Transfer Of Charge Carriers Research Articles

Modulating Pore Wall Chemistry Empowers Sonodynamic Activity of Two‐Dimensional Covalent Organic Framework Heterojunctions for Pro‐Oxidative Nanotherapy

AbstractCovalent organic frameworks (COFs) have garnered growing interest in the field of biomedicine; however, their application in sonodynamic therapy remains underexplored due to limited understanding of their intrinsic activity and structure–property relationships. Here, we present a pore wall chemistry modulation strategy for empowering sonodynamic activity to two‐dimensional (2D) COF heterojunctions through in situ growth of COFs on bismuth oxycarbonate nanosheets (B NSs). Compared to the negligible sonodynamic effects observed in the pristine B NSs, the 2D heterojunction with vinyl‐decorated COF pore walls demonstrates a 3.6‐fold enhancement in sonocatalytic singlet oxygen generation. This performance also significantly outperforms that of isoreticular COFs functionalized with methoxy or non‐substituted groups. Mechanistic studies reveal that the vinyl groups in the B@COF (BC) heterojunction facilitate the separation and transfer of charge carriers while also enhancing the adsorption of oxygen molecules. Furthermore, peroxymonosulfate (PMS) loading into the porous COFs boosts the therapeutic efficacy of antitumor nanotherapy via sonocatalytic dual oxidative species generation. These findings underscore the critical role of pore wall chemistry in modulating the sonocatalytic properties of COFs, and advance the development of COF‐based sonosensitizers for pro‐oxidative applications.

Exploring Ultrafast Carrier Dynamics in Photoelectrochemical Water Splitting Using Transient Absorption Spectroscopy

AbstractHydrogen fuel produced from water splitting using sunlight remains one of the cleanest and most sustainable energy sources. However, photoelectrochemical hydrogen production faces several challenges, including poor sunlight absorption, deficient charge carrier lifetime and transfer rates, and very sluggish kinetics of the water oxidation half‐reaction. To address these challenges, researchers have concentrated on enhancing the efficiency of photoelectrochemical water splitting. A critical factor in this enhancement is a deeper understanding of the fundamental processes involved in photoabsorption and the subsequent oxidation evolution reaction. The advent of ultrafast lasers has enabled the detailed tracking of charge carriers within materials after sunlight absorption, including their separation and migration to the surface for water oxidation. Ultrafast transient absorption spectroscopy is a powerful technique that allows real‐time observation of the behavior of excited states and charge carriers on femtosecond to nanosecond timescales. Recent studies utilizing ultrafast transient absorption spectroscopy are explored to investigate the dynamics of charge carriers in photoelectrochemical water splitting, providing insights into the mechanisms that lead to the design of enhanced photoanodes with improved efficiency.

Exploring the Relationship Between Electrical Characteristics and Changes in Chemical Composition and Structure of OSG Low-K Films Under Thermal Annealing

The influence of annealing temperature on the chemical, structural, and electrophysical properties of porous OSG low-k films containing terminal methyl groups was investigated. The films were deposited via spin coating, followed by drying at 200 °C and annealing at temperatures ranging from 350 °C to 900 °C. In the temperature range of 350–450 °C, thermal degradation of surfactants occurs along with the formation of a silicon-oxygen framework, which is accompanied by an increase in pore radius from 1.2 nm to 1.5 nm. At 600–700 °C, complete destruction of methyl groups occurs, leading to the development of micropores. FTIR spectroscopy reveals that after annealing at 700 °C, the concentration of silanol groups and water reaches its maximum. By 900 °C, open porosity is no longer observed, and the film resembles dense SiO2. JV measurements show that the film annealed at 450 °C exhibits minimal leakage currents, approximately 5 × 10−11 A/cm2 at 700 kV/cm. This can be attributed to the near-complete removal of surfactant residues and non-condensed silanols, along with non-critical thermal degradation of methyl groups. Leakage current models obtained at various annealing temperatures suggest that the predominant charge carrier transfer mechanism is Poole–Frenkel emission.

Z-Scheme Enabled 1D/2D Nanocomposite of ZnO Nanorods and Functionalized g-C3 N4 Nanosheets for Sustainable Degradation of Terephthalic Acid.

The urgent need to mitigate water pollution and achieve Sustainable Development Goal 14 (SDG 14)-Life below water, necessitates developing efficient and eco-friendly wastewater treatment technologies. This research addresses this challenge by photocatalytic degradation of terephthalic acid, a precursor for PET bottles using environment-friendly and biocompatible photocatalysts. The 1D/2D nanocomposite comprising zinc oxide (ZnO) nanorods and functionalized graphitic carbon nitride (Zn-TG) nanosheets were synthesized and thoroughly characterized. The nanocomposite effectively mitigated the individual drawbacks of Zn-TG agglomeration and the wide band gap of ZnO as confirmed through zeta potential and Tauc's plot studies, respectively. The synthesized nanocomposite achieved ~100 % degradation within 60 minutes, exhibiting superior kinetics (~2.5 times) compared to pristine samples. The enhanced degradation efficiency was elucidated by efficient charge carrier transfer (~5 times faster) and separation (~2 times improved) as confirmed through electrochemical impedance spectroscopy and time-resolved photoluminescence studies. The proposed Z-scheme pathway provides mechanistic insights. This proposed mechanism is supported by extensive electron paramagnetic resonance (EPR) and scavenger studies. The liquid chromatography-mass spectrometry (LC-MS) analysis confirms the formation of less toxic byproducts for ensuring that the wastewater treatment process is efficient and environmentally friendly. This research helps in developing a highly effective and sustainable wastewater treatment technology.

Enhanced Degradation of Norfloxacin Under Visible Light by S-Scheme Fe2O3/g–C3N4 Heterojunctions

S-scheme Fe2O3/g–C3N4 heterojunctions were successfully fabricated by the ultrasonic assistance method to remove norfloxacin (NOR) under visible light irradiation. The synthesized catalysts were well studied through various techniques. The obtained Fe2O3/g–C3N4 heterojunctions exhibited an optimal photocatalytic degradation of 94.7% for NOR, which was 1.67 and 1.28 times higher than using Fe2O3 and g–C3N4 alone, respectively. In addition, the kinetic constant of NOR removal with Fe2O3/g–C3N4 composites was about 0.6631 h−1, and NOR photo-deegradation was still 86.7% after four cycles. The enhanced photocatalytic activity may be mainly attributed to the formation of S-scheme Fe2O3/g–C3N4 heterojunctions with built-in electric fields, which were beneficial to the separation and transfer of photostimulated charge carriers. Furthermore, a possible photo-degradation mechanism of NOR for S-scheme Fe2O3/g–C3N4 heterojunctions is described.

Photothermal-assisted S-scheme heterojunction of NiPS3 nanosheets modified ZnIn2S4 microspheres for promoting photocatalytic hydrogen evolution

Exploring high-efficiency photocatalysts for solar hydrogen (H2) generation through water splitting is of great significance for addressing both energy shortage and environmental contamination. In this work, a facile self-assembly strategy was developed to couple NiPS3 nanosheets (NPS NSs) with ZnIn2S4 (ZIS) microspheres to synthesize NPS NSs/ZIS (NPS/ZIS) composites, featuring a characteristic of S-scheme charge transfer mechanism. The NPS/ZIS composites possess broad-spectrum light absorption property, improved photothermal effect and efficient charge transfer, showcasing exceptional solar-to-chemical energy conversion capability for visible-light-driven photocatalytic hydrogen evolution (PHE). The photothermal effect derived from NPS NSs loading can facilitate charge carrier transfer across the interfaces and surface reaction kinetics. By carefully adjusting the mass ratio of NPS NSs, the optimized 4-NPS/ZIS exhibits excellent stability and significantly improved PHE activity (1827.6 μmol⋅g−1⋅h−1) in water, which is 18.4 times higher than that of bare ZIS (99.4 μmol⋅g−1⋅h−1). Furthermore, the 4-NPS/ZIS also shows the high PHE efficiency of 312.2 μmol⋅g−1⋅h−1 in seawater. Diverse characterization results reveal that the remarkably enhanced PHE performance primarily arises from the synergistic effect of S-scheme heterostructure, heightened light harvesting capacity, and enhanced photothermal effect. On the basis of density functional theory (DFT) simulations and experimental verifications, a possible PHE mechanism via the S-scheme heterojunction with photothermal assistance in NPS/ZIS is proposed. This study serves as inspiration for the development of novel photothermal-assisted S-scheme photocatalysts, paving the way for efficient and sustainable green energy production.

Anchoring Ag Atom on Carbon Vacancy Enriched Carbon Nitride to Synergistically Promote CO2 Photoredution with Water

AbstractPristine carbon nitride (CN) has low CO2 reduction ability due to its sluggish charge carriers transfer and CO2 activation. Herein, carbon vacancy (CV) and Ag single atoms (SAs) with N2 coordination are simultaneously introduced into CN with the ordered structure for stable and efficient photoreduction of CO2 in the presence of H2O. The optimal sample loaded with 0.053 wt.% Ag evolve 173.0 µmol g−1 CO in 3 h with 89% selectivity, which is 11.7 times higher than that of pristine CN (14.7 µmol g−1). Experiments and theoretical calculations reveal that the CV and Ag–N2 sites promote CO2 adsorption/activation and the generation of *COOH and *CO. KSCN‐assisted calcination induces more ordered arrangement of melon chains, which can accelerate charge transfer/separation and facilitate H2O oxidation, thus accounting for the largely improved CO2 photoreduction performance. This study adopts a new method to prepare Ag SA‐anchored and C‐deficient CN, and provides insights into their synergistic roles in enhancing CO2 reduction.

Lattice Distortion Creates Enhancements in Photocatalytic and Electrocapacitive Performance of Sol–Gel‐Derived Cu‐Doped NiTiO3

A remarkable 35% enhancement in the photocatalytic and electrocatalytic abilities of an ilmenite nickel titanate (NiTiO3) material is reported. This boost in catalytic performance is achieved by simply creating a static distortion in the rhombohedral unit cell by replacing a small proportion of a small‐size nondegenerate Ni (69 pm) with a large‐size degenerate Cu (73 pm). The materials are synthesized by using a simple sol–gel method. The appropriate doping amount of Cu facilitates the better separation of intrinsic charge carrier pairs by inhibiting their recombination. The photocatalytic and electrochemical activities of durable materials in aqueous MB dye (10 ppm) and KOH (1 molar) electrolyte solutions are found to be directly associated with this improvement in inherent charge carrier transfer characteristics. The enhanced photodissociation of MB dye (42–56%) and specific capacitance (381–450 F g−1) in a KOH (1 molar) electrolyte are in full accord with the investigations carried out using crystallographic and optoelectronic analysis, charging–discharging measurements, and electrochemical impedance (EIS) spectroscopy investigations. Same material with high textural surface areas or controllable particle morphologies might show a far better photo/electrocatalytic performance in a variety of practical applications.

Metal-organic framework-derived in situ-grown Cu2Sb@NC octahedra for high-performance stable lithium/sodium storage

Intermetallic compounds are considered a special class of alloy-type anode materials that show great potential for use in lithium/sodium-ion batteries due to their inherent advantages, such as high specific capacity and enhanced safety features. However, their practical application is often impeded by the substantial volume changes that occur during the insertion and extraction of Li+/Na+ ions, leading to capacity decay and reduced service life. To address this challenge, we developed a novel composite material comprising Cu2Sb nanoparticles encapsulated within a N-doped octahedral carbon matrix (Cu2Sb@N-C). This composite structure features a heteroatom-doped conductive network, a three-dimensional carbon framework, and finely dispersed Cu2Sb nanoparticles. Benefiting from the heteroatom-doped conductive network, three-dimensional carbon framework and ultrafine Cu2Sb nanoparticles, they not only provide a penetrating network for the fast transfer of charge carriers and improve the accessibility of ions, but also alleviate the agglomeration and volume expansion of Cu2Sb during cycling. For LIBs, the material exhibited a reversible capacity of 1001.0 mAh/g after 330 cycles at 0.2 A/g, while maintaining a substantial capacity of 565.5 mAh/g after 1000 cycles at 1.0 A/g. In the case of SIBs, the material exhibited a capacity of 375.6 mAh/g after 100 cycles at 0.2 A/g. Post-cycling electrode analyses revealed that the Cu2Sb@N-C anode material retained its structural integrity, demonstrating its ability to withstand the continuous insertion and extraction of Li+/Na+ ions. This research contributes insights into the effective design of innovative high-capacity alloy-based anode materials for advanced secondary batteries.

Homo-Nuclear Hetero-Atomic Conjugated Reticular Oligomers for Heterojunction: A Novel "Electron Medium" for Panel Photoelectrocatalysis.

A substantial challenge in employing covalent organic frameworks (COFs) for photoelectrochemical (PEC) water splitting lies in improving their solution-processability while concurrently facilitating the transfer of charges and mass to the catalytic sites. Herein, we synthesize a solution-processable conjugated reticular oligomers (CROs), and further embed ruthenium (Ru) into the CRO, forming a CRO-Ru with homo-nuclear hetero-atomic. Thereafter, CRO and CRO-Ru construct an organic-organic heterojunction membrane at the nanoscale. Thisdesign achieves perfect lattice matching, significantly reducing the energy barrier of mass transfer, and effectively lowering the recombination rate of charge carriers. The optimized photocathode, CuI/CRO-Bpy:CRO-Bpy-Ru-1:1+P3HT/SnO2/Pt, exhibits an efficiency of 111.0µAcm-2 at 0.4V versus a reversible hydrogen electrode (RHE). Compared with the original bulk COFs and CROs, the efficiency is significantly improved. The apparent improvements in charge carrier separation and transfer are responsible for the high PEC activity. In the heterojunction, the incorporation of CRO-Bpy-Ru with a longer excited-state lifetime and a substantial built-in electric field has effectively accelerated the photo-induced electron transfer from the conduction band (CB) of CRO-Bpy to the valence band (VB) of CRO-Bpy-Ru, effectively suppressing the recombination of charges. These findings offer significant guidance for the design and optimization of high-performance photoelectrochemical catalysts.

Z-scheme driven charge transfer in g-C3N4/α-Fe2O3 nanocomposites enabling photocatalytic degradation of crystal violet and chromium reduction

In this study, we demonstrated the design and fabrication of iron oxide-embedded protonated graphitic carbon nitride (α-Fe2O3/p-g-C3N4) nanocomposites for photocatalytic dye degradation and heavy metal reduction applications under sunlight irradiation. The developed nanocomposites, with varying weight percentages of α-Fe2O3, were characterized for their structural (XRD, FTIR, XPS), optical (absorption and photoluminescence), morphological (FE-SEM, TEM), and electrochemical (EIS) properties to elucidate their structure-property relationships. The synthesis method ensures the uniform dispersion of α-Fe2O3 nanoparticles, with a particle size range of 50–60 nm, onto p-g-C3N4. XPS analysis suggests the formation of an electrical layer at the interface of α-Fe2O3/p-g-C3N4, facilitating the formation of a Z-scheme heterojunction. The photoluminescence and EIS spectra of the nanocomposite indicated effective separation and transfer of photo-induced charge carriers, aided by a reduced bandgap energy of ∼2.63 eV. Notably, the optimized 10 wt% α-Fe2O3/p-g-C3N4 nanocomposite exhibited superior photocatalytic activity, degrading nearly 100 % of crystal violate dye and reducing 98 % of Cr(VI) ions, compared to bare p-g-C3N4, which degraded around 43 % of the dye and reduced 39 % of Cr(VI) ions under sunlight irradiation. Scavenger studies indicated that α-Fe2O3/p-g-C3N4 nanocomposites produce adequate superoxide anions and hydroxyl radicals for dye degradation and heavy metal ion reduction. The composite also demonstrated consistent recyclability up to 5 cycles with around 100 % cyclical efficiency. The pH-dependent photoreduction and cyclic dye degradation by the 10 wt% α-Fe2O3/p-g-C3N4 photocatalyst indicated excellent stability, making it suitable for the treatment of multi-pollutant wastewater.

Photocatalytic seawater splitting by Earth-abundant catalysts: metal-semiconductor metamaterials made of plasmonic magnesium diboride and transitional metal dichalcogenides.

Metal-semiconductor metamaterials hold great promise for photocatalytic water splitting due to their excellent light harvesting in a broad spectral range as well as efficient charge carrier generation and transfer. In majority of such metamaterials, semiconductors are used to initiate the water splitting reaction, while their metal counterparts are employed to improve light harvesting through plasmonic effects. Here, we describe for the first time an exceptional reversed case of metal-semiconductor photocatalysts in which metals are used to initiate the water splitting reaction and semiconductors are employed to improve light harvesting through blackbody effect and serve as co-catalysts. The studied photoanodes are made of non-noble plasmonic MgB2 combined with transition metal dichalcogenides (TMDCs). The plasmonic resonances of the MgB2 component contribute to field confinement, plasmon-exciton coupling, and hot-electron transfer providing an enhancement of photoactivity in the entire solar spectrum capable of water splitting. The TMDC component provides impedance matching and enhances light absorption by the metal catalyst. We demonstrate seawater splitting with MgB2-TMDCs photoanodes attaining current densities of ~ 3 mA⋅cm-2 at solar radiation. The overall efficiency of hydrogen production in seawater splitting by sunlight with the help of the studied photoanodes is 3% at bias voltage of Vbias = 0.3 V.

Novel S-scheme derived Mo–Bi2WO6/WO3/Biochar composite for photocatalytic removal of Methylene Blue dye

Presently, the distinct charge transport and interface interaction of the S-scheme heterojunction has garnered significant interest. Herein, a S-scheme-based charge transportation Mo-doped Bi2WO6/WO3/Biochar heterojunction was synthesized in situ using a coprecipitation technique to improve methylene blue adsorption and photocatalytic reactive oxygen species production. The doped Mo altered the band gap of Bi2WO6 to increase light absorption, which can facilitate electron-hole separation and transfer. Likewise, the S-scheme band structure improved sunlight utilization, enhanced the reduction and oxidation power of photogenerated electrons, and boosted charge carrier separation and transfer. Thus, due to the synergetic impact of doping and the S scheme band structure, the photocatalysts efficiently eliminated Methylene blue up to 87.5 % in 30 min of photoirradiation. Fabricated heterojunction Mo–Bi2WO6/WO3/Biochar photocatalyst have highest Kapp values 0.02816 min−1 while Mo–Bi2WO6/WO3, Mo–Bi2WO6, Bi2WO6, and WO3 photocatalysts have 0.02816, 0.02273, 0.01527, 0.00643, and 0.00735 min−1, respectively which was 4.38 times greater than pristine Bi2WO6. The study offers a novel perspective for the in-situ production of S-scheme heterojunction with doping to remove different types of contaminants.

Construction of BaTiO3/g-C3N4 heterojunction for promoting atrazine degradation of hydraulic-driven piezocatalytic ozonation

Catalytic ozonation, as a popular water purification technology, was restrained with the dilemma of slow Me(n+m)+/Men+ redox cycle of the convention catalysts. To this end, BaTiO3/g-C3N4 (BTO/CN) piezoelectric heterojunction was designed to enhance atrazine (ATZ) degradation in piezocatalytic ozonation, utilizing the overlooked mechanical forces to activate O3 into reactive oxygen species (ROS). Characterization results demonstrated that the couple of BTO and CN successfully formed a Type-II heterojunction, enhancing the separation of piezoelectric carriers (e- and h+). Moreover, BTO/CN showed the better O3 affinity and O3 activation capability over that of BTO and CN. BTO/CN/O3 process achieved 90.1 % ATZ removal, which was 3.5 and 1.7 times over that of the BTO/O3 and CN/O3 processes, respectively. ATZ removal in BTO/CN/O3 process increased with the initial pH value. Cl-, SO42- and NO3- inhibited ATZ removal, but HCO3- enhanced ATZ removal. O3, •OH, O2- and 1O2 were all involved in ATZ degradation and •OH served as the main ROS, accounting for 79.3 % in degrading ATZ. The internal electric field along with the interfacial electric field synergistically boosted the separation and transfer of charge carriers to provide e- for O3 activation and ROS generation. This study broke through the basic need of continuous sacrifice of e- for O3 activation induced by metal redox cycle and provided a novel catalyst design strategy for piezoelectric ozonation.

Tailoring Perovskite/C60 Interface by Reactive Passivators for Stable Tandem Solar Cells

AbstractIntegrating perovskite solar cells with crystalline silicon bottom cells in a monolithic two‐terminal tandem configuration enables power conversion efficiency (PCE) surpassing the theoretical limits of single‐junction cells. However, wide bandgap (WBG) perovskite films face challenges related to phase stability and open circuit voltage (VOC) deficit, particularly due to severe non‐radiative recombination at the perovskite/C60 interface. Here, the interfacial defects are passivated by incorporating a reactive passivator that reacts with lead halides to form low‐dimensional phases. The target product obtained by optimizing the reaction temperature not only suppresses recombination across the interface, but also facilitates the transfer of charge carriers. More importantly, this product can suppress phase segregation of WBG perovskite films under exposure to light illumination and moisture. This strategy enables a high VOC of 1.25 V for WBG perovskite device based on polymer hole transport layer and a certified stabilized PCE of 30.52% for a monolithic perovskite/silicon tandem solar cell. The unencapsulated tandem device retains 94% of its initial PCE over 200 h under continuous 1‐sun full spectrum illumination in air, demonstrating the improved phase stability.

Recent innovations in engineering Zinc Oxide (ZnO) nanostructures for water and wastewater treatment: Pushing the boundaries of multifunctional photocatalytic and advanced biotechnological applications

Owing to its rapid advancement in nanotechnology, latest publications (recent 5 years) related to zinc oxide (ZnO) in various aspects and applications have been reviewed. Trend has shifted to the innovation of pristine ZnO nanostructures functionalized with elemental dopants and heterojunction to improve the photoactivities on micropollutant degradation and heavy metals removal as well as the antibacterial effect towards microorganisms. The fundamentals of improved photoactivities (i.e., low recombination rate of charge carrier and effective charge transfer) and enhanced antibacterial properties (i.e., dissolution of ions and generation of reactive oxygen species) are accentuated. Subsequently, a detailed examination is undertaken to elucidate the key impacts of ZnO on actual wastewater treatment systems. This review concludes with a consolidated overview on the recent advances of ZnO for environmental wastewater decontamination and the future prospects on tailoring ZnO based on their photocatalytic and antibacterial properties to match various expectations from practical applications while minimising the adverse impacts on surrounding environment.

High-Voltage Stable Perovskite Light-Emitting Diodes Enabled by an Optoelectric-Tunable Sandwiched Nanostructure.

While metal halide light-emitting diodes (PeLEDs) with unique optoelectronic properties are promising emitters for next-generation displays, their performance degrades rapidly due to severe ion migration during continuous operation, especially at high voltages. Here, we realize highly stable PeLEDs by designing inorganic dielectric/perovskite semiconductor emitter/organic dielectric sandwiched nanostructures to mitigate ion migration via regulating the electric field distribution. The bilateral cesium carbonate (Cs2CO3) and tetraoctylammonium bromide (TOAB) thin interlayers can not only largely reduce the voltage imposed on the perovskite layer by serving as series resistors and, thus, mitigate the ion migration but also regulate the charge carrier transfer to improve the radiative recombination efficiency. In addition, the underneath inorganic Cs2CO3 film also provides more heterogeneous nucleation sites for growing high-crystallinity perovskite crystals, while the atop TOAB with bifunctional groups (organic amino and Br- ions) refines the morphology and enhances the optical properties of the perovskite film. As a result, efficient and stable green PeLEDs based on such an optoelectric-tunable nanostructure exhibit extremely slow efficiency decay as the applied voltage increases, and the external quantum efficiencies were maintained over 10% at a high bias up to 20 V.

Modulating Pore Wall Chemistry Empowers Sonodynamic Activity of Two-Dimensional Covalent Organic Framework Heterojunctions for Pro-Oxidative Nanotherapy.

Covalent organic frameworks (COFs) have garnered growing attracted interest in the field of biomedicine; however, their application in sonodynamic therapy remains underexplored due to limited understanding of their intrinsic activity and structure-property relationships. Here, we present a pore wall chemistry modulation strategy for empowering sonodynamic activity to two-dimensional (2D) COF heterojunctions through in situ growth of COFs on bismuth oxycarbonate nanosheets (B NSs). Compared to the negligible sonodynamic effects observed in the pristine B NSs, the 2D heterojunction with vinyl-decorated COF pore walls demonstrates a 3.6-fold enhancement in sonocatalytic singlet oxygen generation. This performance also significantly outperforms that of isoreticular COFs functionalized with methoxy or non-substituted groups. Mechanistic studies reveal that the vinyl groups in the BC heterojunction facilitate the separation and transfer of charge carriers while also enhancing the adsorption of oxygen molecules. Furthermore, peroxymonosulfate (PMS) loading into the porous COFs boosts the therapeutic efficacy of antitumor nanotherapy via sonocatalytic dual oxidative species generation. These findings underscore the critical role of pore wall chemistry in modulating the sonocatalytic properties of COFs, and advance the development of COF-based sonosensitizers for pro-oxidative applications.

Enhancement of visible light adsorption and photocatalytic degradation activity of organic dye by coating semiconducting TiO2 shell on plasmonic Au particles

The plasmonic effect enhances light absorption in semiconductor photocatalysts, while the noble metal-semiconductor interface promotes charge carrier transfer and separation, boosting photocatalytic activity. However, current methods for synthesizing metal-core TiO2-shell nanoparticles face challenges, such as keeping stable and preventing aggregation. This study presents a simple and moderate synthesis method for Au@TiO2 core-shell nanoparticles, enabling precise control over the TiO2 shell thickness and stable photocatalytic performance. Various characterization techniques were employed to assess the optical and structural properties of the synthesized Au@TiO2 core-shell nanostructures. The results demonstrated that increasing the Au core concentration led to a gradual decrease in TiO2 shell thickness. The adsorption properties and photocatalytic degradation efficiency of the synthesized Au@TiO2 core-shell nanostructured catalysts were thoroughly examined, particularly focusing on their performance with methyl orange (MO) and methylene blue (MB). Au@TiO2 achieved excellent adsorption performance for MO, with a maximum capacity of 231±6 mg/g. Furthermore, Au@TiO2 exhibited higher photocatalytic degradation activity of both MO and MB than pure TiO2. The mechanism study indicated that it attributed to enhanced visible light absorption, reduced bandgap, and higher valence band energy. Additionally, the Au@TiO2 catalysts showed good cyclic stability, making them promising for future applications. This research offers insights into designing efficient photocatalysts, addressing existing synthesis challenges, and contributing valuable references for future advancements.

Impact of Dual Functionalities of Mo‐Doped BiFeO3 Decorated with Bi4MoO9 Heteroatoms for Piezo‐Photocatalytic Activity

AbstractPiezocatalysts have shown great promise for effcient hydrogen generation. However, their application is limited by the rapid charge recombination and sluggish charge transfer rate of piezo‐induced charge carriers. This work aims to address the preceding limitations by controlled synthesis of a representative piezocatalyst, BiFeO3 doped with Mo atoms and decorated with Bi4MoO9 (BMO) heteroatoms using sol‐gel method. The substitutional doping of Mo on BFO (BFMO) was shown to induce a shallow energy level near the conduction band that acted as a trapping state, to suppress recombination of charge carriers, enhance charge mobility for transport to the surface, modulate band alignment, and lower the energy barrier for surface reaction. The formation of BFMO/BMO heterostructures induced electrical band bending, leading to the electric potential gradient, hence promoting charge carrier separation and transfer. The BFMO/BMO with 0.5 mol % Mo (Mo‐5) demonstrated four times faster piezocatalytic Rhodamine B (RhB) dye degradation rate (k of 0.032 min−1) compared to pristine BFO (0.009 min−1). Further, the Mo‐5 exhibited a 45% higher piezocatalytic H2 production rate (14.4 µmol/g/h) compared to pristine BFO (9.8 µmol/g/h) while being cocatalyst‐free. Coupling piezocatalysis with photocatalysis was found to reduceperformance relative to the individual processes, which is attributed to Auger recombination which impedes any potential synergistic effect.