Interfacial Electronic Properties Research Articles

Controllable electrical contact characteristics of graphene/Ga2X3 (X = S, Se) ferroelectric heterojunctions

Reducing the interface barrier between metals and semiconductors is crucial for designing high-performance optoelectronic devices based on van der Waals heterojunctions (HJs). This study proposes four models of HJs composed of graphene (GR) and Ga2X3 (X = S, Se) and systematically investigates their interface electronic properties, along with strain engineering and electric field effects. The results indicated that exploiting the interface dipole-induced potential step allows modulation of the Schottky barrier height (SBH) and contact type of the HJs by altering the contact interfaces. In the BGR/Ga2S3 HJs (BGR means GR positioned at the bottom of Ga2X3), only a small positive (negative) electric field is required to realize the transition from n-type Schottky to p-type Schottky (Ohmic) contacts. Also, strain engineering provides additional means for flexible and controllable contact types, facilitating the design of reversible logic circuits. It indicates the physical insights and strategic interventions of GR/Ga2X3 HJs tunable SBH and offers theoretical guidance for the design of two-dimensional ferroelectric nanodevices with high-quality electrical contact interfaces.

First-principles study of the structure, magnetism, and electronic properties of the all-Heusler alloy Co2MnGe/CoTiMnGe(100) heterojunction.

Based on first-principles calculations in the density functional theory, we systematically investigated the possible interface structure, magnetism, and electronic properties of the all-Heusler alloy Co2MnGe/CoTiMnGe(100) heterojunction. The calculation indicated that the Co2MnGe Heusler alloy is a half-metal with a magnetic moment of 4.97μB. CoTiMnGe is a narrow-band gap semiconductor and may act as an ultra-sensitive photocatalyst. We cannot find an "ideal" spin-polarization of 100% in CoCo termination and MnGe termination. Due to the interface interaction, the direct magnetic hybridization or indirect RKKY exchange will be weakened, leading to an increase in the atomic magnetic moment of the interfacial layer. For eight possible heterojunction structures, the half-metallic gaps in the Co2MnGe bulk have been destroyed by the inevitable interface states. The spin-polarization value of 94.31% in the CoCo-TiGe-B heterojunction revealed that it is the most stable structure. It is feasible to search for high-performance magnetic tunnel junction by artificially constructing suitable all-Heusler alloy heterojunctions.

Intrinsic polarity extend β-Ga2O3/Janus-XP (X=P, As) heterostructures potential in UV/IR dual-band photodetector: A theoretical study

Although β-Ga2O3/black phosphorus (α-BP) has been employed to realize ultraviolet and infrared (UV/IR) dual-band photodetector, how to employ intrinsic polarity to improve the optoelectronic properties of β-Ga2O3/α-BP heterostructure further has not been demonstrated yet. Here, by investigating the interfacial electronic and optical properties of β-Ga2O3/Janus-XP (X=P, As) heterostructures with intrinsic polarity, we found that all β-Ga2O3/Janus-XP heterostructures exhibit type-II band alignment, regardless of the direction of intrinsic polarity. Moreover, β-Ga2O3/Janus-AsP heterostructures with intrinsic polarity possess stronger stability, more effective charge transfer with a lower tunneling barrier, and better UV/IR dual-band optical detection, which could be further improved when the direction of intrinsic polarity points away from the interface. The underlying mechanism is the extra carriers driving force introduced by intrinsic polarity. Our findings provide a deep understanding of β-Ga2O3/Janus-XP heterostructures and suggest an effective way to design high-performance β-Ga2O3 UV/IR dual-band photodetectors.

Interfacial electronic modulation of NiCo decorated nano-flowered MoS2 on carbonized wood as a remarkable bifunctional electrocatalyst for boosting overall water splitting

The development of a cost-effective and efficient bifunctional electrode for overall water splitting holds significant importance in accelerating the sustainable advancement of hydrogen energy. The present study involved a bifunctional catalytic electrode was prepared by loading NiCo-modified 1 T/2H MoS2 onto carbonized wood (NiCo-MoS2-CW) using the hydrothermal and electrodeposition techniques. The XPS analysis revealed that NiCo-modified MoS2 exhibited a weak electron characteristic, which facilitated the ionization of H2O and significantly enhanced the Volmer step. The XPS analysis unveiled that NiCo-modified MoS2 displayed a weak electron characteristic, thereby promoting the ionization of H2O and substantially augmenting the Volmer step. The electrocatalytic performance of the NiCo-MoS2-CW in 1.0 M KOH is remarkably impressive, exhibiting minimal overpotentials of only 64 mV (10 mA cm−2) and 216 mV (50 mA cm−2) for the hydrogen evolution reaction and oxygen evolution reaction, respectively. The NiCo-MoS2-CW || NiCo-MoS2-CW electrolytic cell can achieve a cell voltage of only 1.69 V to achieve a current density of 50 mA cm−2. Overall, this study proposes a potential approach to improve the catalytic efficiency of overall water splitting by modulating the interfacial electronic properties of MoS2.

Adsorption structure and properties of Ni/Fe electrodeposition interface: a DFT study

The density functional theory calculations of the adsorption model of NiCl2, Ni, and Cl on the Fe surface, as well as interface electronic properties, provide theoretical guidance for improving the Ni electrodeposition process. The adsorption properties of these three species on the Fe (100) crystal surface at different coverages, and the adsorption properties of the single Ni on three different crystal surfaces of Fe (100), Fe (110), and Fe (111), were studied through calculations of adsorption energy, charge density, charge occupancy, and DOS. The results indicate that the H sites are the most favorable for the adsorption of Ni and Cl on the Fe (100) surface. T sites, B sites, and H sites are all potential adsorption sites for NiCl2. The order of adsorption strength is Ni > Cl > NiCl2. In response to changes in charge, the adsorption effect exhibits a negative correlation with surface coverage. In addition, the hybridization of Ni’s 3d orbitals, Cl’s 3p orbitals, and Fe’s 3d orbitals changes the distribution of the interface charge, resulting in an increase of the charge in the Fe surface. Ni exhibits better adsorption performance on Fe (100) surface, driven by the lattice structure, surface electron configuration, and Ni–Fe atomic interactions.

Pd promoted oxygen species activation of ZnO nanosheets for enhanced hydrogen sensing performance and its DFT investigation

The sensing performance of ZnO-based metal oxide semiconductors to H2 can be significantly enhanced after decoration of noble metals, and it is of great significant to understand the mechanism and structure-activity relationship between materials and sensing performance, which facilitate the designation of high-performance sensing materials. Herein, we have synthesized Pd-decorated two-dimensional (2D) ZnO nanosheets. A contrastive study based on H2 gas sensing performance of pristine ZnO and Pd-loaded ZnO (PZO) are carried out. According to the results, PZO exhibit superior sensing performance towards H2 (Ra/Rg=17.6, 160 °C), which is much higher than the pristine ZnO nanosheets. Moreover, the PZO also exhibit robust sensing stability and selectivity, detailed structural investigations illustrate that the electronic and surface properties of Pd-ZnO interface play the vital role in H2 sensing process. Density functional theory (DFT) calculation illustrates that H atoms trend to be dissociated at the surface Pd0 sites and the more surface oxygen vacancies are extremely desirable for H2 sensing. The superior H2 sensing of PZO is mainly attributed to the synergistic mechanism of Pd catalytic site and oxygen vacancy (OV). Our works pave the way for designation of high performance H2 sensing materials for the safety of development and utilization of H2.

Influence of interposed graphene sheets on mechanical and electronic properties of Al/graphene superlattice

Graphene-reinforced aluminum matrix composites have drawn remarkable attention in several fields of high-tech industries, but the understanding of their material properties remains unclear. This work reports a first-principles study of interface binding nature, mechanical strength, and electronic properties of aluminum/graphene (Al/G) composites using superlattice models as varying graphene content. Our calculations reveal the weak binding between Al and graphene layers with no new chemical bonding at the interface and the gradual decrease in binding strength as increasing graphene content. While demonstrating the enhancement of mechanical strength by interposing graphene layers, the critical value of graphene content for keeping ductility is determined to be 14.7%. Atom-projected band structures and local density of states are analyzed to get an insight into electronic conductance of superlattices.

Structures, electronic properties, and delithiation thermodynamics of the heteroepitaxial α-Al2O3//LiMn2O4 (001) and (111) interfaces

Surface coatings play a pivotal role in enhancing the performance of secondary lithium-ion batteries by mitigating undesirable electrolyte activity towards the cathode materials. Metal oxide candidates have been investigated extensively, with α-Al2O3 emerging as a particularly promising coating material owing to its exceptional mechanical and thermal stability alongside low electrical conductivity. Despite the extensive exploration of this application of α-Al2O3, insight into the interplay between the coating layer and the cathode substrate remains incomplete. To address this lack of knowledge, this study employs density functional theory calculations with a Hubbard Hamiltonian and long-range dispersion corrections (DFT+U-D3) to comprehensively investigate the interfacial geometries, stabilities, and electronic properties of α-Al2O3-coated LiMn2O4 (001) and (111) interfaces of varying thicknesses. The individual surfaces were modelled first before constructing the interfaces. We found that the α-Al2O3 (112¯0) and (0001) surfaces match the LiMn2O4 (001) and (111) facets well, exhibiting {1132} and {3121} configurations, respectively, with corresponding misfits of 2.40 and 2.75 %. We calculated the largest adhesion energies of 0.16 and 0.10 eV/Å2 for monolayers with the {1132} and {3121} configurations, respectively, with the stability decreasing as the thickness of the α-Al2O3 layer increases. Further analysis reveals a minor charge accumulation on the substrate, attributed to charge accumulation on the oxygen atoms that participate in the Al-O bond. In contrast, we observed a depletion of charge on the manganese atoms that form the MnO6 units. The vacancy formation energies increase following partial delithiation, prompting minor charge depletion on neighbouring Mn atoms in the form of charge redistribution. The calculated work function increases with respect to the pristine surfaces, indicating that the coated interfaces are less reactive.

The first-principles and ab initio molecular dynamics simulations revealing the interface energy of the NbC/α-Fe

The low index interfacial configuration, interface energy and electronic properties of NbC/α-Fe are calculated using the first-principles method based on density functional theory and ab initio molecular dynamics simulation. Additionally, the NbC/α-Fe interface with the low index interfacial configuration is calculated by two-dimensional disregistry method. It is demonstrated that the Fe-C type has an interface energy of -1.553 J/m2 , the smallest interface energy and the most stable structure, therefore the Fe-C type is the most stable conformation of the NbC(001) /α-Fe(001). Strong orbital resonance phenomenon exists between Fe-3d, Nb-4d and C-2p, producing strong metallic and covalent bonds. The results of disregistry calculation by different interfacial structures of NbC/α-Fe shows that the disregistry of NbC(001)/α-Fe(001) crystalline surface is the smallest at 10.19%, which corresponds to the results of interface energy calculation. It can be shown that the α-Fe(001) is the optimal orientation surface of the NbC(001) . Herein, we have revealed the site-oriented and stable bonding mode relationship of NbC/α-Fe interface in steel, which provides important theoretical guidance to explore the mechanism of grain refinement of NbC particles in shipbuilding steels.

The Energy Level Alignment at the Buffer/Cu(In,Ga)Se2 Thin‐Film Solar Cell Interface for CdS and GaOx

AbstractSputter‐deposited GaOx (i.e., oxygen‐deficient gallium oxide) films are evaluated as a potential replacement for the standard CdS buffer layers in Cu(In,Ga)Se2 (CIGSe) based thin‐film photovoltaics. The energy level alignment at the GaOx/CIGSe and CdS/CIGSe interfaces are compared by means of direct and inverse photoemission. For the GaOx/CIGSe a (0.04 ± 0.07) eV (i.e., a small spike‐like) conduction band offset (CBO) and a (−3.21 ± 0.19) eV (i.e., a large cliff‐like) valence band offset (VBO) are found, which suggests a nearly ideal charge‐selective contact. The derived GaOx band gap of (4.80 ± 0.25) eV confirms its utility as a highly transparent buffer layer. However, the GaOx (with x derived to be 1.1 ± 0.1) exhibits considerable (presumably) defect‐related occupied states above the valence band maximum. It is proposed that these states may increase charge carrier recombination and decrease open circuit voltage in respective devices; also explaining why solar cells with standard CdS buffer outperform devices with GaOx buffer, despite less ideal electronic interface properties (CBO: (−0.18 ± 0.07) eV, VBO: (−0.98 ± 0.15) eV) and the smaller CdS band gap of (2.35 ± 0.22) eV.

High‐performance BCN‐C heterostructured electrocatalyst derived from covalent triazine frameworks for nitrogen reduction

AbstractDesigning and synthesizing heterostructure‐based catalysis combining two‐dimensional (2D) materials has attracted enormous attention in materials chemistry, especially for electrocatalysis, due to their tunable electronic properties and structure. In this work, a boron carbon nitride (BCN)‐coupled carbon (BCN‐C) heterostructure with improved electronic performance was synthesized starting from C‐ and N‐enriched 2D covalent triazine frameworks (CTFs) via a simple thermal transformation process using NaBH4 as the B source. The characterizations results showed that the B released from NaBH4 reacted with N and C in CTF, forming the BCN‐C heterostructure coupling the BCN and carbon with a strong interfacial effect. The electrocatalytic NRR experiments and density functional theory (DFT) calculation revealed that the interfacial electronic properties and large numbers of active sites of the BCN‐C heterostructure benefited the NRR. The BCN‐C‐1 catalyst showed a high Faradaic efficiency of 27.8% and an NH3 yield of 4.3 μg h−1 mgcat.−1 in 0.1 M HCl electrolyte, owing to its high specific surface area (288 m2/g) with a large number of exposed active sites and the Mott–Schottky effect from the BCN‐C heterostructure. This work highlights the design and synthesis of metal‐free catalysts with high activity and selectivity and makes them excellent candidates for electrocatalytic applications.

Unraveling the origin of the high photocatalytic properties of earth-abundant TiO2/FeS2 heterojunctions: insights from first-principles density functional theory.

Herein, first-principles density functional theory calculations have been employed to unravel the interfacial geometries (composition and stability), electronic properties (density of states and differential charge densities), and charge carrier transfers (work function and energy band alignment) of a TiO2(001)/FeS2(100) heterojunction. Analyses of the structure and electronic properties reveal the formation of strong interfacial Fe-O and Ti-S ionic bonds, which stabilize the interface with an adhesion energy of -0.26 eV Å-2. The work function of the TiO2(001)/FeS2(100) heterojunction is predicted to be much smaller than those of the isolated FeS2(100) and TiO2(001) layers, indicating that less energy will be needed for electrons to transfer from the ground state to the surface to promote photochemical reactions. The difference in the work function between the FeS2(100) and TiO2(001) heterojunction components caused an electron density rearrangement at the heterojunction interface, which induces an electric field that separates the photo-generated electrons and holes. Consistently, a staggered band alignment is predicted at the interface with the conduction band edge and the valence-band edge of FeS2 lying 0.37 and 2.62 eV above those of anatase. These results point to efficient charge carrier separation in the TiO2(001)/FeS2(100) heterojunction, wherein photoinduced electrons would transfer from the FeS2 to the TiO2 layer. The atomistic insights into the mechanism of enhanced charge separation and transfer across the interface rationalize the observed high photocatalytic activity of the mixed TiO2(001)/FeS2(100) heterojunction over the individual components.

The interface structural, electronic and optical properties of ZnO nanowires/Graphene nanohybrid (ZnO NWs/G): Experimental and theoretical DFT investigations

In this work, a ZnO nanowires/graphene nanohybrid was synthesized by a three steps approach. Copper substrates were covered with graphene by chemical vapor deposition, further ZnO nanowires were electrochemically deposited on the as grown graphene on copper and finally a transfer process was employed for moving the heterostructure onto a different substrate. A comprehensive structural analysis which included scanning electron microscopy, X-ray diffraction and Raman measurements revealed that the ZnO nanowires crystallize in wurtzite structure perpendicular to graphene, the process leading to the formation of a nanohybrid heterostructure. The band gap energy of the ZnO nanowires deposited on graphene was estimated to be 3.11 eV, as calculated from the reflectance spectrum analysis. The GGA-PBE+U within Grimme (DFT-D) approach was used to provide an accurate description of the interface structure in terms of electronic and optical properties, confirming that the decrease in the band gap energy of ZnO nanowires is caused by the interaction with the graphene surface. The findings of this study could serve as an experimental and theoretical reference for upcoming studies on ZnO NWs/Graphene nanohybrid-based optoelectronic applications.

Controlled dynamic variation of interfacial electronic and optical properties of lithium intercalated ZrO2/MoS2 vdW heterostructure

Efficient strategies for modifying the characteristics of van der Waals (vdW) layered materials in a precise and reversible mode remain challenging. Our suggested method for customization entails the implementation of layer-sliding and intercalation. In this work, a norm-conserving approach within the context of density functional theory has been used to examine the electronic and optical properties of two-dimensional (2D) van der Waals heterostructure (vdWHS), which is modeled by using 2D zirconium dioxide (1T-ZrO2) and molybdenum disulfide (1T-MoS2) monolayers of similar phase. Both contributing monolayers have similar lattice structures, with a minimum lattice mismatch of 0.83 %, and have corrugation on both sides that can successfully retain foreign species at the vdW-gap. In the next step, interfacial engineering through Li-intercalation and layer-sliding was employed to modify physical properties of the vdWHS. It is the worth mentioning that a narrow bandgap of 0.102 eV (0.22 eV) has been observed in the unintercalated ZrO2/MoS2 vdWHS when employing PW-LDA (hybrid-functional). Li-intercalation and sliding process significantly influenced the electronic properties of the studied vdWHS. Furthermore, un-slided and fully-slided Li-intercalated vdWHS exhibit an increase in the vdW-gap by 3.78 % and 27.14 %, respectively, as compared to unintercalated vdWHS. To further understand the electrical behaviour at the interface of contributing monolayers, a comparative study has also been made for the variation in the planar average charge density difference, charge transfer, and interface dipole moment for unintercalated and intercalated vdWHS. In the unintercalated vdWHS, the calculated values of ΔQ and μ(z) provide evidence of significant charge transfer from 1T-ZrO2 to 1T-MoS2 before sliding, whereas in the fully-slided vdWHS, there is 80.11 % more charge transfer from 1T-MoS2 to 1T-ZrO2. Li-intercalation increases the magnitude of ΔQ (by 90.27 %) near 1T-MoS2, indicating a sufficient quantity of charge transfer from the 1T-MoS2 monolayer. The results of the anisotropic analysis show that the calculated in-plane and out-of-plane components of the real and imaginary parts of the dielectric function differ significantly. The optical absorption and energy losses of Li-intercalated vdWHS experience a substantial decrease of about 90 % and 50 %, respectively, as compared to unintercalated vdWHS. Our employed method promotes the notion that interfacial engineering through simultaneous layer-sliding and intercalation approach can be used to regulate and modify the physical properties of 2D insulator/metal based vdWHS.

CO adsorption on two-dimensional 2H-ZrO2 and its effect on the interfacial electronic properties: implications for sensing

Environmental pollution is commonly caused by direct and indirect greenhouse gasses and various traces of toxic gasses. CO is a tasteless, colourless and highly hazardous greenhouse gas that can bind with the hemoglobin much easier than oxygen. Materials with effective CO sensing capability are highly desirable. In this work, we have studied the repercussions of the molecular adsorption of toxic carbon monoxide (CO) on the structural, electronic, interfacial electronic and gas sensing properties of the two-dimensional (2D) 2H phase of zirconium dioxide (2H-ZrO2) using density functional theory (DFT) calculations. The most suitable adsorbent structure is screened out and interaction strengths between adsorbate molecule and adsorbent layer are provided in terms of binding energies. As a result of CO adsorption, the energy band gap (Eg) is altered and the resulting change in the conductivity of 2H-ZrO2 monolayer has implications for sensing. Energy band profiles relating to CO adsorbed 2H-ZrO2 reveal that fermi level shifts towards conduction bands exhibiting a development of n-type semiconducting character. Eg values relating to pristine and CO adsorbed 2H-ZrO2 sites such as TM, H, CB and B are 1.58, 1.98, 2.05, 2.06 and 2.03 eV, respectively. Further insights into the adsorption reveal that charge is accumulated near 2H-ZrO2 in the case of H and B adsorption sites, whereas for the case of TM and CB sites, depletion is noted. Essential gas sensing properties such as conductivity sensitivity (S), and recovery time (τ) are also reported. Notably, TM, CB, and B absorption sites depicted 17%, 2%, and 6% lower S values than H site. Furthermore, the H site achieved a shorter (32 ps) than the other adsorption sites. Response of pristine and CO adsorbed 2H-ZrO2 to that of incident photons is investigated with the help of real and imaginary parts [ and ] of complex dielectric function, electron energy loss function [] and joint density of states [] for a broader range of 0 to 10 eV. Major differences in dielectric function exist along in-plan and out-of-plan directions. After a detailed comparison, it is reported that more number of optical transitions exist between the linked states for the case of CO adsorbed 2H-ZrO2.

Achieving controllable multifunctionality through layer sliding

Dynamical variation of physical properties in a controllable fashion provides exciting possibilities to obtain multifunctional materials. In this work, layer-sliding is employed to modify the structural, interfacial electronic and optical properties of unintercalated and Mg-intercalated two-dimensional (2D) van der Waals heterostructure (vdW-HS) consisting of buckled silicene and hexagonal boron nitride (hBN). The most stable stacking configuration of silicene over hBN is screened out and then intercalated with Mg at the interface. Dynamical-dependent changes in the properties of vdW-HS are performed by sliding silicene over hBN monolayer in the absence and presence of the intercalant. Layer-sliding is carried out in equal length intervals, and various parametric quantities related to the physical characteristics of the vdW-HS are repeatedly calculated and compared. Apart from various parametric quantities, stability of unintercalated and Mg-intercalated vdW-HS is also checked by means of relative total energies, binding energies and vdW gaps along the sliding pathway. Comparison of binding energies shows that the un-slided, half-slided, and fully-slided Mg-intercalated vdW-HS are 1.52, 1.44 and 1.42 eV more stable than the unintercalated vdW-HS. Opening of a small band gap of 12, 31 and 28 meV for un-slided, half-slided and fully-slided unintercalated vdW-HS, respectively, is worth mentioning. To study the interfacial electronic behavior, planar average charge density difference (Δρ) and charge transfer (ΔQ) are also calculated and varied via layer-sliding. Further, we calculated diverse optical spectra such as the complex dielectric function (DF), electron energy loss function [L(ω)], diagonal components of dielectric tensor [ε(iω)], refractive index [n(ω)], extinction coefficient [k(ω)], absorption coefficient [α(ω)], and reflectivity [R(ω)] for un-slided, half-slided and fully-slided unintercalated and Mg-intercalated vdW-HS. Interestingly, the polarization and energy losses have been reduced in the case of Mg-intercalated vdW-HS. The suggested layer-sliding method can be established as a general scheme for bringing multifunctionality into a layered material.

First principles calculation of interfacial stability, electronic and mechanical properties of WC-304 cemented carbides

Based on first-principles Density functional theory (DFT), the binding work, interface energy, electronic structure and interface bonding mechanism of WC-304 stainless steel with Fe-Cr-Ni cemented carbides were calculated. The results show that the interface between Fe (100) and WC (100) C-teminations has the lowest interface distance and the highest binding work when it is constructed with MT position. The subsitution of Fe atoms with Ni atoms results in a decrease in the interfacial distance, measured at 0.9412 Å, accompanied by a simultaneous increase the adhesion work to 9.3647 J/m2. The stability of the interface structure is significantly influenced by the bonding strength of FeC bonds. Furthermore, the CCr bond at the interface exhibits greater strength compared to the CW bond when the W atom is replaced by Cr atom. Therefore, the doping of Cr and Ni atoms in 304 stainless steel results in a more stable interface structure between WC and Fe. The results have important guiding significance for improving the interfacial strength and stability of WC-Fe cemented carbide.

Interfacial electronic properties of hybrid interfaces

A detailed understanding of interfacial electronic properties of organic–inorganic hybrid junctions is crucial for their technological applications. In case of organic–inorganic hybrid junctions information about interfacial charge transfer, band bending and work function is crucial for efficient charge carrier movement across interfaces. In this context, investigation of filled and empty starts near Fermi level is relevant in molecular electronics to know electron affinity, and charge injection barriers. A multi-technique approach using ultraviolet photoemission and Inverse photoemission spectroscopy provides quantitative information about frontier occupied and unoccupied states near Fermi level, thereby providing crucial information about energy level alignment. Inverse photoemission spectroscopy technique is particularly helpful for the study of the electronic properties at metal–molecule interfaces and thus provides information about transport gap for conjugated organic molecules. Organic molecular beam epitaxy has been extensively utilized to deposit conjugated organic molecular thin films on various oxide, transition metal dichalcogenides and metallic substrates. Novel approaches have been investigated explored in order to control the interfacial energy level alignment by introducing intermediate electron donor and electron acceptor organic molecular layers across interfaces to tune the work function of electrodes. This review summarizes recent advances in exploiting combined approach using photoemission and inverse photoemission spectroscopy for the investigation of electronic properties of conjugated organic molecular interfaces.

Structure and Electronic Properties of SrTiO3–TiO2 Eutectic for Water Splitting Applications

Semiconductors with bandgaps and edges corresponding to the solar energy spectrum are found to be suitable for the water splitting applications using photoelectrochemical reactions. However, many present‐day materials used in these applications do not have high stability and/or high effectiveness over the complete sunlight spectral range. The recently proposed eutectic compounds, which combine two or more semiconducting materials, can overcome many present difficulties and extend the light absorbance spectrum improving the effectiveness of the water splitting cells. Herein, structural and electronic properties studies of the SrTiO3–TiO2 eutectic material, which is a representative example of this family, are presented. It is found that structural properties of this material, particularly the phase separation and formation of the sharp interface between two phases, can be significantly improved up on the thermal annealing, which is very important for their application in the water splitting reactors. The findings present the deep understanding of the interface structure and electronic properties of the SrTiO3–TiO2 eutectic, which can help to improve the functionality of these class of materials in different applications.

Boosting Electro- and Photo-Catalytic Activities in Atomically Thin Nanomaterials by Heterointerface Engineering.

Since the discovery of graphene, two-dimensional ultrathin nanomaterials with an atomic thickness (typically <5 nm) have attracted tremendous interest due to their fascinating chemical and physical properties. These ultrathin nanomaterials, referred to as atomically thin materials (ATMs), possess inherent advantages such as a high specific area, highly exposed surface-active sites, efficient atom utilization, and unique electronic structures. While substantial efforts have been devoted to advancing ATMs through structural chemistry, the potential of heterointerface engineering to enhance their properties has not yet been fully recognized. Indeed, the introduction of bi- or multi-components to construct a heterointerface has emerged as a crucial strategy to overcome the limitations in property enhancement during ATM design. In this review, we aim to summarize the design principles of heterointerfacial ATMs, present general strategies for manipulating their interfacial structure and catalytic properties, and provide an overview of their application in energy conversion and storage, including the hydrogen evolution reaction (HER), the oxygen evolution reaction (OER), the oxygen reduction reaction (ORR), the CO2 electroreduction reaction (CO2RR), photocatalysis, and rechargeable batteries. The central theme of this review is to establish correlations among interfacial modulation, structural and electronic properties, and ATMs' major applications. Finally, based on the current research progress, we propose future directions that remain unexplored in interfacial ATMs for enhancing their properties and introducing novel functionalities in practical applications.