < 0.01). Conclusion: Despite previous published data, that shows a decrease of s-Klotho in chronic kidney disease, in our study the rapid annual decline of kidney function but not the level of eGFR was associated with increased s-Klotho. A possible explanation could be a more severe proximal tubule injury that could lead to a reduction of tubular excretion of s-Klotho as suggested by the correlation of s-Klotho levels with the serum levels of KIM-1. Resumen: Antecedentes: Klotho se encuentra en el organismo en dos formas: una forma transmembranaria y una forma soluble (s-Klotho). Para excretarse s-Klotho, que es demasiado grande para ser filtrado, llegará en el túbulo contorneado proximal por un proceso de transcitosis. El objetivo del presente estudio es indicar la relación entre el nivel de s-Klotho y lesión tubular en los pacientes con la enfermedad renal diabética (DKD), utilizando como marcador de lesión tubular renal kidney injury molecule-1 (KIM-1). Métodos: Nuestro estudio incluye 63 pacientes con DKD (etapas 1-5, eGFR medio 65,15 +/− 32,45 ml/min) con una edad media de 58,13 +/− 12 años. En todos los pacientes hemos determinado el nivel sérico de: KIM-1 y s-Klotho utilizando el método ELISA, coeficiente albúmina/creatinina urinaria (UACR) y la reducción de la tasa de filtración glomerular estimada (eGFR) al año. Resultados: Hemos encontrado una correlación fuerte significativa desde el punto de vista estadístico de s-Klotho con una tasa de reducción de eGFR/año (r = 0,714, p = 0,0004) y con el marcador de lesión tubular KIM-1 (r = 0,758, p = 0,005) y una fuerte correlación de UACR con una tasa de reducción de eGFR/año (r = 0,53, p < 0,01), KIM-1 (r = 0,49, p < 0,05) y s-Klotho (r = 0,52, p < 0,01). Conclusiones: A pesar de los datos publicados anteriormente en la literatura, que demuestran una reducción de s-Klotho en la enfermedad crónica de riñones, en nuestro estudio, la disminución rápida anual de la función renal y no el nivel de eGFR se correlaciona con el crecimiento de s-Klotho. Una posible explicación podría ser una lesión tubular proximal más grave que podría llevar a la reducción de la excreción tubular de s-Klotho, sugerida por la correlación de s-Klotho con el nivel sérico de KIM-1. Keywords: s-Klotho, KIM-1, Tubular injury, Diabetic kidney disease, Palabras clave: s-Klotho, KIM-1, Lesión tubular, Enfermedad renal diabétic