Probe Force Research Articles

Tunable Rectification in 2D Porphyrinic Metal–Organic Framework Nanosheets Molecular Heterojunctions

AbstractAs functional electrical devices advance, new strategies for regulating electrical properties are essential for achieving diverse electrical performance. In this study, molecular heterojunction rectifiers are constructed by connecting porphyrinic 2D metal–organic framework (2D MOF) nanosheets and oligophenylene thiols self‐assembled monolayers (OPT SAMs) within metal electrodes. The rectification characteristics can be tuned by the molecular length of OPT and the coordinated metal atom in the center of 2D MOFs. Specifically, a rectification ratio of more than 1.67 orders of magnitude is achieved in the heterojunction composed of 2D Zn‐TCPP MOF nanosheet (TCCP, tetrakis(4‐carboxyphenyl) porphyrin) and OPT3 SAM. Combining Kelvin probe force microscopy measurements and first‐principles calculations of the 2D MOF nanosheets, it elucidates that the rectification variations come from the adjustment of energy level alignment at OPT SAMs//2D MOF interface, leading to asymmetric charge transport with the voltage polarities. This strategy can be further extended to Cu‐MOF nanosheets, which also exhibit rectification behaviors when placed on OPT2 SAMs. This work provides a universal and flexible strategy for regulating the electrical behaviors of MOFs without the need for specific design and synthesis, paving the way for the development of MOF‐based functional electronic devices.

Real-space investigation of polarons in hematite Fe2O3.

In polarizable materials, electronic charge carriers interact with the surrounding ions, leading to quasiparticle behavior. The resulting polarons play a central role in many materials properties including electrical transport, interaction with light, surface reactivity, and magnetoresistance, and polarons are typically investigated indirectly through these macroscopic characteristics. Here, noncontact atomic force microscopy (nc-AFM) is used to directly image polarons in Fe2O3 at the single quasiparticle limit. A combination of Kelvin probe force microscopy (KPFM) and kinetic Monte Carlo (KMC) simulations shows that the mobility of electron polarons can be markedly increased by Ti doping. Density functional theory (DFT) calculations indicate that a transition from polaronic to metastable free-carrier states can play a key role in migration of electron polarons. In contrast, hole polarons are significantly less mobile, and their hopping is hampered further by trapping centers.

Probing Nanoscale Charge Transport Mechanisms in Quasi-2D Halide Perovskites for Photovoltaic Applications.

Quasi-2D layered halide perovskites (quasi-2DLPs) have emerged as promising materials for photovoltaic (PV) applications owing to their advantageous bandgap for absorbing visible light and the improved stability they enable. Their charge transport mechanism is heavily influenced by the grain orientation of their crystals as well as their nanostructures, such as grain boundaries (GBs) and edge states─the formation of which is inevitable in polycrystalline quasi-2DLP thin films. Despite their importance, the impact of these features on charge transport remains unexplored. In this study, we conduct a detailed investigation on polycrystalline quasi-2DLP thin films and devices, carefully analyzing how grain orientation and nanostructures influence charge transport. Employing nondestructive atomic force microscopy (AFM) topography, along with transient absorption spectroscopy (TAS) and grazing-incidence wide-angle X-ray scattering (GIWAXS), we obtained significant insights regarding the phase purity, crystallographic information, and morphologies of these films. Moreover, our systematic investigation using AFM-based techniques, including Kelvin probe force microscopy (KPFM) and conductive AFM (c-AFM), elucidates the roles played by GBs and edge states in shaping charge transport behavior. In particular, the local band structure along the GBs and edge states within both vertical and parallel grains was found to selectively repel electrons and holes, thus facilitating charge carrier separation. These findings provide perspectives for the development of high-performance quasi-2DLP PV devices and highlight potential approaches that can leverage the intrinsic properties of quasi-2DLPs to advance the performance of perovskite solar cells.

Reactive Spark Plasma Sintering and Oxidation of ZrB2-SiC and ZrB2-HfB2-SiC Ceramic Materials

This study presents the fabrication possibilities of ultra-high-temperature ceramics of ZrB2-30 vol.%SiC and (ZrB2-HfB2)-30 vol.% SiC composition using the reaction spark plasma sintering of composite powders ZrB2(HfB2)-(SiO2-C) under two-stage heating conditions. The phase composition and microstructure of the obtained ceramic materials have been subjected to detailed analysis, their electrical conductivity has been evaluated using the four-contact method, and the electron work function has been determined using Kelvin probe force microscopy. The thermal analysis in the air, as well as the calcination of the samples at temperatures of 800, 1000, and 1200 °C in the air, demonstrated a comparable behavior of the materials in general. However, based on the XRD data and mapping of the distribution of elements on the oxidized surface (EDX), a slightly higher oxidation resistance of the ceramics (ZrB2-HfB2)-30 vol.% SiC was observed. The I-V curves of the sample surfaces recorded with atomic force microscopy demonstrated that following oxidation in the air at 1200 °C, the surfaces of the materials exhibited a marked reduction in current conductivity due to the formation of a dielectric layer. However, data obtained from Kelvin probe force microscopy indicated that (ZrB2-HfB2)-30 vol.% SiC ceramics also demonstrated enhanced resistance to oxidation.

Fabrication of solid-state plasmonic solar cell device using FTO|TiO2|Ag-nanoparticle assembly to generate hot electrons surpassing Schottky barrier

This work presents a detailed investigation into the fabrication and performance evaluation of plasmonic solar cells, where a thin film of silver nanoparticles is deposited onto a TiO₂ layer, with the silver film itself functioning as the active layer for light absorption and energy conversion. The study compares two deposition techniques—DC Magnetron Sputtering and Thermal Vapor Deposition (TVD)—revealing significant differences in the resulting device performance. The device fabricated using TVD demonstrated a significantly higher open circuit voltage of 440.3 mV and short circuit current density of 1.6 mA/cm² compared to the device fabricated via DC Magnetron Sputtering, which recorded an open circuit voltage of 56.92 mV and a short circuit current density of 0.03 mA/cm². These results indicate that TVD offers superior electron-hole separation, reduced recombination losses, and enhanced light absorption efficiency. The main contribution of this work lies in demonstrating that the TVD technique significantly improves the photovoltaic performance of plasmonic solar cells compared to DC Magnetron Sputtering. The study validates the hot-electron mechanism at the TiO2|Ag junction using Kelvin probe force microscopy, contributing valuable insights into the role of plasmonic effects in enhancing solar cell efficiency. Additionally, it underscores the potential of TVD for developing advanced solar cell technologies with higher energy conversion efficiency.

Interfacial coordination bonds accelerate charge separation for unprecedented hydrogen evolution over S-scheme heterojunction

Inspired by natural photosynthesis, fabricating high-performance S-scheme heterojunction is regarded as a successful tactic to address energy and environmental issues. Herein, NH2-MIL-125(Ti)/Zn0.5Cd0.5S/NiS (NMT/ZCS/NiS) S-scheme heterojunction with interfacial coordination bonds is successfully synthesized through in-situ solvothermal strategy. Notably, the optimal NMT/ZCS/NiS S-scheme heterojunction exhibits comparable photocatalytic H2 evolution (PHE) rate of about 14876.7 μmol h−1 g−1 with apparent quantum yield of 24.2% at 420 nm, which is significantly higher than that of recently reported MOFs-based photocatalysts. The interfacial coordination bonds (Zn–N, Cd–N, and Ni–N bonds) accelerate the separation and transfer of photogenerated charges, and the NiS as cocatalyst can provide more catalytically active sites, which synergistically improve the photocatalytic performance. Moreover, theoretical calculation results display that the construction of NMT/ZCS/NiS S-scheme heterojunction also optimize the binding energy of active site-adsorbed hydrogen atoms to enable fast adsorption and desorption. Photoassisted Kelvin probe force microscopy, in-situ irradiation X-ray photoelectron spectroscopy, femtosecond transient absorption spectroscopy, and theoretical calculations provide sufficient evidence of the S-scheme charge migration mechanism. This work offers unique viewpoints for simultaneously accelerating the charge dynamics and optimizing the binding strength between the active sites and hydrogen adsorbates over S-scheme heterojunction.

Dual efficacy of potassium-doping in perovskite solar cells: Reducing hysteresis and boosting open-circuit voltage

The incorporation of potassium into perovskite solar cells (PSCs) has been empirically validated to mitigate hysteresis phenomena and boost the power conversion efficiency (PCE). However, the doping mechanism of potassium ions in the perovskite film and their effect on photocarrier recombination remains a topic of debate. Here, we grew doped MAPbI3: K single crystals by inverse temperature crystallization using KI as a dopant, and then perovskite thin films were spin-coated with dissolved MAPbI3: K crystals as a precursor. The doped MAPbI3: K perovskite films exhibit better crystal quality with large columnar grains and lower defect density. Employing Hall effect, ultraviolet photoelectron spectroscopy, and Kelvin probe force microscopy measurements, we definitively demonstrate that K-doping transforms the conductivity type of the perovskite film from a marginally N-type to a distinct P-type semiconductor. Furthermore, this doping strategy induces a concurrent downward shift in both the conduction band minimum and valence band maximum. As a result, the PCE of the PSCs increases from 15.15% to an impressive 20.66%, and the J–V curve hysteresis almost disappears. Additionally, theoretical simulations using SCAPS-1D software reveal a profound modification in the device's energy band diagram after K+-doping. Specifically, the energy level offset between the perovskite layer and the electron transport layer diminishes from 0.24 to 0.14 eV, with a result of bigger quasi-Fermi energy level splitting. This, in turn, elevates the open-circuit voltage (Voc) of the doped perovskite solar cell, underscoring the profound impact of potassium doping on enhancing PSC performance.

Ultrafast Charge Transfer-Induced Unusual Nonlinear Optical Response in ReSe2/ReS2 Heterostructure.

Ultrafast charge transfer in van der Waals heterostructures can effectively engineer the optical and electrical properties of two-dimensional semiconductors for designing photonic and optoelectronic devices. However, the nonlinear absorption conversion dynamics with the pump intensity and the underlying physical mechanisms in a type-II heterostructure remain largely unexplored, yet hold considerable potential for all-optical logic gates. Herein, two-dimensional ReSe2/ReS2 heterostructure is designed to realize an unusual transition from reverse saturable absorption to saturable absorption (SA) with a conversion pump intensity threshold of approximately 170 GW/cm2. Such an intriguing phenomenon is attributed to the decrease of two-photon absorption (TPA) of ReS2 and the increase of SA of ReSe2 with the pump intensity. Based on the characterization results of X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, femtosecond transient absorption spectrum, Kelvin probe force microscopy, and density functional theory calculation, a type-II charge-transfer-energy level model is proposed combined with the TPA of ReS2 and SA of ReSe2 processes. The results reveal the critical role of ultrafast interfacial charge transfer in tuning the unusual nonlinear absorption and improving the SA of ReSe2/ReS2 under different excitation wavelengths. Our finding deepens the understanding of nonlinear absorption physical mechanisms in two-dimensional heterostructure materials, which may further diversify the nonlinear optical materials and photonic devices.

Adaptive resolution force probe simulations: Coarse graining in the ideal gas approximation.

The unfolding of molecular complexes or biomolecules under the influence of external mechanical forces can routinely be simulated with atomistic resolution. To obtain a match of the characteristic time scales with those of experimental force spectroscopy, often coarse graining procedures are employed. Here, building on a previous study, we apply the adaptive resolution scheme (AdResS) to force probe molecular dynamics (FPMD) simulations using two model systems as examples: One system is the previously investigated calix[4]arene dimer that shows reversible one-step unfolding, and the other example is provided by a small peptide, a β-alanine octamer in methanol solvent. The mechanical unfolding of this peptide proceeds via a metastable intermediate and, therefore, represents a first step toward a complex unfolding pathway. We show that the average number of native contacts serves as a robust order parameter for the forced unfolding of this small peptide. In addition to increasing the complexity of the relevant conformational changes, we study the impact of the methodology used for coarse graining. Apart from the iterative Boltzmann inversion method, we apply an ideal gas approximation, and therefore, we replace the solvent by a non-interacting system of spherical particles. In all cases, we find excellent agreement between the results of FPMD simulations performed fully atomistically and those of the AdResS simulations also in the case of fast pulling. This holds for all details of the unfolding pathways, such as the distributions of the characteristic forces and also the sequence of hydrogen-bond opening in case of the β-alanine octamer. Therefore, the methodology is very well suited to simulate the mechanical unfolding of systems of experimental relevance.

Flower-like SnS2/rGO composites with efficient iodide-triiodide redox performance for counter electrodes in Pt-free dye-sensitized solar cells

The work function (WF) of the counter electrode (CE) predominantly determines the device performance of dye sensitized solar cells (DSSCs) as it controls the electron transfer rate for dye regeneration. Hence in this work, tin disulphide/reduced graphene oxide (SnS2/rGO) composites were synthesized with different wt.% of rGO (3, 5, 7, 10 %) and investigated their performance in DSSCs applications. At the outset, the formation of pristine SnS2 and SnS2/rGO composites were confirmed through X-ray diffraction and Raman spectral analysis. The morphological imaging revealed the micro flower-like structure of SnS2 with cross-sectional width of 5 ± 0.2 μm, and petal thickness ranges from 30.7 nm to 46.4 nm. The binding energy spectra confirms the 4+ oxidation state of Sn in both SnS2 and 7 wt% SnS2/rGO, suggesting that the rGO does not alter the chemical states of SnS2. Further, the peak-to-peak separation values obtained from Cylic-Voltammetry analysis were found to be 0.37 and 0.57 V for S7 and Pt CE respectively, indicating the rapid electrolyte reduction of 7 wt% SnS2/rGO. Finally, a photo conversion efficiency (PCE) of 7.3 % has been achieved with 7 wt% SnS2/rGO CE which is greater than that of the PCE with Pt CE (6.5 %) and also higher than that of pristine SnS2 with 4.7 %. The improved PCE is attributed to the reduced WF of the 7 wt% SnS2/rGO composite as measured from the Kelvin probe force microscopy analysis, enabling the rapid redox reaction towards triiodide reduction.

Inhibiting the current spikes within the channel layer of LiCoO2-based three-terminal synaptic transistors

Synaptic transistors, which emulate the behavior of biological synapses, play a vital role in information processing and storage in neuromorphic systems. However, the occurrence of excessive current spikes during the updating of synaptic weight poses challenges to the stability, accuracy, and power consumption of synaptic transistors. In this work, we experimentally investigate the main factors for the generation of current spikes in the three-terminal synaptic transistors that use LiCoO2 (LCO), a mixed ionic-electronic conductor, as the channel layer. Kelvin probe force microscopy and impedance testing results reveal that ion migration and adsorption at the drain–source-channel interface cause the current spikes that compromise the device's performance. By controlling the crystal orientation of the LCO channel layer to impede the in-plane migration of lithium ions, we show that the LCO channel layer with the (104) preferred orientation can effectively suppress both the peak current and power consumption in the synaptic transistors. Our study provides a unique insight into controlling the crystallographic orientation for the design of high-speed, high-robustness, and low-power consumption nano-memristor devices.

Interface and Defect Engineering in 3D Co3O4‐Ov/TiO2 to Boost Simultaneous Removal of BPA and Cr(VI) upon Photoelectrocatalytic/Peroxymonosulfate (PEC/PMS) System

AbstractThe combination of photoelectrocatalytic (PEC) and peroxymonosulfate (PMS) is an innovative strategy for environmental treatment. And fabricating a highly efficient photoelectrode is the most pivotal factor in PEC reactions. This study designs an advanced Co3O4‐Ov/TiO2 photoelectrode by a dual‐modification strategy encompassing interface engineering and defect engineering. The photoelectric characterization validates the synergy of oxygen vacancies and dual heterojunctions. Simulated electron density distribution and Kelvin probe force microscopy (KPFM) elucidate the charge transfer pathway between Co3O4‐Ov and TiO2. 1O2 and SO4 .− are confirmed to be primarily responsible for the BPA oxidation in PEC/PMS system by radical scavenger experiments and the EPR technique. And the attack sites of BPA are precisely identified based on the Fukui index. Furthermore, density functional theory (DFT) calculations testify that Co3O4‐Ov can improve the adsorption capacity of PMS and reduce the energy barrier of the reaction process, while XPS analysis showed Co3+/Co2+ redox couple can accelerate PMS activation. Enhanced anode oxidation can effectively promote cathode reduction and consequently Co3O4‐Ov/TiO2‐PMS/PEC system presents a superior removal of both pollutants within only 15 min with fast kinetics (0.15 min−1 for BPA, 0.29 min−1 for Cr(VI)). This work provides unique insight into designing a highly efficient PMS/PEC system for simultaneous pollutant treatment.

Characterization of identical lithium-ion battery electrodes before and after charge/discharge cycles via in-plane large-area polishing

As an effective method to fabricate a large-area cross-sectional sample for lithium-ion battery electrodes, we perform in-plane polishing of LiNi0.8Co0.15Al0.05O2(NCA) cathode samples and obtain a large cross-sectional area with a diameter of 1.5 mm. The polished cross-sections of NCA cathode particles are sufficiently flat to perform the atomic force microscopy (AFM) measurements on each cathode particle. Following AFM-based Kelvin probe force microscopy and scanning spreading resistance microscopy measurements, an identical in-plane polished NCA sample is assembled into a coin cell for the charge and discharge processes. After 90 charge/discharge cycles, the in-plane-polished sample is successfully disassembled from the coin cell without causing critical damage. In addition, a microcrack structure, which is a typical degradation feature of the cycles of NCA particles, is observed for the identical in-plane polished NCA sample. This indicates that the in-plane polishing method is effective for investigating identical NCA electrode samples before and after the charge/discharge process. Furthermore, the in-plane polishing method can be successfully applied to the large-area polishing of a Si-based anode which is a mixture of Si carbon complexes and graphite particles. This study presents a novel methodology for analyzing the degradation of lithium-ion battery electrode materials.

Point defect distributions in ultrafast laser-induced periodic surface structures on β-Ga2O3

β-Ga2O3 has received widespread attention due to its ultrawide bandgap, which potentially permits applications in extreme conditions. Ultrafast laser irradiation of β-Ga2O3 provides a means for exploring the response of the material under such conditions, which could result in the generation of point defects as well as a localized modification of structural features that could yield properties that differ from the pristine surface. However, an understanding of defects generated by femtosecond laser irradiation in the vicinity of laser-induced periodic surface structures (LIPSS) remains to be explored. We correlate topographic features with optical and electronic properties by combining near-nm scale resolution cathodoluminescence with Kelvin probe force microscopy. Defects are found to correlate with crystalline order and near-surface morphology, as well as changes in work function. They are also suggested to be closely related to the formation of high spatial frequency LIPSS. These results suggest a need for precise tuning of laser irradiation conditions as well as possible post-processing to control defects in future Ga2O3 devices.

Robust photocatalytic hydrogen evolution performance of 0D/1D NiO/CdS S-scheme heterojunction

Constructing heterojunction, especially S-scheme heterojunction, is an effective strategy for achieving effective separation of photogenerated electron-hole pairs and obtaining high electrode potential. In this study, a unique 0D/1D NiO/CdS S-scheme heterojunction was constructed by solvent evaporation induced self-assembly method. The loading of NiO was found to greatly enhance the photogenerated carrier separation efficiency of CdS by photoluminescence (PL) spectroscopy, electrochemical impedance spectroscopy (EIS), Kelvin probe force microscopy (KPFM) and transient photocurrent tests. The best photogenerated carrier separation effect was observed at a NiO loading ratio of 15 wt% and the largest photocatalytic hydrogen evolution rate reached 7.89 mmol h-1g−1 under visible light, which was 24.66 times that of pristine CdS. In addition, the cycling experiments showed that the loading of NiO led to the alleviation of the photocorrosion phenomenon of CdS, and the performance remained at 94.2 % after five cycles. This is due to the fact that the formation of S-type heterojunction combines the photogenerated holes of CdS with the photogenerated electrons of NiO, which hinders the oxidation of S2- on the surface of CdS, thus alleviating the photocorrosion phenomenon of CdS and improving the stability of CdS. This work furnishes a new strategy for the development of stable and high-performance photocatalysts with inexpensive co-catalysts.

Citric acid modulated strong magnetic CoFe-LDH/CoFe2O4 coupled dielectric barrier discharge plasma for efficient levofloxacin degradation: Enhanced internal electric field and accelerated electron migration

A novel citric acid (CA) modulation strategy was developed to prepare strong magnetic CoFe-LDH/CoFe2O4-C composites, which were combined with dielectric barrier discharge (DBD) to effectively degrade levofloxacin (LEV) in wastewater. Kelvin probe force microscopy (KPFM) test showed that CA modulation facilitated a more powerful internal electric field to drive rapid charge migration. The addition of CoFe-LDH/CoFe2O4-C increased LEV degradation from 78.2% to 98.6% and reduced energy efficiency from 24.77 to 8.93 kWh m–3. Quenching experiments and electron paramagnetic resonance (EPR) spectra showed the CoFe-LDH/CoFe2O4-C could take full advantage of the active substances originating from DBD plasma and highlighted the role of 1O2 and ·O2–. Density functional theory (DFT) calculation revealed that the heterojunction can not only drive faster electron migration but also reduce the energy barrier of O3 decomposition. Possible degradation pathways for LEV were proposed. This study opened up a new avenue for the synthesis of applicable catalysts for plasma systems in water treatment areas.

Ni0.25Cu0.5Sn0.25 Nanometallic Glasses As Highly Efficient Catalyst for Electrochemical Nitrate Reduction to Ammonia

AbstractElectrochemical nitrate reduction to ammonia (NRA) is a promising approach for alleviating energy crisis and water pollution. Current NRA catalysts are challenged to simultaneously improve the rate of the adsorption and desorption processes to further increase the total activity due to the Brønsted−Evans−Polanyi (BEP) relationships. Herein, a two‐step Joule heating method is utilized for the preparation of Ni0.25Cu0.5Sn0.25 nanometallic glass containing synergistic catalytic sites to simultaneously enhance the adsorption and desorption processes. Kelvin probe force microscopy reveals a pronounced oscillatory behavior in the surface potential of Ni0.25Cu0.5Sn0.25 nanometallic glass, which is an important feature of the synergistic catalytic site, and an empirical formula is proposed to quantitatively characterize its oscillatory characteristic. In situ electrochemical Raman spectroscopy indicates the promotion of nickel and tin atoms for nitrate adsorption and ammonia desorption processes, respectively. DFT calculations demonstrated that Ni0.25Cu0.5Sn0.25 presents a wide range of adsorption energy distributions to favor the multisite synergistic catalysis. The present work provides new ideas for the design and understanding of highly active NRA catalysts.

Dual electric field and defect engineering induced multi-channel electron transfer for boosting photocatalytic hydrogen production on Cu2+-doped ZnMoO4/ZnIn2S4 heterojunction

Serious recombination of photogenerated carriers is the bottleneck problem of achieving high-performance photocatalytic reaction. A high efficient Cu2+-doped ZnMoO4/ZnIn2S4 (CZMOZIS) heterojunction was synthesized by hydrothermal method. The CZMOZIS heterostructure achieved hydrogen production of 11637.5 µmol g−1 within 5 h, which was 9.7 times higher than that of pure ZnIn2S4. Comprehensive characterization and theoretical calculation demonstrated that the CZMOZIS composites exhibited broad light absorption, an increased specific surface area and an optimized Gibbs free energy. The presence of oxygen vacancies in CZMOZIS composites was confirmed by X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy, revealing the formation of defect levels below the conduction band (CB) of ZnMoO4. Kelvin probe force microscopy (KPFM) and Zeta potential demonstrated that the intrinsic electric field (IEF) of the CZMOZIS heterojunction was enhanced, which may be attributed to the generation of polarization electric field (PEF). The double electric field provided a robust driving force for the photogenerated carrier migration and separation. The electrons in the CB and defect levels of Cu2+-ZnMoO4 could be coupled with the holes of ZnIn2S4, thereby forming a multi-channel electron transfer. This work provides a theoretical support for promoting charge transfer to improve photocatalytic performance by dual electric field and defect engineering.

Amorphous-Crystalline Interface Induced Internal Electric Fields for Electrochromic Smart Window.

Balancing optical modulation and response time is crucial for achieving high coloration efficiency in electrochromic materials. Here, internal electric fields are introduced to titanium dioxide nanosheets by constructing abundant amorphous-crystalline interfaces, ensuring large optical modulation while reducing response time and therefore improving coloration efficiency. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) reveals the presence of numerous amorphous-crystalline phase boundaries in titanium dioxide nanosheets. Kelvin probe force microscopy (KPFM) exhibits an intense surface potential distribution, demonstrating the presence of internal electric fields. Density functional theory (DFT) calculations confirm that the amorphous-crystalline heterointerfaces can generate internal electric fields and reduce diffusion barriers of lithium ions. As a result, the amorphous-crystalline titanium dioxide nanosheets exhibit better coloration efficiency (35.1cm2C-1) than pure amorphous and crystalline titanium dioxide nanosheets.

Beta-cyclodextrin supported Bi2Fe4O9-based n-p/n hetero-homojunction: A leach proof S-scheme photocatalyst for mitigation of micropollutants

The work proffers a novel Bi2Fe4O9 based n-p/n hetero-homojunction that offers excellent photocatalytic activity towards mitigation of three potential pharmaceutical and agrochemical pollutants. Nanoparticles of Prunus Amygdalus Dulcis shell derived carboxyl functionalized reduced graphene oxide (rGO) were encrusted over the surface of hydrothermally fabricated Bi2Fe4O9 nanoplates. Further, hydroxyl functionalization of fabricated composites was performed using beta-cyclodextrin (β-CD) and the fabricated materials were utilized for oxidative degradation of doxorubicin, levofloxacin drugs and malathion pesticide. The proffered modification not only enhanced the catalytic activity but also protected the surface of Bi2Fe4O9, which resulted 89.06 % and 86.84 % suppression in leaching of Fe and Bi ions as that of pristine bismuth ferrite (BF) was achieved with this beneficial modification. Practical viability of fabricated hetero-homojunction was testified via treating real pharmaceutical wastewater at lower concentration. Mott-Schottky (MS), Diffuse reflectance spectroscopy (DRS) and Kelvin Probe Force Microscopy (KPFM) studies were employed to investigate the band structure and charge transfer mechanism of fabricated n-p/n hetero-homojunction.