Conduction Band Energy Research Articles

Fermi-Level Engineering of Nitrogen Core-Doped Armchair Graphene Nanoribbons.

Substitutional heteroatom doping of bottom-up engineered 1D graphene nanoribbons (GNRs) is a versatile tool for realizing low-dimensional functional materials for nanoelectronics and sensing. Previous efforts have largely relied on replacing C-H groups lining the edges of GNRs with trigonal planar N atoms. This type of atomically precise doping, however, only results in a modest realignment of the valence band (VB) and conduction band (CB) energies. Here, we report the design, bottom-up synthesis, and spectroscopic characterization of nitrogen core-doped 5-atom-wide armchair GNRs (N2-5-AGNRs) that yield much greater energy-level shifting of the GNR electronic structure. Here, the substitution of C atoms with N atoms along the backbone of the GNR introduces a single surplus π-electron per dopant that populates the electronic states associated with previously unoccupied bands. First-principles DFT-LDA calculations confirm that a sizable shift in Fermi energy (∼1.0 eV) is accompanied by a broad reconfiguration of the band structure, including the opening of a new band gap and the transition from a direct to an indirect semiconducting band gap. Scanning tunneling spectroscopy (STS) lift-off charge transport experiments corroborate the theoretical results and reveal the relationship among substitutional heteroatom doping, Fermi-level shifting, electronic band structure, and topological engineering for this new N-doped GNR.

Compositional dependence of physical parameters of Sb-doped InSe nanochalcogenide alloys

ABSTRACT InSe is a III-VI semiconducting layered compound having potential applications in memories, solar cells, infrared sensors, switching devices and optical fibers. In this article various physical parameters of In0.1Se0.9-x Sb x (x = 0, 0.04, 0.08, 0.12) chalcogenide alloy depending on the varying composition of Se and Sb are discussed. The physical parameters include the theoretical calculations of average coordination number, number of constraints, floppy modes, number of lone pair electrons, deviation of stoichiometry, average heat of atomization, mean bond energy, density, molar volume, compactness, cohesive energy, electronegativity, energy band gap, conduction and valance band energy and glass transition temperature. The number of lone pair electrons and floppy modes is found to decrease, whereas the average coordination number, mean bond energy, average heat of atomization and density are found to increase with increasing Sb content. The theoretical values of glass transition temperature are calculated using the Tichy-Ticha and Lankhorst approach.

Achieving beyond 26.6% efficiency for graded bandgap perovskite solar cell: Theoretical study

The graded energy band gap is an effective method for improving solar spectrum efficiency. To reduce the short-circuit current density (JSC) losses, creation of suitable spike-like alignment at the electron transport (ETL)/perovskite junction is a proper method. Also, simulations model is calibrated with the experimental current-voltage (J–V) and power conversion efficiency (PCE) to validate obtained data. The graded FAPbI3 perovskite solar cell has been proposed, and the effect of (Br, I) on the device efficiency is researched. The results illustrate that iodide values in FAPb (IxBr1-x)3 significantly influence the adjustment of conduction band energy states at the perovskite/ETL interface. The Br flexibility ranging from 0% to 40% allows the target perovskite solar cell (PSC) to produce an optimum conduction band offset (CBO) at the perovskite/ETL interface. The CBO creation between the FAPbI3/ETL causes achieving (open-circuit voltage) VOC to 1.22 V, JSC to 26.9 mA cm−2, and fill factor (FF) to 81.1. Here, we demonstrate that graded energy band gap PSC could achieve steady-state conversion efficiencies of ∼26.63%. According to the results, this enhancement is owing to the proper carrier's transport among the perovskite/ETL junction due to a recombination decrement in the junction with spike-like band alignment.

All-Solution-Processed Perovskite Light-Emitting Diodes Based on a Thiol-Modified ZnO Electron-Transporting Layer.

All-solution-processed perovskite light-emitting diodes (LEDs) have the potential to be inexpensive and easily manufactured on a large scale without requiring vacuum thermal deposition of the emissive and charge transport layers. Zinc oxide (ZnO), which possesses superior optical and electronic properties, is commonly used in all-solution-processed optoelectronic devices. However, the polar solvent of ZnO inks can corrode the perovskite layer and cause severe photoluminescence quenching. In this work, we report the successful dispersion of ZnO nanoparticles in nonpolar n-octane by controlling the surface ligands from acetates to thiols. The nonpolar ink prevents the destruction of perovskite films. In addition, thiol ligands upshift the conduction band energy level, which also helps inhibit exciton quenching. Consequently, we demonstrate the fabrication of high-performance all-solution-processed green perovskite LEDs with a brightness of 21 000 cd/m2 and an external quantum efficiency of 6.36%. Our work provides a ZnO ink for fabricating efficient all-solution-processed perovskite LEDs.

Research on Interface Properties of Thermally Grown SiO2 and ALD SiO2 Stacked Structures

This study presents a stacked process of thermal and atomic layer deposition (ALD) SiO2 that reduces the interface trap density of 4H-SiC metal-oxide-semiconductor (MOS) capacitors. The channel mobility of metal-oxide-semiconductor field effect transistors (MOSFETS) are reduced due to the high interface trap density as well as coulomb scattering mechanism. Herein, we investigate SiO2/SiC interface properties of a stacked process, which is accomplished via reducing the thickness of thermal oxidation film. Notably, MOS capacitors fabricated with thermal and ALD SiO2 stacked structures can reduce the interface states density (Dit) by twofold at 0.2 eV below the conduction band energy compared with thermally grown SiO2. Additionally, the leakage current increases at a relatively slow rate in the electric field of 5–10 MV cm−1, whereas the leakage current increases sharply when the electric field is higher than 10 MV cm−1. The resultant ALD SiO2 stacked structure provides a new approach to improving interface quality, which allows a reduction in the thermal budget involved in the fabrication of devices.

Formation of emission in diode lasers with evaporation of various impurities on the main semiconductor crystal having affinity to electron

The introduction contains a summary of modern provisions that make it impossible to interpret many phenomena occurring in diode laser systems on the basis of commonly accepted physical conceptions. The work demonstrates their inadequacy. The goal and tasks of studies have been formulated. Analysis of a solid and its internal structure (crystal) is provided. It is demonstrated that interaction of plane surface clusters determines the surface structure of solids, while the interaction between three-dimensional clusters determines the internal structure of solids (crystals). Each atom inside the crystal interacts with the first, second and third coordination layer. The value of conduction band energy is determined by displacement of the ionization boundary. For implementation of diode lasers, the distribution of electrons by Fermi-Dirac energies must have a sufficiently diffused maximum. N-conductivity emerges when ionization of negative ions occurs, the energy of affinity of which is located near the conduction band. Р-conductivity is determined by ionization of negative ions, the energy of affinity of which is located near the valence band. Р-n junction is mostly formed when two-atom molecules enter the band gap. In this case, some of the atoms have an affinity for an electron with the value of such affinity located is near the conduction band, while other atoms have an affinity for an electron near the valence band. Interband transition energy contains three components: 1 – Fermi level position energy; 2 – energy of external applied electrical field, and 3 – induced energy formed by positive charge in the valence band. Generation of laser emission takes place when two-atom molecules are adsorbed on the surface of the semiconductor crystal, in which atoms have an affinity to the electron for some of the atoms near the conduction band and for other atoms near the valence band. Maximum emission intensity occurs when external applied electrical voltage fully compensates the energy of affinity to the electron located near the conduction band.

Investigation of gate leakage current in TFET: A semi-numerical approach

Tunneling FET (TFET) has been demonstrated as a favorable candidate to replace conventional MOSFETs in low-power applications. However, there are many challenges that should be overcome to efficiently operate the TFET. One of the most limiting factors that can restrict the TFET performance is the gate leakage current. In this paper, the tunneling leakage current through the gate oxide of double gate TFET has been analyzed. The conduction band energy level for gate-oxide-silicon was employed to calculate the tunneling transmission coefficient by utilizing a numerical method. To obtain the potential barrier between the gate and the channel surface, a modified analytical pseudo-2D method has been applied to deduce the corresponding surface potential taking into account a precise calculation of depletion regions. Furthermore, the inclusion of the image charge barrier lowering effect is incorporated in calculating the transmission probability through the oxide. Including such an effect shows a significant influence on determining the gate tunneling current. The gate leakage current has been calculated for various bias voltages and equivalent oxide thicknesses. The presented semi-numerical technique shows good agreement within a suitable CPU time when validated and compared against full numerical TCAD simulation.

Insight into over Repair of Hot Carrier Degradation by GIDL Current in Si p-FinFETs Using Ultra-Fast Measurement Technique

In this article, an experimental study on the gate-induced drain leakage (GIDL) current repairing worst hot carrier degradation (HCD) in Si p-FinFETs is investigated with the aid of an ultra-fast measurement (UFM) technique (~30 μs). It is found that increasing GIDL bias from 3 V to 4 V achieves a 114.7% VT recovery ratio from HCD. This over-repair phenomenon of HCD by UFM GIDL is deeply discussed through oxide trap behaviors. When the applied gate-to-drain GIDL bias reaches 4 V, a significant electron trapping and interface trap generation of the fresh device with GIDL repair is observed, which greatly contributes to the approximate 114.7% over-repair VT ratio of the device under worst HCD stress (-2.0 V, 200 s). Based on the TCAD simulation results, the increase in the vertical electric field on the surface of the channel oxide layer is the direct cause of an extraordinary electron trapping effect accompanied by the over-repair phenomenon. Under a high positive electric field, a part of channel electrons is captured by oxide traps in the gate dielectric, leading to further VT recovery. Through the discharge-based multi-pulse (DMP) technique, the energy distribution of oxide traps after GIDL recovery is obtained. It is found that over-repair results in a 34% increment in oxide traps around the conduction energy band (Ec) of silicon, which corresponds to a higher stabilized VT shift under multi-cycle HCD-GIDL tests. The results provide a trap-based understanding of the transistor repairing technique, which could provide guidance for the reliable long-term operation of ICs.

High-Performance Photodetectors With Polarization Sensitivity Based on p-n and p-p+ Black Phosphorus/Germanium Heterojunctions

The heterostructures between atomically thin 2-D and 3-D semiconductors show great potential for high-performance photodetector. In this work, the efficient light detection of the p-n and p-p+ black phosphorus (bP)/germanium (Ge) heterojunction photodiode has been demonstrated. With the change of Ge doping type, the rectification direction of the heterojunction diode formed by bP and Ge could be reversed. Due to the enhanced photocarrier separation at the reverse bias, the bP/n-Ge (bP/p-Ge) device has a responsivity of 6.08 (3.43) A/W under 1550-nm illumination, with fast response speed in the 10- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{s}$ </tex-math></inline-formula> level. The bP/n-Ge device has a significant photovoltaic effect due to the small conduction band energy offset, with a large open-circuit voltage of 0.34 V. Under the illumination of light with different polarization directions, the device exhibits apparent polarization-sensitive detection, and the dichroic ratio of bP/n-Ge and bP/p-Ge devices is 4.25 and 3.85, respectively. These results suggest that the bP/Ge heterojunction photodetector would have great potential in high-performance, self-powered, and polarization-sensitive photodetection.

Ultrafast Electron Transfer Dynamics of Organic Polymer Nanoparticles with Graphene Oxide.

We prepared organic polymer poly-3-hexylthiophene (p3ht) nanoparticles (NPs) and graphene oxide (GO)/reduced graphene oxide (RGO) composites p3ht NPs-GO/RGO by using the reprecipitation method. We demonstrated that GO/RGO could improve the ordering and planarity of p3ht chains as well as the formation of p3ht NPs, and confirmed the effects of GO/RGO on the fluorescence and carrier transport dynamics of p3ht NPs by using femtosecond fluorescence upconversion and transient absorption (TA) techniques. Ultrafast electron transfer (∼1 ps) between GO/RGO and p3ht NPs quenched the fluorescence of p3ht NPs, indicating excellent properties of p3ht NPs-GO/RGO as the charge transfer complexes. Efficient electron transfer may promote the applications of p3ht NPs-GO/RGO composites in organic polymer solar cells and photocatalysis. Moreover, RGO had stronger interfacial interactions and more matched conduction band energy levels with p3ht NPs than GO did, which implied that p3ht NPs-RGO might have greater application values than p3ht NPs-GO.

Design and Analysis of Gallium Arsenide-Based Nanowire Using Coupled Non-Equilibrium Green Function for RF Hybrid Applications

This research work uses sp3d5s* tight-binding models to design and analyze the structural properties of group IV and III-V oriented, rectangular Silicon (Si) and Gallium Arsenide (GaAs) Nanowires (NWs). The electrical characteristics of the NWs, which are shielded with Lanthanum Oxide (La2O3) material and the orientation with z [001] using the Non-Equilibrium Green Function (NEGF) method, have been analyzed. The electrical characteristics and the parameters for the multi-gate nanowires have been realized. A nanowire comprises a heavily doped n+ donor source and drains doping and n-donor doping at the channel. The specified nanowire has a gate length and channel length of 15 nm each, a source-drain device length LSD = 35 nm, with La2O3 as 1 nm (gate dielectric oxide) each on the top and bottom of the core material (Si/GaAs). The Gate-All-Around (GAA) Si NW is superior with a high (ION/IOFF ratio) of 1.06 × 109, and a low leakage current, or OFF current (IOFF), of 3.84 × 10-14 A. The measured values of the mid-channel conduction band energy (Ec) and charge carrier density (ρ) at VG = VD = 0.5 V are -0.309 eV and 6.24 × 1023 C/cm3, respectively. The nanowires with hydrostatic strain have been determined by electrostatic integrity and increased mobility, making them a leading solution for upcoming technological nodes. The transverse dimensions of the rectangular nanowires with similar energy levels are realized and comparisons between Si and GaAs NWs have been performed.

Synthesis and Spectroelectrochemical Investigation of Anodic Black TiOx Nanotubes

Anodic TiO2 nanotubes were transformed into anatase at 400 °C for 2 h in air and subjected to electrochemical reduction at different conditions. It revealed that the reduced black TiOx nanotubes were not stable in contact with air; however, their lifetime was considerably extended to even a few hours when isolated from the influence of atmospheric oxygen. The order of polarization-induced reduction and spontaneous reverse oxidation reactions were determined. Upon irradiation with simulated sunlight, the reduced black TiOx nanotubes generated lower photocurrents than non-reduced TiO2, but a lower rate of electron-hole recombination and better charge separation were observed. In addition, the conduction band edge and energy level (Fermi level), responsible for trapping electrons from the valence band during the reduction of TiO2 nanotubes, were determined. The methods presented in this paper can be used for determination of the spectroelectrochemical and photoelectrochemical properties of electrochromic materials.

Protoporphyrin-sensitized degradable bismuth nanoformulations for enhanced sonodynamic oncotherapy.

Decreasing the scavenging capacity of reactive oxygen species (ROS) and enhancing ROS production are the two principal objectives in the development of novel sonosensitizers for sonodynamic therapy (SDT). Herein, we designed a protoporphyrin-sensitized bismuth-based semiconductor (P-NBOF) as a sonosensitizer to generate ROS and synergistically depleted glutathione for enhanced SDT against tumors. The bismuth-based nanomaterial (NBOF) is a wide-bandgap semiconductor. Sensitization by protoporphyrin made it easier to excite electrons under ultrasonic stimulation, and the energy of the lowest unoccupied electron orbital in protoporphyrin was higher than the conduction-band energy of NBOF. Under ultrasound excitation, the excited electrons in the protoporphyrin were injected into the conduction band of the NBOF, increasing its reducing ability leading to the production of more superoxide anion radicals and also helping to increase the charge separation of protoporphyrin leading to the production of more singlet oxygen. Meanwhile, P-NBOF continuously depleted glutathione, which was not only conducive to breaking the redox balance of the tumor microenvironment to enhance the therapeutic efficacy of SDT, but also promoted its degradation and metabolism. The construction of this P-NBOF sonosensitizer thus provided an effective strategy to enhance SDT for tumors. STATEMENT OF SIGNIFICANCE: To enhance the efficacy of sonodynamic tumor therapy, we developed a degradable protoporphyrin-sensitized bismuth-based nano-semiconductor (P-NBOF) by optimizing the band structure and glutathione-depletion ability. Protoporphyrin in P-NBOF under excitation preferentially generates free electrons, which are then injected into the conduction band of NBOF, improving the reducing ability of NBOF and promoting the separation of electron-hole pairs, thereby enhancing the production capacity of reactive oxygen species. Furthermore, P-NBOF can deplete glutathione, reduce the scavenging of reactive oxygen species, and reactivate and amplify the effect of sonodynamic therapy. The construction of the nanotherapeutic platform provides an option for enhancing sonodynamic therapy.

Acetylacetone‐TiO2 Promoted Large Area Compatible Cascade Electron Transport Bilayer for Efficient Perovskite Solar Cells

In designing efficient perovskite solar cells (PSCs), the selection of suitable electron transport layers (ETLs) is critical to the final device performance as they determine the driving force for selective charge extraction. SnO2 nanoparticles (NPs) based ETLs have been a popular choice for PSCs due to superior electron mobility, but their relatively deep‐lying conduction band energy levels (ECB) result in substantial potential loss. Meanwhile, TiO2 NPs establish favorable band alignment owing to shallower ECB, but their low intrinsic mobility and abundant surface trap sites impede the final performance. For this reason, constructing a cascaded bilayer ETL is highly desirable for efficient PSCs, as it can rearrange energy levels and exploit on advantages of an individual ETL. In this study, we prepare SnO2 NPs and acetylacetone‐modified TiO2 (Acac‐TiO2) NPs and implement them as bilayer SnO2/Acac‐TiO2 (BST) ETL, to assemble cascaded energy band structure. SnO2 contributes to rapid charge carrier transport from high electron mobility while Acac‐TiO2 minimizes band‐offset and effectively suppresses interfacial recombination. Accordingly, the optimized BST ETL generates synergistic influence and delivers power conversion efficiency (PCE) as high as 23.14% with open‐circuit voltage (VOC) reaching 1.14 V. Furthermore, the BST ETL is transferred to a large scale and the corresponding mini module demonstrates peak performance of 18.39% PCE from 25 cm2 aperture area. Finally, the BST‐based mini module exhibit excellent stability, maintaining 83.1% of its initial efficiency after 1000 h under simultaneous 1 Sun light‐soaking and damp heat (85 °C/RH 85%) environment.

Unravelling the effect of donor-π-acceptor architecture in designing 1,3-indanedione based sensitizers for DSSC applications

• 1,3-indanedione-based electron-acceptor group has been employed in designing new sensitizers and theoretical calculations of the nine sensitizers, that are designed based on D-π-A architecture, were performed at DFT and TDDFT level. • HOMO-LUMO energy levels of the designed dyes are matching with the energy levels of titania and redox couples. • Frontier molecular orbital (FMO) analysis revealed intra-molecular charge transfer from the electron-donor to the 1,3-indanedione electron-acceptor. • Two-fold enhancement of dipole moment was observed in all sensitizers upon binding on (TiO 2 ) 9 nanocluster. • The simulated electronic spectra of free dyes and Dye@TiO 2 encompass the entire visible region. • Phenoxazine (POZ) and phenothiazine (PTZ) electron-donor moieties significantly improved the chemical reactivity and photophysical properties and therefore, corresponding RK4 and RK5 sensitizers are better than others. • The D-π-A architecture is found to be better than D-π-A-D architecture in the case of 1,3-indanedione-based sensitizers. Molecular engineering plays a vital role in the design of efficient organic sensitizers for DSSC applications. The study highlights the density functional theory calculations of nine organic sensitizers, designed based on a new 1,3-indanedione electron-acceptor cum anchoring group. The new sensitizers (RK1-9) have been designed by tailoring a modified 1,3-indanedione electron-acceptor with conventional electron-donors in the form of D-π-A architecture. Geometry optimization studies reveal that the RK7 & RK8 molecules have more twisted geometries. Similarly, the RK5 dye has the smallest energy gap of 2.34 eV compared to other dyes. LUMO energy levels of all the designed dyes are positive, found above the conduction band energy level, and the HOMO energy levels were more negative than the redox potentials. Calculated electrochemical parameters suggest that the dyes RK1-5 and RK9 inject the electrons efficiently into the conduction band of TiO 2 . Further, the Gibbs free energies of the dyes indicate that the RK4 and RK5 dyes regenerate much faster than the other dyes. The electronic absorption spectra of the RK dyes were steadily shifting towards the longer wavelength region with solvent polarity and further red-shifts upon adsorbing on the (TiO 2 ) 9 nanocluster. The LUMO and LUMO+1 wave functions of the RK dye@(TiO 2 ) 9 complexes are confined to the (TiO 2 ) 9 nanocluster, suggesting effective intramolecular charge transfer upon photo-excitation. Overall, the computational study demonstrates the significance of the 1,3-indanedione electron-acceptor and o the D-π-A architecture in the molecular design of new organic sensitizers for DSSC applications.

Photo-plasmonic effect as the hot electron generation mechanism

Based on the effective Schrödinger–Poisson model a new physical mechanism for resonant hot-electron generation at irradiated half-space metal–vacuum interface of electron gas with arbitrary degree of degeneracy is proposed. The energy dispersion of undamped plasmons in the coupled Hermitian Schrödinger–Poisson system reveals an exceptional point coinciding the minimum energy of plasmon conduction band. Existence of such exceptional behavior is a well-know character of damped oscillation which in this case refers to resonant wave–particle interactions analogous to the collisionless Landau damping effect. The damped Schrödinger–Poisson system is used to model the collective electron tunneling into the vacuum. The damped plasmon energy dispersion is shown to have a full-featured exceptional point structure with variety of interesting technological applications. In the band gap of the damped collective excitation,depending on the tunneling parameter value, there is a resonant energy orbital for which the wave-like growing of collective excitations cancels the damping of the single electron tunneling wavefunction. This important feature is solely due to dual-tone wave-particle oscillations, characteristics of the collective excitations in the quantum electron system leading to a resonant photo-plasmonic effect, as a collective analog of the well-known photo-electric effect. The few nanometer wavelengths high-energy collective photo-electrons emanating from the metallic surfaces can lead to a much higher efficiency of plasmonic solar cell devices, as compared to their semiconductor counterpart of electron–hole excitations at the Fermi energy level. The photo-plasmonic effect may also be used to study the quantum electron tunneling and electron spill-out at metallic surfaces. Current findings may help to design more efficient spasers by using the feature-rich plasmonic exceptional point structure.

Control and regulation of the performance of fullerene-based dye-sensitized solar cells with a D-D-A structure by external electric fields.

We investigated the modulating effect of an electric field (Fext) on the photovoltaic properties of triphenylamine-based sensitizers with a D-D-A structure and compared the photovoltaic parameters at different electric field intensities. The results show that Fext can effectively adjust the photoelectric properties of the molecule. From the change of the parameters that measures the degree of electron delocalization, it can be seen that the Fext can effectively strengthen the electronic communication and promote the charge transfer process within the molecule. And the dye molecule under a strong Fext has a narrower energy gap, more favorable injection, regeneration driving force and a larger conduction band energy level shift, which ensures that the dye molecule can exhibit larger Voc and Jsc under a strong Fext. The results of calculations on the photovoltaic parameters of dye molecules show that dye molecules can exhibit better photovoltaic performance under the action of Fext, which provides beneficial predictions and prospects for the development of highly efficient DSSCs.

Negative capacitance field-effect transistor with hetero-dielectric structure for suppression of reverse drain induced barrier lowering

Recently, negative capacitance FETs (NCFET) using ferroelectric materials as a gate oxide have received much attention as one of the candidates for next-generation low power/high-performance devices because they can have sub-60 mV/dec subthreshold swing at room temperature through the channel potential amplification. However, the reverse drain induced barrier lowering phenomenon occurs by the local rising of the drain-side conduction energy band when a high drain voltage is applied to NCFETs, leading to the degradation of on-current and subthreshold swing. In this work, a novel NCFET with hetero-dielectric (HD-NCFET), where the gate dielectric consists of source-side ferroelectric material and drain-side paraelectric silicon dioxide (SiO2), is proposed to prevent the undesirable reverse drain induced barrier lowering phenomenon. Through technology computer-aided design simulations, the effects of operating voltage and SiO2 length on the electrical characteristics of the HD-NCFET are rigorously analyzed to optimize and maximize its device performance.

0D/2D CuFe2O4/MXene Z-scheme heterojunction for improved photocatalytic selective oxidation reaction

The high rate of recombination of photoinduced electrons and holes restricts their utilization in photocatalysis. In this study, an in-situ synthesis route for the fabrication of 0D/2D CuFe2O4/MXene heterojunctions was proposed. The developed heterojunction enhances the charge transfer during the photocatalytic reaction, and the enhanced mechanism is investigated based on the energy band structures of the heterojunction. The conduction band energies of CuFe2O4 and the MXene are 0.17 and − 0.04 eV, respectively, (vs NHE, pH = 7). Moreover, the valence band energies of CuFe2O4 and the MXene are 2.83 and 1.53 eV, respectively, (vs NHE, pH = 7). Therefore, the Z-scheme mechanism of the heterojunctions is proposed, clarifying how the charge separation efficiency of the material is improved through the transfer of the photoinduced holes from the MXene to CuFe2O4. The heterojunctions exhibit superior activity in the photocatalytic selective oxidation of benzyl alcohol to benzaldehyde showing a yield of 99 %, which is significantly higher than that of pure CuFe2O4 and MXene. The results indicate that the novel 0D/2D heterojunction significantly enhances the selective photocatalytic oxidation of benzyl alcohol, and also indicate that ·O2His themainactive species in the photocatalytic oxidation reaction.

Research Progress on Cu2O‐based Type‐II Heterojunction Photocatalysts for Photocatalytic Removal of Antibiotics

AbstractPhotocatalytic degradation technology, using solar energy as the driving force, is considered the most possible alternative to remediate environmental pollution. And it is essential to find a stable and efficient photocatalyst. As promising semiconductor‐based photocatalysts, Cu2O has acquired massive attention owning to its high conduction band energy, superior visible‐light response‐ability, low cost, eco‐friendly, and abundance. However, the application of origin Cu2O faces severe problems due to its photocorrosion and low photoinduced carrier separation. Consequently, it is necessary to improve its photostability and photocatalytic activity by carrying out numerous modification strategies, such as heterostructure construction. Herein, we first summarize the classification and operation principles of Cu2O‐based type‐II heterojunction. Then, the application of the Cu2O‐based type‐II heterojunction photocatalysts for the removal of tetracyclines, quinolones, and sulfonamides have been discussed. Finally, the pressing issues and perspectives in Cu2O‐based type‐II heterojunction photocatalysts application for degrading antibiotics have prospected.