O3 Nanocrystals Research Articles

Improper Background Treatment Underestimates Thermometric Performance of Rare Earth Vanadate and Phosphovanadate Nanocrystals.

Luminescence thermometry is the state-of-the-art technique for remote nanoscale temperature sensing, offering numerous promising cutting-edge applications. Advancing nanothermometry further requires rational design of phosphors and well-defined, comprehensive mathematical treatment of spectral information. However, important questions regarding improper signal processing in ratiometric luminescence thermometry are continuously overlooked in the literature. Here, we demonstrate that systematic errors arising from background/signal superposition impact the calculated thermometric quality parameters of ratiometric thermometers. We designed ultraviolet-excitable (Y,Eu)VO4 and (Y,Eu)(P,V)O4 nanocrystals showing overlapped VO4 3- and Eu3+ emissions to discuss systematically how uncorrected background emissions cause magnified (∼10×) temperature uncertainties and undervalued (∼60%) relative thermal sensitivities. Adequate separation of spectral contributions from the VO4 3- background and the Eu3+ signals via baseline correction is necessary to prevent underestimation of the thermometric performances. The described approach can be potentially extended to other luminescent thermometers to account for signal superposition, thus enabling to circumvent computation of apparent, miscalculated thermometric parameters.

Effect of Ce0.6Zr0.4O2 nanocrystals on boosting hydrogen storage performance of MgH2

Magnesium hydride (MgH2) has been widely recognized as a highly promising solid-state media for hydrogen storage. However, the high operating temperature and the intrinsic sluggish kinetics hinder the practical application as a portable solid storage carrier. To address this issue, we have successfully fabricated a novel rare earth-containing bimetallic oxide additive, namely Ce0.6Zr0.4O2 nanocrystals, which exhibits a significant catalytic effect in enhancing the hydrogen storage properties of MgH2. By incorporating 7 wt% Ce0.6Zr0.4O2 into MgH2, the modified composite releases hydrogen as low as 201 °C. Furthermore, in an isothermal dehydrogenation test conducted at 270 °C for 8 min, approximately 6.15 wt% of H2 was desorbed. The composites can rapidly recharge hydrogen at a low temperature of 50 °C and 6.02 wt% H2 being absorbed within 3 min at 150 °C under 50.0 bar. Comparatively, the dehydrogenation activation energy of the Ce0.6Zr0.4O2-modified MgH2 significantly decreased compared to MgH2 by ball milling. In addition to its improved hydrogen storage properties, the composite also exhibits excellent cycling stability. Through cyclic de-/rehydrogenation experiments conducted at 270 °C, a capacity retention of 98.9 % was achieved over 20 cycles. This exceptional performance can be attributed to the in-situ formation of the CeH2.73/CeO2-x and ZrO2, which originated from the Ce0.6Zr0.4O2 additive following the first de-/rehydrogenation cycle. The uniform dispersion of the multiphase component nano-sized active species within the MgH2 matrix facilitates charge transfer and accelerates hydrogen diffusion. Density functional theory calculations revealed the dissociation energy barrier and dissociation energy of H2 were alleviated by integrating Zr into CeO2. This work provides valuable insights for further rational designs of novel catalysts by transition metals and rare earths in promoting the commercialization of MgH2.

Superior Self‐Lubricating Coatings with Heterogeneous Nanocomposite Structures on Ti–Nb–Zr–Ta–Hf Refractory Multi‐Principal Element Alloy

AbstractThere is tremendous interest in the development of highly wear‐resistant coatings for metallic materials to reduce energy loss and prolong service life. In this study, the authors propose an approach to develop nanocomposite coatings featuring deformable nanocrystals embedded in amorphous matrix for self‐lubrication and superior wear resistance. The dual‐layered nanocomposite coatings are prepared by plasma electrolytic oxidation (PEO) on a Ti‐Nb‐Ta‐Zr‐Hf (TNZTH) refractory multi‐principal element alloy (RMPEA) and commercially pure Ti (cpTi). The inner layers of PEO coatings are composed of substrate element oxides (amorphous TNZTH─O oxide or anatase TiO2), while their outer layers exhibit typical nanocomposite structures. Different from the cpTi‐based PEO coating outer layers composed of brittle rutile TiO2 nanoparticles dispersed in an amorphous matrix of SiO2 and Na2O·nSiO2, the outer layers of TNZTH‐based PEO coatings are featured by deformable Na2Zr(Hf)O3 nanocrystals heterogeneously embedded in an inhomogeneous amorphous matrix composed of TNZTH─O oxide, SiO2, and Na2O·nSiO2. As a result, the TNZTH‐based PEO coatings exhibit favorable self‐lubricating performance and superior wear resistance, while the cpTi‐based PEO coatings are completely destroyed after sliding wear. Thus, this study offers valuable insights into the design and development of self‐lubricating coatings with superior wear resistance for metallic materials.

Lithiophilic Magnetic Host Facilitates Target‐Deposited Lithium for Practical Lithium‐Metal Batteries

Lithium-metal shows promising prospects in constructing various high-energy-density lithium-metal batteries (LMBs) while long-lasting tricky issues including the uncontrolled dendritic lithium growth and infinite lithium volume expansion seriously impede the application of LMBs. In this work, it is originally found that a unique lithiophilic magnetic host matrix (Co3 O4 -CCNFs) can simultaneously eliminate the uncontrolled dendritic lithium growth and huge lithium volume expansion that commonly occur in typical LMBs. The magnetic Co3 O4 nanocrystals which inherently embed on the host matrix act as nucleation sites and can also induce micromagnetic field and facilitate a targeted and ordered lithium deposition behavior thus, eliminating the formation of dendritic Li. Meanwhile, the conductive host can effectively homogenize the current distribution and Li-ion flux, thus, further relieving the volume expansion during cycling. Benefiting from this, the featured electrodes demonstrate ultra-high coulombic efficiency of 99.1% under 1mA cm-2 and 1 mAh cm-2 . Symmetric cell under limited Li (10 mAh cm-2 ) inspiringly delivers ultralong cycle life of 1600 h (under 2mA cm-2 , 1 mAh cm-2 ). Moreover, LiFePO4 ||Co3 O4 -CCNFs@Li full-cell under practical condition of limited negative/positive capacity ratio (2.3:1) can deliver remarkably improved cycling stability (with 86.6% capacity retention over 440 cycles).

Dual Active Sites of Oversaturated Fe-N5 and Fe2 O3 Nanoparticles for Accelerating Redox Kinetics of Polysulfides.

The shuttling effect and sluggish reaction kinetics are the main bottlenecks for the commercial viability of lithium-sulfur (Li-S) batteries. Metal-nitrogen-carbon single atom catalysts have attracted much attention to overcoming these obstacles due to their novel electrocatalytic activity. Herein, a novel cooperative catalytic interface with dual active sites (oversaturated Fe-N5 and polar Fe2 O3 nanocrystals) are co-embedded in nitrogen-doped hollow carbon spheres (Fe2 O3 /Fe-SA@NC) is designed by fine atomic regulation mechanism. Both experimental verifications and theoretical calculations disclose that the dual active sites (Fe-N5 and Fe2 O3 ) in this catalyst (Fe2 O3 /Fe-SA@NC) tend to form "FeS" and "LiN/O" bond, synchronically enhancing chemical adsorption and interface conversion ability of polysulfides, respectively. Specially, the Fe-N5 coordination with 3D configuration and sulfiphilic superfine Fe2 O3 nanocrystals exhibit the strong adsorption ability to facilitate the subsequent conversion reaction at dual-sites. Meanwhile, the nitrogen-doped hollow carbon spheres can promote Li+ /electron transfer and physically suppress polysulfides shuttling. Consequently, Li-S battery with the Fe2 O3 /Fe-SA@NC-modified separator exhibits a high capacity retention of 78% after 800 cycles at 1C (pure S cathode, S content: 70wt.%). Furthermore, the pouch cell with this separator shows good performance at 0.1C for practical application (S loading: 4mgcm-2 ).

Synthesis and Nanostructure Investigation of Hybrid β-Ga2 O3 /ZnGa2 O4 Nanocomposite Networks with Narrow-Band Green Luminescence and High Initial Electrochemical Capacity.

The material design of functional "aero"-networks offers a facile approach to optical, catalytical, or and electrochemical applications based on multiscale morphologies, high large reactive area, and prominent material diversity. Here in this paper, the synthesis and structural characterization of a hybrid β-Ga2 O3 /ZnGa2 O4 nanocomposite aero-network are presented. The nanocomposite networks are studied on multiscale with respect to their micro- and nanostructure by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and are characterized for their photoluminescent response to UV light excitation and their electrochemical performance with Li-ion conversion reaction. The structural investigations reveal the simultaneous transformation of the precursor aero-GaN(ZnO) network into hollow architectures composed of β-Ga2 O3 and ZnGa2 O4 nanocrystals with a phase ratio of ≈1:2. The photoluminescence of hybrid aero-β-Ga2 O3 /ZnGa2 O4 nanocomposite networks demonstrates narrow band (λem = 504nm) green light emission of ZnGa2 O4 under UV light excitation (λex = 300nm). The evaluation of the metal-oxide network performance for electrochemical application for Li-ion batteries shows high initial capacities of ≈714 mAh g-1 at 100mA g-1 paired with exceptional rate performance even at high current densities of 4 A g-1 with 347 mAh g-1 . This study provides is an exciting showcase example of novel networked materials and demonstrates the opportunities of tailored micro-/nanostructures for diverse applications a diversity of possible applications.

Dual-structured oxide coatings with enhanced wear and corrosion resistance prepared by plasma electrolytic oxidation on Ti-Nb-Ta-Zr-Hf high-entropy alloy

The electrochemical oxidation behavior of high-entropy alloys (HEAs) is supposed to be different from that of traditional Ti-based alloys due to the presence of multi-principal elements. In this work, equi-atomic Ti-Nb-Ta-Zr-Hf bio-HEA (PEO-free) was subjected to plasma electrolytic oxidation (PEO) at 150 (PEO-150 V), 200 (PEO-200 V) or 250 V (PEO-250 V). Due to substrate oxidation, the PEO-formed coatings were composed of multiple metallic oxides in their complete oxidation states. Moreover, elements such as Ca, Si, Na and O from the electrolyte were also introduced into the coatings. Different from the amorphous nature PEO-150 V coating, the microstructures of PEO-200 V and PEO-250 V coating were characterized by Hf0.5Zr0.5O2 nano-crystals homogeneously dispersed in amorphous coating matrices, with PEO-250 V group (∼20 μm in diameter) possessing larger nano-crystals than PEO-200 V group (∼6 μm in diameter). The dry-sliding test identified an order of PEO-200 V > PEO-250 V > PEO-150 V > PEO-free group for the wear resistance. The corrosion resistance evaluated by electrochemical impedance spectroscopy followed the trend of PEO-150 V > PEO-200 V > PEO-250 V > PEO-free group. The in vitro experiments confirmed the favorable cyto-compatibility of PEO-treated surfaces. Together, the results indicate that the coating with appropriate amorphous/crystalline dual-structure on Ti-Nb-Ta-Zr-Hf bio-HEA surface is promising for biomedical applications.

Multimodal Synchrotron X-Ray Tools for Studying Spinel Oxide Nanocrystals-Based Mg Cathodes

Magnesium battery has huge potential to meet the future needs of large-scale energy storage due to the high abundance of Mg element, high volumetric and gravimetric capacities, and improved safety compared to Li metal battery. The complex solid-electrolyte interface (SEI) formed on Mg anode surface and slow diffusion rate of magnesium ion in cathode bulk are two critical challenges to achieve high capacity and energy density of Mg battery. Nanostructured spinel oxides with well-defined morphology and crystalline structures are promising candidates for Mg battery cathodes, but their dynamic evolutions of chemical composition and electronic/geometric structure during charging and discharging are still on the early stage, which hinders understanding of the interaction and degradation mechanisms on spinel oxide-based cathodes. Herein, in-situ/or ex-situ soft X-ray absorption spectroscopy (sXAS) and small/wide-angle X-ray scattering (SAXS/WAXS) to track the changes of structure and surface/bulk chemistry of spinel oxide nanocrystals during Mg intercalation/deintercalation processes at both local and macroscopical levels. The Mg0.5Fe2.5O4 (MFO) nanocrystals were tested in a Swagelok cell with an electrolyte of 0.3 M Mg(TFSI)2 and 0.15 M MgCl2 at room temperature. An initial discharge capacity of 187 mAh g-1 was achieved and 83% capacity was retained after 20 cycles. sXAS results reveal that Fe3+/Fe3+ redox is highly reversible during charge/discharge process, and MgF2 slowly formed on the surface as well. In-situ WAXS shows that rocksalt phases of FeO and MgO were both observed during discharge process, and the former one quickly disappeared and the latter one slowly converted to pristine phase during charge process. Moreover, MFO with small size (~5 nm) delivered double specific capacity but poorer cyclability compared to large size (~18 nm), which is ascribed to the nanocrystal aggregation and decrease of active surface area and formation of interfacial crystal boundary based on in-situ SAXS and ex-situ STEM. More structural features of shape and crystallinity degree of MFO were also investigated and correlated to their battery performance. This work highlight the powerful role of multimodal in-situ synchrotron X-ray techniques in understanding the structure-performance of spinel oxide nanocrystals-based Mg cathodes. Figure 1

Improving the stability and scalability of all-inorganic inverted CsPbI2Br perovskite solar cell

All-inorganic perovskite solar cells (PSCs) have potential to pass the stability international standard of IEC61215:2016 but cannot deliver high performance and stability due to the poor interface contact. In this paper, Sn-doped TiO2 (Ti1−xSnxO2) ultrathin nanoparticles are prepared for electron transport layer (ETL) by solution process. The ultrathin Ti0.9Sn0.1O2 nanocrystals have greatly improved interface contact due to the facile film formation, good conductivity and high work function. The all-inorganic inverted NiOx/CsPbI2Br/Ti0.9Sn0.1O2 p-i-n device shows a power conversion efficiency (PCE) of 14.0%. We tested the heat stability, light stability and light-heat stability. After stored in 85 °C for 65 days, the inverted PSCs still retains 98% of initial efficiency. Under continuous standard one-sun illumination for 600 h, there is no efficiency decay, and under continuous illumination at 85 °C for 200 h, the device still retains 85% of initial efficiency. The 1.0 cm2 device of inverted structure shows a PCE of up to 11.2%. The ultrathin Ti1−xSnxO2 is promising to improve the scalability and stability and thus increase the commercial prospect.

Size-Dependent Selectivity of Electrochemical CO2 Reduction on Converted In2 O3 Nanocrystals.

The size modulation of catalyst particles represents a useful dimension to tune catalytic performances by impacting not only their surface areas but also local electronic structures. It, however, has remained inadequately explored and poorly elucidated. Here, we report the interesting size-dependent selectivity of electrochemical CO2 reduction on In2 O3 nanocrystals. 5-nm nanoparticles and 15-nm nanocubes with focused size distribution are prepared via a facile solvothermal reaction in oleylamine by carefully controlling a set of experimental parameters. They serve as the precatalysts, and are reduced to In nanocrystals while largely inherit the original size feature during electrochemical CO2 reduction. Catalyst derived from 15-nm nanocubes exhibits greater formate selectivity (>95 %) at lower overpotential and negligible side reactions compared to bulk-like samples (indium foil and 200-nm cubes) as well as the catalyst derived from smaller 5-nm nanoparticles. This unique size dependence is rationalized as a result of the competition among different reaction pathways by our theoretical computations. Smaller is not always better in the catalyst design.

Tunable bandgap in cobalt doped bismuth ferrite nanoceramics: The role of annealing temperature

Recent years have witnessed an exotic interest in the bandgap tailoring of multiferroic materials for photovoltaic and photocatalytic applications owing to their fascinating physical properties. To enhance the absorption of the solar spectrum, an attempt is made to tune the optical bandgap and investigate the influence on structural, morphological, and optical properties of BiFe0.9Co0.1O3 nanocrystals by controlling thermal annealing temperature. Herein, nanoparticles of undoped and cobalt (10 mol %) doped BiFeO3 are synthesised using citrate precursor technique and annealed at different temperatures (500 °C, 550 °C, and 600 °C). X-ray diffraction studies confirm the rhombohedrally distorted perovskite structure for all the samples. An increasing trend of particle size with the increase in thermal annealing temperature was observed. Microstructural analysis revealed spherical shaped grains for BiFe0.9Co0.1O3 samples. X-ray photoelectron spectroscopy studies confirmed the chemical states of all the constituent elements and validated the presence of oxygen vacancies in our samples. The optical absorption coefficient was found to increase by 45% in BiFe0.9Co0.1O3 compared to pure BiFeO3 at 400 nm. The optical bandgap value of bismuth ferrite was reduced from (2.08 ± 0.02) eV to (1.59 ± 0.02) eV with a combined impact of cobalt doping and thermal annealing temperature. Also, an inverse correlation of bandgap values and thermal annealing temperature was observed. Therefore, this study suggests that control on thermal annealing temperature has a decisive effect on the optical bandgap of complex oxide nanocrystals.

Multi-Component Mesocrystalline Nanoparticles with Enhanced Photocatalytic Activity.

Mesocrystals, consisting of small subunits, have gained research interests owing to their ability to simultaneously modify material-specific properties and interactions among subunits. However, despite these unique characteristics, most mesocrystals are composed of a single material, and there is a disjunction between academic discovery and practical application. In this study, the synthesis of multi-component mesocrystalline nanoparticles composed of Fe3 O4 , ZnFe2 O4 , and ZnO subunits using a polymerization induced heterogeneous nucleation method is reported. The structure has small ZnFe2 O4 and ZnO nanocrystals covering the Fe3 O4 crystallites. It exhibits not only magnetic and catalytic properties determined by the size of each subunit nanocrystal, but also enhances photocatalytic and colloidal properties that originates because of its crowded arrangement. The magnetically recoverable catalysts exhibit remarkable photodegradation of organic molecules under the irradiation of visible light for 1 h; thus, improving its applicability in purifying a large amount of wastewater during the daytime.

Hexagonal La2O3 Nanocrystals Chemically Coupled with Nitrogen‐Doped Porous Carbon as Efficient Catalysts for the Oxygen Reduction Reaction

The construction of nano-scale hybrid materials with a smart interfacial structure, established by using rare earth oxides and carbon as building blocks, is essential for the development of economical and efficient catalysts for oxygen reduction reactions (ORRs). In this work, hexagonal La2 O3 nanocrystals on a nitrogen-doped porous carbon (NPC) derived from crop radish, served as building bricks, are prepared by chemical precipitation and then calcination at elevated temperatures. The obtained La2 O3 /NPC hybrid exhibits a very high ORR activity with a half-wave potential of 0.90 V, exceeding that of commercial Pt/C (0.83 V). Both DFT theoretical and experimental results have verified that the significantly enhanced catalytic performance is ascribed to the formation of the C-O-La covalent bonds between carbon and La2 O3 . Through the covalent bonds, electrons can transfer from the carbon to La2 O3 and occupy the unfilled eg orbital of the La2 O3 phase. This results in the accelerated adsorption of active oxygen and the facilitated desorption of the surface hydroxides (OHad - ), thereby promoting the ORR over the catalyst.

Epitaxially Strained CeO2 /Mn3 O4 Nanocrystals as an Enhanced Antioxidant for Radioprotection.

Nanomaterials with antioxidant properties are promising for treating reactive oxygen species (ROS)-related diseases. However, maintaining efficacy at low doses to minimize toxicity is a critical for clinical applications. Tuning the surface strain of metallic nanoparticles can enhance catalytic reactivity, which has rarely been demonstrated in metal oxide nanomaterials. Here, it is shown that inducing surface strains of CeO2 /Mn3 O4 nanocrystals produces highly catalytic antioxidants that can protect tissue-resident stem cells from irradiation-induced ROS damage. Manganese ions deposited on the surface of cerium oxide (CeO2 ) nanocrystals form strained layers of manganese oxide (Mn3 O4 ) islands, increasing the number of oxygen vacancies. CeO2 /Mn3 O4 nanocrystals show better catalytic activity than CeO2 or Mn3 O4 alone and can protect the regenerative capabilities of intestinal stem cells in an organoid model after a lethal dose of irradiation. A small amount of the nanocrystals prevents acute radiation syndrome and increases the survival rate of mice treated with a lethal dose of total body irradiation.

Nanocrystalline Heterogeneous Multiferroics Based on Yttrium Ferrite (Core) with Calcium Zirconate (Titanate) Shell

Nanocrystalline YFeO3–CaZr(Ti)O3 powders were synthesized by the sequential deposition method. The structure of the YFeO3–CaZr(Ti)O3 nanocrystals fits into the core–shell spherical particle model. The nanocrystalline YFeO3–CaZr(Ti)O3 powders synthesized contain yttrium orthoferrite and calcium zirconate (titanate) single phases. Materials based on YFeO3–CaZr(Ti)O3 are magnetically soft.

Chemical Synthesis and High-Pressure Reaction of Nb5+ Monodoped Rutile TiO2 Nanocrystals

Identifying the doping effects of extrinsic ions both during chemical reactions and in resultant products is important to deeply understand the associated material properties and to develop novel materials for practical applications. Here, we experimentally demonstrate the significant inhibitor effect of Nb5+ dopants on the formation of rutile TiO2 nanocrystals through dopant concentration-modified solvothermal reaction processes. A lower Nb5+ doping level (≤9.09 atom %) is found to be more beneficial for the nucleation and growth of rutile Ti1 – 2x4+Tix3+Nbx5+O2 nanocrystals while a higher one (>9.09 at.%) leads to the preferable formation of the anatase phase. At a pressure range of up to 30 GPa, the synthesized Nb5+ monodoped rutile TiO2 nanocrystals almost possess an equal slope in their respective plot of the pressure-dependent Raman frequency shifts and a similar structural transformation from rutile to baddeleyite-like (pressurization) and then to an α-PbO2-like phase (depressurization). They thus present a dopant concentration-independent high-pressure reaction behavior due to a small change in their average and local defect structures evidenced by the bond valence sum analysis and density functional theory calculations. This work not only emphasizes the key roles of dopants in material synthesis but also broadens insights into the intrinsic correlations between material properties and their specific local defects.

Growth of LiNi0.5Mn1.5O4 crystals on reduced graphene oxide sheets for high energy and power density charge storage

Spinel-type lithium manganates are actively considered to develop cost-effective energy/charge storage devices. In this article, we show the growth of LiNi0.5Mn1.5O4 nanocrystals on reduced graphene oxide (rGO) sheets, which offer impressive improvements in their charge storage capability than that can be achieved using bare LiNi0.5Mn1.5O4 nanocrystals. X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and electron microscopy techniques are employed to demonstrate the embedment of LiNi0.5Mn1.5O4 particles on rGO sheets. As a single electrode, LiNi0.5Mn1.5O4-rGO composite electrode deliver ∼3-fold enhanced charge storability (∼572 F g−1 /∼175 mA h g-1 at 3.75 A g-1) in 5 M LiNO3 electrolyte than the bare LiNi0.5Mn1.5O4 electrode. The electrochemical charge storage processes are investigated via the Dunn’s approach. The major charge storage mechanism of the samples is diffusion controlled at slow scan rate. A practical hybrid battery – supercapacitor device is fabricated in the LiNi0.5Mn1.5O4-rGO//activated carbon configuration, which deliver energy density in the 60 – 23 Wh kg-1 range at a power density in the 1.2−13 kW kg-1 range with an output voltage of 0–2.0 V, excellent cycling stability, and rate capability.

Hole‐Boosted Cu(Cr,M)O2 Nanocrystals for All‐Inorganic CsPbBr3 Perovskite Solar Cells

AbstractThe all‐inorganic CsPbBr3 perovskite solar cell (PSC) is a promising solution to balance the high efficiency and poor stability of state‐of‐the‐art organic–inorganic PSCs. Setting inorganic hole‐transporting layers at the perovskite/electrode interface decreases charge carrier recombination without sacrificing superiority in air. Now, M‐substituted, p‐type inorganic Cu(Cr,M)O2 (M=Ba2+, Ca2+, or Ni2+) nanocrystals with enhanced hole‐transporting characteristics by increasing interstitial oxygen effectively extract holes from perovskite. The all‐inorganic CsPbBr3 PSC with a device structure of FTO/c‐TiO2/m‐TiO2/CsPbBr3/Cu(Cr,M)O2/carbon achieves an efficiency up to 10.18 % and it increases to 10.79 % by doping Sm3+ ions into perovskite halide, which is much higher than 7.39 % for the hole‐free device. The unencapsulated Cu(Cr,Ba)O2‐based PSC presents a remarkable stability in air in either 80 % humidity over 60 days or 80 °C conditions over 40 days or light illumination for 7 days.

Hole‐Boosted Cu(Cr,M)O2 Nanocrystals for All‐Inorganic CsPbBr3 Perovskite Solar Cells

The all-inorganic CsPbBr3 perovskite solar cell (PSC) is a promising solution to balance the high efficiency and poor stability of state-of-the-art organic-inorganic PSCs. Setting inorganic hole-transporting layers at the perovskite/electrode interface decreases charge carrier recombination without sacrificing superiority in air. Now, M-substituted, p-type inorganic Cu(Cr,M)O2 (M=Ba2+ , Ca2+ , or Ni2+ ) nanocrystals with enhanced hole-transporting characteristics by increasing interstitial oxygen effectively extract holes from perovskite. The all-inorganic CsPbBr3 PSC with a device structure of FTO/c-TiO2 /m-TiO2 /CsPbBr3 /Cu(Cr,M)O2 /carbon achieves an efficiency up to 10.18 % and it increases to 10.79 % by doping Sm3+ ions into perovskite halide, which is much higher than 7.39 % for the hole-free device. The unencapsulated Cu(Cr,Ba)O2 -based PSC presents a remarkable stability in air in either 80 % humidity over 60 days or 80 °C conditions over 40 days or light illumination for 7 days.

Synthesis of single-crystalline Pb(Zr0.52Ti0.48)O3 nanocrystals by hydrothermal method

Abstract PbZr0.52Ti0.48O3 nanocrystals were synthesized by a hydrothermal method. The effect of NaOH concentration, reaction temperature and time on nucleation and growth of PbZr0.52Ti0.48O3 nanocrystals was investigated. As the 0.05 mol/L PbZr0.52Ti0.48O3 precursors were heated at 200 °C for 21 h with NaOH concentration of 0.5 mol/L, the tetragonal PbZr0.52Ti0.48O3 nanocrystals were formed, and the grain size was more than 20 nm. With increasing the NaOH concentration from 0.5 to 1.5 mol/L, the grain size of PbZr0.52Ti0.48O3 nanocrystals decreased. When the precursors were heated at different temperatures (140 °C to 200 °C) for 21 h with 1.0 mol/L NaOH, single-phase PbZr0.52Ti0.48O3 nanocrystals were obtained at 160 °C to 200 °C. With increasing the reaction temperature from 160 °C to 200 °C, the grains size of PbZr0.52Ti0.48O3 nanocrystals increased from 5 nm to 9 nm. When the precursors were heated at 160 °C in different reaction times from 6 h to 21 h, the evolution from amorphous to crystalline PbZr0.52Ti0.48O3 nanocrystals in correlation with the reaction time was observed. Single crystalline PbZr0.52Ti0.48O3 nanocrystals with narrow size distribution (from 5 nm to 9 nm) were synthesized by controlling the NaOH concentration, reaction temperature and time. The obtained results can find potential application in preparing PbZr0.52Ti0.48O3 thin films on flexible substrates.