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Aims: Globally, the nursing shortage is a growing concern. Much of the research on retention of nurses focuses on the experience of those who left positions. In this study, we set out to listen to critical care nurses (CCRNs) who have chosen to remain in their positions to understand the factors retaining them in critical care. Design: This interpretive descriptive study was guided by the following research question: 'what factors influence CCRN's decision to continue to work in critical care?' Methods: Digitally recorded interviews and a focus group were conducted between July 2022 and January 2023 using a semi‐structured, strengths‐based interview guide with CCRNs from three critical care units at a tertiary hospital in a city in a central Canadian province. Transcribed interviews were analysed using open, axial and selective coding and constant comparative analysis. Results: Twenty‐two CCRNs participated in interviews and three in a focus group. The theme of Respect, demonstrated through the interconnected concepts of Working to Full Scope, Team, Rotations and Compensation was identified. Working to Full Scope was described as providing nursing care aligned with how each nurse envisions what nursing is. Being part of a Team led by strong nurse leaders that provides opportunities and supports the sharing of their perspectives was also found. Respect was also found to be demonstrated through Rotations that recognize that work is one part of these nurses' lives. Compensation that reflects the increased education, knowledge and skills required in critical care was the final concept of Respect. Conclusion: Organizations should focus their efforts across the identified concepts to demonstrate Respect for CCRNs and retain them. Implications for Practice: The findings of this study provide ways to support the retention of CCRNs. Impact: This research will have an impact on nursing leaders by providing tangible ways to retain CCRNs. Reporting Method: Reporting of this work was guided by the Standards for Reporting Qualitative Research. Patient or Public Contribution: No patient or public contribution. [ABSTRACT FROM AUTHOR]

This paper focusses on the complex relationship between vacancy, temporary responses and uncertainty during turbulent times by analysing how a selection of cities—New York City, São Paulo, Milan, Moscow, Abu Dhabi, Esfahan, Karachi, Mumbai and Jakarta—addressed testing, treating, isolating and vaccinating the public in response to the coronavirus (COVID-19) pandemic. These highly visible spatial responses offer immediate, pragmatic answers to unexpected conditions and, we argue, allow a more nuanced understanding of how planning might leverage flexibility and adaptability in a (post-)pandemic world. [ABSTRACT FROM AUTHOR]

Spinel ferrites demonstrate extensive applications in different areas, like electrodes for electrochemical devices, gas sensors, catalysts, and magnetic adsorbents for environmentally important processes. However, defects in the real spinel structure can change the many physical and chemical properties of spinel ferrites. Although the number of defects in a crystal spinel lattice is small, their influence on the vast majority of physical properties could be really decisive. This review provides an overview of the structural characteristics of spinel compounds (e.g., CoFe2O4, NiFe2O4, ZnFe2O4, Fe3O4, γ–Fe2O3, Co3O4, Mn3O4, NiCo2O4, ZnCo2O4, Co2MnO4, etc.) and examines the influence of defects on their properties. Attention was paid to the classification (0D, 1D, 2D, and 3D defects), nomenclature, and the formation of point and surface defects in ferrites. An in-depth description of the defects responsible for the physicochemical properties and the methodologies employed for their determination are presented. DFT as the most common simulation approach is described in relation to modeling the point defects in spinel compounds. The significant influence of defect distribution on the magnetic interactions between cations, enhancing magnetic properties, is highlighted. The main defect-engineering strategies (direct synthesis and post-treatment) are described. An antistructural notation of active centers in spinel cobalt ferrite is presented. It is shown that the introduction of cations with different charges (e.g., Cu(I), Mn(II), Ce(III), or Ce(IV)) into the cobalt ferrite spinel matrix results in the formation of various point defects. The ability to predict the type of defects and their impact on material properties is the basis of defect engineering, which is currently an extremely promising direction in modern materials science. [ABSTRACT FROM AUTHOR]

Filling of oxygen vacancies in manganese-oxide nanosheets with Pt single-atoms or nanoparticles yields nanozymes with high catalytic activity. Catalytic activity depended on the diameter of the Pt nanoparticles used for loading the nanosheet. Pt nanoparticles with intermediate diameters (3.0 nm), possessing well-developed (1 1 1) crystal planes, yielded equal catalytic activities as Pt single-atoms. [Display omitted] • Manganese-oxide nanosheets loaded with Pt single-atoms or Pt nanoparticles are compared. • Sheets with Pt single-atoms or 3.0 nm diameter Pt nanoparticles have high catalytic activities. • 1.5 nm Pt nanoparticles do not possess well-developed, highly reactive (1 1 1) crystal planes. • 7 nm Pt nanoparticles coalesce on a nanosheet, changing the Mn oxidation state. • Under-sized (1.5 nm) and over-sized Pt (7.0 nm) nanoparticles yield lower catalytic activity. Hybrid-nanozymes are promising in various applications, but comprehensive comparison of hybrid-nanozymes composed of single-atoms or nanoparticles on the same support has never been made. Here, manganese-oxide nanosheets were loaded with Pt-single-atoms or differently-sized nanoparticles and their oxidase- and-peroxidase activities compared. High-resolution Transmission-Electron-Microscopy and corresponding Fast Fourier Transform imaging showed that Pt-nanoparticles (1.5 nm diameter) had no clear (1 1 1) crystal-planes, while larger nanoparticles had clear (1 1 1) crystal-planes. X-ray Photo-electron Spectroscopy demonstrated that unloaded nanosheets were composed of MnO 2 with a high number of oxygen vacancies (V o /Mn 0.4). Loading with 7.0 nm Pt-nanoparticles induced a change to Mn 2 O 3 , while loading with 1.5 nm nanoparticles increased the number of vacancies (V o /Mn 1.2). Nanosheets loaded with 3.0 nm Pt-nanoparticles possessed similarly high catalytic activities as Pt-single-atoms. However, loading with 1.5 nm or 7.0 nm Pt-nanoparticles yielded lower catalytic activities. A model is proposed explaining the low catalytic activity of under- and over-sized Pt-nanoparticles as compared with intermediately-sized (3.0 nm) Pt-nanoparticles and single-atoms. Herewith, catalytic activities of hybrid-nanozymes composed of single-atoms and intermediately-sized nanoparticles are put a par , as confirmed here with respect to bacterial biofilm eradication. This conclusion facilitates a balanced choice between using Pt-single-atoms or nanoparticles in further development and application of hybrid-nanozymes. [ABSTRACT FROM AUTHOR]

Interfacial phase‐change materials (iPCM), which are alternatively stacked with GeTe and Sb2Te3 in the superlattice structure, have been highlighted as next‐generation PCM with improved overall phase‐change characteristics. However, several studies have reported that a melt‐quenching process, whereby the initial superlattice structure is not maintained within the reversible switching process, rather than the initially proposed melting‐free phase‐change mechanism, occurs during operation. Herein, GeSbTe superlattices are synthesized using molecular beam epitaxy, and the reversible phases of the superlattice obtained by irradiation with an optical pulsed laser (KrF; 280 nm, 25 ns) and re‐annealing or by applying different electrical pulses are investigated through careful structural analyses. The results revealed that Te atoms are aligned parallel to the interface regardless of the reversible phase, whereas cations and inherent vacancies are distributed differently during the phase‐change process. The stability of memory cells with cycling operations can be enhanced by enriching inherent vacancies, and the switching energy can be reduced by expanding the interspaces via doping engineering. [ABSTRACT FROM AUTHOR]

The crystalline dependent discharge process shows strong structure-reforming ability on surface and promotes the formation of vacancies and thus reducing the adsorption energy of intermediate. [Display omitted] Alkaline water electrolysis is apreferred technology for large-scale green hydrogen production. For most active transition metal-based catalysts during anodic oxygen evolution reaction (OER), the atomic structure of the anodic catalysts' surface often undergoes reconstruction to optimize the reaction path and enhance their catalytic activity. The design and maintenance of highly active sites during this reconstruction process remain critical and challenging for most OER catalysts. In this study, we explored the effects of crystal structures in pre-catalysts on surface reconstruction at low applied potential. Through experimental observation and theoretical calculation, we found out that catalysts with specific crystal structures exhibit superior surface remodeling ability, which enables them to better adapt to the conditions of the oxygen evolution reaction and achieve efficient catalysis. The discharge process enables the formation of abundant phosphorus vacancies on the surface, which in turn affects the efficiency of the entire oxygen evolution reaction. The optimized crystal structure of the catalyst results in an increase as high as 58.5 mA/cm2 for Ni 5 P 4 , which is twice as high as that observed for Ni 2 P. These results provide essential theoretical foundations and technical guidance for designing more efficient catalysts for oxygen evolution reactions. [ABSTRACT FROM AUTHOR]

Ternary halo‐sulfur bismuth compound Bi19X3S27 (X = Cl, Br, I) with distinct electronic structure and full‐spectrum light‐harvesting properties show great application potential in the CO2 photoreduction field. However, the relationship between photocatalytic CO2 reduction performance and the function of halogens in Bi19X3S27 is still poorly understood. Herein, a series of Bi19X3S27 nanorod photocatalysts with intrinsic X and S dual vacancies were developed, which showed significant near‐infrared (NIR) light responses. The types and concentrations of intrinsic vacancies were confirmed and quantified by positron annihilation spectrometry and electron spin resonance spectroscopy. Experimental results showed that Br atoms and intrinsic vacancies (dual Br‐S) in Bi19Br3S27 could greatly enhance the internal polarized electric field and improve the transfer and separation of photogenerated carriers compared with Bi19Cl3S27 and Bi19I3S27. Theoretical calculations revealed that Br atoms in Bi19Br3S27 could facilitate CO2 adsorption and activation and decrease the formation energy of reactive hydrogen. Among Bi19X3S27 nanorods, Bi19Br3S27 nanorods revealed the highest CO2 photoreduction activity with CO yield rate of 28.68 and 2.28 μmol gcatalyst−1 h−1 with full‐spectrum and NIR lights, respectively. This work presents an atomic understanding of the intrinsic vacancies and halogen‐mediated CO2 photoreduction mechanism. [ABSTRACT FROM AUTHOR]

Understanding the properties of lithium vacancy, LiCV, defects in diamond is crucial for optimizing diamond-based semiconductor performance and unlocking its full potential in advanced electronic applications. In this study, we present a comprehensive theoretical investigation of the neutral LiCV defect, resulting from the interaction between a lithium substitutional and a vacancy, in diamond. Employing periodic supercell calculations, we utilize global (B3LYP and PBE0) and range-separated (HSE06) hybrid functionals, as well as a local basis set, within the CRYSTAL17 code to analyze the relaxed lattice structure, formation energy, magnetic properties, and electronic structures of LiCV and other related isolated defects (LiC V and 2V). Our results reveal that LiCV exhibits three distinct spin states (doublet, quartet, and sextet) with significant differences in spin density distributions on first-neighbor carbon atoms. The quartet state is energetically favored by 0.09 eV and 0.88 eV (B3LYP) compared to the doublet and sextet states, respectively. The Li atom is positioned midway between the two vacancies in the LiCV defect, exhibiting a local D3d symmetry. Our findings reveal that the LiCV defect exhibits remarkable stability within the diamond matrix, with its dissociation into LiC and a vacancy (V) demanding a substantial energy barrier of 6.07 eV. In environments rich in vacancies, LiC shows a strong preference for binding with these vacancies, thereby facilitating the formation of LiCV complexes. Raman scattering calculations offer intriguing insights into the LiCV defect, revealing distinctive spectral features that significantly aid in distinguishing this particular defect among isolated lithium LiC and vacancy (V) defects. This observation is crucial, especially considering the challenges in fabricating shallow donors involving interstitial lithium in diamond, where preexisting vacancies can significantly influence the process. The comprehensive analysis provided in this study not only deepens our understanding of the LiCV defect and its physical properties but also enhances our ability to detect this defect during the synthetic process, and to precisely control the formation conditions. This capability is vital for optimizing the electronic properties of diamond for advanced technological applications. [ABSTRACT FROM AUTHOR]

The combination of single‐atom catalysts and vacancy engineering is an emerging hotspot in the field of single‐atom catalysis. The existence of vacancies provides additional adsorption sites, which can increase the adsorption capacity and diffusion rate of reactant molecules. Single atoms have single‐height atom utilization and steric hindrance effects. The two synergistically show different activation and synergistic processes on different defect materials. Under the synergistic effect of vacancies and single‐atom catalysts, they can affect the adsorption orientation of reactants on the catalyst surface and the formation of intermediate configurations, thereby regulating the reaction path and product selectivity, greatly enhancing the catalytic performance, and maximizing the catalytic effect of the material itself. Therefore, the synergistic effect between pervacancies and single‐atom catalysts can realize more efficient, sustainable, and economical catalytic reaction systems, possessing high‐efficiency performance in photocatalysis, electrocatalysis and thermocatalysis, and setting off a new wave in the fields of energy conversion, environmental protection, and organic synthesis. Therefore, catalysts constructed by vacancies and single atoms have broad and bright application prospects. [ABSTRACT FROM AUTHOR]

Nanoscale defects can induce the effective modulation of carrier concentration, mobility, and phonon scattering to secure high thermoelectric performance in semiconductors. However, it is still limited to effectively controlling nanoscale defects in thermoelectric materials. Here, argon plasma bombardment is employed to introduce a large number of point defects and dislocations in microcrystalline SnSe powders, synthesized by a solvothermal method. After sintering these powders into polycrystalline bulk materials, bulk SnSe shows the ZT increasing by up to 66.7% (from 0.36 to 0.6 at 773 K). Through detailed micro/nanostructure characterizations and first‐principles calculations, the underlying mechanism is elucidated for the evaluation of thermoelectric performance. This work provides a deep understanding of the mechanism of nanoscale defects in modulating thermoelectric performance and presents experimental evidence and experience for the design and synthesis of efficient thermoelectric materials, making significant contributions to future green energy technologies. [ABSTRACT FROM AUTHOR]

Using loan-level data, this analysis considers the intersection of race, subprime home loans, and the current vacancy crisis in St. Louis, Missouri. Borrowers in Black areas in the north of St. Louis City and St. Louis County received subprime home loans at higher frequencies during the subprime boom period of 2003–2007 than those in White areas, with differences in balloon loans especially stark. Specifically, borrowers in Black neighborhoods received subprime loans more frequently than those with equal FICO scores in White neighborhoods. As a result of these differential loan terms, North City and inner ring "First Suburb" areas saw more foreclosure and borrower payment delinquency, which in turn were highly associated with home vacancy, controlling for other risk factors. However, foreclosure was no longer a significant predictor of home vacancy after controlling for demographic factors and FICO score, indicating that the unequal loan terms may have driven much of the increase in home vacancy in the St. Louis area since the Great Recession. [ABSTRACT FROM AUTHOR]

Abstract This paper focusses on the complex relationship between vacancy, temporary responses and uncertainty during turbulent times by analysing how a selection of cities—New York City, São Paulo, Milan, Moscow, Abu Dhabi, Esfahan, Karachi, Mumbai and Jakarta—addressed testing, treating, isolating and vaccinating the public in response to the coronavirus (COVID-19) pandemic. These highly visible spatial responses offer immediate, pragmatic answers to unexpected conditions and, we argue, allow a more nuanced understanding of how planning might leverage flexibility and adaptability in a (post-)pandemic world.

[Display omitted] • A novel catalytic behavior was revealed in defective nanozymes. • Defects and self-supplied vacancies greatly boosted the generation of reactive oxygen species. • The catalytic behavior was confirmed for the degradation of tetracycline. • Defective nanozymes exhibited an ultrafast degradation rate (26.0 min−1 g−1 L). • Breaking the limitation of pH and expanding its scope of action (pH>5.0). Although nanozymes have shown significant potential in wastewater treatment, enhancing their degradation performance remains challenging. Herein, a novel catalytic behavior was revealed for defective nanozymes with catalase-mimicking characteristics that efficiently degraded tetracycline (TC) in wastewater. Hydroxyl groups adsorbed on defect sites facilitated the in-situ formation of vacancies during catalysis, thereby replenishing active sites. Additionally, electron transfer considerably enhanced the catalytic reaction. Consequently, numerous reactive oxygen species (ROS) were generated through these processes and subsequent radical reactions. The defective nanozymes, with their unique catalytic behavior, proved effective for the catalytic degradation of TC. Experimental results demonstrate that •OH, •O 2 −, 1O 2 and e− were the primary contributors to the degradation process. In real wastewater samples, the normalized degradation rate constant for defective nanozymes reached 26.0 min−1 g−1 L, exceeding those of other catalysts. This study reveals the new catalytic behavior of defective nanozymes and provides an effective advanced oxidation process for the degradation of organic pollutants. [ABSTRACT FROM AUTHOR]

Highlights Vacancy in the transition metal layer of sodium cathode material induces the formation lone-pair electrons in the O 2p orbital. Material delivers more capacity from the oxygen redox validated by density functional calculation. Widened dominance of the OP4 phase without releasing O2 gas.

Highlights: Vacancy in the transition metal layer of sodium cathode material induces the formation lone-pair electrons in the O 2p orbital. Material delivers more capacity from the oxygen redox validated by density functional calculation. Widened dominance of the OP4 phase without releasing O2 gas. This study explores the impact of introducing vacancy in the transition metal layer of rationally designed Na0.6[Ni0.3Ru0.3Mn0.4]O2 (NRM) cathode material. The incorporation of Ru, Ni, and vacancy enhances the structural stability during extensive cycling, increases the operation voltage, and induces a capacity increase while also activating oxygen redox, respectively, in Na0.7[Ni0.2VNi0.1Ru0.3Mn0.4]O2 (V-NRM) compound. Various analytical techniques including transmission electron microscopy, X-ray absorption near edge spectroscopy, operando X-ray diffraction, and operando differential electrochemical mass spectrometry are employed to assess changes in the average oxidation states and structural distortions. The results demonstrate that V-NRM exhibits higher capacity than NRM and maintains a moderate capacity retention of 81% after 100 cycles. Furthermore, the formation of additional lone-pair electrons in the O 2p orbital enables V-NRM to utilize more capacity from the oxygen redox validated by density functional calculation, leading to a widened dominance of the OP4 phase without releasing O2 gas. These findings offer valuable insights for the design of advanced high-capacity cathode materials with improved performance and sustainability in sodium-ion batteries. [ABSTRACT FROM AUTHOR]

Understanding the hydrogen (H) capacity, which represents the tritium capacity in Li2TiO3 crystal has become an important aspect of the tritium release process of nuclear fusion. In this work, a systematic density-functional-theory (DFT) study is performed to investigate the trapping and accumulation of H in Li2TiO3 crystal. In perfect crystal, the H adsorption properties are investigated and the maximum number of trapped H atoms are obtained. In the defect models, by calculating the trapping energy and Bader charge, we find that a Li vacancy can capture four H atoms while the capacity of a Ti vacancy is seven and then other H atoms tend to be trapped by interstitial sites outside the vacancy. Then the H capacity both inside and outside the vacancy in the defect models is studied and analyzed. According to our calculations, crystals containing a vacancy present stronger H trapping abilities than perfect crystals, especially for the crystal with a Ti vacancy. In addition, the increase of H atoms in the vacancy facilitates the formation of the neighboring vacancy so that more H atoms can be accommodated in the crystal with vacancy. Our results reveal the H capacity of different Li2TiO3 models, which provide theoretical support for related tritium release experiments. [ABSTRACT FROM AUTHOR]

In this work, effective modulation of the electronic and magnetic properties of Janus Si 2 PAs monolayer is proposed using vacancy engineering and doping with Ge atom. Pristine Si 2 PAs monolayer is a non-magnetic indirect gap two-dimensional (2D) material with energy gap of 1.29(2.47) eV obtained from PBE(HSE06)-based calculations. The monolayer is metallized under effects of single Si1 (bound to P atom), Si2 (bound to As atom), P, and As vacancies, preserving its non-magnetic nature. Similar effects are induced by creating P+Si1 double vacancies. Meanwhile, the diluted magnetic semiconductor nature is induced by As+Si2 and Si1+Si2 pair vacancies with total magnetic moment of 0.98 and 1.81 μ B , respectively. Herein, magnetic properties are produced mainly by As and P atoms around defect sites. Interestingly, the indirect-to-direct gap transition is achieved by doping with Ge atom at Si1 and Si2 sites, and simultaneous doping at both Si1+Si2 sites, where the energy gap exhibits only slight change. In these cases, similar valence electronic configuration of Ge and Si atoms leads to the preservation of the non-magnetic nature. In contrast, the monolayer is significantly magnetized by doping at P and As sites, as well as simultaneous doping at P+Si1 sites. Such that a total magnetic moment of 1.00 μ B is obtained, which is generated mainly by Ge impurities. The spin-polarized band structures assert the diluted magnetic semiconductor nature of these doped Si 2 PAs systems. Our results provide deep insights into the electronic properties of a new Janus Si 2 PAs monolayer, and propose efficient approaches to make potential optoelectronic and spintronic candidates from this 2D material. [ABSTRACT FROM AUTHOR]

We examine the utility of data on active and vacant residential addresses to inform local and timely monitoring and assessments of how areas impacted by wildfires and extreme weather events more broadly lose (or not) and subsequently recover (or not) their populations. Provided by the U.S. Postal Service to the U.S. Department of Housing and Urban Development and other users, these data are an underutilized and potentially valuable tool to study population change in disaster-affected areas for at least three reasons. First, as they are aggregated to the ZIP + 4 level, they permit highly local portraits of residential and, indirectly, of population change. Second, they are tabulated on a quarterly basis starting in 2010 through the most recent quarter, thereby allowing for timely assessments than other data sources. Third, one mechanism of population change—namely, underlying changes in residential occupancies and vacancies—is explicit in the data. Our findings show that these data are sufficient for detecting signals of residential and, indirectly, of population change during and after particularly damaging wildfires; however, there is also noticeable variation across cases that requires further investigations into, for example, the guidance the U.S. Postal Services provides its postal offices and carriers to classify addresses as vacant. [ABSTRACT FROM AUTHOR]

It is well known that carbon addition enhances the strength of steel, but it also increases the sensitivity to delayed fracture. The origin of the increased sensitivity to delayed fracture at higher carbon content is not clarified yet. In this study, high-strength steels with different carbon contents were fabricated, and their delayed fracture properties were evaluated. As the amount of carbon in the material increased, the carbon concentration at the grain boundary (GB) and the dislocation density also increased, and the material became more sensitive to delayed fracture. Subsequently, a GB model was developed on the basis of the samples used in the experiments, and the effect of hydrogen on the GB cohesive energy was evaluated using first-principles calculations. The cohesive energy without carbon atoms was 3.47 J/m² in the presence of hydrogen, whereas that with one additional carbon atom was 3.70 J/m². This result is inconsistent with the experimental results. Therefore, based on the dislocation density measurements, we assumed that more vacancies are generated in materials with higher carbon content. By adding a vacancy at the GB, the cohesive energy decreased to 1.79 J/m² and exhibited the same tendency as in the experiment. This suggests that not only hydrogen and carbon atoms but also vacancies are responsible for a decrease in delayed fracture resistance. [ABSTRACT FROM AUTHOR]

The paper presents the results of a theoretical study of the electronic structure and electrical conductivity of single-walled gold nanotubes with chirality indices (4, 0), (5, 0), (6, 0), (7, 0), (4, 4), and (5, 5). The simulations were performed using the density functional theory and the method of nonequilibrium Green's functions. The Perduew–Burke–Ernzerhof exchange-correlation functional and a two-exponential basis set were used. The importance of using polarized basis sets for the study of electrical properties of gold nanotubes is demonstrated. Analysis of the results showed that the transmission functions of the studied nanotubes depend on their structure in a complex way but, in general, increase with increasing diameter. The dependence of the transmission function on the electron energy does not allow us to speak a priori about the linearity of the current–voltage characteristic of gold nanotubes within a certain finite voltage range. In addition to defect-free single-walled gold nanotubes, gold nanotubes of different diameters with a vacancy-type defect-were also studied. This allowed us to evaluate the effect of such a defect on the atomic structure and electrical conductivity of the single-walled gold nanotubes. It was demonstrated that the conductivity drop can vary within a wide range, correlating with changes in the atomic structure. [ABSTRACT FROM AUTHOR]

Semiconductor photocatalysis is a promising method for utilizing solar energy to decompose water and degrade pollutants. However, the limited visible light absorption capacity and high carrier complexation rate hinder the utilization of sunlight for photocatalysts. The study prepared V O BiOBr/V S ZnIn 2 S 4 S-scheme heterojunction photocatalysts with sulfur and oxygen vacancies using a two-step solvothermal method. The photocatalyst was then used to simulate sunlight decomposition of water for hydrogen production and degradation of dye wastewater. Characterisation tests revealed that the incorporation of sulfur and oxygen vacancies effectively enhanced the visible light absorption of BiOBr and ZnIn 2 S 4. The construction of S-scheme heterojunction resulted in an improvement in visible light absorption capacity, as well as the promotion of separation and migration of photogenerated carriers. The study demonstrates that V O BiOBr/V S ZnIn 2 S 4 exhibits superior hydrogen precipitation and degradation properties compared to BiOBr/ZnIn 2 S 4 without S and O vacancies and V S ZnIn 2 S 4 without a heterojunction when subjected to simulated sunlight irradiation. The results of the tests and mechanistic analyses suggest that the synergistic effect of S and O vacancies and heterojunction enhances the photocatalytic performance. This study offers novel perspectives on the production of multifunctional photocatalysts that effectively utilize sunlight. [Display omitted] • Novel dual vacancy V O BiOBr/V S ZnIn 2 S 4 heterojunctions were successfully constructed. • V O BiOBr/V S ZnIn 2 S 4 photocatalysts demonstrate high photocatalytic activity under simulated sunlight. • The synergistic effect of vacancy and heterojunction greatly enhances the photocatalytic performance of ZnIn 2 S 4. • The built-in electric field at the heterojunction interface can effectively promote carrier separation. [ABSTRACT FROM AUTHOR]

In Asian countries, including Japan, the rapid demolition and new construction of housing continues, causing demand for old housing stock to fall. Employing unit-level listing information obtained from a real estate portal in the Tokyo rental housing market, this study differentiates vacancies by time dimension and documents that old properties are likely to spend a long time on the market, exceeding several months. This low demand for old houses can be attributed to functional obsolescence (lack of contemporary housing amenities and services) and owner resignation (lack of adequate countermeasures to fill vacancies regardless of their effectiveness). Our results indicate that even in popular property segments and neighbourhoods at the macro level, low demand broadly arises among old houses and is not always socially inefficient. Moreover, accelerating early redevelopment may improve social welfare by avoiding older properties sitting on the market for long periods. [ABSTRACT FROM AUTHOR]

The activation parameters for various iron structures were calculated by the analytical method based on the paired four-parameter Mie–Lennard-Jones interatomic interaction potential. Within the framework of a single method, all the activation processes parameters were calculated: Gibbs energy, enthalpy, entropy and volume for both the process of electroneutral vacancy formation and for the process of atom self-diffusion. The isobaric temperature dependences of the indicated activation parameters for BCC and FCC iron structures from T = 10 to 1810 K along two isobars: P = 0 and 10 GPa were calculated. It is shown that at the α–γ transition temperature (1184 K), the activation parameters decrease during the isobaric transition from the BCC to the FCC structure. At the γ–δ transition temperature (1667 K), the activation parameters increase during the transition from the FCC to the BCC structure. With increasing pressure, the jumps magnitude for the Gibbs energy and the enthalpy of the activation process increases, and for the entropy and volume of the activation process decreases. It is shown that, at low temperatures, due to quantum regularities, activation parameters strongly depend on temperature, and the entropy of activation processes in this region is negative. In the high temperature region, a good agreement has been obtained with the experimental estimates of activation parameters for different iron structures known from the literature. [ABSTRACT FROM AUTHOR]

The precise engineering of surface active sites is deemed as an efficient protocol for regulating surfaces and catalytic properties of catalysts. Defect engineering is the most feasible option to modulate the surface active sites of catalysts. Creating specific active sites on the catalyst allows precise modulation of its electronic structure and physicochemical characteristics. Here, we outlined the engineering of several types of defects, including vacancy defects, void defects, dopant-related defects, and defect-based single atomic sites. An overview of progress in fabricating structural defects on catalysts via de novo synthesis or post-synthetic modification was provided. Then, the applications of the well-designed defective catalysts in energy conversion and environmental remediation were carefully elucidated. Finally, current challenges in the precise construction of active defect sites on the catalyst and future perspectives for the development directions of precisely controlled synthesis of defective catalysts were also proposed. [ABSTRACT FROM AUTHOR]

This work highlights the novel approach of incorporating potassium iodide (KI) doping during the synthesis of In0.53P0.47 core quantum dots (QDs) to significantly reduce the concentration of vacancies (i.e., In vacancies; VIn−) within the bulk of the core QD and inhibit the formation of InPOx at the core QD–Zn0.6Se0.4 shell interfaces. The photoluminescence quantum yield (PLQY) of ~97% and full width at half maximum (FWHM) of ~40 nm were achieved for In0.53P0.47/Zn0.6Se0.4/Zn0.6Se0.1S0.3/Zn0.5S0.5 core/multi-shell QDs emitting red light, which is essential for a quantum-dot organic light-emitting diode (QD-OLED) without red, green, and blue crosstalk. KI doping eliminated VIn− in the core QD bulk by forming K+-VIn− substitutes and effectively inhibited the formation of InPO4(H2O)2 at the core QD–Zn0.6Se0.4 shell interface through the passivation of phosphorus (P)-dangling bonds by P-I bonds. The elimination of vacancies in the core QD bulk was evidenced by the decreased relative intensity of non-radiative unpaired electrons, measured by electron spin resonance (ESR). Additionally, the inhibition of InPO4(H2O)2 formation at the core QD and shell interface was confirmed by the absence of the {210} X-ray diffraction (XRD) peak intensity for the core/multi-shell QDs. By finely tuning the doping concentration, the optimal level was achieved, ensuring maximum K-VIn− substitution, minimal K+ and I− interstitials, and maximum P-dangling bond passivation. This resulted in the smallest core QD diameter distribution and maximized optical properties. Consequently, the maximum PLQY (~97%) and minimum FWHM (~40 nm) were observed at 3% KI doping. Furthermore, the color gamut of a QD-OLED display using R-, G-, and B-QD functional color filters (i.e., ~131.1%@NTSC and ~98.2@Rec.2020) provided a nearly perfect color representation, where red-light-emitting KI-doped QDs were applied. [ABSTRACT FROM AUTHOR]

Electrocatalytic water splitting seems to be an efficient strategy to deal with increasingly serious environmental problems and energy crises but still suffers from the lack of stable and efficient electrocatalysts. Designing practical electrocatalysts by introducing defect engineering, such as hybrid structure, surface vacancies, functional modification, and structural distortions, is proven to be a dependable solution for fabricating electrocatalysts with high catalytic activities, robust stability, and good practicability. This review is an overview of some relevant reports about the effects of defect engineering on the electrocatalytic water splitting performance of electrocatalysts. In detail, the types of defects, the preparation and characterization methods, and catalytic performances of electrocatalysts are presented, emphasizing the effects of the introduced defects on the electronic structures of electrocatalysts and the optimization of the intermediates' adsorption energy throughout the review. Finally, the existing challenges and personal perspectives of possible strategies for enhancing the catalytic performances of electrocatalysts are proposed. An in‐depth understanding of the effects of defect engineering on the catalytic performance of electrocatalysts will light the way to design high‐efficiency electrocatalysts for water splitting and other possible applications. [ABSTRACT FROM AUTHOR]

Abstract Ternary halo‐sulfur bismuth compound Bi19X3S27 (X = Cl, Br, I) with distinct electronic structure and full‐spectrum light‐harvesting properties show great application potential in the CO2 photoreduction field. However, the relationship between photocatalytic CO2 reduction performance and the function of halogens in Bi19X3S27 is still poorly understood. Herein, a series of Bi19X3S27 nanorod photocatalysts with intrinsic X and S dual vacancies were developed, which showed significant near‐infrared (NIR) light responses. The types and concentrations of intrinsic vacancies were confirmed and quantified by positron annihilation spectrometry and electron spin resonance spectroscopy. Experimental results showed that Br atoms and intrinsic vacancies (dual Br‐S) in Bi19Br3S27 could greatly enhance the internal polarized electric field and improve the transfer and separation of photogenerated carriers compared with Bi19Cl3S27 and Bi19I3S27. Theoretical calculations revealed that Br atoms in Bi19Br3S27 could facilitate CO2 adsorption and activation and decrease the formation energy of reactive hydrogen. Among Bi19X3S27 nanorods, Bi19Br3S27 nanorods revealed the highest CO2 photoreduction activity with CO yield rate of 28.68 and 2.28 μmol gcatalyst−1 h−1 with full‐spectrum and NIR lights, respectively. This work presents an atomic understanding of the intrinsic vacancies and halogen‐mediated CO2 photoreduction mechanism.

Fe2WO6, known for its potential in photocatalytic and electrocatalytic applications due to its chemical stability and band structure, can exhibit various defects that influence its performance. Density functional theory (DFT) calculations were employed to determine the formation energies of iron, tungsten, and oxygen vacancies under different thermo-chemical environments within the Fe-W-O ternary system. The study reveals that oxygen vacancies are more likely to form in reducing environments rich in FeO and Fe3O4 and it can offer practicality through facilitating the formation of reactive oxygen species (ROS), which contribute to photocatalytic performance. Meanwhile, the formation of iron vacancies is more readily achieved in oxygen-rich conditions, particularly when Fe-W-O compounds can be constructed. Similarly, tungsten vacancies form more often in oxygen-rich environments but less in iron oxide-rich conditions. In conclusion, this study provides a more comprehensive understanding of the nature of vacancy defects in Fe2WO6 and elucidates the environmental conditions that can be exploited to maximize or minimize vacancy formation for the control of catalytic activity.

Owning to the factors of external mechanical loads and high heat flux deposition, various degrees of strain or stress are inevitably introduced into the structural materials of nuclear fusion reactors. The uniaxial compression effects on the geometries, electronic structures, mechanical properties, and stabilities of Fe128Hen and Fe127VacHen were studied by first-principles calculations in this work. The results show that the lattice suffers from a noticeable inclination or disorder as the strain reaches 15%. The maximum stress of the stress–strain curves implied that the mechanical characteristics decay considerably as the number of He atoms increases, but the presence of a vacancy mitigated this effect. Compressive strain decreases the stability of Fe atom in the perfect pure Fe system, but it slightly elevates the monovacancy formation energy from Fe128He3 onward. According to the binding energy of He-He, compressive strain enhanced the aggregation of He. The migration barriers of an interstitial He atom exhibit anisotropy under uniaxial compressive strain, which was explained by the variations of the surrounding architectures.

Changes in the labor market are constantly occurring, and the IT specialist market is no exception. In this field, it is important to follow new trends in order to remain in demand as a specialist. In recent years, the demand for IT specialists has continued to grow, especially in the fields of software development, artificial intelligence, machine learning and cybersecurity. This opens up great opportunities for graduates of IT fields, especially in the light of universal digitalization and the transition to remote work. Currently, the market in the IT sector is striving for saturation, the offer of vacancies practically corresponds to demand. Employers are interested in mid- and high-level specialists. Applicants for IT professions require high salaries. For successful employment, you need to be a professional or go into scarce areas. The most in-demand and almost the only IT field where there is a shortage of specialists is 1C. The labor market in 1C is characterized by an excess of vacancies in relation to available resumes. A future specialist in this field should have skills in 1C programming, have knowledge in the subject areas of economics and continuously engage in their professional growth. Purpose – identification of trends in the labor market of IT specialties and employment prospects in the 1C stack. Methodology: the article used methods of analysis and synthesis of statistical information, methods of comparison and generalization. Results: the trend of increasing demand for 1C specialists in the labor market has been revealed. Practical implications it is advisable to apply the obtained results to enterprises, industries, municipalities, regions that monitor the labor market and the education system.

In this study, molecular dynamics (MD) simulations are employed to investigate the interactions between point defects and grain boundaries (GBs) in tungsten. Firstly, the segregation energy of vacancies (Vs) and self-interstitial atoms (SIAs) to GBs is examined. The results indicate that both Vs and SIAs tend to segregate towards GBs. Notably, the different types of GBs exhibit varying attraction to Vs and SIAs. The interaction radius is applied to investigate the degree of segregation, which is a significant index of GBs’ attraction to Vs and SIAs. The segregation radius of SIAs is typically larger than that of Vs. High-angle grain boundaries (HAGBs) show strong segregation for SIAs, facilitating the aggregation at GBs. Additionally, elastic theory is applied to qualitatively discuss the factors influencing the segregation energy distribution. The differences in atomic free volume caused by hydrostatic stress and the lattice distortion induced by point defects lead to Vs and SIAs occupying different sites. Finally, the nudged elastic band (NEB) method is employed to study the migration of Vs and SIAs near GBs, revealing that migration energy barriers for Vs and SIAs in GBs are much lower than in bulk. GBs facilitate the migration of point defects. Low-angle grain boundaries (LAGBs) present a higher energy barrier for V migration. Vs tend to occupy the compressive region, while SIAs tend to occupy the tensile region. Particularly, in comparison to Vs, SIAs are more likely to segregate to GBs due to higher binding energy, wider interaction radius, and extremely lower diffusion energy barrier. This provides some insights into the segregation and migration of point defects in GBs.

The thermoelectric performance of SnSe strongly depends on its low-energy electron band structure that provides high density of states in a narrow energy window due to the multi-valley valence band maximum (VBM). Angle-resolved photoemission spectroscopy measurements, in conjunction with first-principles calculations, reveal that the binding energy of the VBM of SnSe is tuned by the population of Sn vacancy, which is determined by the cooling rate during the sample growth. The VBM shift follows precisely the behavior of the thermoelectric power factor, while the effective mass is barely modified upon changing the population of Sn vacancies. These findings indicate that the low-energy electron band structure is closely correlated with the high thermoelectric performance of hole-doped SnSe, providing a viable route toward engineering the intrinsic defect-induced thermoelectric performance via the sample growth condition without an additional ex-situ process.

There is still a lack of research on the effect of the S and Fe vacancy on the adsorption mechanism of peroxide (H2O2) on the pyrite surface. In this work, the adsorption of H2O2 molecules on the perfect and defective pyrite surface is simulated based on density functional theory (DFT). The results indicated that the adsorption energy of H2O2 molecules on the S‐vacancy surface is relatively lower than that on the perfect surface and dissociative adsorption entirely occurs, while the adsorption behavior of H2O2 molecules on the S‐rich pyrite surface has not occurred. When the H2O2 molecules are adsorbed on the Fe‐rich pyrite surface, two products appear, one with two OH− species and the other with an H2O molecule and an O atom. The analysis of the transition state (TS) found that the dissociation of the H2O2 molecule producing two OH− species that bond with two Fe atoms is more likely to occur. In addition, based on the coordination chemistry, it is demonstrated that Fe atoms are more reactive around an S vacancy than on a perfect surface. [ABSTRACT FROM AUTHOR]

Surface chemistry and bulk structure jointly play crucial roles in achieving high-performance supercapacitors. Here, the synergistic effect of surface chemistry properties (vacancy and phosphorization) and structure-derived properties (hollow hydrangea-like structure) on energy storage is explored by the surface treatment and architecture design of the nanostructures. The theoretical calculations and experiments prove that surface chemistry modulation is capable of improving electronic conductivity and electrolyte wettability. The structural engineering of both hollow and nanosheets produces a high specific surface area and an abundant pore structure, which is favorable in exposing more active sites and shortens the ion diffusion distance. Benefiting from its admirable physicochemical properties, the surface phosphorylated MnCo2O4.5 hollow hydrangea-like structure (P-MnCoO) delivers a high capacitance of 425 F g−1 at 1 A g−1, a superior capability rate of 63.9%, capacitance retention at 10 A g−1, and extremely long cyclic stability (91.1% after 10,000 cycles). The fabricated P-MnCoO/AC asymmetric supercapacitor achieved superior energy and power density. This work opens a new avenue to further improve the electrochemical performance of metal oxides for supercapacitors. [ABSTRACT FROM AUTHOR]

Ceramic samples of Mn 1- x Zr x WO 4 (0.00 ≤ x ≤ 0.20) were prepared by a solid-state reaction to study changes in the structural, magnetic, and dielectric properties of multiferroic MnWO 4 caused by replacing Mn2+ ions with Zr4+ ions. The results indicate that Zr4+ replacement caused lattice deformation but did not affect the monoclinic lattice structure of any of the MnWO 4 samples. The concentration of vacancies, investigated by positron annihilation lifetime spectroscopy, increased with as the Zr4+ content x from 0.00 to 0.20. It was observed that Zr4+ replacement enhanced the dielectric constant of Mn 1- x Zr x WO 4 but slightly increased the dielectric loss. The magnetization and transition temperatures (T AF3 and T AF2) of the Mn 1- x Zr x WO 4 system were increased by the Zr4+ replacement, and the existing temperature range of the AF2 phase was extended upon the substitution of Zr4+ for Mn2+. This study demonstrated that the magnetic properties of Mn 1- x Zr x WO 4 were closely related to the vacancy concentration and lattice distortion. [ABSTRACT FROM AUTHOR]

TiC-14 wt%TiC 0.4 and TiC-7.63 wt%Ti ceramics were fabricated by spark plasma sintering (SPS) at a sintering temperature of 1600 °C and an applied pressure of 40 MPa. The impact of ex-situ addition and in-situ formation of vacancies on the microstructures and mechanical properties of TiC composites were investigated. The microstructures were analysed by XRD, SEM, EDS and TEM. The results reveal that TiC 1-x phases with different Ti/C ratios exist in the TiC-14 wt%TiC 0.4 ceramics, which have the same crystal structure and similar lattice parameters. In contrast, only a single phase of TiC 1-y exists in the TiC-7.63 wt%Ti ceramics. The introduced carbon vacancies not only lowered the sintering temperature, but also had a toughening effect on the material. At a sintering temperature of 1600 °C, the TiC-14 wt%TiC 0.4 and TiC-7.63 wt%Ti materials had densities of 98.5% and 99.2%, both materials exhibited excellent mechanical properties Vickers hardness and fracture toughness of 22.5 GPa, 5.2 MPa m1/2 and 23.5 GPa, 4.9 MPa m1/2, respectively. [ABSTRACT FROM AUTHOR]

Annealing behaviors of vacancy‐type defects in ion‐implanted GaN are studied by positron annihilation. Mg+ and N+ ions are implanted to obtain 700 nm deep box profiles with Mg and N concentrations of 1 × 1018 cm−3, and the samples are annealed using an ultrahigh‐pressure annealing system. For as‐implanted samples, the major defect species is identified as Ga‐vacancy (VGa)‐type defects. For N‐implanted GaN, the size of the vacancies increases as the annealing temperature increases up to 1100 °C and then shrank above 1200 °C. This behavior is attributed to recombinations between N‐vacancy (VN)‐type defects and excess N. For Mg‐implanted GaN, the major defect species after annealing above 1000 °C is vacancy clusters such as (VGaVN)3. Some of them act as nonradiative recombination centers for blue and ultraviolet luminescence. Their energy levels corresponding to the transition from positive to neutral are located between 2.6 eV above the valence band maximum and the conduction band minimum. The thermal activation process of electron detrapping from the vacancy clusters is also studied. For Mg‐implanted GaN, one of the major secondary defects is collapsed vacancy disks forming dislocation loops. They are eliminated by additional N implantation, which is associated with vacancy agglomerations under the annealing in VGa‐rich condition. [ABSTRACT FROM AUTHOR]

Following the global financial crisis, an increasing amount of attention has been directed towards examining the Beveridge curve (BC), which indicates the relationship between unemployment and vacancy rates. This research analyzes the unemployment–vacancy rate dynamics in the Turkiye labor market during both the global financial crisis and COVID-19 periods. The findings from this study demonstrate that the labor market exhibits deteriorating efficiency, as evidenced by movement of BC away from the origin. The unemployment and vacancy rates both increase over time, with a leftward (rightward) shift of BC during the global financial crisis (COVID-19) period. The study also reveals that both crises had no significant effect on unemployment–vacancy rate dynamics. In the Turkish labor market, there exists a situation where the vacancy rate is in shortfall of the unemployment level in Turkiye. This creates a positive relationship between these two factors. The labor market in Turkiye experiences inefficiencies as it struggles to generate a sufficient number of jobs to meet the demand from job seekers. [ABSTRACT FROM AUTHOR]

Molybdenum disulfide (MoS2) exhibits exceptional mechanical and wear properties combined with thermal stability, which makes it an outstanding solid lubricant. While numerous studies have reported on the tribological behavior of few-layer pristine MoS2, little attention has been given to the impact of defects, such as sulfur vacancies, which are inevitable during large-scale fabrications. Understanding the factors that affect friction at the atomic level is essential for the design and optimization of high-performance materials. Here, we present a systematic study of the tribology of one- and two-layer MoS2 nanosheets, with controllably introduced atomic vacancies, performed by atomic force microscopy. We find that the friction coefficient of mono- and bilayer MoS2 suffers more than a 3-fold increase from the as-prepared layer (with an initial defect density of 1 × 1012 cm–2) to those with an induced atomic defect density of 1.2 × 1013 cm–2. Comparison of the results reported here with analogous results in graphene shows that MoS2 presents an attractive high resilience of the friction coefficient to monatomic defect generation in the atomic defect density range typically obtained by scalable techniques. [ABSTRACT FROM AUTHOR]

We performed first principles calculations to study silicon carbide (SiC) crystal structure of mechanical with five interatomic potentials. We calculate elastic constants, bulk, shear, Young's moduli, hardness, and Poisson's ratio for polytypes of SiC. For each property, we report perfect and deformity crystal structures. In perfect condition, we appear the cubic structure (3C) is the most steady than hexagonal structures (4H, 6H). We compare interatomic potentials for structural parameters, formation energy, and elastic constants. Among potentials Edip, Meam, Tersoff 2005, and Vashishta are the most excellent results in lattice parameters, cohesive energy, density, and cell volume. Additionally, Tersoff 2005 is a better potential for elastic properties and formation energy calculation. We follow our calculations by investigating the brittleness/ductility of SiC by calculating Stability conditions, Cauchy's pressure, Pugh's ratio, and hardness. Among mechanical properties, we find out less stability in the point defect effect on hexagonal structures. The calculated results indicate that silicon vacancy has more rate in the mechanical properties; however, the C44, bulk shear, and Young's modulus are comparable to higher changing within the three types of SiC structures. In the random vacancy of SiC, C11, and C12 have a swing than carbon and silicon vacancies. Moreover, we demonstrate that carbon vacancy has a higher range than other vacancies. [ABSTRACT FROM AUTHOR]

A vacancy-rich Co/MnO@NC was synthesized using hydrothermal and high-temperature pyrolysis strategies for oxygen reduction reaction (ORR). The abundant vacancies and synergistic coupling of metallic Co with MnO precisely tuned the electronic configuration, resulting in enhanced electron transport within Co/MnO@NC. Research indicates that the effective Co/MnO@NC ORR catalyst demonstrated elevated peak power densities, reaching 217.7 in liquid-state and 63.3 mW cm−2 in solid-state zinc-air batteries. [Display omitted] • Spherical Co/MnO@NC is synthesized by a hydrothermal-pyrolysis strategy. • The catalyst displays notable ORR activity (J L = 5.1 mAcm−2) comparable to Pt/C. • Aqueous/solid-state ZABs exhibit high power density (217.7/63.3 mW cm−2). • Vacancies, conductivity and hydrophilicity dominate the delightful performance. The pursuit of efficient and economically viable catalysts for liquid/solid-state zinc-air batteries (ZABs) is of paramount importance yet presents formidable challenge. Herein, we synthesized a vacancy-rich cobalt/manganese oxide catalyst (Co/MnO@NC) stabilized on a nitrogen-doped mesoporous carbon (NC) nanosphere matrix by leveraging hydrothermal and high-temperature pyrolysis strategy. The optimized Co/MnO@NC demonstrates fast reaction kinetics and large limiting current densities comparable to commercial Pt/C in alkaline electrolyte for oxygen reduction reaction (ORR). Moreover, the Co/MnO@NC serves as an incredible cathode material for both liquid and flexible solid-state ZABs, delivering impressive peak power densities of 217.7 and 63.3 mW cm−2 and robust long-term stability (459 h), outperforming the state-of-the-art Pt/C and majority of the currently reported catalysts. Research indicates that the superior performance of the Co/MnO@NC catalyst primarily stems from the synergy between the heightened electrical conductivity of metallic Co and the regulatory capacity of MnO on adsorbed oxygen intermediates. In addition, the abundance of vacancies regulates the electronic configuration, and superhydrophilicity facilitates efficient electrolyte diffusion, thereby effectively ensuring optimal contact between the active site and reactants. Besides, the coexisting NC layer avoids the shedding of active sites, resulting in high stability. This work provides a viable approach for designing and advancing high-performance liquid/solid-state ZABs, highlighting the great potential of energy storage technology. [ABSTRACT FROM AUTHOR]

The presented main studies of point defects in CdGa2Se4 chalcopyrite are considered to quantify the formation energies of three possible models of Cd, Ga and Se vacancy defects using various local density approximation (LDA) and general gradient approximation (GGA) approximations. Using supercells with 56 atoms, interatomic distances were calculated both for an ideal cell and a supercell containing vacancies. It was found that interatomic distance does not change only in a supercell containing Ga vacancy. Investigation shows that the Ga vacancy has a high defect formation energy (DFE) among other intrinsic vacancies and is therefore unstable. We found that for all vacancies, − 2 charge states are favorable. [ABSTRACT FROM AUTHOR]

The rational design of an electrocatalyst with excellent catalytic activity and high stability is at the core of large-scale hydrogen production from water splitting. As a fascinating, innovative class of effective electrocatalysts for hydrogen evolution reaction (HER), two-dimensional (2D) pentagonal noble metal sulfide MX 2 (M = Pd, Pt; X = S, Se, Te) have emerged as promising materials, but they are still suffering from the intrinsic activity for practical applications. The catalytic performance of the catalyst was adjusted by optimizing the electronic configuration of the catalyst and introducing Janus asymmetry and defect engineering. Here, we successful designed and demonstrated 2D defect Janus pentagonal noble metal sulfide materials (defect penta-MXY; M = Pd, Pt; X,Y S, Se, Te (X≠Y)). The results show that the catalytic performance was significantly improved after the introduction of defects and Janus, with the best hydrogen adsorption Gibbs free energy (from |ΔG H* |>1eV of penta-MX 2 to |ΔG H* |<0.2 eV of defect penta-MXY), and has excellent exchange current density (−16.96 A cm2). Interestingly, among the six catalysts, penta-PtSSe-V Se , penta-PdSSe-V Se , penta-PtSTe-V Te and penta-PtSeTe-V Te have higher work functions (∼5.52 eV), which promote the Volmer reaction step of HER at lower overpotentials (The energy barrier of penta-PtSSe-V Se 1 is only 1.01 eV). Moreover, we further revealed that the penta-MXY-V Y 1 materials exhibit excellent thermal and electrochemical stability, and the reasons for the improvement of electrocatalytic activity were investigated by studying the charge density difference, Bader charges, crystal orbital Hamilton population and d-band center (The penta-PtSSe-V Se 1 is −0.15 eV). The procedure followed in this work may be extended to the Janus pentagonal materials, thus expanding their potential application fields. • First-principles study of hydrogen evolution reaction. • Introducing Janus Asymmetry and Defect Engineering in Penta-MX 2. • The higher work function of penta-MXY promoted the hydrogen evolution reaction. • The Gibbs free energy of penta-PtSSe-VSe is as low as 0.02 eV. [ABSTRACT FROM AUTHOR]

The presented main studies of point defects in CdGa2Se4 chalcopyrite are considered to quantify the formation energies of three possible models of Cd, Ga and Se vacancy defects using various local density approximation (LDA) and general gradient approximation (GGA) approximations. Using supercells with 56 atoms, interatomic distances were calculated both for an ideal cell and a supercell containing vacancies. It was found that interatomic distance does not change only in a supercell containing Ga vacancy. Investigation shows that the Ga vacancy has a high defect formation energy (DFE) among other intrinsic vacancies and is therefore unstable. We found that for all vacancies, − 2 charge states are favorable. [ABSTRACT FROM AUTHOR]

Exploring efficient non-precious metal sulfides as electrocatalysts for the hydrogen evolution reaction (HER) is crucial. Cobalt disulfide (CoS 2) has gained attention for its favorable intrinsic activity, impressive metal conductivity, and cost-effectiveness. However, the weak adsorption of H* at the sulfur (S) sites on the surface of CoS 2 leaves room for enhancing its HER intrinsic activity. Vacancy engineering emerges as a valuable strategy to modulate the local charge density, optimizing hydrogen adsorption free energy and catalytic performance in HER. Taking advantage of plasma technology, known for its rapid and efficient defect creation, we synthesized porous CoS 2 nanowire arrays enriched with S vacancies (V s -CoS 2 /CC) through Ar plasma treatment. Notably, at a current density of 10 mA cm−2, V s -CoS 2 /CC exhibits a lower overpotential (170 mV) compared to pure CoS 2 /CC (236 mV). Furthermore, V s -CoS 2 /CC demonstrates exceptional electrochemical stability. Experimental data and density functional theory calculations jointly reveal that introducing S vacancies reduces local charge density around S atoms, activating inert sulfur sites and enhancing the intrinsic activity of CoS 2 for HER. This study introduces a novel concept of defect-engineered activation in metal compound catalysts, employing a plasma approach to advance HER performance. [Display omitted] • By introducing V s through plasma treatment, V s -CoS 2 /CC is obtained. • V s -CoS 2 /CC exhibits excellent HER catalytic performance. • The introduction of V s activates the inert S sites in CoS 2. [ABSTRACT FROM AUTHOR]