Low Formation Energy Research Articles

Promoting Surface Reconstruction in Spinel Oxides via Tetrahedral‐Octahedral Phase Boundary Construction for Efficient Oxygen Evolution

AbstractUnderstanding the origin of surface reconstruction is crucial for developing highly efficient lattice oxygen oxidation mechanism (LOM) based spinel oxides. Traditionally, the reconstruction has been achieved through electrochemical procedures, such as cyclic voltammetry (CV), linear sweep voltammetry (LSV). In this work, we found that the surface reconstruction in LOM‐based CoFe0.25Al1.75O4 catalyst was an irreversible oxygen redox chemical reaction. And a lower oxygen vacancy formation energy (EO‐V) could benefit the combination of the activated lattice oxygen atoms with adsorbed water molecular. Motivated by this finding, a strategy of phase boundary construction from Co tetrahedral to octahedral was employed to decrease EO‐V in CoFe0.25Al1.75O4. The results showed that as the Co octahedral occupancy ratio rose to 64 %, a 3.5 nm‐thick reconstructed layer formed on the catalyst surface with a 158 mV decrease in overpotential. Further experiments indicated that the coexistence of tetrahedral‐octahedral (O−T) phase would result in lattice mismatch, promoting non‐bonding oxygen states and lowering EO‐V. Then more active lattice oxygen combined with H2O molecules to generate hydroxide ions (OH−), followed by soluble cation leaching, which enhanced the reconstruction process. This work provided new insights into the relationship between the intrinsic structure of pre‐catalysts and surface reconstruction in LOM‐based spinel electrocatalysts.

BiOBr/FeMoO4 composite achieves oxygen vacancy concentration adjustment to promote persulfate activation degradation of organic pollutants in saline water

The investigation about the mechanism of crystal plane regulation on the generation of oxygen vacancies remains a challenge. In this paper, BiOBr/FeMoO4 composites were synthesized by precise control of crystal plane growth, and it exhibited the enhanced concentration of oxygen vacancies due to lower formation energy of oxygen vacancies. The composite performs higher photo-Fenton-like ability for degrading oxytetracycline hydrochloride (OTC). Structural analyses and theoretical calculations reveal that crystal plane regulation induces significant changes in oxygen vacancy concentration. The BiOBr/FeMoO4/peroxydisulphate (PDS) /light system, which dominated by the non-radical pathway, degraded 96.8 % ± 1.0 % of OTC within 30 min. The activation mechanism of the system and the degradation pathway of OTC were elucidated. The intermediates in the degradation process of OTC were evaluated using liquid chromatograph-mass spectrometer (LC-MS), toxicity evaluation software tool (T.E.S.T) and soybean germination experiments. This work offers novel insights into the pivotal role of crystal plane directional regulation in the quantitative generation of oxygen vacancies.

First principles study of the electronic structure and Li-ion diffusion properties of co-doped LIFex-1MxPyNy-1O4 (M=Co/Mn, N[dbnd]S/Si) Li-ion battery cathode materials

In this work, a first-principles method based on density functional theory was systematically employed to investigate the stability, electronic properties, lithium-ion migration rates, and capacity-voltage curves of the LiFex-1MxPyNy-1O4 (M = Co/Mn, NS/Si) system. The results indicate that the lattice constants of the LiFex-1MxPyNy-1O4 (M = Co/Mn, NS/Si) system show little variation, and the system exhibits low formation and binding energies. Among the investigated systems, LFP-Mn/S demonstrates the best structural and thermodynamic stability. The bandgap of the doped systems decreases, leading to enhanced electronic conductivity. The LiFe0.875Co0.125P0.875Si0.125O4 and LiFe0.875Mn0.125P0.875Si0.125O4 systems remain semiconductors, while the LiFe0.875Co0.125P0.875S0.125O4 and LiFe0.875Mn0.125P0.875S0.125O4 systems exhibit semi-metallic properties due to the introduction of sulfur. Differential charge density calculations reveal changes in the covalent bond strength of the doped systems, with the introduction of Si and S respectively increasing and decreasing the covalency of their bonds with surrounding oxygen atoms. Additionally, doping reduces the Li-ion diffusion energy barriers, with the LiFe0.875Co0.125P0.875Si0.125O4 system exhibiting the lowest migration energy barrier. The Li-ion diffusion rate is four orders of magnitude faster than that of the intrinsic system. This is attributed to changes in the average lengths of Li–O, Co–O, and Fe–O bonds. Finally, doping also alters the de-lithiation voltage, with values ranging from 2.69 V to 3.65 V for the doped systems, and the LiFe0.875Co0.125P0.875Si0.125O4 system shows the highest complete de-lithiation voltage of 3.65 V. The overall performance improvements of the doped system have significant implications for enhancing the performance of Li-ion batteries.

Evolutionary Pathways of T-Phase Transition Metal Dichalcogenides: A Comprehensive Study of PtxSey Clusters.

Understanding the transition from nonplanar to planar clusters is crucial for the controllable synthesis of transition metal dichalcogenide (TMDC) monolayers. Using PtSe2 as a model, we investigate how the chemical environment influences the nucleation and growth stages of monolayer PtSe2 through structure searching and first-principles calculations. We established a comprehensive database of platinum selenide clusters (PtxSey, x = 1-10), analyzing 2095 unique clusters and identifying 191 stable isomers and 63 structures with the lowest formation energy on the convex hull. Our findings reveal a chemical environment-dependent phase transition from 3D structures to the planar T-phase of PtxSey clusters, representing an evolutionary route for PtSe2 growth. Clusters such as PtSe6, Pt2Se9, Pt3Se10, and Pt7Se10 in Pt-rich environments, as well as Pt2Se15 and Pt10Se32 in Se-rich environments, have been found to exhibit high stability. Additionally, the impact of varying chemical potentials of Pt and Se on the stability of these clusters is explored. PtSe4 and PtSe6 are found to be highly stable under most experimentally achievable chemical potential conditions and may serve as dominant precursors during PtSe2 growth. This work advances our understanding of the nucleation processes of PtSe2 and other T-phase TMDC materials.

Homo-Site Nucleation Growth of Twisted Bilayer MoS2 with Commensurate Angles.

Moiré superlattices, composed of two layers of transition metal dichalcogenides with a relative twist angle, provide a novel platform for exploring the correlated electronic phases and excitonic physics. Here, a gas-flow perturbation chemical vapor deposition (CVD) approach is demonstrated to directly grow MoS2 bilayer with versatile twist angles. It is found that the formation of twisted bilayer MoS2 homostructures sensitively depends on the gas-flow perturbation modes, correspondingly featuring the nucleation sites of the second layer at the same (homo-site) as or at the different (hetero-site) from that of the first layer. The commensurate twist angle of ≈22° in homo-site nucleation strategy accounts for ≈16% among the broad range of twist angles due to its low formation energy, which is in consistence with the theoretical calculation. More importantly, moiré interlayer excitons with the enhanced photoluminescence (PL) intensity and the prolonged lifetime are evidenced in the twisted bilayer MoS2 with a commensurate angle of 22°, which is owing to the reason that the strong moiré potential facilitates the interlayer excitons to be trapped in the moiré superlattices. The work provides a feasible route to controllably built twisted MoS2 homostructures with strong moiré potential to investigate the correlated physics in twistronics systems.

Stable crystal structure prediction using machine learning-based formation energy and empirical potential function

Crystal structure prediction aims to predict stable and easily experimentally synthesized materials, which accelerates the discovery of new materials. It is worth noting that the stability of materials is the basis for ensuring high performance and reliable application of materials. Among which, the thermodynamic and molecular dynamics stability is especially important. Therefore, this paper proposes a method to predict stable crystal structures using formation energy and Lennard-Jones potential as evaluation indicators. Specifically, we use graph neural network models to predict the formation energy of crystals, and employ empirical formulas to calculate the Lennard-Jones potential. Then, we apply Bayesian optimization algorithms to search for crystal structures with low formation energy and Lennard-Jones potential approaching zero, in order to ensure the thermodynamic stability and dynamics stability of materials. In addition, considering the impact of the bonding situation between atoms in the crystal on the structural stability, this article uses contact map to analyze the atomic bonding situation of each crystal to screen out more stable materials. Finally, the experimental results show that the method we proposed can not only reduce the time for crystal structure prediction, but also ensure the stability of crystal materials.

Experimental and theoretical assessment of bioinspired next-generation intercalated graphene oxide-based ceramic membranes for oil-in-water emulsion separation

2D graphene oxide (GO) membranes are gaining prominence for water reclamation from oily wastewater. Unresolved challenges include low membrane permeance from tight sheets and fouling during separation. In this work, a bioinspired Arabic gum (AG) was used as an intercalated agent with the help of glutaraldehyde to improve the GO membranes’ permeation and fouling resistance. The 2D-laminated separating layer is crafted through a self-assembling innovative approach utilizing pressurized dead-end assembly. The Arabic gum intercalated graphene oxide-modified ceramic membrane (AGIGO-CM) appeared superhydrophilic and underwater (UW) superoleophobic with a UW oil contact angle (UWOCA) of 156.1 ± 1.2°. The membrane prepared with 1 mg of AGIGO (AGIGO-1-CM) offers a flux of 17 times higher than pristine graphene oxide (p-GO) while maintaining a separation efficiency of >99% during the separation of the oil-in-water emulsions. Molecular dynamics (MD) simulations showed AG intercalation expanding the interlayer distance by up to 20 Å, with AGIGO having a higher fractional free volume (FFV) of 0.986 compared to p-GO’s 0.599. AGIGO-CM displayed lower interfacial formation energy (EIFE) of −1865.2 kcal/mol versus −765.5 kcal/mol for p-GO, indicating easier separation. It is further supported by the substantial interfacial thickness of 148 Å for AGIGO-CM compared to 53.0 Å for the p-GO membranes. AGIGO-CM showed minimal fouling, retaining >99% separation efficiency for 6 h. Compared to p-GO-CM, AGIGO-CM flux decreased by only 17.84% versus 44.72%. AGIGO-CM exhibited stability even in acidic and basic environments, showcasing its potential for high performance.

Template Selection Strategy for Synthesis of One-Dimensional CrSbSe3 Ferromagnetic Semiconductor Nanoribbons.

CrSbSe3─the only experimentally validated one-dimensional (1D) ferromagnetic semiconductor─has recently attracted significant attention. However, all reported synthesis methods for CrSbSe3 nanocrystals are based on top-down methods. Here we report a template selection strategy for the bottom-up synthesis of CrSbSe3 nanoribbons. This strategy relies on comparing the formation energies of potential binary templates to the ternary target product. It enables us to select Sb2Se3 with the highest formation energy, along with its 1D crystal structure, as the template instead of Cr2Se3 with the lowest formation energy, thereby facilitating the transformation from Sb2Se3 to CrSbSe3 by replacing half of the Sb atoms in Sb2Se3 with Cr atoms. The as-prepared CrSbSe3 nanoribbons exhibit a length of approximately 5 μm, a width ranging from 80 to 120 nm, and a thickness of about 5 nm. The single CrSbSe3 nanoribbon presents typical semiconductor behavior and ferromagnetism, confirming the intrinsic ferromagnetism in the 1D CrSbSe3 semiconductor.

Role of intrinsic point defects on electrocatalytic activity of a metal-free two-dimensional Polyaramid for enhanced hydrogen evolution reaction

Despite the current research aims at replacing expensive metals like Platinum with non-noble metals for producing hydrogen via hydrogen evolution reaction (HER), practical challenges like oxidation continue to be a significant concern. Our study aims at providing the metal-free alternative to such noble Pt-based catalysts. Taking care of the fact that the defects are inevitable during the material's growth process, we propose thermodynamically and thermally stable two-dimensional (2D) Polyaramid (2DPA) with possible intrinsic point defects as HER active materials with overpotentials comparable to that of Pt catalysts using density functional theory (DFT). Creating single carbon (VC), single nitrogen (VN), and single oxygen (VO) vacancies helps reducing its wide band gap upon creation of several defect states, thereby improving conductivity. VO-2DPA exhibits lowest ΔGH* value of −0.04 eV which is closest to thermoneutrality condition, i.e., ΔGH*≈0 while VN-2DPA is not found suitable for HER. The calculated low formation energies for generating point-vacancies under defect-poor growth conditions and the minimal bond length fluctuations within, serve as strong validation for the feasibility of their synthesis. Furthermore, underlying reaction mechanisms are also investigated for the HER process favouring the Heyrovsky reaction path over Tafel as the former requires lesser activation energy: 0.53 eV v. 0.86 eV for VC-2DPA and 0.34 eV v. 1.01 eV for VO-2DPA.

Vacancy formation modulating the local atomic environment for remarkable Multi-functional Magnetic properties in Ni–Co–Mn–In alloy

Defect (mainly vacancy) engineering has shown its potential for modulating the functional behavior of magnetic materials. In this work, dense Ni vacancies are introduced in Ni45Mn36.5In13.5Co5 alloy and the effect of these vacancies on the magnetic properties is both theoretically and experimentally clarified. In detail, Ni vacancy with the lowest formation energy is introduced by high energy electron irradiation, which shortens the distance between adjacent Mn atoms to strengthen the interaction between them and increase the corresponding magnetic moments, leading to the dTm/dH increase from −2.89 to 6.28 KT−1. As a result, a breakthrough in the magnetocaloric performance is correspondingly achieved, i.e., the entropy change (ΔSM) increases up to an ultra-high value of 48.15 J/(kg·K), much higher than all other reported values. Moreover, the reversible magnetostrain is also improved from 80 to 200 ppm. In summary, this work provides strong guidance for optimizing the magnetic performance of Ni–Mn based Heusler alloys via vacancy modulation.

Combined experimental and density functional theory approaches to address different mechanisms of nitrogen and sulfur doping on the enhancement of capacitive performance of hierarchical porous biochars

Activated carbon derived from biomass as hierarchical porous biochars (HPB) has been developed as electrode materials for supercapacitors. Nitrogen is known as the doping element that enhances quantum capacitance, but the mechanisms of sulfur doping on the quantum capacitance enhancement remain ambiguous. In this study, conventional approaches to assess the characteristics and capacitive performance of biochars were combined with density functional theory (DFT) calculations to assess different mechanisms of nitrogen and sulfur doping. The Bbiochar samples were prepared from the pyrolyzed fish bone powder at 800 °C without additional doping possessed a specific capacitance of 240 F g−1 at 1 A/g within 1 M H2SO4. Interestingly, additional nitrogen doping through urea mixing and additional sulfur doping through thiosulfate mixing prior to the pyrolysis enhanced the specific capacitance of biochar samples to exceed 400 F g−1 under the same condition. The urea mixed sample possessed low porosity but high charge transfer resistance, while the thiosulfate mixed sample possessed high porosity but low charge transfer resistance. The different underlying mechanisms were discussed through DFT calculations on graphene models designed based on the x-ray photoelectron spectroscopy (XPS) results. Nitrogen-doped configurations with topological defects mainly stored charge at the dangling atoms and possessed a relatively high quantum capacitance. Meanwhile, doped configurations of oxidized sulfur groups required relatively low formation energy and possessed large bond dipoles, corresponding to larger pore size and surface area of the thiosulfate mixed biochars. Understanding the contrary between effects of nitrogen and sulfur doping could resolve the bottleneck on enhancing the performance of electronic double layer supercapacitors.

Oxygen vacancy–rich K-Mn3O4@CeO2 catalyst for efficient oxidation degradation of formaldehyde at near room temperature

Synthesis of catalysts with high catalytic degradation activity for formaldehyde (HCHO) at room temperature is highly desirable for indoor air quality control. Herein, a novel K-Mn3O4@CeO2 catalyst with excellent catalytic oxidation activity toward HCHO at near room temperature was reported. In particular, the K addition in K-Mn3O4@CeO2 considerably enhanced the oxidation activity, and importantly, 99.3 % conversion of 10 mL of a 40 mg/L HCHO solution at 30 °C for 14 h was achieved, with simultaneous strong cycling stability. Moreover, the addition of K species considerably influenced the chemical valence state of Mn from +4 (ε-MnO2) to +8/3 (Mn3O4) on the surface of CeO2, which obviously changed the tunnel structure and the number of oxygen vacancies. One part of K species is uniformly dispersed on K-Mn3O4@CeO2, and the other part exists in the tunnel structure of Mn3O4@CeO2, which is mainly used to balance the negative charge of the tunnel and prevent collapse of the structure, providing enough active sites for the catalytic oxidation of HCHO. We observed a phase transition from tunneled KMnO2 to Mn3O4 to tunneled MnO2 with the decreasing K+ content, in which K-Mn3O4@CeO2 exhibited higher HCHO oxidation activity. In addition, K-Mn3O4@CeO2 exhibited lower oxygen vacancy formation and HCHO adsorption energies in aqueous solution based on density functional theory calculations. This is because the K species provide more active oxygen species and richer oxygen vacancies on the surface of K-Mn3O4@CeO2, promote the mobility of lattice oxygen and the room-temperature reduction properties of oxygen species, and enhance the ability of the catalyst to replenish the consumed oxygen species. Finally, a possible HCHO catalytic oxidation pathway on the surface of K-Mn3O4@CeO2 catalyst is proposed.

Atomically Precise Vacancy Lattices in Epitaxially Grown FeBr2 and CoBr2 on Au(111)

The generation of extensive 2D periodic patterns of point defects in 2D materials, such as vacancy lattices, has been a challenging task until now. Here, we report on 2D transition metal dihalides grown epitaxially on Au(111) featuring periodically assembled halogen vacancies that result in alternating coordination of the transition metal ion and can function as antidot lattices. [1] Using low-temperature STM/ncAFM and LEED, we identified the structural properties of intrinsically patterned FeBr2 and CoBr2 monolayers grown epitaxially on Au(111). Density-functional theory indicates that Br-vacancies are favored due to low formation energies, and the formation of a vacancy lattice substantially reduces the lattice mismatch with the underlying Au(111). We demonstrate that interfacial strain engineering presents a versatile strategy for controlled patterning in 2D with atomic precision over several hundred nanometers to solve a longstanding challenge of growing atomically precise antidot lattices.[1] https://doi.org/10.48550/arXiv.2305.06489

First-Principles study of the electronic Structure, Optical, and thermoelectric properties of novel WSeX (X=S, Te) Chalcogenides: For energy harvesting application

Excellent thermal stability and tunable optoelectronic features are twouniquecharacteristicsof ternary chalcogenides. The first −principles investigations were carried out to look into the intricate interactions between the optical, thermoelectric, and electronicfeatures of novel ternary chalcogenides. The stability of these studied materials was confirmed by the computed formation energy values. There is a strong correlation between the formation energy and the ionicity of W-X bonds, indicating that materials with lower formation energy are connected to a higher number of ionic bonds. The valence band maximum and conduction band minimum of both WSeS and WSeTe materials are located at the Γ-point, which confirms they are direct band gap semiconductors. The heavier element Te is incorporated, making the electronicstructure of WSeTe more complex than that of WSeS. The ε1(ω) was negative at higher photon energy, which is associated with these materials’ response being closer to that of a metallic in the specified energy range. WSeS and WSeTe exhibit peaks in ε2(ω) representing the highest densities of electronic states that can take part in optical transitions. As fewer states become accessible for the high-energy transitions that make these materials ideal for use in optoelectronics and photovoltaics, as confirmed by the n(ω) decreases as a result of a drop in absorption. The behavior of charge carriers and their interactions with the lattices leads to an almost linear increase in electrical thermal conductivity with temperature. Because electron–phonon scattering, the main type of scattering, increases with temperature, electrical conductivity in these materials often decreases as temperature rises.

Location preference of boron and nitrogen dopants at graphene/copper interface

Controlling the placement of dopants can significantly tailor graphene's properties, but this process is influenced by copper substrates during vapor deposition. Understanding the influence of interfacial atomic structures on the preference for dopant locations is crucial. In this work, we conducted a systematic first-principles study of boron- and nitrogen-doped graphene on copper {111}, considering both sublattice and superlattice configurations. Our calculations revealed that the formation energy is minimized at the top-fccb site (−0.60 eV) for boron and the hcp-fcca site (1.94 eV) for nitrogen, suggesting a possible selective distribution of dopants in both sublattice and superlattice arrangements at the graphene/copper interface. Furthermore, a lower formation energy indicates a higher release of energy during doping, resulting in a stronger interfacial binding. Since formation energy is closely associated with out-of-plane interactions, while in-plane interactions remain relatively stable, these differences offer potential avenues for modifying dopant distribution at graphene/copper interfaces.

Exploring defect engineering in monolayer TiS[formula omitted] for next-generation electronic devices: Insights from first-principles study

Titanium trisulfide monolayer (TiS3) is a quasi-1D crystal with promising applications in a range of fields, including photoelectrochemical cells and thermoelectrics. Despite the emerging importance of monolayer TiS3, little is known regarding its intrinsic defects. In this work, we systematically investigate the stability, electronic, and magnetic properties of native defects in single layer TiS3, using Density Functional Theory. We consider S and Ti monovacancies, divacancies, extended Ti-nS (n=2−8) vacancy complexes, S and Ti antisites, as well as their complexes. We show that the likelihood of the formation of sulfur vacancies is strongly dependent on the symmetrically inequivalent lattice site at which the S vacancy is located. Under S-rich conditions, single sulfur vacancies are shown to be energetically more favorable than divacancies. In contrast, under Ti-rich conditions sulfur divacancies are more favorable than single S vacancies. We show that STi and TiS1 are most likely to form under S-rich and Ti-rich conditions, respectively, with low formation energies of -10.42 eV and -9.18 eV, and are therefore likely to be prevalent in single layer TiS3. We further consider defect levels in the band-gap, and show that several of these intrinsic defects are potential n-type or p-type dopants, while others will form deep electron/hole traps. Further, we show that while a number of these intrinsic defects induce no spin in the host, most intrinsic defects will induce a net magnetic moment in the host. The commonality of these defects in TiS3, will significantly impact applications such as spintronics, thermoelectrics, and the manufacturing of electronic devices.

Stabilization of Sn2+ in FA0.75MA0.25SnI3 perovskite thin films using an electron donor polymer, PCDTBT, and an improvement in the charge transport properties of perovskite solar cells

Lead-free tin halide perovskites for the fabrication of perovskite solar cells have attracted considerable attention due to their outstanding optoelectronic and ecofriendly properties. These materials face severe issues, such as poor environmental stability, low formation energy and faster oxidation of tin from the Sn2+ to Sn4+ state, leading to poor film quality and self-doping. In this work, we have fabricated FA0.75MA0.25SnI3 perovskite thin films via a solution processing method and studied the conjugated polymer poly [N-9′-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadia-zole)] (PCDTBT)-induced effects in perovskite thin films. The micro-strain of PCDTBT-doped FA0.75MA0.25SnI3 perovskite reduced without any change in the crystal structure. Reductions in electron trap density have been observed due to improved film quality and enlarged perovskite grains. We have observed that the Sn4+ content in 0.050 wt% PCDTBT-doped FA0.75MA0.25SnI3 perovskite film gets reduced, as shown in the x-ray photoelectron spectroscopy (XPS) results. The reduction in Sn4+ (cause of self-doping) content shows that PCDTBT doping maintains the stability of Sn2+ in FA0.75MA0.25SnI3 perovskite thin film. A decrement in hole density from 3.2 × 1018 cm−3 for pristine films to 1.3 × 1017cm−3 for 0.050 wt% PCDTBT-doped FA0.75MA0.25SnI3 perovskite has been observed from C–V measurement, which is consistent with the XPS results. Thus, PCDTBT doping in perovskite films can effectively tackle the severe issues of tin oxidation and defects in the lead-free tin halide perovskite photoactive layer for solar cell application.

Geological Modeling of Shale Oil in Member 7 of the Yanchang Formation, Heshui South Area, Ordos Basin

In recent years, the Chang 7 member of the Mesozoic Triassic Yanchang Formation in the Ordos Basin has emerged as a significant repository of abundant and distinctive unconventional oil resources. The Heshui area boasts substantial shale oil reserves, with reported third-level reserves surpassing 600 million tons. However, the region in the southern part of Heshui is marked by pronounced variability in reservoir quality, intricate oil–water dynamics, low formation energy, and suboptimal fluid properties, leading to divergent development outcomes for horizontal wells. There is an imperative need to devise and refine new geological models to underpin the efficient exploitation of shale oil in the southern Heshui area. This study focuses on the shale oil reservoir of the Chang 7 member in the southern Heshui area of the Ordos Basin, conducting detailed stratigraphic correlation and establishing a refined isochronous stratigraphic framework. Utilizing PetrelTM modeling software (version 2018), we integrate deterministic and stochastic modeling approaches, adhering to the principles of isochronous and phased modeling. By assessing the thickness of sand and mudstone layers and the overall stratigraphic sequence, we derive a geological probability surface. Subsequently, this surface is harnessed to constrain the lithofacies, yielding a constrained lithofacies model. Employing sequential indicator simulation and sequential Gaussian stochastic simulation, we develop a reservoir attribute model that is anchored in the lithofacies model and its controls, culminating in a robust and dependable static model. Employing the geological probability surface constraint method, we meticulously construct the reservoir matrix model, amalgamating individual well data with the inherent certainty and randomness of reservoir plane thickness. This approach further enhances the model’s accuracy and mitigates the uncertainty and randomness associated with inter-well interpolation to a significant degree.

Ionic liquid engineering enables 1D/3D perovskite photovoltaics with > 25 % efficiency: A real-time study exploring formation mechanism of 1D perovskites

The advancements in low-dimensional/three-dimensional (LD/3D) perovskite devices represent a promising approach to enhancing both the efficiency and stability of of perovskite solar cells (PSCs). However, while significant efforts have been dedicated to understanding the role of already formed low-dimensional perovskites in passivating defects, refining the work function, little attention has been given to the crystallization process of LD perovskites, particularly when induced by ionic liquids (ILs) as green and stable additive. In this work, the formation process of IL Tetrabutylammonium Thiocyanate (TBASCN)-induced 1D perovskite onto the 3D perovskite under varying annealing conditions were explored by in-situ Grazing-Incidence Wide-Angle X-ray Scattering (GIWAXS) technology, providing a comprehensive investigation into the distinct impacts of 1D perovskite formed under diverse annealing processes on device performance. Owing to the robust interaction and favorable binding energy between the IL TBASCN and perovskite components, coupled with the low formation energy of 1D perovskites, 1D perovskites exhibit rapid formation on the surface of 3D perovskites and display markedly distinct crystallization processes under distinguished annealing conditions. Achieving full crystallization of 1D perovskites necessitates optimal temperature of 100 °C and adequate duration of 100 s. Once fully crystallized, the highly crystalline 1D perovskites and anions SCN- present in ILs can synergistically passivate defects in 3D perovskites, mitigate ion migration and impeding moisture infiltration. Benefiting from the optimized formation process of 1D perovskites, the champion device achieves a power conversion efficiencie (PCE) of 25.18 % and retains 91.0 % of its initial efficiency after 2000 h under RH=40 %. Our research provides new insights for optimizing the formation process of LD perovskites induced by different materials and their application in high-performance LD/3D PSCs.

Facilitating the Hydrogen Evolution Reaction on Basal-Plane S Sites on MoS2@Ni3S2 by Dual Ti and N Plasma Treatment.

Atomic engineering of the basal plane active sites in MoS2 holds great promise to boost the electrocatalytic activity for hydrogen evolution reactions (HER), yet the performance optimization and mechanism exploration are still not satisfactory. Herein, we proposed a dual-plasma engineering strategy to implant Ti and N heteroatoms into the basal plane of MoS2 supported by Ni3S2 nanorods on nickel foam (MSNF) for efficient electrocatalysis of HER. Owing to the low formation energy of Ti dopants in MoS2 and the extra charge carriers introduced by N dopants, the optimally codoped samples N1.0@Ti500-MSNF demonstrate significant morphology changes from nanorods to urchin-like nanospheres with the surface active areas increased by seven-fold, as well as enhanced electrical conductivity in comparison with the nondoped counterparts. The HER performance of N1.0@Ti500-MSNF is comparable with the Pt-based catalyst: overpotential of 26 mV at 20 mA cm-2, Tafel slope of 35.6 mV dec-1, and long-term stability over 50 h. First-principles calculation reveals that N doping accelerates the dissociation of water molecules while Ti doping activates the adjacent S sites for hydrogen adsorption by lowering the Gibbs free energy, resulting in excellent HER activity. This work thus provides an effective strategy for basal plane engineering of MoS2 heterostructures toward high-performance HER and sustainable energy supply at reasonable costs.