Separation Of Charge Carriers Research Articles

Ultrathin TiS2@N,S-Doped Carbon Hybrid Nanosheets as Highly Efficient Photoresponsive Antibacterial Agents.

Nanobactericides are employed as a promising class of nanomaterials for eradicating microbial infections, considering the rapid resistance risks of conventional antibiotics. Herein, we present a pioneering approach, reporting the synthesis of two-dimensional titanium disulfide nanosheets coated by nitrogen/sulfur-codoped carbon nanosheets (2D-TiS2@NSCLAA hybrid NSs) using a rapid l-ascorbic acid-assisted sulfurization of Ti3C2Tx-MXene to achieve efficient alternative bactericides. The as-developed materials were systematically characterized using a suite of different spectroscopy and microscopy techniques, in which the X-ray diffraction/Raman spectroscopy/X-ray photoelectron spectroscopy data confirm the existence of TiS2 and C, while the morphological investigation reveals single- to few-layered TiS2 NSs confined by N,S-doped C, suggesting the successful synthesis of the ultrathin hybrid NSs. From in vitro evaluation, the resultant product demonstrates impressive bactericidal potential against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria, achieving a substantial decrease in the bacterial viability under a 1.2 J dose of visible-light irradiation at the lowest concentration of 5 μg·mL-1 compared to Ti3C2Tx (15 μg·mL-1), TiS2-C (10 μg·mL-1), and standard antibiotic ciprofloxacin (15 μg·mL-1), respectively. The enhanced degradation efficiency is attributed to the ultrathin TiS2 NSs encapsulated within heteroatom N,S-doped C, facilitating effective photogenerated charge-carrier separation that generates multiple reactive oxygen species (ROS) and induced physical stress as well as piercing action due to its ultrathin structure, resulting in multimechanistic cytotoxicity and damage to bacterial cells. Furthermore, the obtained results from molecular docking studies conducted via computational simulation (in silico) of the as-synthesized materials against selected proteins (β-lactamasE.coli/DNA-GyrasE.coli) are well-consistent with the in vitro antibacterial results, providing strong and consistent validation. Thus, this sophisticated study presents a simple and effective synthesis technique for the structural engineering of metal sulfide-based hybrids as functionalized synthetic bactericides.

Regulating the Topology of Covalent Organic Frameworks for Boosting Overall H2O2 Photogeneration

AbstractPhotocatalytic oxygen reduction reactions and water oxidation reactions are extremely promising green approaches for massive H2O2 production. Nonetheless, constructing effective photocatalysts for H2O2 generation is critical and still challenging. Since the network topology has significant impacts on the electronic properties of two dimensional (2D) polymers, herein, for the first time, we regulated the H2O2 photosynthetic activity of 2D covalent organic frameworks (COFs) by topology. Through designing the linking sites of the monomers, we synthesized a pair of novel COFs with similar chemical components on the backbones but distinct topologies. Without sacrificial agents, TBD‐COF with cpt topology exhibited superior H2O2 photoproduction performance (6085 and 5448 μmol g−1 h−1 in O2 and air) than TBC‐COF with hcb topology through the O2‐O2⋅−‐H2O2, O2‐O2⋅−‐O21‐H2O2, and H2O‐H2O2 three paths. Further experimental and theoretical investigations confirmed that during the H2O2 photosynthetic process, the charge carrier separation efficiency, O2⋅− generation and conversion, and the energy barrier of the rate determination steps in the three channels, related to the formation of *OOH, *O21, and *OH, can be well tuned by the topology of COFs. The current study enlightens the fabrication of high‐performance photocatalysts for H2O2 production by topological structure modulation.

MoS2@MWCNTs with Rich Vacancy Defects for Effective Piezocatalytic Degradation of Norfloxacin via Innergenerated-H2O2: Enhanced Nonradical Pathway and Synergistic Mechanism with Radical Pathway.

Molybdenum disulfide (MoS2)-based materials for piezocatalysis are unsatisfactory due to their low actual piezoelectric coefficient and poor electrical conductivity. Herein, 1T/3R phase MoS2 grown in situ on multiwalled carbon nanotubes (MWCNTs) was proposed. MoS2@MWCNTs exhibited the interwoven morphology of thin nanoflowers and tubes, and the piezoelectric response of MoS2@MWCNTs was 4.07 times higher than that of MoS2 via piezoresponse force microscopy (PFM) characterization. MoS2@MWCNTs exhibited superior activity with a 91% degradation rate of norfloxacin (NOR) after actually working 24 min (as for rhodamine B, reached 100% within 18 min) by pulse-mode ultrasonic vibration-triggered piezocatalysis. It was found that piezocatalysis for removing pollutants was attributed to the synergistic effect of free radicals (•OH and O2•-) and nonfree radical (1O2, key role) pathways, together with the innergenerated-H2O2 promoting the degradation rate. 1O2 can be generated by electron transfer and energy transfer pathways. The presence of oxygen vacancies (OVs) induced the transformation of O2 to 1O2 by triplet energy transfer. The fast charge transfer in MoS2@MWCNTs heterostructure and the coexistence of sulfur vacancies and OVs enhanced charge carrier separation resulting in a prominent piezoelectric effect. This work opens up new avenues for the development of efficient piezocatalysts that can be utilized for environmental purification.

A novel type-II–II heterojunction for photocatalytic degradation of LEV based on the built-in electric field: carrier transfer mechanism and DFT calculation

Heterojunctions play a crucial role in improving the absorption of visible light and performance of photocatalysts for organic contaminants degradation in water. In this work, a novel type-II–II Ag2CO3/Bi2WO6 (AB) heterojunction was synthesized by hydrothermal reaction and in situ-precipitation methods. The mechanisms of charge transfer and carrier separation at the interface of heterojunctions and the influence on the photocatalytic activity were investigated. The degradation of levofloxacin (LEV) under visible light irradiation was employed to evaluate the photocatalytic performance of AB. The results showed that 85.4% LEV was degraded by AB, which was 1.38 and 1.39 times higher than that of Bi2WO6 and Ag2CO3, respectively. The work functions of the different crystal planes in the AB heterojunction, which was calculated by density functional theory, are a significant difference. The Fermi energy (Ef) of Ag2CO3 (− 6.005 eV) is lower than Bi2WO6 (− 3.659 eV), but the conduction band (CB) is higher. Therefore, using AB heterojunctions as an example, the research explored the mechanism of type-II–II which CB and Ef of one semiconductor cannot simultaneously surpass those of another material, based on the built-in electric field theory. Through this analysis, a deeper understanding of type-II heterojunctions was achieved, and providing valuable insights into the behavior of this specific heterojunction system.

Sensitizer created defective metal organic framework as a new platform for boosting visible-light photocatalysis of g-C3N4

We developed herein for the first time a sensitizer created defective MOF (SCD-MOF), simultaneously possessing sensitizers and defects as visible-light harvester and electron trapper, respectively, which can synergistically improve the visible-light photocatalysis of polymeric graphitic carbon nitride (g-C3N4). Based on this discovery, the resulting 5.0 wt% FeTCPP⊂UiO-66@g-C3N4 shows a significant 6.6 and 3.9 times improvement in catalytic efficiency compared with its parent materials of FeTCPP⊂UiO-66 and g-C3N4 in degrading organic pollutants. Moreover, it shows a 10.4 times enhancement in catalytic efficiency compared with commercial TiO2 (P25). Mechanism studies suggest that sensitizer molecules and defects in SCD-MOF can synergistically improve photocatalytic efficiency because of broadening the visible-light response and strengthening the charge carrier separation. This work illustrates a remarkably triple synergetic effect among visible-light harvester, electron/hole separator, and semiconductor and thus established SCD-MOF as a class of new platform to greatly improve the visible-light photocatalytic performance of conventional semiconductors.

Surface-Grafted Single-Atomic Pt-Nx Complex with a Precisely Regulating Coordination Sphere for Efficient Electron Acceptor-Inducing Interfacial Electron Transfer.

Based on the electron-withdrawing effect of the Pt(bpy)Cl2 molecule, a simple post-modification amide reaction was firstly used to graft it onto the surface of NH2-MIL-125, which formed a highly efficient electron acceptor that induced the conversion of the photoinduced charge migration pathway from internal BDC→TiOx migration to external BDC→PtNx migration, significantly improving the efficiency of photoinduced electron transfer and separation. Furthermore, precise control over the first coordination sphere of Pt single atoms was achieved using further post-modification with additional bipyridine to investigate the effect of Pt-Nx coordination numbers on reaction activity. The as-synthesized NML-PtN2 exhibited superior photocatalytic hydrogen evolution activity of 7.608 mmol g-1 h-1, a remarkable improvement of 225 and 2.26 times compared to pristine NH2-MIL-125 and NML-PtN4, respectively. In addition, the superior apparent quantum yield of 4.01% (390 nm) and turnover frequency of 190.3 h-1 (0.78 wt% Pt SA; 129 times compared to Pt nanoparticles/NML) revealed the high solar utilization efficiency and hydrogen evolution activity of the material. And macroscopic color changes caused by the transition of carrier migration paths was first observed. It holds profound significance for the design of MOF-Molecule catalysts with efficient charge carrier separation and precise regulation of single-atom coordination sphere.

Surface‐Grafted Single‐Atomic Pt‐Nx Complex with a Precisely Regulating Coordination Sphere for Efficient Electron Acceptor‐Inducing Interfacial Electron Transfer

Based on the electron‐withdrawing effect of the Pt(bpy)Cl2 molecule, a simple post‐modification amide reaction was firstly used to graft it onto the surface of NH2‐MIL‐125, which formed a highly efficient electron acceptor that induced the conversion of the photoinduced charge migration pathway from internal BDC→TiOx migration to external BDC→PtNx migration, significantly improving the efficiency of photoinduced electron transfer and separation. Furthermore, precise control over the first coordination sphere of Pt single atoms was achieved using further post‐modification with additional bipyridine to investigate the effect of Pt‐Nx coordination numbers on reaction activity. The as‐synthesized NML‐PtN2 exhibited superior photocatalytic hydrogen evolution activity of 7.608 mmol g−1 h−1, a remarkable improvement of 225 and 2.26 times compared to pristine NH2‐MIL‐125 and NML‐PtN4, respectively. In addition, the superior apparent quantum yield of 4.01% (390 nm) and turnover frequency of 190.3 h−1 (0.78 wt% Pt SA; 129 times compared to Pt nanoparticles/NML) revealed the high solar utilization efficiency and hydrogen evolution activity of the material. And macroscopic color changes caused by the transition of carrier migration paths was first observed. It holds profound significance for the design of MOF‐Molecule catalysts with efficient charge carrier separation and precise regulation of single‐atom coordination sphere.

Performance optimization of CsPbIBr2-Based Perovskite Solar Cells through Device Modeling

Abstract Among all-inorganic perovskite materials, CsPbIBr2 provides the optimal equilibrium between optical bandgap and phase stability. However, notwithstanding these advantageous, interfacial defects and improper band alignment continue to diminish the photovoltaic efficacy of CsPbIBr2-based PSCs. This study used the SCAPS-1D software to undertake a thorough examination of operating mechanism of CsPbIBr2-based devices. A comprehensive analysis is conducted on a range of physical parameters pertaining to the FTO/ZnOS/CsPbIBr2/CZTS configuration, encompassing doping concentration, operating temperature, defect density, electron affinity, thickness, series and shunt resistance. The simulation outcomes revealed that PSCs characterized by a low defect density and an ideal band structure enhance the performance of the devices by facilitating the transport and separation of charge carriers. The optimized device achieved an efficiency of 16.68%, short-circuits current density (JSC) of 11.52 mA/cm2, open-circuit voltage (VOC) of 1.64V, and Fill factor (FF) of 87.83%. These simulation findings will provide useful information for experimental fabrication of efficient CsPbIBr2-based inorganic PSC.

Molecularly Tunable Heterostructured Co-polymers Containing Electron-deficient and -rich Moieties for Visible-light and Sacrificial-agent-free H2O2 Photosynthesis.

As an alternative to hydrogen peroxide (H2O2) production by complex anthraquinone oxidation process, photosynthesis of H2O2 from water and oxygen without sacrificial agents is highly demanded. Herein, a covalently connected molecular heterostructure is synthesized via sequential C-H arylation and Knoevenagel polymerization reactions for visible-light and sacrificial-agent-free H2O2 synthesis. The subsequent copolymerization of the electron-deficient benzodithiophene-4,8-dione and the electron-rich biphenyl (B) and p-phenylenediacetonitrile (CN) not only expands the π-conjugated domain but also increases the molecular dipole moment, which largely promotes the separation and transfer of the photoinduced charge carriers. The optimal heterostructured BTDB-CN0.2 manifested an impressive photocatalytic H2O2 production rate of 1920 μmol g-1 h-1, which is 2.2 and 11.6 times that of BTDB and BTDCN. As revealed by the femtosecond transient absorption (fs-TA) and theoretical calculations, the linkage serves as a channel for the rapid transfer of photogenerated charge carriers, enhancing the photocatalytic efficiency. Further, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) uncovers that the oxygen reduction reaction occurs through the step one-electron pathway and the mutual conversion between C=O and C-OH with the anchoring of H+ during the catalysis favored the formation of H2O2. This work provides a novel perspective for the design of efficient organic photocatalysts.

Molecularly Tunable Heterostructured Co‐polymers Containing Electron‐deficient and ‐rich Moieties for Visible‐light and Sacrificial‐agent‐free H2O2 Photosynthesis

As an alternative to hydrogen peroxide (H2O2) production by complex anthraquinone oxidation process, photosynthesis of H2O2 from water and oxygen without sacrificial agents is highly demanded. Herein, a covalently connected molecular heterostructure is synthesized via sequential C−H arylation and Knoevenagel polymerization reactions for visible‐light and sacrificial‐agent‐free H2O2 synthesis. The subsequent copolymerization of the electron‐deficient benzodithiophene‐4,8‐dione and the electron‐rich biphenyl (B) and p‐phenylenediacetonitrile (CN) not only expands the π‐conjugated domain but also increases the molecular dipole moment, which largely promotes the separation and transfer of the photoinduced charge carriers. The optimal heterostructured BTDB‐CN0.2 manifested an impressive photocatalytic H2O2 production rate of 1920 μmol g‐1 h‐1, which is 2.2 and 11.6 times that of BTDB and BTDCN. As revealed by the femtosecond transient absorption (fs‐TA) and theoretical calculations, the linkage serves as a channel for the rapid transfer of photogenerated charge carriers, enhancing the photocatalytic efficiency. Further, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) uncovers that the oxygen reduction reaction occurs through the step one‐electron pathway and the mutual conversion between C=O and C−OH with the anchoring of H+ during the catalysis favored the formation of H2O2. This work provides a novel perspective for the design of efficient organic photocatalysts.

Dual Channel H2O2 Photosynthesis in Pure Water over S-Scheme Heterojunction Cs3PMo12/CC Boosted by Proton and Electron Reservoirs.

Dual channel photo-driven H2O2 production in pure water on small-scale on-site setups is a promising strategy to provide low-concentrated H2O2 whenever needed. This process suffers, however, strongly from the fast recombination of photo-generated charge carriers and the sluggish oxidation process. Here, insoluble Keggin-type cesium phosphomolybdate Cs3PMo12O40 (abbreviated to Cs3PMo12) is introduced to carbonized cellulose (CC) to construct S-scheme heterojunction Cs3PMo12/CC. Dual channel H2O2 photosynthesis from both H2O oxidation and O2 reduction in pure water has been thus achieved with the production rate of 20.1mmolL-1gcat. -1h-1, apparent quantum yield (AQY) of 2.1% and solar-to-chemical conversion (SCC) efficiency of 0.050%. H2O2 accumulative concentration reaches 4.9mmol L-1. This high photocatalytic activity is guaranteed by unique features of Cs3PMo12/CC, namely, S-scheme heterojunction, electron reservoir, and proton reservoir. The former two enhance the separation of photo-generated charge carriers, while the latter speeds up the torpid oxidation process. In situ experiments reveal that H2O2 is formed via successive single-electron transfer in both channels. In real practice, exposing the reaction system under natural sunlight outdoors successfully results in 0.24mmol L-1 H2O2. This work provides a key practical strategy for designing photocatalysts in modulating redox half-reactions in photosynthesis.

Photocatalytic degradation of p-aminobenzoic acid on N-biomass charcoal etched with Fe-Al-bilayer hydroxide: New insights through spectroscopic investigation

We investigated the photocatalytic property of etched iron‑aluminum layered double hydroxide (LDH) composites using urea-modified biochar (N-BC) carrier to degrade para-aminobenzoic acid (PABA), a refractory organic pollutant. The prepared FeAl-LDH@FeSx-N-BC composite exhibited excellent photocatalytic performance, attributed to the enhanced photogenerated charge-carrier separation by the etched LDH and the improved comparative surface areas by the doped N-BC. The composite photocatalytically degraded 96 % of PABA. The performance was affected by solute concentration, pH and photocatalyst dose. Adding p-benzoquinone and EDTA-2Na significantly decreased the degradation rate, suggesting that superoxide radicals and holes were co-involved in PABA degradation. The excellent PABA removal efficiency was consistent for three consecutive runs. The samples' reactive oxygen species was confirmed, as electron paramagnetic reverberation explained the photodegradation mechanism. Under xenon lamp irradiation, two PABA photocatalytic degradation pathways were proposed using Liquid Chromatograph Mass Spectrometer (LCMS) and density functional theory. As expected, FeAl-LDH@FeSx-N-BC showed excellent photocatalytic performance, expanding a new direction and possibility for future photocatalytic treatment of water pollutants.

Construction of functionalized In-based metal organic framework/BiOCl1−xIx Z-scheme heterojunction for efficient photocatalytic degradation of tetracycline: Performance and mechanism

The environmental implications of antibiotics have drawn widespread attention. Numerous monomer-based bismuth oxide halide catalysts have been extensively studied to remove tetracycline (TC) from aquatic environments. Integrating bismuth oxide halide composites with In-based metal organic framework (NH2-MIL-68(In)) might potentially serve as a novel strategy. By meticulously adjusting Cl and I within the composite bismuth halide oxide (B-x), a suite of purpose built heterojunctions (NMB-x) were synthesized, which were engineered to facilitate the efficient photodegradation of TC in simulated and actual aquatic environments. The incorporation of Z-scheme heterojunctions yielded a significant enhancement in photocatalytic responsiveness and charge carrier separation. Notably, NMB-0.3 demonstrated remarkable TC removal efficiency of 88.52 ± 3.05%, which is 3.74 times of B-0.3 within 90 min. The apparent quantum yield was also increased from 8.97% (B-0.3) to 19.68% (NMB-0.3). The removal of TC from natural water bodies was also assessed. Moreover, the photocatalyst concentration, assessed using response surface method, was found to show influential factors on TC removal. In addition, density functional theory (DFT) simulations were employed to identify vulnerable sites within TC. Intermediates and pathways in the photodegradation of TC have also been inferred. Furthermore, a comprehensive environmental toxicity assessment of representative intermediates demonstrated that these intermediates exhibited significantly reduced environmental toxicity compared to TC. This study provides a new approach to the design strategy of efficient and environmentally friendly MOF-based photocatalysts.

Inclusion of metal nanoparticles at the core-shell interface of GaAs0.99Bi0.01/ZnO/ITO core-shell nanowire solar cell for photovoltaic performance enhancement

Optoelectronic performance analysis of perpendicularly aligned conformally coated GaAs0.99Bi0.01/ZnO/ITO core–shell nanowire solar cell having a core length of 1 μm, core diameter of 160 nm, shell thickness of 10 nm and period of 280 nm, decorated with Au metal nanoparticles(MNPs) of variable diameters at the core–shell interface is done employing FDTD method. Diameter optimization of MNPs with four different diameters values around core GaAs0.99Bi0.01 nanowire is accomplished in terms of maximum short circuit current density (Jsc), which offered an optimized diameter combination of D1 = D2 = 50 nm and D3 = 34 nm, D4 = 10 nm, resulting in a maximum Jsc of 32.6 mA cm−2. A detailed analysis of the electric field profile including its top view and longitudinal view is presented to investigate the distribution of electric field upon optical illumination at different wavelength range. The overall photo generation rate profile is also presented to focus on the localized surface plasmon resonance effect caused by the metal nanoparticles (MNPs). In order to boost the electrical performance, a thin coating of electron selective ZnO shell is used around p type GaAs0.99Bi0.01core, which aids in charge carrier separation, thereby improving open circuit voltage (Voc) and overall power conversion efficiency (PCE). The electrical characteristics of bare NW and MNP decorated GaAs0.99Bi0.01/ZnO core–shell nanowire solar cell for different MNP diameters have been compared. For the optimized diameter combination, as stated above, a Voc of 941 mV, Jsc of 28 mA cm−2, FF of 84.35% and PCE of 22.19% is obtained for SRV of 105 cm s−1 at the interfaces and SRH recombination lifetime as less as 10 ns. For SRV of 105 cm s−1 at the interfaces and SRH recombination lifetime of 1 μs, this proposed structure can achieve a Voc of 1.06 V, Jsc of 31.5 mA cm−2, PCE of 29.37% and FF of 87.88% for equal diameters of D1 = D2 = D3 = D4 = 50 nm.

Enhanced charge separation of Cu-BTC@CuSe@TiO2 hollow octahedrons for efficient CO2 photoreduction with superior CO selectivity

Solar-driven photocatalytic conversion of CO2 into high-value-added fuels has attracted widespread attention. However, the relatively low conversion efficiency and product yield severely limited photocatalytic applications. In this work, binary Cu-BTC@TiO2 catalysts with adjustable inner cavity were prepared using copper-based metal organic framework (Cu-BTC) octahedrons as substrate via a solvothermal reaction. In this process, the inner Cu-BTC octahedrons can be controllably etched into a hollow octahedral structure in the presence of HF. Subsequently, the Cu-BTC@CuSe@TiO2 hollow octahedrons (HOs) were fabricated by selenization reaction and exhibited various properties such as abundant active sites for CO2 adsorption and reduction reactions, shortened charge transfer distance to prevent electron-hole recombination, and internal reflection/scattering effects to improve solar light utilization. Moreover, the formed dual p-n heterostructures between p-type CuSe and n-type semiconductors (Cu-BTC and TiO2) effectively promote spatial separation and migration of charge carriers. The synergistic effect of these advantages makes the optimized Cu-BTC@CuSe@TiO2 HO catalyst exhibit remarkable CO2 photoreduction performance with a CO production rate of 72.3 μmol h−1 g−1 and near 100 % selectivity. This work opens a new pathway for designing highly active photocatalysts with excellent product selectivity.

Photocatalytic properties of BaTiO3/Fe2O3 under visible and ultraviolet irradiation

Nanosized composite materials based on BaTiO3 with 0.5 % and 1 % Fe2O3 were prepared by the sol-gel method and subsequent heat treatment. This work showed that increasing the content of iron(III) oxide in a heterostructured material affects the bleaching of the dye rhodamine B upon irradiation with visible and ultraviolet light. The highest photocatalytic activity was observed on the solid surface of the samples in an air environment under both visible and UV irradiation. The BaTiO3/0.5 % Fe2O3 sample was found to be most effective in an air environment when irradiated with an artificial visible light source. The increase in efficiency could be due to the best separation of charge carriers at the interface between the barium titanate and iron(III) oxide structures and the highest concentration of the resulting radical anions. An increase in the mass fraction of Fe2O3 led to a decrease in the efficiency of the nanoscale composite photocatalyst, which was due to a greater recombination of charge carriers.

Photocatalytic performance of Au/Bi4Ti3O12 composite improved by synergistic piezoelectric effect and exciton-plasmon

Bi4Ti3O12 (BiTO) is a typical bismuth-layered Aurivillius ferroelectric material for its potential application in photocatalysis. In this study, Au/BiTO hybrid was fabricated by precipitating Au nanoparticles onto BiTO nanoflake using a sodium citrate reduction route. This integration has led to a remarkable enhancement in the photocatalytic efficiency of the composite, which is attributed to the synergistic coupling of piezoelectric effect with the localized surface plasmon resonance (LSPR) of Au nanoparticles. The incorporation of Au nanoparticles onto the BiTO matrix has significantly boosted the light absorption and charge carrier separation, thereby augmenting the photocatalytic activity. Notably, Au/BiTO-2 composite exhibits exceptional photocatalytic performance, demonstrating the complete degradation of RhB within 40 min under full-spectrum light irradiation. Moreover, Au/BiTO-2 displays a robust photocatalytic action against other organic pollutants, including methyl orange (MO), ofloxacin (OFLX) and tetracycline hydrochloride (TC). Further enhancement of photocatalytic process is achieved when combing light irradiation with ultrasonic excitation. The ultrasonic waves break the static spontaneous polarization through alternating piezoelectric potential, which accelerates the catalytic reaction. The photocatalytic action rate of Au/BiTO-2 toward RhB reaches a value as high as 0.0984 min-1, which is nearly 2.3 folds increasement compared to that of pristine BiTO. The possible synergistic mechanism caused by piezoelectric effect and exciton-plasmon effect is discussed in detail. The work not only enriches our understanding of the underlying principles but also supply a new strategy to design high-performance catalysts in the field of environmental remediation and energy conversion.

Extremely interfacial bonding and photocatalytic environmental remediation on amouphous-TiO2/g-C3N4 heterojunctions by mechanochemical synthesis

TiO2/g-C3N4 composites have emerged as the most potent alternative for green photocatalysis, but are plagued by low photoactivity due to poor interfacial bonding. Herein, we report a straightforward mechanical ball milling method to fabricate an amorphous TiO2/g-C3N4 heterojunction. EPR, XPS and XAFS are used to prove that the N atoms of g-C3N4 was successfully doped into the crystal lattice of Am-TiO2 and formed typical Ti···N structure. The obtained 30-AT/CN (30 wt% g-C3N4) composites can form more heterojunction interfacial bonds and extremely improve the separation of charge carriers, showing superior photocatalytic reduction performance of perrhenate (non-radioactive chemical substitute for pertechnetate) and higher photochemical degradation rate of rhodamine B than the bulk counterpart. The material has a progressive Z-scheme heterojunction (S-scheme heterojunction), which increases the transfer ability and prolongs the lifetime of the photogenerated charge carriers. These results suggest a wide range of applications in the preparation method of heterojunction photocatalysts that are potential candidates for environmental remediation.

Maximizing photovoltaic performance of all-inorganic perovskite CsSnI3-xBrx solar cells through bandgap grading and material design

In the modern era of technology, worldwide paradigms have been shifted toward the utilization of green energy. Sun energy is the most astonishing eco-friendly resource of energy and can be harnessed with the help of photovoltaic cells. Hybrid (Organic-Inorganic) perovskite solar cells (PSCs) are emerged with incredible photovoltaic (PV) performance. Nevertheless, a significant challenge lies in their lower stability under diverse environmental conditions. To deal with this challenge, all inorganic cesium-based PSC has been studied and analyzed, results improved stability in comparison to hybrid PSC. However, the noxious nature of lead is deleterious to the environment. So, this work primarily aimed, to study lead-free all inorganic tin-based perovskite compound CsSnI3-xBrx, as the main light absorber layer. Further, to elevate the PV performance of PSC, bandgap grading is performed on CsSnI3-xBrx by varying bromide concentration x from 0 to 3. Bandgap grading encourages the absorption of a wide range of the light spectrum, by modulating bandgap (Eg) / affinity(χ) through the distance of the CsSnI3-xBrx layer. Additionally, it enhances light-generated charge carrier separation and collection by end electrodes. In this work, two different strategies have been adopted, linear and parabolic. During linear grading, the impact of variation in x (0 to 3) has been analyzed over the thickness 50–––500 nm in 10 linear steps for CsSnI3-xBrx. The highest PCE fetched from linearly graded layered FTO / CeO2 / CsSnI3-xBrx / CFTS / Gold PSC is 21.68 %. Similarly, in the parabolic graded absorber layer, the influence of change in the bowing factor (0 to 1), has been analyzed relative to different values of x (0 to 3). With improvement in PV performance, the maximum PCE delivered by parabolic-graded PSC is 23.61 %. Additionally, this work extends to check the compatibility of distinct electron transport layers (ETLs) and hole transport layers (HTLs). Upon analysis, it has been found that the best PV performance was obtained while selecting SnO2 / PEDOT as ETL / HTL respectively.

Electric field driven tourmaline/hematite dual mineral photocatalysis for efficient antibiotic removal

Hematite (Fe2O3) has garnered attention due to its stability, economic viability, and non-toxic nature. However, the rapid recombination of charge carriers hampers its practical application. On the other hand, tourmaline's inherent surface electric field facilitates the rapid separation of photogenerated electrons and holes. In this study, two directly mined natural minerals, tourmaline and hematite (TFO), were successfully combined. Characterization and experiments indicate that the pronounced enhancement of photocatalytic activity in Fe2O3 is attributed to the electric field effect on the surface of tourmaline. TFO successfully removes 93% of tetracycline (TC, 50 ppm) within 60 minutes. The reaction rate constant for TFO composite material (0.0410 min-1) is 8.5 times that of tourmaline (0.0048 min-1) and 14.1 times that of hematite (0.0029 min-1). Simultaneously, it markedly improves light absorption and charge carrier separation capabilities. Through simulations of various natural environmental factors, TFO demonstrates excellent practicality. Analyzing and detecting active species revealed the involvement of four types of active species, with ·OH radicals making the most significant contribution. The photocatalytic mechanism was proposed. Furthermore, the degradation pathway of tetracycline and the toxicity of its metabolites were investigated. This work provides additional inspirations and insights for photocatalytic materials performance enhancement and natural resources green governance environment.