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V2O5 nanoclusters can inhibit CoS2 from serious surface oxidation in air, and the lower surface oxidation degree, the better HER performance.

A neutral carbolong complex boosts the efficiency of p–i–n perovskite solar cells to 22.7%, and greatly enhances device thermal stability.

A carbolong derivative with a M-PCCO framework was employed as the cathode interlayer, boosting the performance and stability of inverted PSCs.

CsPbIxBry-based all-inorganic perovskite materials are a potential candidate for stable semitransparent and tandem structured photovoltaic devices. However, poor film (morphological and crystalline...

Herein, we have synthesized a series of hexaphenylbenzene (HPB) derivatives: HPB-H, HPB-COOCH3 and HPB-COOH that differs in functional groups attached to the periphery of the outer benzene rings. Among them, the HPB with carboxyl functional group (HPB-COOH) as LIB anode shows a superior capacity of 997.4 mAh g−1 and better rate performance than HPB and HPB-COOCH3. Such superior anode properties can be attributed to the fact that HPB-COOH has a layered morphology, a pseudo-2D structure, lower LUMO energy, and higher electron conductivity, compared with that of HPB-COOCH3 and HPB-H, respectively. Moreover, low energy packing with transport channels is beneficial for Li ions diffusion during the lithiation and extraction processes. Furthermore, HPB-COOH shows excellent cycling stability presumably due to its layered molecular packing structures. Our work paves the way for the design synthesis of novel organic molecules with suitable electrochemical redox-active groups and layered hierarchical structure to achieve high capacity, good rate performance, and high cyclic stability for next generation Li ion batteries (LIBs).

Radioactive aerosols are highly hazardous aerosols containing radionuclides. Inhalation of radioactive aerosols can lead to serious internal exposure hazards to human body. If discharged without proper treatment, it will also harm the working environment and even the ecological environment. Therefore, radioactive aerosol protection is a significant part of environmental protection and personnel protection in the nuclear field. However, majority of existing protective fabrics for radioactive aerosol filtration always meet the trade-off among filtration capacity, mechanical properties and air permeability. In this study, nanofiber layers were prepared by electrospinning technology using TPU, PVDF, PVA polymer materials and electret materials SiO2 as spinning materials. Composite membranes, prepared by coating different nanofiber layers on the PET non-woven fabrics substrate, were investigated. The results show that the 12wt% TPU nanofiber membrane has a three-dimensional spatial hierarchical structure. Its ultra-fine fiber diameter with small pore size greatly enhances the PM capture ability (PM0.3 filtration efficiency 99.99%); and the beaded spatial structure is beneficial to reduce the air resistance to 299 Pa (flow rate 95 L/min). Meanwhile, TPU nanofiber membrane has high extensibility, and it is superior to PVDF and PVA composite membranes in mechanical properties after thermal compounding. Appropriate content of SiO2 can improve filtration performance. The study shed light on developing electrospun nanofiber for radioactive aerosol protection, which can be used in the purification of ambient air in nuclear facilities, or as a high-performance fabric for radioactive aerosol protective clothing.

Low-work-function (WF) metals (including silver (Ag), aluminum (Al), and copper (Cu)) used as external cathodes in inverted perovskite solar cells (PSCs) encounter oxidation caused by air exposure and halogen-diffusion-induced corrosion, which threaten the long-term stability of the device. The cathode interlayer (CIL) has shown promise in reducing the metal WF and thus boosting the device power conversion efficiency (PCE). However, it remains a challenge for current CIL materials to enable high-WF metals (e.g., Au) to be used as cathodes to achieve PSCs with a superior PCE and long-term stability. Here, we use a series of synthesized (carbolong-derived) organometallic complexes as CILs to tune the electrode WF in inverted PSCs. Density functional theory calculations and surface characterizations show that the organometallic complexes that contain anions and cations are prone to form anion-cation dipoles on the metal surface, hence drastically reducing the metal's WF. Photovoltaic devices based on a Ag cathode, which was modified with these organometallic complexes, received a boosted PCE up to 21.29% and a remarkable fill factor that reached 83.52%, which are attributed to the dipole-enhanced carrier transport. The environmental stability of PSCs was further improved after employing Au as a cathode with these organometallic complexes, and the modified devices exhibited no efficiency loss after 4080 h storage measurements.

The family of monolayer two-dimensional (2D) materials hosts a wide range of interesting phenomena, including superconductivity, charge density waves, topological states and ferromagnetism, but direct evidence for antiferromagnetism in the monolayer has been lacking. Nevertheless, antiferromagnets have attracted enormous interest recently in spintronics due to the absence of stray fields and their terahertz resonant frequency. Despite the great advantages of antiferromagnetic spintronics, controlling and detecting N\'eel vectors have been limited in bulk materials. In this work, we developed a sensitive second harmonic generation (SHG) microscope and detected long-range N\'eel antiferromagnetic (AFM) order and N\'eel vector switching down to the monolayer in MnPSe$_3$. Temperature-dependent SHG measurement in repetitive thermal cooling surprisingly collapses into two curves, which correspond to the switching of an Ising type N\'eel vector reversed by the time-reversal operation, instead of a six-state clock ground state expected from the threefold rotation symmetry in the structure. We imaged the spatial distribution of the N\'eel vectors across samples and rotated them by an arbitrary angle irrespective of the lattice in the sample plane by applying strain. By studying both a Landau theory and a microscopic model that couples strain to nearest-neighbor exchange, we conclude that the phase transition of the XY model in the presence of strain falls into the Ising universality class instead of the XY one, which could explain the extreme strain tunability. Finally, we found that the 180{\deg} AFM domain walls are highly mobile down to the monolayer after thermal cycles, paving the way for future control of the antiferromagnetic domains by strain or external fields on demand for ultra-compact 2D AFM terahertz spintronics., Comment: Submitted version; To appear in Nature Nanotechnology

The exploration of efficient oxygen reduction reaction (ORR) electrocatalysts with low-cost and facile process is crucial for the commercialization of fuel cells and metal–air batteries. Herein, we demonstrate a template-free strategy to synthesize N-doped porous carbon spheres (NPCS-X, X denotes the pyrolysis temperature) composed of nanosheets via pyrolysis of self-assembled urea formaldehyde (UF) resin as a single precursor. The resultant NPCS-900 exhibits an outstanding electrocatalytic activity towards ORR with a half-wave potential (E1/2) of 0.87 V (vs. RHE), superior long-term stability and methanol resistance compared with the commercial Pt/C catalyst in alkaline solution. Furthermore, NPCS-900 also has an impressive ORR electrocatalytic activity and durability in an acid electrolyte. The excellent electrochemical performance of NPCS-900 can be attributed to the abundant exposed active sites of N-species and carbon defects distributed throughout the porous carbon nanosheets of NPCS-900.

Designing a structurally stable anode with a high reversible capacity for sodium ion batteries (SIBs) is particularly crucial so that batteries are able to meet the requirements for large-scale applications in grid electrical energy storage. Polyaromatic hydrocarbons (PAHs) are organic molecules with well-defined structures that demonstrate excellent performance in lithium storage. Based on our well-established correlation between battery property and molecular structure, for the first time, we applied a recently synthesized hexabenzocoronene (HBC) and corresponding derivate HBC–OMe to engage in sodium storage. The HBC molecule forms self-assemblies with a long-range ordered face-center cubed (fcc) structure due to the interaction between two HBC moieties. Such a unique 3D structure is expected to generate a strong π–π interaction between flakes and thus yield amazing durability during the long-term cycling process. In addition, the surface-dominated Na+ storage mechanism can facilitate the Na+ transport kinetics and simultaneously alleviate the structural strain during charging–discharging cycles. Benefiting from the coupling effect of the surface-driven capacitive process and the robust 3D self-assembled hierarchical nature, an oxygen-containing sample, HBC–OMe, exhibited an extraordinary sodium storage capability, attaining a high capacity of 506 mA h g−1 at 0.1 A g−1 with excellent rate capability (217 mA h g−1 at 5 A g−1) and superior long-term cycling performance (290 mA h g−1 at 2 A g−1 with negligible capacity fade after 1000 cycles).

Green and sustainable electrochemical conversion and storage devices possess the nature to repress a negative effect on sustainability during energy conversion and storage. However, the sustainabil...

Perovskite materials have attracted widespread attention in the photovoltaic community due to their excellent intrinsic electronic properties and very high device efficiency. Interfacial passivatio...

In this study, size-selected platinum (Pt) nanoclusters were imaged with aberration-corrected scanning transmission electron microscopy in high-angle annular dark field (HAADF) mode. For image analysis, a relatively simple macro program was developed by making the use of existing ImageJ plug-ins. The macro allows effectively for assessing criterions chosen for intensity threshold and filter blurring factors. It can extract the integrated HAADF intensity, peak intensity and projected area of the clusters. Here, the effects of magnification and objective lens defocus on nanocluster measurement were investigated. It was found that the integrated HAADF intensity of Pt clusters is a more robust sample descriptor than the peak intensity and the projected area. The macro program developed is freely available. LAY DESCRIPTION: Measuring precisely the size of nanoclusters plays an important role in the investigation of nanocluster-based material systems. Aberration-corrected scanning transmission electron microscopy (STEM) is one of the most powerful tools to extract the size of clusters directly from their images. In this study, we developed a macro program based on existing ImageJ plug-ins, allowing easy-assessment of criterions chosen for image intensity threshold and filter blurring factors. It can be used to extract the integrated intensity, peak intensity, and projected area of the clusters for size determination. Using the program, we investigated the effects of magnification and objective lens defocus on measurements performed on size-selected platinum (Pt) nanoclusters, and found that the integrated intensity of Pt clusters is a more robust sample descriptor than the peak intensity and the projected area. The macro developed allows a rapid assessment of factors affecting the accuracy with which size information can be obtained from clusters.

The combination of ferroelectric–optical properties in halide perovskites has attracted tremendous interess because of its potential for optoelectronic and energy applications. However, very few re...

Organic carbon materials, such as graphene and nanotubes, with a high specific capacity show promise in improving the energy density for lithium ion batteries (LiBs). Here, we report on the synthesis and characterization of C60(OH)12 and the C60(OH)12/graphene oxide (GO) composite and demonstrate their use as anode materials in LiBs. We find that the C60(OH)12/GO composite forms due to the chemical reactions between the carboxyl and epoxy groups of GO and the hydroxyl of C60(OH)12 nanoparticles and that C60(OH)12 uniformly grows on the surface of GO nanosheets. Using a suite of spectroscopy probes, we unequivocally show the mixing between C60(OH)12 and GO at the molecular level, which leads to superior battery performances. This composite has a reversible capacity of 1596 mAh g-1 at 0.2 A g-1, higher than the capacities of C60(OH)12 and GO. This composite has a superior cycling stability and excellent rate performance, making it a promising organic anode material for high-performance LiBs.

A mechanistic understanding of perovskite degradation is one of the most urgent issues to push perovskite devices toward commercial applications. Surface coverings will lower the electrical injection and light extraction efficiency of perovskites. Therefore, structural modification of Zn doped perovskites has been proposed herein. The Zn doping will induce local lattice strain due to smaller ionic radius. It is interesting that the lattice structure at atomic resolution has been observed directly through cryo-TEM. Under light illumination, the photostriction will compensate for the local lattice strain, which leads to structural stability as evidence suggests no phase transition in temperature ranges of the temperature-dependent photoluminescence spectra. In addition, MPZB also shows less than 3% decrease in PL intensity after 60 days. This is because the Zn doping induced the lowest defect density in the MPZB SC (density of trap-states ntrp = 6.33 × 108 cm−3), which has been confirmed by the high performance of the photodetector. Such strain compensation is expected to fundamentally improve the stability of photoelectric devices.

Graphene fibres have been recognized as ideal building blocks to make advanced, macroscopic, and functional materials for a variety of applications. Direct fabrication of graphene fibres with ideal graphene sheets is still far from reality due to the weak intermolecular bonding between graphene sheets. In contrast, the construction of graphene oxide fibres by following a reduction process is a common compromise. The self-assembly of graphene oxide is an effective strategy for the continuous fabrication of graphene fibre. Different fabrication strategies endow graphene fibres with different performances. Over the past decade, various studies have been carried out into integrating graphene oxide nanosheets into graphene fibres. In this review, we summarize the assembly methods of graphene fibres and compare the mechanical and electrical performances of the graphene fibres fabricated by different strategies. Also the influence of the fabrication strategy on mechanical performance is discussed. Finally, the expectation of macroscopic graphene fibres in the future is further presented.

Organic solar cells have become an important development direction in solar cell materials because of their low cost, light weight, and good flexibility. However, the size of their bandgap is difficult to continuously regulate, resulting in a low power conversion efficiency. In this work, an organic molecule TPEPA was synthesized, and its luminescence performance and polymerization under high pressure were studied by performing

Chlorine-rich argyrodite-type solid electrolyte Li

All-inorganic CsPbIBr

Perovskite solar cells (PSCs) via two-step sequential method have received great attention in recent years due to their high reproducibility and low processing costs. However, the relatively high trap-state density and poor charge carrier extraction efficiency pose challenges. Herein, highly efficient and stable PSCs via a two-step sequential method are fabricated using organic-inorganic (OI) complexes as multifunctional interlayers. In addition to reduce the under-coordinated Pb

Traditional preparation of ZnO nanocrystal requires heating zinc acetate to a temperature over 350°C, whereas in this work, zinc acetate was first electrospun with PVDF to form a nanofiber, followed by thermal treatment at only 140°C to give nanocrystalline ZnO. The much lower temperature required in thermal treatment is attributed to the high reactivity of zinc acetate at nano dimension. The as-prepared ZnO-doped PVDF nanofiber mat shows excellent effect in the photocatalytic degradation of Rhodamine B, comparable to ZnO particle thermally treated at 600°C. Highly-oriented ZnO nanorods were obtained by further hydrothermal synthesis of the electrospun nanofiber mat, giving nanostructured ZnO of different morphologies well-aligned on the surface of organic nanofiber. Notably, the hydrothermal synthesis of the successful preparation of these nanostructured ZnO requires a processing temperature below 100°C at atmospheric pressure, showing great potential to be scaled up for vast manufacturing.

Sarcosine is a recently identified biomarker for prostate cancer. However, the rapid detection methods for sarcosine are relatively lack because of the low concentration and the presence of complicated interfering substances in serum or urine. In this manuscript, hollow nanospheres of Fe3O4 was synthesized and used as carrier to disperse Pt (Pt) nanoparticles. In order to achieve excellent electron transfer ability, we use polyaniline to coat Pt–Fe3O4 nanoparticles, and pyrolyze the polyaniline to carbon (C). Thus, hollow magnetic Pt–Fe3O4@C nanocomposites with good electron transfer ability are formed. The Pt–Fe3O4@C nanocomposites have high catalytic activity and stability. The nanocomposites were immobilized on glassy carbon electrode (GCE) to construct a nonenzyme hydrogen peroxide (H2O2) sensor (Pt–Fe3O4@C/GCE). We further construct a sensitive sarcosine biosensor by immobilizing sarcosine oxidase (SOx) on the Pt–Fe3O4@C/GCE. The high catalytic activity and good biocompatibility of Pt–Fe3O4@C nanocomposites greatly retained the bioactivity of immobilized SOx, and the prepared sarcosine biosensor has good electrocatalytic performance towards sarcosine. It has a linear detection range between 0.5 and 60 μM with a limit of detection (LOD) of 0.43 μM (the signal to noise ratio is 3), and the sensitivity is 3.45 nA μM−1 (48.8 nA μM−1 cm−2), which has the potential to be used for rapid screening of prostate cancer.

The oxygen evolution reaction (OER) is involved in various renewable energy systems, such as water-splitting, metal–air batteries and CO2 electroreduction. Ni–Fe layered double hydroxides (LDHs) have been reported as promising OER electrocatalysts in alkaline electrolytes. Herein, we demonstrate that the introduction of elemental selenium (Se) with an optimized phase composition, i.e., monoclinic (m-) or trigonal (t-) Se, could effectively tailor the OER activity of NiFe-LDH. Compared to t-Se doped NiFe-LDH, the presence of hybrid m/t-Se could effectively tune the electronic states of Ni–O and Fe–O sites, promote the generation of OER-active γ-NiOOH, and inhibit Fe-migration during the OER process, thus enhancing the OER performance. The optimized Ni0.8Fe0.2-m/t-Se0.02-LDH catalyst exhibits extraordinarily high OER activity, with an overpotential of 200 mV at 10 mA cm−2, which is superior to those of IrO2 and most of the reported Se-based OER catalysts. The Ni0.8Fe0.2-m/t-Se0.02-LDH catalyst is further implemented as an anode for overall water splitting and demonstrates a low cell voltage of 1.50 V to achieve 10 mA cm−2.

Exploiting platinum-group-metal (PGM)-free electrocatalysts with remarkable activity and stability toward oxygen reduction reaction (ORR) is of significant importance to the large-scale commercialization of proton exchange membrane fuel cells (PEMFCs). Here, a high-performance and anti-Fenton reaction cobalt-nitrogen-carbon (Co-N-C) catalyst is reported via employing double crosslinking (DC) hydrogel strategy, which consists of the chemical crosslinking between acrylic acid (AA) and acrylamide (AM) copolymerization and metal coordinated crosslinking between Co2+ and P(AA-AM) copolymer. The resultant DC hydrogel can benefit the Co2+ dispersion via chelated Co-N/O bonds and relieve metal agglomeration during the subsequent pyrolysis, resulting in the atomically dispersed Co-Nx/C active sites. By optimizing the ratio of AA/AM, the optimal P(AA-AM)(5-1)-Co-N catalyst exhibits a high content of nitrogen doping (12.36 at%) and specific surface area (1397 m2 g-1 ), significantly larger than that of the PAA-Co-N catalyst (10.59 at%/746 m2 g-1 ) derived from single crosslinking (SC) hydrogel. The electrochemical measurements reveal that P(AA-AM)(5-1)-Co-N possesses enhanced ORR activity (half-wave potential (E1/2 ) ≈0.820 V versus the reversible hydrogen electrode (RHE)) and stability (≈4 mV shift in E1/2 after 5000 potential cycles in 0.5 m H2 SO4 at 60 oC) relative to PAA-Co-N, which is higher than most Co-N-C catalysts reported so far.

Inspired by the structural advantages of spiro-OMeTAD, which is the most commonly used hole-transporting material (HTM), two rationally designed HTMs with butterfly-shaped triarylamine groups based on dibenzofulvene-bridged indacenodithiophene (IDT) core (attaching hexyl and octyl chains) have been synthesized, namely, IT-C6 and IT-C8, respectively. Shorter alkyl-chain-based IT-C6 exhibits a marked increase in glass-transition temperature (Tg) of 105 °C, whereas IT-C8 shows a Tg of 95 °C. Moreover, it is demonstrated that IT-C6 exhibits a higher hole-transporting mobility, more suitable band energy alignment, better interfacial contact, and passivation effect. The inverted devices of employed HTM based on IT-C6 obtained a champion PCE of 18.34% with a remarkable fill factor (FF) of 82.32%, whereas the IT-C8-based device delivered an inferior PCE of 16.94% with an FF up to 81.20%. Both HTMs embodied inverted devices present high FF values greater than 81%, which are among the highest reported values of small molecular HTM-based PSCs. This work reveals that cutting off the symmetrical spiro-core and subsequently combining IDT (attaching tailored alkyl chains) with the spiro-linkage fluorine to construct the orthogonal molecular conformation is a significant principle for the design of promising dopant-free HTMs.

Biopolymer-based optical hydrogels represent an emerging class of materials with potential applications in biocompatible integrated optoelectronic devices, bioimaging applications, and stretchable/flexible photonics. We have synthesized stimuli-responsive three-dimensional hydrogels from genetically engineered elastin-like polymers (ELPs) and have loaded these hydrogels with an amine-containing p-phenylenevinylene oligomer (OPPV) derivative featuring highly tunable, environmentally sensitive optical properties. The composite ELP/OPPV hydrogels exhibit both pH- and temperature-dependent fluorescence emission, from which we have characterized a unique optical behavior that emerged from OPPV within the hydrogel environment. By systematic comparison with free OPPV in solution, our results suggest that this distinct behavior is due to local electronic effects arising from interactions between the hydrophobic ELP microenvironment and the nonprotonated OPPV species at pH 7 or higher.

Phase change materials (PCMs) provide a state-of-the-art thermal energy storage capability and offer enormous potential for solar energy storage systems. However, the widespread adaptation of PCMs in advanced energy systems is often limited by low energy harvesting efficiency and poor shape stability. Thus, developing shape-stable PCMs for high-efficiency solar-thermal energy storage has remained an impediment to further advancement. Herein, we devised novel shape-stable composite PCMs based on monodispersed CuS disk-like nanoparticles and solid-solid PCM polyurethane (PU). In our devised composite system, the incorporated CuS nanoparticles act as a photonic nanoheater and the PU matrix acts as the heat reservoir which can store thermal energy via the latent heat while the phase transition occurs. The fabricated CuS@PU composite with 4 wt % doping of CuS nanodisks exhibits a phase change enthalpy of around 120 J/g, which is only 14% lower than that of the neat PU PCM. Owing to the solid-state phase transition of the PU PCM, only 0.6% of energy storage loss occurred over 100 repeated heating and cooling cycles. Besides, the solar-thermal energy storage efficiency of the CuS@PU composite exceeds 92% at 1 sun illumination under the full solar spectrum. Based on these outstanding thermophysical properties such as excellent shape stability, thermal stability, and thermal reliability, the developed CuS@PU composite PCMs are imperative candidates for real-world applications.

Objectives To explore the barriers to early diagnosis of HIV infection and timely initiation of antiretroviral therapy (ART). Methods We assessed the annual number and proportion of ART-naive people living with HIV infection (PLWH) with severe immunosuppression in Shenzhen, China, from 2008 to 2019. Selected ART-naive PLWHs with severe immunosuppression who were seeking treatment for the first time in the hospital in 2019 were subjected to an in-depth interview. Results The proportion of severely immunosuppressed, ART-naive PLWH decreased from 36.73% in 2008 to 8.94% in 2015, and then plateaued at approximately 10% from 2015 to 2019. Overall, 55 patients, 70% of whom were men who had sex with men, participated in the qualitative interviews. Ten of them delayed treatment after diagnosis, with a median [interquartile range (IQR)] interval of 5.83 (3.98-8.54) years between diagnosis and ART. More than 80% of the patients reported casual sexual contact within a median period of 6 years and with a median (IQR) of nine (4-20) casual sex partners. The major barriers to HIV testing and diagnosis included lack of knowledge about HIV and high-risk behaviours, low awareness about HIV testing, and resistance to HIV testing. The major barriers to ART initiation included lack of knowledge about the importance of ART and change of national ART eligibility policy, and HIV-related stress. Conclusions The number of PLWHs with severe immunosuppression who seek treatment remains high in Shenzhen, China. Thus, current HIV-related care programmes targeting access to early diagnosis and treatment need to be improved.

Objectives To investigate the seroreversion time in HIV-1-exposed but uninfected infants from two tertiary hospitals in China. Methods This study retrospectively investigated the data of perinatal, HIV-1-exposed infants from hospitals in Beijing and Shenzhen. Maternal and infant medical records from both hospitals from January 2009 to December 2019 were reviewed, and the HIV antibody seroreversion times of infants were determined. From 2009 to 2019, a total of 485 HIV-1-exposed but uninfected infants were enrolled. The majority of infants were born at term with normal birth weight. Results The seroreversion rates were 89.3%, 94.2% and 100% at 12, 18 and 24 months of age, respectively. There were no significant associations between seroreversion and several risk factors, such as gender, birth weight, gestational age, mode of delivery, postpartum prophylaxis and antiretroviral treatment duration. The mean value of HIV-specific immunoglobulin G concentration decreased from 15.4 at day 42 to 0.03 after 24 months in HIV-exposed, uninfected infants. Conclusions Clearance of HIV antibodies could take more than 18 months in a small number of perinatally exposed infants. Caution should be used in excluding or diagnosing perinatal HIV infection in children with long persistence of HIV antibodies.

We report measurements on ${\mathrm{Ti}}_{4}{\mathrm{MnBi}}_{2}$, where a crystal structure involving linear chains of Mn ions suggests one-dimensional magnetic character. The electrical resistivity is metallic, consistent with the results of electronic-structure calculations that find a robust Fermi surface albeit with moderate electronic correlations. A Curie-Weiss fit to the magnetic susceptibility suggests that the Mn moments are in the low-spin $S=1/2$ configuration. Neutron diffraction measurements detect weak antiferromagnetic order within the Mn chains, with further evidence for the small staggered moment coming from the entropy associated with the ordering peak in the specific heat as well as from the results of spin-polarized electronic-structure calculations. The antiferromagnetic moments are apparently associated with the ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ and ${d}_{xy}$ orbitals of Mn while the remaining Mn orbitals are delocalized and nonmagnetic. Strong quantum fluctuations, possibly related to an electronic instability that forms the Mn moment or to the one-dimensional character of ${\mathrm{Ti}}_{4}{\mathrm{MnBi}}_{2}$, nearly overcome magnetic order.

It is of great importance to develop highly efficient and stable Pt-free catalysts for electrochemical hydrogen generation from water electrolysis. Here, monodisperse 7.5 nm copper-doped ruthenium hollow nanoparticles (NPs) with abundant defects and amorphous/crystalline hetero-phases were prepared and employed as efficient hydrogen evolution electrocatalysts in alkaline electrolyte. Specifically, these NPs only require a low overpotential of 25 mV to achieve a current density of 10 mA cm-2 in 1.0 M KOH and show acceptable stability after 2000 potential cycles, which represents one of the best Ru-based electrocatalysts for hydrogen evolution. Mechanism analysis indicates that Cu incorporation can modify the electronic structure of Ru shell, thereby optimizing the energy barrier for water adsorption and dissociation processes or H adsorption/desorption. Cu doping paired with the defect-rich and highly open hollow structure of the NPs greatly enhances hydrogen evolution activity.

A mechanistic understanding of perovskite degradation is one of the most urgent issues to push perovskite devices toward commercial applications. Surface coverings will lower the electrical injection and light extraction efficiency of perovskites. Therefore, structural modification of Zn doped perovskites has been proposed herein. The Zn doping will induce local lattice strain due to smaller ionic radius. It is interesting that the lattice structure at atomic resolution has been observed directly through cryo-TEM. Under light illumination, the photostriction will compensate for the local lattice strain, which leads to structural stability as evidence suggests no phase transition in temperature ranges of the temperature-dependent photoluminescence spectra. In addition, MPZB also shows less than 3% decrease in PL intensity after 60 days. This is because the Zn doping induced the lowest defect density in the MPZB SC (density of trap-states n