Low-temperature Solution Synthesis Research Articles

Highly Efficient Broadband Near‐Infrared Emission in Cr3+‐Activated Organic Hafnium Chlorine for Multi‐Optoelectronic Applications

AbstractCr3+ ions doped broadband emission near‐infrared (NIR) phosphors are pertinent to widespread emerging applications and get rapid developed. However, it remains a challenge to simultaneously achieve highly efficient and broadband near‐infrared emission in Cr3+ ions doped phosphors. Herein, the Cr3+ ions firstly doped into organic–inorganic hafnium chlorine TEA2HfCl6 (TEA = Tetraethylammonium, C8H20N), which show broadband emission at a range of 700–1300 nm, a full width at half maximum (FWHM) of 164 nm, and a high photoluminescence quantum yield (PLQY) of 60%. The organic–inorganic metal halides show huge advantages than traditional inorganic phosphors, like high luminescence efficiency, low temperature solution synthesis progress, and low cost, which provide an efficiency strategy for lighting industry. Based on these advantages, a high power NIR light emitting diode (LED) is fabricated by TEA2HfCl6:Cr3+ with a high‐power 530 nm chip, which is used in food analysis, night vision, and biomedical imaging as a demonstration. This work indicates the feasibility of organic–inorganic metal halides as host materials for developing Cr3+ ions emitting phosphor toward multi‐optoelectronic applications.

Cu2O@Au-CsPbI3 heterostructures for plasmon hot carrier transfer enhanced optoelectronics

Plasmon hot carrier devices have tremendous potential applications in broadband photovoltaics, photodetection, photocatalysis, and intelligent optoelectronics, as they have the ability to generate hot carriers with energy lower than the optical bandgap at Schottky junctions and broaden the spectral range. However, this is mostly challenged by the lack of effective methods for the separation, migration, and extraction of plasmon hot carrier. In this work, a Cu2O@Au-CsPbI3 heterostructure was fabricated using facile low-temperature solution synthesis and spin-coating technique. The proposed heterostructure benefits from the simultaneous transfer of plasmon hot holes to Cu2O and hot electrons to CsPbI3, as well as enhanced charge separation driven by the built-in electric field at the p-n heterojunction interface. The heterostructure realizes remarkably enhanced light absorption, reduces carrier recombination, and further improves conversion efficiency. It exhibits a wide spectrum response of ultraviolet-visible-near infrared and achieves enhanced photodetection performance. The results suggest that Cu2O@Au-CsPbI3 heterostructure is a promising candidate for optoelectronic devices based on the harvesting of plasmonic hot carriers.

Black Phosphorus-Based ZnO-Ag Nanocomposite for Antibacterial Activity against Tigecycline-Resistant Acinetobacter baumannii

Acinetobacter baumannii is a critically hard-to-treat gram-negative pathogen responsible for a range of infectious diseases. Tigecycline is a last-resort antibiotic for A. baumannii infection; however, tigecycline-resistant (TIG-R) A. baumannii has been increasingly reported. Therefore, new strategies must be developed to treat these detrimental infections. Nanoantibiotics composed of two-dimensional (2D) black phosphorus (BP) and its derived nanocomposites have emerged as excellent alternatives to current antibiotics. However, the development of unique materials to target specific pathogens is challenging. Here, we report the preparation of a BP-based ZnO-Ag (ZPBA) nanocomposite. A low-temperature solution synthesis method was used to prepare ZnO and Ag nanoparticles immobilized on BP nanosheets. X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy were used to characterize the ZPBA nanocomposite. The antibacterial activity of ZPBA nanocomposite was assessed by determining its minimum inhibitory concentration against type (ATCC 19606, ATCC 15150) and TIG-R (ATCC 19606-R) A. baumannii strains. From the assays, ZPBA showed superior activity against TIG-R A. baumannii strain with MIC of 12.5 µg·mL−1 compared to all other prepared samples. Finally, the combination of bacterial membrane disruption and ROS generation was demonstrated to be a potential antibacterial mechanism of ZPBA. Our results show that ZPBA could be a potential nanoantibiotic platform for eradicating TIG-R A. baumannii.

Controlled Synthesis of Transition Metal Phosphide Nanoparticles to Establish Composition-Dependent Trends in Electrocatalytic Activity

Transition-metal phosphides (TMPs) are versatile materials with tunable electronic and structural properties that have led to exceptional catalytic performances for important energy applications. Identifying predictive relationships between the catalytic performance and key features such as the composition, morphology, and crystalline structure hinges on the ability to independently tune these variables within a TMP system. Here, we have developed a versatile, low-temperature solution synthesis route to alloyed nickel phosphide (Ni1.6M0.4P, where M = Co, Cu, Mo, Pd, Rh, or Ru) nanoparticles (NPs) that retains the structure of the parent Ni2P NPs, allowing investigation of compositional effects on activity without convoluting factors from differences in morphology and crystalline phase. As a measure of the controlled changes introduced within the isostructural series by the second metal, the binary and alloyed ternary TMP NPs supported on carbon at a nominal 5% weight loading were studied as electrocatalysts for the hydrogen evolution reaction (HER). The resultant activity of the electrocatalyst series spanned a 125 mV range in overpotential, and composition-dependent trends were investigated using density functional theory calculations on flat (0001) and corrugated (101̅0) Ni1.67M0.33P surfaces. Applying the adsorption free energy of atomic H (GH) as a descriptor for HER activity revealed a facet-dependent volcano-shaped correlation between the overpotential and GH, with the activity trend well represented by the corrugated (101̅0) surfaces on which metal–metal bridge sites are available for H adsorption but not the flat (0001) surfaces. The versatility of the rational synthetic methodology allows for the preparation of a wide range of compositionally diverse TMP NPs, enabling the investigation of critical composition–performance relationships for energy applications.

Black phosphorus-based CuS nanoplatform: Near-infrared-responsive and reactive oxygen species-generating agent against environmental bacterial pathogens

Over the last few years, the two-dimensional (2D) material black phosphorus (BP) has been highlighted for its potential in various biomedical applications, owing to its excellent physical and chemical properties. Nevertheless, the synergistic photothermal–antibacterial effects of BP when combined with other semiconducting materials against pathogenic bacteria have rarely been explored. In this study, the synergistic photothermal–antibacterial activity of a BP-based CuS (CB) nanoplatform against environmental bacterial pathogens was evaluated. A low-temperature solution synthesis method was utilized to prepare CuS nanoparticles that were immobilized onto BP nanosheets. The resulting CB nanocomposite was characterized using X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The antibacterial activity of the samples was evaluated by determining their minimum inhibitory concentration and bactericidal activity following near-infrared irradiation. The results revealed that CB nanocomposites showed higher antibacterial activity than other samples owing to the high photothermal conversion efficiency. In addition, the plausible antibacterial mechanisms, such as the formation of reactive oxygen species and bacterial membrane disruption, were evaluated. The prepared 2D semiconductor exhibiting synergistic photothermal–antibacterial activity will serve as a good nanoplatform against multidrug-resistant pathogens shed in the environment.

Lightwave irradiation-assisted low-temperature solution synthesis of indium-tin-oxide transparent conductive films

Transparent conductive oxide (TCO) films have important applications in many areas. Unfortunately, TCOs are usually fabricated using vacuum and high-temperature methods, preventing them from applications in low-cost flexible devices. In this paper, facile low-temperature sol-gel method is described that can be used to fabricate high-quality TCO films. This study uses lightwave (LW) irradiation (at ∼280 °C) with indium-tin-oxide (ITO) as a typical example. Both structure and key properties of ITO films are investigated for different LW irradiation conditions. ITO can be formed via LW irradiation after a period as short as 5 min. Furthermore, it is found that LW irradiation can promote the formation of M − O framework, effectively remove Cl impurities, and facilitate the elimination of hydroxyl oxygen defects - even at temperatures as low as ∼280 °C. The optimal ITO films show excellent electronic properties, including low sheet-resistance (14.5 Ω·sq−1) and high conductivity (1.7 × 103 S cm−1). Moreover, ITO films also show high transmittance (above 87%). Overall, our ITO films have a figure of merit (FOM) of 1.72 × 10−2 Ω−1, which is comparable to (or higher than) those of previous ITO films that were produced using conventional vacuum and high-temperature methods. Our LW irradiation method provides facile and effective approach to produce high-performance TCO films at remarkably low cost. This means these films could be used in affordable flexible large-area devices.

Au-ZnO Conjugated Black Phosphorus as a Near-Infrared Light-Triggering and Recurrence-Suppressing Nanoantibiotic Platform against Staphylococcus aureus.

Antibiotic therapy is the gold standard for bacterial infections treatment. However, the rapid increase in multidrug-resistant (MDR) bacterial infections and its recent use for secondary bacterial infections in many COVID-19 patients has considerably weakened its treatment efficacy. These shortcomings motivated researchers to develop new antibacterial materials, such as nanoparticle-based antibacterial platform with the ability to increase the chances of killing MDR strains and prevent their drug resistance. Herein, we report a new black phosphorus (BP)-based non-damaging near-infrared light-responsive platform conjugated with ZnO and Au nanoparticles as a synergistic antibacterial agent against Staphylococcus aureus species. First, BP nanosheets containing Au nanoparticles were assembled in situ with the ZnO nanoparticles prepared by a low-temperature solution synthesis method. Subsequently, the antibacterial activities of the resulting Au–ZnO–BP nanocomposite against the non-resistant, methicillin-resistant, and erythromycin-resistant S. aureus species were determined, after its photothermal efficacy was assessed. The synthesized nanocomposite exhibited excellent anti-S. aureus activity and good photothermal characteristics. The non-resistant S. aureus species did not produce drug-resistant bacteria after the treatment of multiple consecutive passages under the pressure of the proposed nanoantibiotic, but rapidly developed resistance to erythromycin. This work clearly demonstrates the excellent photothermal antibacterial properties of Au–ZnO–BP nanocomposite against the MDR S. aureus species.

Low-Temperature Solution Synthesis of Black Phosphorus from Red Phosphorus: Crystallization Mechanism and Lithium Ion Battery Applications.

As a thermodynamically stable semiconductor material, black phosphorus (BP) has potential application in the field of energy storage and conversion. The preparation of black phosphorus is still limited to the laboratory, which is far from adequate to meet the requirements of future industrial applications. Here, the gram-scale black phosphorus is synthesized in the ethylenediamine medium using a 120-200 °C low-temperature recyclable liquid phase method directly from red phosphorus. A crystallization mechanism from red to black phosphorus based on FTIR, XPS, and DFT calculations is proposed. Black phosphorus as the anode material for lithium ion batteries is superior in discharge specific capacity, rate capability, and cycling stability in comparison with red phosphorus. The facile low-temperature synthesis of BP by the ethylenediamine-assisted liquid phase process will facilitate the extended application of BP in the field of energy storage and conversion.

Low-temperature solution synthesis and characterization of enhanced titanium dioxide photocatalyst on tailored mesoporous γ-Al2O3 support

Abstract TiO2/γ-Al2O3 composite powder was prepared by the low-temperature hydrothermal synthesis in an alcohol solution without subsequent high-temperature calcination. When the as-prepared mesoporous γ-Al2O3 particles were added into the reaction solution, their surfaces with a negative potential were adsorbed by Ti(OH)4, forming mesoporous structure with the ink bottle type. These mesopores can absorb varisized organic molecules into their cavities, so that the mesoporous γ-Al2O3 is highly suitable for use as the adsorption and degradation material. Lots of oxygen defects formed during the synthesis process can hinder the recombination of the excited electrons and holes in TiO2. More free excited holes and electrons react with dissolved oxygen and water molecules in the solution to form the key functional groups of superoxide anion radicals (·O2−) and hydroxyl radicals (·OH), making the organic dye completely degrade to CO2 and H2O.

A nontoxic biocompatible nanocomposite comprising black phosphorus with Au-γ-Fe2O3 nanoparticles.

Black phosphorus (BP) has emerged as the latest 2D material within the post-graphene scenario, which can be used for various biomedical applications. In this study, we reported a promising nanocomposite material, which could be assembled with Au nanoparticles and γ-Fe2O3 nanoparticles on BP nanosheets (AIB), and studied its biocompatibility that promises to be useful for various biomedical applications. The synthesis of the Au–γ-Fe2O3 nanomaterial was attained through low-temperature solution synthesis and the exfoliation of BP nanosheets was performed through a liquid ultrasonication process. The individual components were then composited by ultrasonication and stirring. X-ray diffraction and transmission electron microscopic analyses confirmed the existence of Au and γ-Fe2O3 nanoparticles (NPs) assembled over BP nanosheets. Moreover, the surface chemical composition and valence state of the elements present in the AIB nanocomposite were evaluated with the help of an X-ray photoelectron spectroscopy study. The AIB nanocomposite exhibited excellent biocompatibility with HCT-15 cells after evaluating through WST assay. Therefore, the excellent biocompatible nature of this BP nanocomposite could be beneficial for various potential biomedical applications.

Magnetic and Electrocatalytic Properties of Nanoscale Cobalt Boride, Co3B.

The use of low-temperature solution synthesis followed by a brief annealing step allows metastable single-phase Co3B nanoparticles to be obtained, with sizes ranging from 11 to 22 nm. The particles are ferromagnetic with a saturation magnetization of 91 A m2 kg-1 (corresponding to 1.02 μB/Co) and a coercive field of 0.14 T at 5 K, retaining the semihard magnetic properties of bulk Co3B. They display a magnetic blocking temperature of 695 K and a Curie temperature near 710 K, but the measurement of these high-temperature properties was complicated by decomposition of the particles during heating in the magnetometer. Additionally, the nanoparticles of Co3B were investigated as an electrocatalyst in the oxygen evolution reaction and showed a low onset potential of 1.55 V vs RHE. XPS measurements were performed before and after the electrocatalytic measurements to study the surface of the catalyst, to pinpoint what appear to be the active surface species.

Effect of Ag2O on cell viability of ZnO nanoparticle synthesized by low temperature solution synthesis process

The synthesis, characterization and biomedical applications of mixed metal oxide is receiving increasing interest due to their property related specific applications.In this regard, ZnO and Ag2O have been applied for different biomedical applications individually but the effect of Ag2O on cell viability of ZnO has not been reported yet. The objective of this study is to see the effect of Ag2O nanoparticle on cell viability of ZnO nanoparticles synthesized by adopting a two-step low temperature solution process. X-ray diffraction study confirms the co-existence of ZnO and Ag2O phases. Transmittance electron microscopy has been used to characterize the morphological properties of the samples. X-ray photoelectron spectroscopic analysis also confirms the formation of ZnO-Ag2O nanocomposite. The in vitro cytotoxicity with the help of MTT assay (upto a maximum of 200 μg/mL) on HeLa cell line approves thatthe ZnO-Ag2O (ZSO) nanocomposite is more biocompatible than the individual ZnO and Ag2O nanoparticle. This nanocomposite ZSO can be used as a vehicle for drug delivery systems.

\u221260\u2009\xb0C solution synthesis of atomically dispersed cobalt electrocatalyst with superior performance

Temperature can govern morphologies, structures and properties of products from synthesis in solution. A reaction in solution at low temperature may result in different materials than at higher temperature due to thermodynamics and kinetics of nuclei formation. Here, we report a low-temperature solution synthesis of atomically dispersed cobalt in a catalyst with superior performance. By using a water/alcohol mixed solvent with low freezing point, liquid-phase reduction of a cobalt precursor with hydrazine hydrate is realized at −60 °C. A higher energy barrier and a sluggish nucleation rate are achieved to suppress nuclei formation; thus atomically dispersed cobalt is successfully obtained in a catalyst for oxygen reduction with electrochemical performance superior to that of a Pt/C catalyst. Furthermore, the atomically dispersed cobalt catalyst is applied in a microbial fuel cell to obtain a high maximum power density (2550 ± 60 mW m−2) and no current drop upon operation for 820 h.

Low-Temperature Synthesis and Magnetostructural Transition in Antiferromagnetic, Refractory Nanoparticles: Chromium Nitride, CrN

Nanostructured chromium nitride (CrN), both a hard material and a high-melting compound that is used in the medical industry and for new energy-harvesting applications, was synthesized phase-pure for the first time via low-temperature solution synthesis in liquid ammonia. TEM analysis confirms the nanoscale character of CrN. The antiferromagnetic properties of the agglomerates of nanoparticles are discussed in comparison to literature data on the bulk materials. SQUID and DSC measurements show the transition from paramagnetic to antiferromagnetic at 258.5 K. In situ low-temperature X-ray diffraction patterns confirm the magnetostructural phase transition at this temperature, not seen before for nanoscale CrN. This structural distortion was calculated earlier to be driven by magnetic stress. The bottom-up synthesis of CrN allows for the production of nearly oxygen- and carbon-free and highly dispersed fine particles.

Polyaniline coated graphene hybridized SnO2 nanocomposite: Low temperature solution synthesis, structural property and room temperature ammonia gas sensing

An inorganic-organic hybrid of SnO2-reduced graphene oxide (rGO)-polyaniline (SGP) nanocomposite has been successfully synthesized from surfactant-free precursor by a low temperature solution process. The SGP nanocomposite is found to form from in situ synthesized SnO2-rGO (SG) and polyaniline (PANI), generated via polymerization of aniline monomer at 5–10 °C. The structural properties of SGP have been analyzed by X-ray diffraction, transmission electron and atomic force microscopes. The chemical interaction existed in the nanocomposite has been examined by X-ray photoelectron, Fourier transform infrared and Raman spectroscopies. Compare to pristine SnO2 and SG, the SGP sample shows an enhanced ammonia gas sensing at room temperature. At an optimum content of PANI, high sensitivity, fast response and good selectivity of the gas sensing are observed in the nanocomposite. This enhanced sensing performance can be attributed to well-defined p-n hetero junction formation in the hybridized polyaniline and rGO with nano SnO2 in SGP as confirmed from structural characterization of the sample. It is also seen that the presence of PANI layers in SGP, enhances the chemical stability as reflected from the observation of negligible decrease in the sensing performance of sample up to 30 days period. This facile process can create an avenue for development of various metal oxide semiconductor-graphene-polyaniline nanocomposites for improving room temperature stable ammonia gas sensor.

Low temperature solution synthesis of silicon, germanium and Si-Ge axial heterostructures in nanorod and nanowire form.

Herein, we report the formation of silicon, germanium and more complex Si-SixGe1-x and Si-Ge axial 1D heterostructures, at low temperatures in solution. These nanorods/nanowires are grown using phenylated compounds of silicon and germanium as reagents, with precursor decomposition achieved at substantially reduced temperatures (200 °C for single crystal nanostructures and 300 °C for heterostructures), through the addition of a reducing agent. This low energy route for the production of these functional nanostructures as a wet chemical in high yield is attractive to meet the processing needs for next generation photovoltaics, batteries and electronics.

Low temperature solution synthesis of reduced two dimensional Ti3C2 MXenes with paramagnetic behaviour.

MXenes - two dimensional, 2D, early transition metal, M, carbides and nitrides, X - are the latest addition to the 2D materials' world. Herein, we report on a facile low temperature solution chemical synthesis method to reduce Ti3C2Tx multilayered, ML, MXenes. Using X-ray photoelectron spectroscopy, electron spin resonance, magnetization measurements and other techniques, we concluded that immersing Ti3C2Tx MLs in the reducing agent Li-ethylenediamine (Li-EDA) - held at temperatures varying from room to 120 °C - reduces the 2D layers creating Ti3+ ions and oxygen vacancies. Above a temperature (T) of ≈10 K, the magnetic susceptibilities, χ, are temperature independent, implying that the resulting powders are Pauli paramagnetic. The loss of the magnetic signal upon intercalation of Li+ or EDA, together with a Curie-like increase in χ at T < 10 K, is consistent with that of a disordered metal that is close to a metallic to insulator transition and proves that the magnetism is associated with the 2D flakes. This result is the first evidence of any magnetism of any MXene.

Raymond Schaak

Angewandte Chemie International EditionVolume 57, Issue 12 p. 3002-3002 Author ProfileFree Access Raymond Schaak First published: 24 November 2017 https://doi.org/10.1002/anie.201711024Citations: 2AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract “The downside of my job is having to sometimes be the bearer of bad news. My favorite food is anything I can cook on a grill, especially salmon ...” This and more about Raymond Schaak can be found on page 3002. Raymond Schaak The author presented on this page has published more than 10 articles in Angewandte Chemie in the last 10 years, most recently: “Size and Interface Modulated Metal–Insulator Transition in Solution-Synthesized Nanoscale VO2–TiO2–VO2 Heterostructures”: Angew. Chem. Int. Ed. 2017, 56, 15348; Angew. Chem. 2017, 129, 15550. The work of R. E. Schaak has been featured on the cover of Angewandte Chemie: “Sequential Anion and Cation Exchange Reactions for Complete Material Transformations of Nanoparticles with Morphological Retention”: J. M. Hodges, K. Kletetschka, J. L. Fenton, C. G. Read, R. E. Schaak, Angew. Chem. Int. Ed. 2015, 54, 8669; Angew. Chem. 2015, 127, 8793. Date of birth: October 12, 1975 Position: DuPont Professor of Materials Chemistry, Penn State University E-mail: res20@psu.edu Homepage: http://chem.psu.edu/directory/res20 ORCID: 0000-0002-7468-8181 Education: 1998 BS, Lebanon Valley College, Pennsylvania 2001 PhD supervised by Thomas Mallouk, Penn State University 2001–2003 Postdoc with Robert Cava, Princeton University Awards: 2006 Beckman Young Investigator Award; 2006 DuPont Young Professor; 2007 Sloan Research Fellow; 2007 Camille Dreyfus Teacher–Scholar Award; 2011 National Fresenius Award; 2016 Inorganic Nanoscience Award, ACS Current research interests: Synthetic inorganic nanochemistry; retrosynthetic design of solid-state materials; nanoparticle synthesis; chemical reactions of nanoparticles; nanoparticle formation pathways; new materials discovery; earth-abundant catalytic materials for energy applications Hobbies: Photography, painting, music, road trips The downside of my job is having to sometimes be the bearer of bad news. My favorite food is anything I can cook on a grill, especially salmon. My favorite quote is “fortune favors the prepared mind” (Pasteur). The biggest problem that scientists face is communicating the excitement, importance, and implications of fundamental research to many different audiences. What I look for first in a publication is the key result(s)—what is new in it that advances the field. The most important thing I learned from my parents is the value of balance and priorities in life: work hard, but also make time for family, friends, hobbies, and rest. My favorite place on earth is a place (not to be named!) where I can escape without access to internet or a phone for a few days. I chose chemistry as a career because I liked doing experiments, using math to solve problems, and piecing together different concepts in creative ways. In high school, chemistry “clicked” as a career where I could integrate these interests. My not-so-secret passion is macro photography. I like taking pictures of the small things in the world around us that we wouldn't normally see. If I were not a scientist, I would be a graphic designer, a photographer, or an architect. I lose track of time when I am doing something creative, like photography, art, or brainstorming. My 5 top papers: 1“Metallurgy in a Beaker: Nanoparticle Toolkit for the Rapid Low-Temperature Solution Synthesis of Functional Multimetallic Solid State Materials”: R. E. Schaak et al., J. Am. Chem. Soc. 2005, 127, 3506. (Defined our approach to using nanoparticles as reagents for low-temperature solid-state reactions.) 2“Orthogonal Reactivity of Metal and Multimetal Nanostructures for Selective, Stepwise, and Spatially-Controlled Solid State Modification”: B. M. Leonard, M. E. Anderson, K. D. Oyler, T. H. Phan, R. E. Schaak, ACS Nano 2009, 3, 940. (Our vision for applying molecule-inspired orthogonal reactivity to nanoparticles.) 3“A total-synthesis framework for the construction of high-order colloidal hybrid nanoparticles”: M. R. Buck, J. F. Bondi, R. E. Schaak, Nature Chem. 2012, 4, 37. (Applies concepts from natural-product synthesis to complex multicomponent nanoparticles.) 4“Nanostructured Nickel Phosphide as an Electrocatalyst for the Hydrogen Evolution Reaction”: E. J. Popczun, J. R. McKone, C. G. Read, A. J. Biacchi, A. M. Wiltrout, N. S. Lewis, R. E. Schaak, J. Am. Chem. Soc. 2013, 135, 9267. (Transition-metal phosphides were introduced as a viable family of earth-abundant HER catalysts.) 5“Structure-Selective Cation Exchange in the Synthesis of Zincblende MnS and CoS Nanocrystals”: J. L. Fenton, R. E. Schaak, Angew. Chem. Int. Ed. 2017, 56, 6464; Angew. Chem. 2017, 129, 6564. (Multiple distinct crystal structures can be retained during nanocrystal cation exchange.) Citing Literature Volume57, Issue12March 12, 2018Pages 3002-3002 ReferencesRelatedInformation

An effective low-temperature solution synthesis of Co-doped [0001]-oriented ZnO nanorods

We demonstrate an efficient possibility to synthesize vertically aligned pure zinc oxide (ZnO) and Co-doped ZnO nanorods (NRs) using the low-temperature aqueous chemical synthesis (90 °C). Two different mixing methods of the synthesis solutions were investigated for the Co-doped samples. The synthesized samples were compared to pure ZnO NRs regarding the Co incorporation and crystal quality. Electron paramagnetic resonance (EPR) measurements confirmed the substitution of Co2+ inside the ZnO NRs, giving a highly anisotropic magnetic Co2+ signal. The substitution of Zn2+ by Co2+ was observed to be combined with a drastic reduction in the core-defect (CD) signal (g ∼ 1.956) which is seen in pure ZnO NRs. As revealed by the cathodoluminescence (CL), the incorporation of Co causes a slight red-shift of the UV peak position combined with an enhancement in the intensity of the defect-related yellow-orange emission compared to pure ZnO NRs. Furthermore, the EPR and the CL measurements allow a possible model of the defect configuration in the samples. It is proposed that the as-synthesized pure ZnO NRs likely contain Zn interstitial (Zni+) as CDs and oxygen vacancy (VO) or oxygen interstitial (Oi) as surface defects. As a result, Co was found to likely occupy the Zni+, leading to the observed CDs reduction and hence enhancing the crystal quality. These results open the possibility of synthesis of highly crystalline quality ZnO NRs-based diluted magnetic semiconductors using the low-temperature aqueous chemical method.

Low-temperature synthesis TiOx passivation layer for organic-silicon heterojunction solar cell with a high open-circuit voltage

Organic/silicon (Si) heterojunction solar cells may promise for high performance and low cost solar cell manufacture because they can combine advantages of Si and organic semiconductors. However, the performances of organic-Si solar cells were still mainly jeopardized by Si rear contact recombination losses. Here, titanium oxide (TiOx) layer via low-temperature solution synthesis way was deposited on Si rear side to reduce electrical losses. Minority carrier lifetime, transient photovoltage decay and external quantum efficiency measurements indicated that TiOx could effectively suppress the recombination losses of Si rear side, which reflected in the improvement of open circuit voltage (Voc) and long-wavelength photoresponse. Contact resistance and capacitance-voltage measurements further showed that resistance and rear adverse barrier height (Φ-) between Si and aluminum could be dramatically reduced. A power conversion efficiency (PCE) of 14.3% was achieved for textured Si/poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT: PSS) solar cell by incorporating TiOx layer between Si and aluminum. A Voc of 643mV was achieved based on this low-temperature processed organic-Si heterojunction solar cell. The outstanding performance was ascribed to Si-O-Ti bonding at TiOx/Si interface, which was identified by X-ray photoelectron spectroscopy. This simple low-temperature solution processed metal oxide layer provided a facile way for Si surface passivation to achieve high performance solar cells.