14.31 % Power Conversion Efficiency of Sn-Based Perovskite Solar Cells via Efficient Reduction of Sn4+

The photoelectric properties of nontoxic Sn-based perovskite make it a promising alternative to toxic Pb-based perovskite. It has superior photovoltaic performance in comparison to other Pb-free counterparts. The facile oxidation of Sn²⁺ to Sn⁴⁺ presents a notable obstacle in the advancement of perovskite solar cells that utilize Sn, as it adversely affects their stability and performance. The study revealed the presence of a Sn⁴⁺ concentration on both the upper and lower surfaces of the perovskite layer. This discovery led to the adoption of a bi-interface optimization approach. A thin layer of Sn metal was inserted at the two surfaces of the perovskite layer. The implementation of this intervention yielded a significant decrease in the levels of Sn⁴⁺ and trap densities. The power conversion efficiency of the device was achieved at 14.31 % through the optimization of carrier transportation. The device exhibited operational and long-term stability.     

Local structure of magnesium in silicate glasses: a 25Mg 3QMAS NMR study

We have reported the 25Mg triple-quantum magic-angle spinning (3QMAS) NMR spectra of silicate glasses. The two-dimensional spectra suggest that the magnesium ions in MgSiO3, CaMgSi2O6, Ca2MgSi2O7, Mg3Al2Si3O12, and Li2MgSi2O6 glasses are mainly in octahedral environments, although in Na2MgSi2O6, K2MgSi2O6, and K2MgSi5O12 glasses they form tetrahedral species. We discussed the coordination environments of Mg based on the field strength of competing Mg2+, Ca2+, Na+, K+, and Li+ cations, and convincingly demonstrated that there is a correlation between them. These results indicate that the two-dimensional NMR spectroscopy such as MQMAS technique is a very useful method to analyze the local environments of nonframework cations in noncrystalline solids.     

Gold nanoparticle/charged silsesquioxane films immobilized onto Al/SiO2 surface applied on the electrooxidation of nitrite

In this work, gold nanoparticles lower than 10?nm were prepared in an aqueous medium using two charged silsesquioxanes, the propylpyridinium chloride and propyl-1-azonia-4-azabicyclo[2.2.2]octane chloride, as stabilizer agents which revealed to be water-soluble. This stabilization method is innovative allowing thin films containing gold nanoparticles to be obtained, and it was used for the first time in the preparation of carbon paste electrodes (CPEs). The charged silsesquioxanes were characterized by liquid ¹³C NMR. The gold nanoparticle/silsesquioxane systems were characterized by ultraviolet–visible spectroscopy (UV–Vis) and transmission electron microscopy. In sequence, they were immobilized on silica matrix coated with aluminum oxide. The resulting solid materials designated as Au-Py/AlSi and Au-Db/AlSi were characterized by infrared spectroscopy and N₂ adsorption/desorption isotherms. The results showed that the gold nanoparticle/silsesquioxane systems are strongly adhered to the surface-forming thin films. The Au-Py/AlSi and Au-Db/AlSi materials were used to prepare CPEs for the electrooxidation of nitrite (NO ₂ ^? ) using cyclic voltammetry and differential pulse voltammetry. The Au-Py/AlSi and Au-Db/AlSi CPEs showed high sensitivity and detection limits of 71.87 and 53.66?μA?mmol^–1?L and 1.3 and 3.0?μmol?L^–1, respectively.     

Gold nanoparticles on a thiol-functionalized silica network for ascorbic acid electrochemical detection in presence of dopamine and uric acid

A simple preparation methodology able to stabilize gold nanoparticles and to obtain an electrode which detects ascorbic acid, uric acid, and dopamine by different techniques is presented. A 3-mercaptopropyl-functionalized silica network was synthesized using the sol–gel method. Gold nanoparticles (nAu) were immobilized on the material at synthesis by adding a sol of these previously prepared particles to the reaction mixture. The electrochemical behavior of the SiO₂/MPTS/Au carbon paste electrode was studied using cyclic voltammetry in the presence of a hexacyanoferrate probe molecule. The presence of nAu in the functionalized silica network changes the electrochemical characteristics of the material, favoring the electron transfer process of this complex ion. The SiO₂/MPTS/Au electrode was proven to be an efficient tool in the simultaneous determination of ascorbic acid (H₂AA), dopamine (DA), and uric acid (UA) using square wave voltammetry techniques. With the nAu on the electrode, an increase in the peak current related to the redox process of the H₂AA, DA, and UA was observed. The separations of the anodic peak potentials between DA/H₂AA and UA/H₂AA were 310 and 442?mV, respectively. The results obtained show that the SiO₂/MPTS/Au electrode can be used in the simultaneous determination of H₂AA, DA, and UA.     

Percolative proton conductivity of sol-gel derived amorphous aluminosilicate thin films

The finite size effect of proton conductivity of amorphous aluminosilicate thin films, a-Al(n)Si(1-n)O(x) (n = 0.07, 0.1, 0.2, 0.3 and 0.45), prepared by a sol-gel process was investigated by experimental and numerical techniques. High-resolution TEM clarified that a-Al(n)Si(1-n)O(x) films had the heterogeneous nanoscale microstructures comprised of the ion-conducting, condensed glass microdomain and the poor-conductive, uncondensed glass microdomain. σ of the films with n≤0.1 exponentially increased upon decreasing thickness in the sub-100 nm range because the volume fraction of conductive domains was less than the percolation threshold and cluster size scaling of the conductive domain was operative. The numerical simulation suggested that conductance of the condensed domain was higher than that of the uncondensed domain by 2 orders of magnitude. Volume fractions of the condensed domain increased with increasing Al/Si molar ratio and were over the percolation threshold (24.5%) with n≥0.2. However, conductance of the condensed domain decreased with increasing Al/Si ratio with n≥0.2 because the aluminosilicate glass framework made of 4-fold-connected MO(4) tetrahedra was deformed by forming the octahedral AlO(6) moieties, as checked by Al K-edge XAS. It was found that the optimal Al/Si composition in terms of the conductance of the condensed domain is not in coincidence with that in terms of the average conductivity of the films.     

Electrochemical Design of Mesoporous Pt–Ru Alloy Films with Various Compositions toward Superior Electrocatalytic Performance

Mesoporous Pt–Ru alloy films with various compositions were synthesized by electrochemical plating in an aqueous surfactant solution. After the removal of surfactants, continuous mesoporous Pt–Ru alloy films possessing uniform mesopores with diameter about 7 nm were obtained. The Ru content in the films could be controlled from 0 to 13 at % by changing the precursor compositions. For all the films, the mesostructural periodicities and the mesopore sizes in the films were not changed. Due to the mesoporous structure and the doped Ru content, our mesoporous Pt–Ru films showed superior electrocatalytic activity for methanol oxidation reaction in comparison with the commercially available Pt catalyst.     

Hybridization of sugar alcohols into brucite interlayers via a melt intercalation process

We report the preparation of organic-brucite (BR) hybrids using harmless sugar alcohols (xylitol, XYL, and sorbitol, SOR). Since XYL and SOR are solid materials at room temperature, the hybridization was investigated by comparing two separate methods, hydrothermal treatment and melt mixing. BR-sugar alcohol hybrids were successfully prepared by a melt intercalation method at 175 °C. X-ray diffraction and Fourier transform infrared spectroscopy analyses indicated that organic molecules were intercalated into the brucite layers, overcoming the barrier of hydroxyl bonds between the BR layers. Moreover, X-ray photoelectron spectroscopy and thermal analyses showed that the intercalated materials at 175 °C resulted in the formation of covalent Mg-O-C bond linkages on the interlayer surface of BR.     

Synthesis of Olive‐Shaped Mesoporous Platinum Nanoparticles (MPNs) with a Hard‐Templating Method Using Mesoporous Silica (SBA‐15)

Well‐ordered mesoporous Pt nanoparticles (MPNs) with uniform olive shapes are synthesized by using two‐dimensional (2D) hexagonal mesoporous silica (SBA‐15) as a hard template. The average particle sizes are controllable in the range of 150 to 230 nm by changing the reduction time. Low‐angle XRD profiles for the obtained MPNs show three distinct peaks assignable to the (10), (11), and (20) planes of a highly ordered 2D hexagonal symmetry. From high‐magnification SEM images, periodically arranged Pt nanowires are observed clearly, which are a negative replica of the 2D hexagonally ordered mesoporous silica (SBA‐15). Furthermore, the single crystallinity of the Pt fcc structure coherently extends over the whole particles. As a result of such unique character as well as high surface area, the obtained MPNs show distinctly enhanced electrocatalytic properties for methanol oxidation reaction compared to other Pt samples, such as Pt black.     

DNA strand break: structural and electrostatic properties studied by molecular dynamics simulation

Due to their lethal consequences and a relatively high probability of introduction of repair errors and mutations, single and double strand breaks are among the most important and dangerous DNA lesions. However, the mechanisms of their recognition and repair processes are only poorly known at present. This work defines and analyzes a DNA with single strand break as a template study for future complex analyses of biologically serious double strand break damage and its enzymatic repair mechanisms. Besides a non-damaged DNA serving as a reference system with no surprising results, system with open valences of the atoms at the strand break ends as well as a system with filled valences were simulated. In both cases during the first few nanoseconds the broken ends of strand breaks are significantly exposed to the outside of the molecule. However, with increasing time, the system with single strand break with open valences is partially disrupted. On the contrary, the system with filled valences shows stable conformation with newly created hydrogen bond between the two strand break endings. Moreover, these endings are steadily situated in the inner part of the molecule, thus making the recognition and docking process of a repair enzyme more complicated in the case of filled valences.     

Crystal structure and physical properties of Fe1.5Pb5.5In10S22

A new compound, Fe2+(1.5)Pb2+(5.5)In3+(10)S2-(22), was found in the Fe-Pb-In-S system. The crystals had a shiny metallic gray luster and were obtained in a barlike shape. The melting and recrystallizing points are 1098 and 1090 K, respectively. The crystal structure determined by X-ray diffraction is P2/m, a = 14.558(1) A, b = 3.8556(3) A, c = 15.558(1) A, beta = 96.876(1) degrees , V = 867.0(1) A(3), Z = 1, Dc = 5.893 g/cm(3), and R1 = 3.78%, which is an isostructure with Sn(5.5)In(11)S(22). In the structure, lead atoms exist at three crystallographically independent sites, and one of them, Pb1, is occupied by a quarter of indium atoms. All of the Fe ions are randomly distributed at six indium sites. This compound is a semiconductor with a band gap, E(a) = 0.95 eV. The dominant magnetic interaction is antiferromagnetic, but magnetic orderings are not observed down to 2 K.