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A D–A conjugated polymer was used in fabrication of memory devices. However, devices using polymers as active layers alone do not lead to satisfactory results. In this paper, we have synthesized a donor–acceptor conjugated polymer by the Suzuki coupling reaction. The memory devices prepared by the polymer exhibit a ternary memory behavior. MoO3nanoparticles have a large number of oxygen vacancies on their surface that can act as charge traps. MoO3nanoparticles (NPs) are mixed with polymers to prepare memory devices for improved memory performance. The relationship between the mass percentage of MoO3NPs and the storage performance and mechanism of the storage device is studied. The first and second threshold voltages of the memory device are −0.5 and −0.75 V, respectively. A current ratio of 1:102.14:104.75for the “0″, “1”, and “2” resistance states of the device indicates a low probability of read/write errors. This work shows that polymer-embedded nanoparticle materials have practical application value in the field of next-generation nonvolatile memories.

Flexible metal–organic framework (MOF) compounds can exhibit very pronounced structural changes, which may be favorable for gas storage and gas separation applications. The noble gases xenon and krypton are increasingly important for both research and applications. Therefore, separation approaches with lower energy consumption are of great interest. In the present paper, the adsorption of pure xenon and krypton as well as their mixture by the flexible gate pressure MOFs is investigated using in situ high-pressure 129Xe NMR spectroscopy and volumetric gas adsorption in combination with density-functional theory (DFT) calculations. The chosen model MOF compound DUT-8(Ni) can be synthesized as a flexible or rigid structure by tuning the crystallite size. This allows us to discriminate possible effects exerted by the framework flexibility from influences of structure and composition.

Conjugated polymers composed of alternating electron donor and acceptor segments have come to dominate the materials being considered for organic photoelectrodes and solar cells, in large part because of their favorable near-infrared absorption. The prototypical electron-transporting push–pull polymer poly(NDI2OD-T2) (N2200) is one such material. While reasonably efficient organic solar cells can be fabricated with N2200 as the acceptor, it generally fails to contribute as much photocurrent from its absorption bands as the donor with which it is paired. Moreover, transient absorption studies have shown N2200 to have a consistently short excited-state lifetime (∼100 ps) that is dominated by a ground-state recovery. In this paper, we investigate whether these characteristics are intrinsic to the backbone structure of this polymer or if these are extrinsic effects from ubiquitous solution-phase and thin-film aggregates. We compare the solution-phase photophysics of N2200 with those of a pair of model compounds composed of alternating bithiophene (T2) donor and naphthalene diimide (NDI) acceptor units, NDI-T2-NDI and T2-NDI-T2, in a dilute solution. We find that the model compounds have even faster ground-state recovery dynamics (τ = 45, 27 ps) than the polymer (τ = 133 ps), despite remaining molecularly isolated in solution. In these molecules, as in the case of the N2200 polymer, the lowest excited state has a T2 to NDI charge-transfer (CT) character. Electronic-structure calculations indicate that the short lifetime of this state is due to fast nonradiative decay to the ground state (GS) promoted by strong CT–GS electronic coupling and strong electron-vibrational coupling with high-frequency (quantum) normal modes.

When density functional theory (DFT) is used for modeling polaron defects, the delocalized electronic states often appear due to self-interaction errors. Conventionally, the DFT + Umethod may possibly correct the self-interaction error and thus promote electron localization, but this does not always work. In this paper, based on the GGA + Uapproach, we have modeled small electron polarons by using bond distortion method (BDM) and occupation matrix control (OMC) method in TiO2. Both of these methods can control the position of the polaron at will. We evaluate the appropriate parameters for constructing stable polarons using the BDM. Meanwhile, the occupation of all orbitals of rutile and only low-energy orbitals of anatase was successfully realized using the OMC method. Calculation results show that the polarons constructed by the BDM are more stable irrespective of the crystal structure for TiO2. Furthermore, whichever method is used, the polarons formed in rutile are more stable. Electronic structure calculations demonstrate that rutile has a larger band gap after successful localization through BDM and OMC methods. On the contrary, the band gap of anatase decreases after localization because of the emergence of a new flat energy level at the Fermi level, generated mainly by localized Ti atoms. In order to better understand the polaron formation, we have studied charge transfer, bonding states, and electrostatic potential distributions around the polaron. In the localized solution, the Ti–O bonds around the polaron are all lengthened, while the stability and covalency of these bonds are reduced. The charge is strongly trapped in a potential well caused by lattice distortion, which leads to a lower electrostatic potential energy at the polaron position. In this work, polaron modeling methods and localized structure in TiO2contribute to a better understanding of the polaron structure and its related properties.

In this work, temperature dependent transient absorption spectroscopy measurements are presented on gallium-alloyed CdSe/ZnS core–shell nanoparticles between 30 and 130 °C. To our knowledge, temperature dependent measurements in these systems have been reported only in a few papers, although all processes related to carrier recombination are affected by temperature. For these experiments, gallium-alloyed CdSe/ZnS QD samples were used with nominal doping percentages of 2.5%, 7.5%, 15%. The experimental results show that the transient absorption decay is faster for the pristine CdSe/ZnS samples than in the gallium-alloyed samples at all temperatures. It is assumed that Ga-alloying promotes the formation of trions in the samples by introducing occupied impurity levels within the bandgap of CdSe. The resulting Coulomb blockade will, in turn, prolong the hot-electron relaxation process. By variation of the temperature, the distribution of charge carriers in the different recombination channels can be altered to accelerate recombination in the Ga-alloyed samples at higher temperatures. These measurements demonstrated their usefulness for observing the redistribution of charge carriers among different relaxation pathways.

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is one of the most popular hole transport materials for replacing traditional high-temperature boron diffusion technology due to its low cost and easy preparation. However, pristine PEDOT:PSS has drawbacks, such as poor work function (WF) and poor film quality, which inhibit the improvement of cell efficiency. According to current research reports, a single dopant can improve only one of these two drawbacks. In this paper, we used Nafion to simultaneously improve the WF and wettability of PEDOT:PSS for preparing novel PEDOT:PSS/n-Si hybrid heterojunction solar cells with a tunnel-oxide passivated contact (TOPCon) back surface field structure, which we call PEDOT:PSS-Nafion (PPN)/n-Si hybrid heterojunction TOPCon solar cell. A cell efficiency of 11.08% was achieved after optimizing the ratio of PEDOT:PSS and Nafion. The three easily improved parameters, namely, series resistance (RS), reflectivity, and WF, were studied and optimized through simulation, achieving a cell efficiency of 20.66%. To reduce RSin the experiment, the Triton X-100-doped PEDOT:PSS film (PPTX) was introduced between the n-Si and PPN films to form highly conductive PPN/PPTX double hole transport layers, and the cell efficiency was increased from 11.08 to 13.7%. The experimental and simulated work presented a new thought and practical guidance for realizing low-cost, easy preparation, and high-efficiency silicon-based solar cells.

A proper understanding of the physical properties at the interface between a nonmagnetic topological insulator and a magnetic film is an indispensable input to develop high-functional spintronics devices using topological insulators. In this paper, we show the physical properties of manganese(II) phthalocyanine (MnPc)-adsorbed Bi2Se3and TlBiSe2, two topological insulators with similar electronic states but different surface compositions. The adsorption of MnPc induces significant electron doping on Bi2Se3, while only a small hole doping was induced on TlBiSe2. This difference in doping is due to the different molecular orientations on the two topological insulators: the flat-lying configuration on Bi2Se3that leads to a large overlap between the d-orbital of Mn and orbitals of surface Se, and the upright configuration on TlBiSe2that results from the presence of Tl atoms on the surface and leads to a negligible orbital overlap. These results pave the way for applications in spintronics devices combining magnetic organic molecules and topological insulators.

Graphene functionalization has been widely used in improving the thermal transport of graphene/epoxy composites owing to its performance in enhancing thermal conductivity and facilitating the formation of graphene networks. However, the heat transfer law and mechanism between functionalized graphene remain unclear. In this paper, the effects of distribution, type, and coverage of functional groups on the graphene–graphene interfacial thermal resistance (ITR) are analyzed by nonequilibrium molecular dynamics simulations. The results demonstrate that the graphene–graphene ITR depends on the synthetic effect of the graphene–graphene interaction, graphene–functional group interaction, and interaction between functional groups. The heat transfer contributions of those three interactions vary with the relative positions between functional groups. Then, the potential distribution of graphene is evaluated to compare the effects of different types of functional groups. It indicates that the potential difference is mainly attributed to functional groups. Compared with methyl, amino, and fluorine groups, hydroxyl groups have the largest potential difference and interaction. As the coverage of functional groups increases, the ITR of methylated graphene, aminated graphene, and hydroxylated graphene decreases inversely, whereas that of fluorinated graphene increases first and then decreases inversely. This work provides practical importance for the design and application of functionalized graphene in composite materials.

Biosensors have been used for a remarkable array of applications, including infectious diseases, environmental monitoring, cancer diagnosis, food safety, and numerous others. In particular, the global COVID-19 pandemic has exposed a need for rapid tests, so the type of biosensor that has gained considerable interest recently is immunoassays, which are used for rapid diagnostics. The performance of paper-based lateral flow and dipstick immunoassays is influenced by the physical properties of the nanoparticles (NPs), NP–antibody conjugates, and paper substrate. Many materials innovations have enhanced diagnostics by increasing the sensitivity or enabling unique readouts. However, negative side effects can arise at the interface between the biological sample and biomolecules and the NP or paper substrate, such as nonspecific adsorption and protein denaturation. In this Perspective, we discuss the immunoassay components and highlight chemistry and materials innovations that can improve sensitivity. We also explore the range of biointerface issues that can present challenges for immunoassays.

This paper presents an electrochemical SERS (EC-SERS) and computational study of the common herbicide atrazine. Herein, we highlight that the atrazine molecule shows a clear potential-dependent SERS signal that manifests as two different adsorption orientations at the nanostructured silver surface. This finding is supported by computational work and indicates that the initial adsorption orientation is perpendicular to the surface with the C–Cl moiety pointed away from the surface, and upon stepping to negative applied voltages, the atrazine molecule rotates such that the C–Cl and isopropyl moieties are orientated more planar to the surface, while the molecule remains oriented perpendicular to the surface. To the best of our knowledge, this paper represents the first EC-SERS study of atrazine and paves the way for a rapid point-of-need detection tool for atrazine monitoring in the environment wherein an enhanced signal can be detected at negative applied voltages.

Surface-enhanced Raman spectroscopy (SERS) is a perspective nondestructive analytic technique enabling the detection of individual nanoobjects, even single molecules. In this paper, we have studied the morphology of Ga islands deposited on chemical vapor deposition graphene by ultrahigh vacuum evaporation and local optical response of this system by the correlative Raman imaging and scanning electron microscopy (RISE). Contrary to the previous papers, where only an integral Raman response from the whole ununiformed Ga nanoparticles (NPs) ensembles on graphene was investigated, the RISE technique has enabled us to detect graphene Raman peaks enhanced by single Ga islands and particularly to correlate the Raman signal with the shape and size of these single particles. In this way and by a support of numerical simulations, we have proved a plasmonic nature of the Raman signal enhancement related to localized surface plasmon resonances. It has been found that this enhancement is island-size-dependent and shows a maximum for medium-sized Ga islands. A reasonable agreement between the simulations of the plasmon enhancement of electric fields in the vicinity of Ga islands and the experimental intensities of corresponding Raman peaks proved the plasmonic origin of the observed effect known as SERS.

In this paper, conductivity and magnetism in alternant hydrocarbons are discussed based on the topology of π-conjugated networks. In a molecular system with two spin centers, when the spins are separated by an odd-length walk, they interact antiferromagnetically with each other, but when they are separated by an even-length walk, they interact ferromagnetically. The conduction through the pathway connecting the two spins is expected to be effective for the former case, while ineffective for the latter case, but both show almost the same conductance in a magnetic system. This is because in the latter case, a feature in the electron transmission spectrum that causes destructive quantum interference is localized away from the Fermi level of the electrode and in a very narrow energy range, not affecting the zero-bias conductance. This tendency is further accentuated by generating weak coupling between the electrode surfaces and the spins to preserve the radical character of the molecule sandwiched between two electrodes. Although there is a challenge on how to stabilize radical molecules in a confined environment between electrodes, what is presented in this paper would give a clue on how to construct a system where magnetism and conductivity coexist.

This paper presents the synthesis and characterization of cobalt bismuth oxide (CBO) nanosheets with high surface area through a one-step low-temperature solvothermal method. The nanosheets were investigated for their photocatalytic ability for organic pollutant removal. High-resolution transmission electron microscopy and N2adsorption–desorption showed that the interconnected nanosheet morphology of CBO has a high surface area of 177 m2g–1. CBO-4 exhibited excellent photocatalytic performance for the degradation of the model organic pollutant tetracycline, with a degradation efficiency of 66.28% in the presence of H2O2. The proposed tetracycline degradation mechanism involved hydroxylation, demethylation, and ring-opening reactions. Furthermore, the CBO-4 catalyst showed good stability over five consecutive cycles. This study presents CBO-4 as a promising catalyst for photocatalytic organic pollutant removal, offering potential applications in environmental remediation.

The addition of a lateral alkyl chain is a well-known strategy to reduce π-stacked ensembles of molecules in solution, with the intention to minimize the interactions between the molecules’ backbones. In this paper, we study whether this concept generalizes to single-molecule junctions by using a combination of mechanically controllable break junction (MCBJ) measurements and clustering-based data analysis with two small series of model compounds decorated with various bulky groups. The systematic study suggests that introducing alkyl side chains also favors the formation of electrode-molecule configurations that are not observed in their absence, thereby inducing broadening of the conductance peak in the one-dimensional histograms. Thus, the introduction of alkyl chains in aromatic compounds for molecular electronics must be carefully designed and optimized for the specific purpose, balancing between increased solubility and the possibility of additional junction configurations.

Atom-substituting doping by atmospheric-pressure chemical vapor deposition (AP-CVD) is an effective and promising strategy for changing the properties of two-dimensional transition-metal dichalcogenides (2D TMDs). In this paper, we successfully grew V-doped MoSe2films. The photoluminescence (PL) spectra gradually red-shifted with the increase of the doping concentration, the X-ray photoelectron spectroscopy (XPS) after doping shifted toward a lower binding energy, and the change of polarity before and after doping can be seen in the transfer characteristic curves of back-gated field-effect transistors (FETs) based on V-doped and undoped MoSe2films and proves that the V atom successfully replaces the Mo atom and acts as a p-type dopant, which greatly improves the properties of back-gated FETs based on 2D V-doped MoSe2. The hole mobility of the doped samples can reach 111.34 cm2V–1s–1, the Ion/Ioffratio of the hole branch can reach 107, and the detector has a fast response time of 2.3 ms. The results show that the band gap, polarity, optical properties, and electrical properties of 2D MoSe2can be effectively adjusted by changing the V concentration, which provide a feasible way for 2D materials to realize high-performance scalable microelectronic devices and also provide new opportunities for 2D materials in electronic or optoelectronic applications.

There is a significant lack of literature addressing changes in the microstructure of different interfacial metal layer combinations employed in fabricating electrochemical sensors based on carbon nanomaterials. This research gap extends to analyzing their influence on the electrochemical performance, which, in turn, impacts the understanding of the properties of materials incorporating these layers. In this study, microstructural variations and electrochemical activity of chromium and titanium adhesion layers, in combination with nickel catalyst layers (designated as TiNi and CrNi), on silicon wafers were analyzed post annealing. Interestingly, during a brief annealing period of 5 min, TiNi developed a surface layer comprising graphitic carbon, alongside the formation of TiO2, TiC, and NiSi, and exhibited electrochemical activity toward both dopamine (DA) and ascorbic acid (AA). Conversely, CrNi annealed for 5 min did not show the presence of such a carbon layer and displayed no discernible electrochemical activity toward the target molecules. Only after an extended annealing time of 20 min, signs of a carbon layer appear on CrNi, displaying a moderate electrochemical activity toward DA and AA. The formation of a carbon layer on CrNi is delayed due to the presence of Ni near the surface, which disrupts the local equilibrium. Consequently, the formation of the Cr2O3barrier layer is delayed, which in turn permits carbon diffusion into the underlying Cr layer. Conversely, Ni stabilizes the β-Ti form and markedly decreases the solubility of carbon and oxygen within the TiNi system. By providing a comprehensive analysis of microstructural changes and their impact on the surface chemistry and electrochemical responses of commonly used interfacial metal layers, this paper offers invaluable insights in selecting suitable adhesion and catalyst layer combinations for carbon nanomaterial fabrication.

In this study, we explore the impact of halogen functionalization on the photophysical properties of the commonly used organic light-emitting diode (OLED) host material, 1,3-bis(N-carbazolyl)benzene (mCP). Derivatives with different numbers and types of halogen substituents on mCP were synthesized. By measuring steady-state and transient photoluminescence at 6 K, we study the impact of the type, number, and position of the halogens on the intersystem crossing and phosphorescence rates of the compounds. In particular, the functionalization of mCP with 5 bromine atoms results in a significant increase of the intersystem crossing rate by a factor of 300 to a value of (1.5 ± 0.1) × 1010s–1, and the phosphorescence rate increases by 2 orders of magnitude. We find that the singlet radiative decay rate is not significantly modified in any of the studied compounds. In the second part of the paper, we describe the influence of these compounds on the reverse intersystem crossing of the 7,10-bis(4-(diphenylamino)phenyl)-2,3-dicyanopyrazino-phenanthrene (TPA-DCPP), a TADF guest, via the external heavy atom effect. Their use results in an increase of the reverse intersystem crossing (RISC) rate from (8.1 ± 0.8) × 103s–1for mCP to (2.7 ± 0.1) × 104s–1for mCP with 5 bromine atoms. The effect is even more pronounced for the mCP analogue containing a single iodine atom, which gives a RISC rate of (3.3 ± 0.1) × 104s–1. Time-dependent DFT calculations reveal the importance of the use of long-range corrected functionals to predict the effect of halogenation on the optical properties of the mCP, and the relativistic approximation (ZORA) is used to provide insight into the strength of the spin–orbit coupling matrix element between the lowest-lying excited singlet and triplet states in the different mCP compounds.

In this study, we investigate LiMOF (oxyfluoride, M = Mn, Fe, Co, and Ni) via density functional theory calculations as potential electrode material candidates for Li-ion batteries. For the first time, we evaluate their structural, electrical, and electrochemical properties with various proven approaches. Moreover, we compare their properties with each other and with the most relatable in-demand Li electrode materials, e.g., LiCoO2. The structural stability of these materials is remarkable due to their 3D solid framework. We find that LiCoOF represents the highest electrical rate capability and conductivity as well as appropriate cell voltage among considered LiMOF materials. After that, LiFeOF demonstrates the appropriate properties; nonetheless, its high voltage may be its limitation. We also debate the pros and cons of other considered materials, i.e., LiNiOF and LiMnOF, which are also promising electrodes. This paper, using novel approaches for more accurate approximations, evaluates these novel materials’ properties as promising electrodes, paving the way for future studies.

Inorganic metal halide CsPbX3(X = Cl, Br, and I) perovskite quantum dots (QDs) are widely used in light-emitting diodes, photodetectors, and solar cells due to their excellent optoelectronic properties. Their disadvantage is poor environmental stability, which can be improved to some extent by dynamic bonding of conventional organic acid/amine ligands to the surface of QDs. Here, we adopt an internal and external synergistic strategy by first introducing 4-sulfamoylbenzoic acid (4-SABA) during the synthesis process, which effectively modifies the uncoordinated Pb2+and Br–vacancies on the surface of QDs. Second, a layered SiO2substrate was generated by (3-aminopropyl) triethoxysilane hydrolysis to encapsulate the QDs, which finally achieved the dual protection effect of surface passivation and inorganic coating of the QDs. Results showed that the as-prepared 4-SABA-CsPbBr3/SiO2composites had a higher photoluminescence quantum yield (96%) and far more stability to water and ethanol than the oleic acid-/oleylamine-passivated QDs. This paper provides an effective way to prepare QD solutions with not only low cost but also high efficiency.

The optical properties of metallic nanoparticles are dominated by localized surface plasmons (LSPs). Their properties depend on the constituting material, the size, and shape of the nano-object as well as its surrounding medium. In anisotropic structures, such as metallic nanorods, two families of modes generally exist, transverse and longitudinal. Their spectral and spatial overlaps usually impede their separate measurements in electron energy loss spectroscopy (EELS). In this work, we propose three different strategies to overcome this difficulty and selectively probe longitudinal and transverse modes. The first strategy is numeric and relies on morphing of nanostructures, rooted in the geometrical nature of LSPs. The two other strategies exploit the relativistic and wave nature of the electrons in an EELS experiment. The first one is the phase-matching between the electron and the plasmon excitation to enhance their coupling by either tilting the sample or modifying the electron kinetic energy. The second one─polarized EELS (pEELS)─exploits the wave nature of electrons to mimic selection rules analogous to the one existing in light spectroscopies. The abovementioned strategies are exemplified─either experimentally or numerically─on a canonical plasmonic toy model: the nanorod. The goal of the paper is to bring together the state-of-the-art concepts of EELS for plasmonics to tackle a pedestrian problem in this field.

The tailored design of bioactive materials based on cellulose or paper is still a challenging task. It requires detailed knowledge of the structure and interaction of the biofunctionalization with the carrier material at the nanoscale. In this work, the small peptide sequence Acetyl-Pro-Ala-Phe-Gly-OH (peptide 1) that can serve as a model for biofunctionalization is synthesized via solid-phase peptide synthesis, purified, and characterized by high-performance liquid chromatography (HPLC) and mass spectrometry (MS). The as-obtained peptide is bound to microcrystalline cellulose (MCC) via a wet chemical approach. Quantification of the peptide on the MCC carrier is performed by replacing l-proline (Pro) in the peptide sequence by 4-fluoro-l-proline (Pro(19F)) (peptide 2) and applying 19F magic angle spinning nuclear magnetic resonance (MAS NMR). Detailed characterization of the model system is provided by using 1H → 13C cross-polarization magic angle spinning (CP MAS NMR) combined with dynamic nuclear polarization (DNP) to enhance sensitivity. Analysis of the binding of the peptide on MCC necessitates the replacement of l-glycine (Gly) in the sequence by 13C-labeled l-glycine (Gly(13C)) (peptide 3). DNP-enhanced 13C–13C correlation experiments carried out with dipolar assisted rotational resonance (DARR) are then used to analyze the proximity between the model peptide and the MCC carrier. The strength of the dipolar coupling is estimated from the DNP-enhanced 1H → 13C CP MAS double-quantum rotational resonance (DQrotres) experiment. The obtained dipolar coupling between the 13C═O carbon of peptide 3 and the C6carbon of the cellulose is equal to a carbon–carbon distance of about two C–O bond lengths, which strongly suggests the binding of significant amounts of the peptide on MCC via an ester bond.

Organic–inorganic hybrid perovskites have demonstrated interesting infrared-to-visible up-conversion light-emitting properties from intrinsic excitons through multiphoton absorption. This paper reports a new approach to develop a broad two-photon up-conversion photoluminescence (PL) by using locally polarized heterostructure two-dimensional (2D) perovskites [(PEA2PbI4)1–x:(PEA2SnI4)x] prepared by mixing Pb and Sn perovskite precursor solutions (PEA2PbI4and PEA2SnI4). Under infrared 1030 nm laser excitation, a charge-transfer exciton relative broad PL is observed with the peak position located at 670 and 660 nm, respectively, when PEA2PbI4and PEA2SnI4are alternatively serving as host and guest components in 2D perovskite heterostructures [(PEA2PbI4)0.95:(PEA2SnI4)0.05] and [(PEA2SnI4)0.95:(PEA2PbI4)0.05]. The transient absorption (TA) studies show that two-photon excitation quickly generates the charge-transfer excitons within 0.42 ps and slowly develops into a broad bleaching signal in 33 ps and lasting up to nanoseconds, forming metastable states ready for up-conversion light emission under two-photon excitation. Therefore, the charge-transfer excitons can be used as an artificial ability to achieve up-conversion light emission. Furthermore, polarization-dependent up-conversion PL studies reveal that charge-transfer excitons experience the orbit–orbit interaction through polarization heterostructures to form locally polarized heterostructures toward developing broad two-photon up-conversion light emission in 2D perovskites. Clearly, the locally polarized heterostructures provide a new design to develop multiphoton up-conversion light emission by forming virtual states functioning as two-photon energy coupling-assisted centers, leading to a large cross-section area for multiphoton absorption in organic–inorganic hybrid perovskites toward thin-film sensing applications.

With the rapid development of renewable energy and semiconductor industries, the preparation of high-quality polysilicon has received more and more attention. Chemical vapor deposition (CVD) is one of the most important methods for high-quality polysilicon fabrication. In this paper, density-functional theory (DFT) is employed to investigate the effect of surface heteroatoms on the growth of polysilicon prepared by CVD. The dissociation activation energy of silane and the migration energy barrier of surface silicon atoms are calculated on three types of silicon (111) surfaces, including a clean silicon surface, a silicon surface with oxygen, and a silicon surface with hydrogen. The calculation results reveal that the activation energy of silane dissociation on the clean silicon surface is 1.71 eV, higher than 1.04 eV on oxidized silicon surfaces and similar to 1.74 eV on silicon surfaces with hydrogen. Therefore, on a partially oxidized silicon substrate silicon deposition would preferentially occur in the oxidized region. On a hydrogenated silicon substrate, silicon deposition would uniformly take place over the entire surface. Furthermore, surface migration barriers of silicon atoms are calculated, with values of 0.27 0.24, and 0.05 eV on clean, oxidized, and hydrogenated surfaces, respectively. The lower migration barriers on the hydrogenated substrate indicate more uniform silicon deposition. Subsequently, this finding is confirmed by experimental evidence. This study provides a theoretical basis for the preparation of high-quality polysilicon and serves as valuable operational guidance for industry-level production of uniform and dense polysilicon rods.

Nanorods have been widely applied in the electrochemistry field due to their excellent electrochemical properties. However, thermodynamic theory of nanorod electrodes still remains a blank, and the effect of the section diameter on the electrochemical thermodynamics of nanorod electrodes has not been clear. In this paper, theoretically, according to the thermodynamic definition of chemical potential, the expression of the surface chemical potential of nanorods was derived; then, the thermodynamic relations of the electrode potential, its temperature coefficient, reaction Gibbs energy, equilibrium constant, reaction enthalpy, reaction entropy, and reversible reaction heat of nanorod electrodes with the section diameter were derived based on the second law of thermodynamics; finally, the influencing regularities and mechanisms of the section diameter on these electrochemical quantities were discussed. Experimentally, the electrode reaction of rod-like nano-SnO2was taken as an example, the solvothermal method was applied to prepare SnO2nanorods with different section diameters, and a potentiometer was used to determine the electrode potentials of the nanorod electrodes. On this basis, we further obtained the standard electrode potentials and their temperature coefficients, reaction Gibbs energies, equilibrium constants, reaction enthalpies, reaction entropies, and reversible reaction heats of nanorod electrodes with different section diameters and discussed the influencing regularities of the section diameter on these electrochemical quantities. The experimental results are in agreement with the above theoretical relations. Both theoretical and experimental results show that the section diameter has a remarkable influence on electrochemical thermodynamics of nanorod electrodes. When the nanorods act as a reactant of an electrode reaction, with the decrease in section diameter, the standard electrode potential and the equilibrium constant of the electrode reaction increase, while the temperature coefficient of the standard electrode potential, the reaction Gibbs energy, the reaction entropy, the reaction enthalpy, and the reversible reaction heat decrease. When the nanorods act as a product of an electrode reaction, the effects of the section diameter on the electrochemical quantities are just reverse. Furthermore, when the section diameter exceeds 20 nm, the logarithm of the equilibrium constant and other electrochemical quantities are linearly related to the reciprocal of the section diameter. Besides, we also found that the additional electrode potential (i.e., surface electrode potential) of a nanorod electrode is exactly half that of the corresponding spherical nanoparticle electrode if the diameters are the same. The theory proposed in this paper can quantitatively describe the influencing regularities and mechanisms of the section diameter on electrochemical quantities of nanorod electrodes and can provide a foundation and guidance for the design, preparation, research, and applications of nanorod electrodes.

In this paper, we investigate the utilization of high-throughput virtual screening (HTVS) to identify and develop novel heat-resistant high explosives (HRHEs) that possess a decomposition temperature exceeding 300 °C and a detonation velocity surpassing 8000 m·s–1. To achieve this, we constructed a molecular library composed of pyrimidine as the parent ring and various five-membered heterocycles as guest rings connected by an amino bridge. The GFN-xTB method, an extended tight binding method, is employed to facilitate geometry optimization and vibrational analysis, thereby enabling the application of more precise and versatile quantum chemical calculation in the HTVS workflow. Our screening efforts resulted in the synthesis of three compounds that exhibited remarkable stability with decomposition temperatures exceeding 320 °C, suggesting their potential as HRHEs. Notably, compound K19-21demonstrated a decomposition temperature of 324.6 °C and a detonation velocity of 8293 m·s–1, surpassing both 2,2′,4,4′,6,6′-hexanitrostilbene (HNS) and 2,6-bis(picrylamino)-3,5-dinitropyridine (PYX) and rivaling l,3,5-triamino-2,4,6-trinitrobenzene (TATB). These results support the efficacy of our molecular library design concepts and screening workflow. Overall, our study underscores the importance and potential of HTVS in accelerating the discovery of new materials possessing the desired properties, especially in the field of energetic materials.

The integration of data science with graphene-based supercapacitors has emerged as a promising approach for optimizing their performance. Graphene-based electrodes exhibit unique pseudo-capacitive properties, but optimizing their supercapacitors requires balancing multiple variables, including electrode features, electrolyte composition, and operating conditions. This is because the pseudo-capacitive effect can create different charge-storage mechanisms via surface redox reactions during charging/discharging. In this paper, we discuss the use of statistical data analysis for gaining insights into the complex interplay between material properties and electrochemical performance. We shed more light on the analysis of large datasets generated from experiments of heteroatom-doped graphene supercapacitors using data preprocessing techniques, such as scattered interpolation–extrapolation and Pearson correlation, instead of traditional machine learning models. We investigate the effects of various electrochemical features on capacitive performance and the influence of heteroatom doping, such as nitrogen, sulfur, and oxygen. Our analysis provides valuable insights into the essential electrochemical features and heteroatom doping that relate to capacitive-boosting performance, serving as a guideline for accelerating the development of energy storage, particularly for graphene-based supercapacitors, in both experimental and machine learning aspects.

The inorganic nanoparticle growth within a polymer matrix is due to generation of the elementary species, the monomers, because of decomposition of the precursor compounds. The nucleation of the nanoparticles can be either homogeneous or heterogeneous. The model for heterogeneous nucleation and growth considered in this paper with some natural assumptions can explain experimentally observed exposure dependence of the UV-initiated CdS nanoparticle growth in poly(methyl methacrylate) (PMMA). The constraints on the values of the parameters imposed by the assumptions are discussed. Analytical solutions for the dynamics of the particle size distributions are obtained by reduction of the set of ordinary differential equations to the partial differential equation. The dependences of the particle size distributions on the parameters involved are found. This allows modeling the evolution of the optical absorption spectrum of the nanocomposite material due to nanoparticle growth.

Graphene-based materials are considered excellent candidates to implement cementitious nanocomposites due to their mechanical properties. This paper presents a comprehensive interface interaction that ends up with computing the elastic properties for four models of the C–S–H gel, taking tobermorite 14 Å as an example, with reduced graphene oxide (rGO) to form reinforced (tobermorite) cementitious nanocomposites within the density functional theory. We found that upon relaxing the model structures, the dissociation of hydroxyl functional groups from the hydroxyl/rGO lattice occurs not only in the presence of Ca2+ions to compensate for local charges but even when the Ca2+charges are compensated with hydroxyl groups. In contrast, rGO/CSH interactions remained close to the initial structural models of the epoxy rGO surface. The elastic constants showed high improvements for the cementitious nanocomposite of tobermorite 14 Å with intercalated hydroxyl/rGO layers. Thus, the bulk modulus, shear modulus, Young’s modulus, and Poisson’s ratio increased up to limits set as 165, 128, 134, and 15% compared to tobermorite 14 Å, respectively. In more detail, the specific values of the elastic constants were influenced by the interface, specifically the presence of hydroxyl or epoxy groups as well as how the charges of the Ca2+ions were compensated. These findings are of interest for the design of future experiments that will help to engineer better rGO/cement composites.

Using fixed atom force fields to model gas adsorption in flexible metal–organic frameworks (MOFs) is known to pose difficulties in accurately reproducing and predicting experimental results. This paper studies the difference in accuracy between flexible and fixed atom force fields in reproducing CO2adsorption measurements in MAF-2 ([Cu(etz)]∞ (MAF-2, Hetz) 3,5-diethyl-1,2,4-triazole), an NbO-type triazolate scaffold with a bcu cavity system and attached ethyl groups. The flexible force field used to run the hybrid molecular dynamics, and grand canonical Monte Carlo calculations were generated using QuickFF software incorporating van der Waals parameters from the universal force field (UFF) and density derived electrostatic and chemical (DDEC) charges. The fixed atom force field used was composed of UFF van der Waals parameters together with DDEC charges. The calculations were run at 298 K and pressures of 0.1, 0.3, 0.5, 0.8, and 1 bar. It was observed that for this MOF the rigid force field overpredicted gas adsorption, whereas the flexible force field values closely matched experimental data. In the flexible structure, the freely moving ethyl groups of MAF-2 hindered adsorption, reducing the interaction energy between CO2and the N atoms of the triazolate framework as well as reducing the size of the largest cavity diameter. The combination of these factors led to improved prediction of adsorption values with the flexible force field as compared to the rigid force field, demonstrating the need for modeling MOFs in a way more indicative of their behavior.

This paper reports on the electrooxidation process of C3 polyalcohols on a Ag roughened electrode decorated with Pt atoms in an alkaline medium. The electrochemical results showed that molecules with vicinal OH, such as glycerol and 1,2-propanediol (1,2-PPD), had higher electrochemical activity than 1,3-propanediol (1,3-PPD). In situ surface-enhanced Raman spectroscopy (SERS) was used to study the electrooxidation process, and it was found that the products of electrooxidation were mainly carboxylates, with selectivity toward lactate. The study highlights the potential of using an Ag&Pt electrode with low load (>1%) of Pt for the selective electrooxidation of C3 polyalcohols in an alkaline medium. The presence of Pt significantly improves the electrocatalytic activity of Ag, making the Ag&Pt electrode work in a tandem mechanism.

In this paper, we theoretically explore the physical mechanism of the fluorescent origin and chiral nature of Möbius carbon nanobelts. The electron–hole recombination is promoted by the electron–hole aggregation on the twisted moiety in the relaxation process of the excited state, which results in strong fluorescence. The chiral nature of Möbius carbon nanobelts is revealed by the interaction between the transition electric and the magnetic dipole moments, which causes the observed Cotton effects in the ECD spectra. Möbius strip molecules are inherently chiral as a result of their topology (i.e., generation of two non-superimposable mirror images due to topological restrictions in the conformational space). Our work promotes a deeper understanding of the relationship between the geometry and optical properties of Möbius strip materials at the nanoscale.

Polydiacetylenes have gained increasing attention as promising smart materials owing to their brilliant blue-to-red color transition in response to various microenvironmental perturbations. In this communication, we report a paper-based naked-eye colorimetric sensor array comprising 10, 12-tricosadiynoic acid (TCDA) and N-1-hexadecyl imidazole derivatives. Sensor arrays were prepared onto a filter paper using the suction technique, followed by UV irradiation. In this sensor system, the clay material hectorite was used as the host/support to enhance the mechanical stability of the paper-based sensor. Both the TCDA-clay and TCDA-clay-N-1-hexadecyl imidazole sensors were studied to sense 12 different volatile organic compounds (VOCs). Interestingly, the TCDA-clay sensor responded to 7 VOCs, whereas the TCDA-clay-N-1-hexadecyl imidazole sensor responded to all 12 VOCs. The presence of N-1-hexadecyl imidazole was advantageous with respect to response time, concentration, and the number of VOCs. Interestingly, the designed sensors also showed distinct response toward gasoline and the presence of kerosene in gasoline. Applications of the designed sensors toward the pollution level of car exhaust have also been demonstrated successfully.

Heterogeneous ice nucleation is an important process in environmental, biological, and atmospheric science. A variety of mineral, organic, and biological materials function as ice nucleating particles (INPs). A major aim of the current research is to determine exactly why and how ice nucleates on certain surfaces but not on others. The lattice match to ice and the atomistic surface morphology have both emerged as important factors, but how these factors interact, and which aspects play a vital role in ice nucleation, is not yet understood. This is the central question addressed in the present paper. We focus on four atmospherically relevant minerals: kaolinite, α-alumina, gibbsite, and hematite. These minerals are structurally similar, but the former pair are excellent INPs, while the latter pair are not. These four minerals provide an opportunity to systematically examine how details of lattice match and/or surface morphology favor or inhibit ice nucleation. We use molecular simulations to examine the interaction of a realistic water model with protonated (001) mineral surfaces. As expected from earlier simulations, ice nucleates via the basal plane for α-alumina, but via the primary prism face for kaolinite. Ice nucleation was not observed for gibbsite and hematite, consistent with experiment. To analyze water structure in the surface layers, we introduce a two-dimensional (2D) lattice perspective. Basal and prism face ice bilayers can be decomposed into two, 2D lattices (triangular for basal, rectangular for prism), and a surface must stabilize both 2D lattices of a bilayer to initiate ice nucleation. We define a 2D lattice mismatch parameter, which, unlike the conventional lattice mismatch criterion, is sensitive to the atomistic structure of a surface. Combining this approach with simulations involving scaled lattices, we clearly show how lattice match, and, more importantly, details of the surface morphology determine the wide range of ice nucleating activity displayed by the four minerals. We believe that the approach followed in this paper will contribute to the general understanding and prediction of ice nucleation (or lack thereof) by other surfaces. Ice nucleation by β-AgI and PbI2, and the absence of nucleation by the mineral boehmite are briefly discussed from a 2D lattice perspective.

Niobate perovskites like the (K,Na)NbO3(KNN) family are among the most important lead-free ferroelectrics. Ba and Ni have been co-doped into KNN to induce Ni2+-oxygen vacancy defect dipoles to significantly reduce the band gap while maintaining the ferroelectricity. This opens doors to novel optoferroelectric applications such as multisensors and photocatalysts. However, obtaining a single phase of the above co-doped KNN is difficult due to the sensitive stoichiometry on phase formation and arduous nickel diffusion into the KNN unit cells during synthesis. This paper reports an alternative approach to simultaneously tune the band gap and ferroelectricity. A-site vacancies are intentionally introduced into the mixtures of starting reactants. The homogeneously distributed vacancies trigger self-assembly of a niobate perovskite and niobate tungsten bronze phase and thus form a composite. The interface between the two phases, which mimics a heterojunction, rather than any individual phase, is proven to be responsible for the resultant narrow band gap and strong ferroelectricity. Hypotheses are proposed based on the results of ferroelectric, photoconductivity, and density functional theory-based studies to explain the mechanism. This paper offers an additional option to engineer polarizations and band structures in complex photoferroelectric oxides, especially alkaline niobates.

We investigated the in-plane (side) light scattering in plasmonic metasurfaces composed of periodic arrays of asymmetric L-shaped Au nanoantennas. We demonstrate that these metasurfaces can exhibit position-dependent in-plane chiral scattering, resulting in distinct responses to photon spins from each side of the arrays. Our results indicate that this phenomenon can be attributed to the formation of photon-spin-dependent lattice modes when these arrays interact with circularly polarized light. In the metasurfaces investigated in this paper, such photonic lattice modes form unique optical networks that coherently couple specific plasmon fields in each arm of the nanoantennas. The geometrical features of such networks are influenced by the polarization of the incident light, which, combined with the structure of the nanoantennas, dictate certain plasmonic near-field asymmetries. Under these conditions, the far-field scattering becomes highly sensitive to the spins of the incident photons, causing in-plane chiral scattering. Furthermore, we demonstrate that such metasurfaces enable polarization optical switching and directional wavelength multiplexing through the detection of in-plane scattering. These processes offer a high degree of control over the directions and spectral ranges of in-plane scattering using incident light polarization.

This paper is aimed at studying the effect of Li cations on the thermal stability of concentrated solid solutions of molecular hydrogen in the Li2O·6SiO2-0.39H2and Li2O·6SiO2-0.25H2compounds synthesized at pressures of 7.5 and 6.6 GPa and a temperature of 280 °C. The decomposition of the solutions was examined by Raman scattering under isothermal annealing at 21–70 °C and by hot hydrogen desorption into a pre-evacuated volume at 0–97 °C. The activation energies Ea= (0.419 ± 0.019) and (0.411 ± 0.06) eV/H2of hydrogen desorption from the near-surface layer of the samples with 0.39H2and 0.25H2, respectively, determined by Raman spectroscopy were higher than Ea= (0.16 ± 0.02) eV/H2previously determined for hydrogenated pure silica glass. This suggests the occurrence of a “Kubas” or similar interaction between the lithium cations and hydrogen molecules. The interaction leads to a large decay time constant of τ = 3220 s at room temperature compared to τ = 3 s for the hydrogen solutions in pure silica glass. The hot desorption showed that the diffusion activation energy was higher than 0.51 eV and also had a great impact on the stability of the hydrogen solutions in bulk lithium silicate glass, which additionally increased the decay time constants several times.

Light–matter interaction in subwavelength-scale optical confinement structures is a hot topic in basic science and the photonic industry. Materials experiencing high electric field strength can change their optical properties according to the intensity of light, as governed by the laws of nonlinear optics. In this paper, we investigate the linear and nonlinear optical behavior of cobalt phthalocyanine (CoPc) placed in the combined local fields of plasmonic and photonic cavity modes. Using polymeric layers, we created a planar microcavity and embedded the cavity layer with CoPc/Au nanocomposites. The enormous field strengths caused by the cavity photon–plasmon coupling significantly enhance the nonlinear optical absorption of the CoPc. The combination of photon–plasmon–exciton interactions in the hybrid microcavity results in an enhancement of the excited-state absorption of the system, even at low excitation intensities. The degree of light coupling can be altered by tuning the angle of light incidence, thereby varying the nonlinear transmittance of the microcavity structure. The proposed system can act as an angle-tunable nonlinear optical switch that works for laser pulses, with high attenuation at normal incidence and high transmittance at oblique incidence. Our findings provide a comprehensive understanding of the resonant light–matter interactions in tailored photonic crystal structures and how these interactions nonlinearly alter the optical properties, with potential for use in photonic applications.

The use of the Jonhson–Mehl–Avrami–Kolomogorov (JMAK) model has become prevalent in the kinetic analysis for Mg-based hydrogen storage alloys. However, the classical JMAK model has shown inadequate results in certain cases, resulting in poor fitness and/or inexplicably low Avrami exponent n. To address this issue, this paper proposes a new model based on the classic JMAK model. The new model considers the preferential growth of the hydride phase from the surface into the bulk, resulting in a diffusion barrier effect during the hydrogenation of Mg-based hydrogen storage alloys. A new parameter, surface diffusion barrier index b, is introduced to quantify the surface diffusion barrier effect. The governing equation is expressed as ln( – ln [1 – Y(t)]) = nln k+ nln t– bt. The modified JMAK model demonstrates improved fitting performance for the hydrogenation analysis in multiple Mg-based systems. Additionally, the relationship between diffusion barrier index band the reaction rate is discussed. The results suggest that the faster initial reaction rate leads to a stronger diffusion barrier, which inhibits the subsequent hydrogenation for the alloy.

In the present paper, we report the chemical vapor deposition of multiwall carbon nanotubes (MWCNTs) coating on stainless steel substrates and the coverage of the individual CNTs by a silicon (Si) thin layer. The study’s goal is to create and evaluate electrochemically Si/MWCNT composites with varying Si loadings to act both as a mechanical support and electrical conducting path to the current collector. MWCNTs incorporated efficiently into the Si layer on their surface and aided Si’s poor stability while maintaining its high-capacity values. The Si/MWCNT composite electrodes operated in a wide potential window of 1.7 V with improved Q/Vratios (charge to voltage) and retention over cycling compared to plain MWCNTs and Si electrodes, despite the similar surface area. In addition, the composite electrodes displayed a larger integration area in cyclic voltammograms, distinct charge/discharge plateaus, and wider discharge potential, indicating a higher energy storage capacity and high relative voltammetric charge retention. In particular, the Si/MWCNT electrodes demonstrated relative voltammetric charge retentions of 99.3% and 68% at 100 mV s–1and stable Q/Vratios of 231 and 209 mF cm–2at a current density of 2 mA cm–2with retention maintained at 100% after 30 cycles in ZnSO4and Al2(SO4)3aqueous electrolytes, respectively. Although the Q/Vratios may have distinct origins, we assumed that both electrolytes incorporate a mix of surface and bulk contributions. A combination of both ionic diffusion and pseudocapacitive behavior is displayed. Combined charge storage mechanisms are present at different electrode states, indicating the electrolyte ions’ adsorption (surface-controlled) and insertion (diffusion-controlled) in the active sites of the composites. The results suggested that the pseudocapacitive nature combined with the reversible diffusion of ions during redox reactions worked synergistically to increase contributions to the overall Q/Vratios. The storage of ions is facilitated by the small ionic radius of Al3+(0.53 Å) and Zn2+(0.75 Å) ions. Diffusion coefficient values of Al3+(4.58 × 10–11cm2s–1) are higher than those of Zn2+(3.16 × 10–11cm2s–1) during oxidation but lower at reduction processes (6.02 × 10–11and 7.1 × 10–11cm2s–1). As a result, the Al3+ions are less effective while extracted with reduced reversibility than Zn2+ions. Agglomerations of smaller ions stored in electrodes might confine the extraction process and possibly the overall stability over intense cycling. The faradaic performance on the one side coupled with the semi-infinite diffusion and pseudocapacitive behavior could offer a promising utilization as working electrodes in Zn2+and Al3+ion hybrid energy storage systems.

Low-energy field-emission scanning probe lithography (FE-SPL) is a benchtop technique that allows fabrication of sub-10 nanometer scale nanostructures in a photoresist transferable to the underlying silicon substrate. Understanding the mechanism of the interaction between low-energy electrons and organic molecule films in the FE-SPL process is crucial for advancing the lithographic resolution. In this paper, we investigated the fabricated patterns on ultrathin calixarene films by FE-SPL and revealed the formation of a silicon oxide layer at the organic molecule/silicon interface by means of nano Fourier transform infrared spectroscopy (nano-FTIR). Our results unraveled that the thin anti-etching layer ensures that the patterns are faithfully transferred into the silicon substrate in the following cryogenic plasma treatment. The evolution of silicon oxides as a function of exposure doses during FE-SPL process was systematically studied. The understanding of the underlying mechanism may assist the further design of molecular photoresists in FE-SPL and expand its application to advanced functional materials.

GaN is a widely used material for optical and power devices. However, the performance of GaN-based devices is often reduced by charge trapping processes due to defect levels in the band gap. In this paper, we studied a GaN-on-silicon sample via Kelvin probe force microscopy under variable illumination. This novel methodology allows the surface photovoltage (SPV) to be followed on the GaN surface as a function of time, light intensity, and topography with nanometric resolution. The measured SPV decay after turning off the light is too slow (on the order of seconds to days) to correspond to electron–hole recombination, suggesting that it is due to charge trapping. Two processes of opposite sign contributing to SPV generation and decay were observed, indicating two different charge trapping mechanisms. In this study, we propose a model that accounts for the observed SPV behavior at different measurement temperatures. Furthermore, the contribution to the electronic behavior of possible contamination surface states is discussed.

Iron carbides play a crucial role in many industrial fields, such as the steel industry, catalysis, carbon material production, and so on. One of the main challenges is that iron carbides are highly susceptible to being oxidized under service conditions, which can significantly reduce the performance and retard their industrial applications. However, the complex chemical structure of iron carbide materials and the dynamic nature of the Fe–C–O system under reactive conditions, such as the Fischer–Tropsch synthesis condition, hindered the understanding of the oxidation process. In this paper, structure evolution of the early-stage oxidation of χ-Fe5C2was investigated through reactive force field molecular dynamics simulations. The impacts of surface structure, oxygen coverage, temperature, and particle size were systemically explored. It was found that the oxidation rate was not only related to the surface carbon content but also to the homogeneity of the subsurface. Meanwhile, the dynamic structure transformation during oxidation was analyzed by various correlation functions. The mechanism of counter-direction migration of surface atoms during the oxidation process was illustrated, where carbon atoms migrate to the bulk region and iron atoms migrate to the surface. Our study reveals the atomistic dynamic mechanism of χ-Fe5C2oxidation, which offers crucial insights for catalyst oxidation and iron carbide materials.

The direct conversion of syngas to ethanol using CuZnAl catalysts is very challenging. In this paper, CuZnAl@S-1, CuZn@S-1, ZnAl@S-1, and CuAl@S-1 catalysts were prepared using a solid-phase method to prepare silicate-1 molecular sieves with Cu, Zn, and Al components encapsulated in them, and their catalytic performance for CO hydrogenation was evaluated in a fixed-bed reaction. The structural and surface properties of the catalysts were characterized using X-ray diffraction, transmission electron microscopy, N2physisorption, and X-ray photoelectron spectroscopy and correlated with the catalytic performance. The results showed that the use of structurally simple S-1 immobilized CuZnAI nanoparticles (CZA@S-1) was effective in enhancing the conversion of ethanol, where C2+OH/ROH up to 50.63% and ROH selectivity up to 27.27% were achieved, and no deactivation was observed within six days. The characterization results indicate that the interaction between CuZn in the CZA@S-1 catalysts is stronger than that between CuAl and ZnAl, that the CuZn active component is able to supply electrons to the molecular sieve, and that the core–shell structure promotes the adsorption and dissociation of CO and enhances C–C coupling. In situ diffuse reflectance infrared Fourier transform spectroscopy measurements of the reaction intermediates for each catalyst inferred a pathway for C–C coupling to ethanol, which provides an alternative pathway to the CuZnAl conventional catalyst.

This paper presents a holographic study of the phase transition that occurs in a nonequilibrium system. The chosen model is a unique Briggs–Rauscher oscillatory reaction that, first, follows a deterministic pattern (namely, an oscillatory behavior) and, later, exhibits a phase transition occurring randomly and without any known link with the previous deterministic state. The presented research opens up a new way to reveal complex chemical phenomena and dynamics in situ, without disturbing significantly the nonequilibrium system and its pathways. Simultaneously, it unfolds a new route for applications of interferometric methods in different areas of materials science. Under the applied conditions, we show that the holographic method is more sensitive to the phase transition dynamics than the commonly used potentiometric method.

In this paper, high-quality β-Ga2O3films were grown on silicon substrates by plasma-enhanced atomic layer deposition (PEALD). Effects of annealing temperature on β-Ga2O3thin films were studied. Atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray reflection (XRR), and ultraviolet (UV) emission spectroscopy were used to systematically characterize Ga2O3thin films. AFM test results showed that as annealing temperature increased from 500 to 900 °C, the roughness of film increased from 0.542 to 1.58 nm. XPS test results showed that the concentration of oxygen vacancies in annealed films was significantly reduced. After annealing, the energy band of the film increased from 4.73 to 5.01 eV, and the valence band maximum (VBM) increased from 2.58 to 2.67 eV, indicating that the annealing treatment under a nitrogen atmosphere can improve the quality of films. Results demonstrate that high-quality Ga2O3films can be obtained by the annealing process after atomic layer deposition (ALD). The proposed method can realize an ideal stoichiometric ratio of the Ga2O3thin film as well as precise control of its optical, electrical, and microstructural properties. This work lays the foundation for future application of Ga2O3materials in photoelectric detection, power devices, transparent electronics, and other fields.

At present, the wide commercial application of Li4Ti5O12(LTO) is limited as an anode for lithium-ion batteries because of its poor conductivity and lower rate performance. In this paper, LTO nanoparticles were embedded in a reduced graphene oxide (rGO) conductive network by an in situ electrostatic self-assembly effect using a simple hydrothermal reduction method. The microstructure and electrochemical performance of the LTO/rGO composite were investigated. The highlighted results showed that LTO nanoparticles were combined with rGO nanosheets by a Ti–O–C covalent bond, which was more stable than other bonding methods. At the same time, the addition of rGO not only enriches the structure and increases the specific surface area but also effectively prevents the agglomeration of LTO. The higher conductivity of LTO nanoparticles was bestowed by the rGO three-dimensional (3D) network, causing structural stability and high electrochemical performance. The LTO/rGO composite has high first discharge capacity (643.9 mAh/g at 0.5C), remarkable rate performance (290 mAh/g at 10C), and excellent cycle stability (271.7 mAh/g after the 1000th cycle at 10C) when tested in a half battery. Furthermore, it has higher discharge capacity (181.8 mAh/g at 1C, the first Coulombic efficiency was 90.1%) and excellent cycle stability (142.8 mAh/g after 500 cycles at 20C) when assembled into a full battery as the anode with commercial LiFePO4(LFP) as the cathode. The lithium storage mechanism of the LTO/graphene composite was further discussed by first-principles calculations. With the addition of graphene to LTO, the electron transport ability was improved and the diffusion energy barrier was reduced. This made the composite expected to become a promising anode material for lithium-ion batteries.

Area-selective deposition (ASD) is a technique to deposit material only on a defined area of a prepatterned surface, while no deposition occurs on adjacent surface areas. It is the subject of intense investigations by the scientific and engineering communities as it offers the prospect to simplify and improve patterning processes for fabrication of nanoelectronic devices as well as to reduce the manufacturing costs. Numerous efforts have been dedicated to identify process conditions for highly selective ASD processes. Still, the search for optimal conditions is often an empirical process due to the limited understanding of the mechanisms that take place at the atomic scale. Understanding the links between precursor reactivity, surface treatments, and the reactor operating conditions could greatly contribute to the development of highly selective ASD processes. In this paper, we therefore combine first-principles calculations with statistical thermodynamics to understand the role of the precursors in area-selective TiO2atomic layer deposition (ALD). First, we investigate the selectivity loss mechanisms for TiCl4/H2O ALD on SiO2nongrowth surfaces with different surface terminations (e.g., OH groups and trimethylsilyl groups). We link the resulting thermodynamic driving forces to experimental reports. Subsequently, we extend the investigation to a total of 26 commercially available titanium precursors and to three different oxygen sources and rank their potential for TiO2ASD for the SiO2surfaces with different surface terminations (OH groups and trimethylsilyl groups). We find that the combination of TiCl4with H2O offers the best performance in terms of selectivity. The theoretical approach proposed here is expected to greatly assist and accelerate the design of precursors for different ASD approaches.

Pyroelectric polarization is considered to be one of the effective ways to promote carrier separation and improve the capacity of PEC water splitting. In this paper, we prepared a BiOIO3catalyst by a one-pot hydrothermal method and investigated the growth process of BiOIO3, based on which HNO3and NaOH were used to cause BiOIO3to grow selectively along the (040) direction, and the regulation mechanism was analyzed so as to improve the pyroelectric polarization intensity of BiOIO3. Under the dual excitation of light and cold–hot cycles, the optimal thickness range of BiOIO3nanoplate (40–50 nm) exhibits the highest photocurrent density of 0.134 μA/cm2at 1.23 V compared with the reversible hydrogen electrode (RHE), which is 1.6 times higher than that of the nanosheet with a thickness of 20–30 nm. A series of experimental results show that the high performance is due to suitable thickness modulation which not only enhances the polarization intensity and thus reduces the chemical reaction barrier but also facilitates the charge separation and transfer. This study provides a different way of thinking for the development of the field of pyro-photo-electric catalysis on the basis of enhanced pyroelectric polarization.

Carbon nitride-based catalysts are nonmetallic materials with efficient photocatalysis for water splitting, degradation of organic dyes, and CO2reduction. In this paper, a one-step molten salt method was employed for the synthesis of ionic doped carbon nitride materials named CNs (carbon nitride catalysts), which exhibited excellent adsorption performance and photocatalytic activity. The adulteration of Zn2+ions created a unique nanosheet stack morphology, leading to more effective active sites and better electron transfer efficiency. Additionally, the degradation mechanism was investigated by the quasi-in situ NMR method. The reaction products and photocatalytic process were fully discussed, providing a new degradative pathway of methylene blue (MB) by such CN-based catalysts.

As a photocatalytic anode material, hematite (α-Fe2O3) is the most promising of the three iron oxides. The two other oxides are FeO, which is seldom available, and Fe3O4, which is found naturally in magnetite. There are both theoretical and experimental methods suggested for enhancing α-Fe2O3’s reactivity. First-principles calculations led to the design of two different doping concentrations of Al-doped α-Fe2O3(0001) structures and an Al2O3/Fe2O3heterostructure in the (0001) plane. A detailed investigation of the state density and stability, band structure, local potentials, charge densities, and Bader charge analysis is presented in this paper. A reduction in energy was observed with the Al-doping of an α-Fe2O3(0001) surface slab. The increase in doping concentration favors the formation of doped systems, and Al’s presence in α-Fe2O3(0001) is an energetically favorable process. The work function increases by increasing the Al concentration on the surface compared to a pure α-Fe2O3(0001) slab. Based on Bader charge analysis and charge density difference studies, it appears that chemical bonding becomes ionic in Al-doped regions. We additionally investigate Al2O3/Fe2O3interfaces by using first-principles calculations, aiming to shed light on their geometric structure and electronic properties. Al2O3/Fe2O3interfaces are more thermodynamically favorable. The results of these studies suggest that the Al2O3/Fe2O3heterojunction is a type-III broken-gap heterojunction rather than a staggered one. Additionally, oxygen evolution reaction (OER) electrocatalysts are discussed for Al-doped systems and the interface. As a result, the most favorable rate-limiting step in high-performance electrocatalysts relies on Al atom doping concentration to modulate the electronic and structural properties of Al-doped sites, while the concentration of active sites is increased and the OER rate is improved. Providing a basic understanding of the OER process at these interfaces, the discussion will be useful for exploring and developing better catalysts and device units.