Internal Electric Field Research Articles

Facile modification of TiO2 as S-Scheme multifunctional materials for environmental protection and energy-storage applications

This paper reports a simple one-step modification of commercial TiO2 with a conducting polytrimethoxyslilypropyl aniline (PTMSPA, a polyaniline derivative having silyl networks) to have multi-functional (photocatalytic, optical, pseudocapacitive, hydrophobic, porous, antibacterial, and electromagnetic interference shielding (EMI)) properties and demonstrates associated applications. We present the S-Scheme heterojunction (SHJ) formation between TiO2 and PTMSPA through band position alignments and designate the resultant TiO2 - TiO2- based SHJ multifunctional materials as MF-TSSM. The internal electric field that is generated at the interface facilitates the transportation of the photogenerated electron transfer . The XRD pattern of MF-TSSM exhibits mainly the peaks of anatase TiO2. The TEM image of MF-TSSM indicates that the TiO2 particles are spherical in shape with sizes showing variations in diameters ranging from 60 nm to 250 nm depending on the experimental conditions of preparation and TiO2 particles are homogeneously distributed within the PTMSPA matrix. The optical energy band gap of MF-TSSM is 1.60 eV, a much lower value than PTMSPA (3.02 eV), suggesting that the composite formation between TiO2 and PTMSPA. The contact angle of MF-TSSM is significantly increased to 47.1 ° from 8.0 of TiO2, informing the increase of hydrophobic characteristics. The rate constant (k) for methylene blue photodegradation was 0.030 min-1, and 0.010 min-1 for MF-TSSM and pristine TiO2, respectively, The MF-TSSM composite exhibits a higher specific capacitance value (28.7 F/g) than TMSPA (21.1 F/g). At a frequency of 0.42 THz, MF-TSSM and PTMSPA exhibit return loss features indicating good EMI shielding performance. The MF-TSSM has been tested against two different Gram-positive and Gram-negative bacterial strains. The nanoparticles were evaluated at doses of 10, 20, 40, and 80 µg/ml. The results indicated that Klebsiella pneumoniae demonstrated a greater zone of inhibition, ranging from 9 mm at 10 µg/ml to 23 mm at 80 µg/ml, indicating increased susceptibility. Pseudomonas aeruginosa exhibited reduced inhibition zones, ranging from 10 mm at 10 µg/ml to 14 mm at 80 µg/ml, indicating increased resistance. The excellent effectiveness of MF-TSSM against various Gram-positive and Gram-negative pathogenic bacteria is explained by the interaction between reactive oxygen species and the cellular components of the bacteria as well the electrostatic interaction arising between positive charges in TMSPA and negative charges in the cell components, resulting in notable cytotoxicity and damage to the bacterial cells. The research underscores the capability of these modified TiO₂ nanoparticles in addressing bacterial infections, with efficiency differing by bacterial strain.

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.

0D/1D p-n heterostructured composite of bismuth ferrite perovskite clusters on sodium titanate nanotube arouse exceptional blue-light-driven photooxidation

This study describes the synthesis of a 0D/1D p-n heterostructured composite of bismuth ferrite perovskite clusters on sodium titanate nanotubes prepared using an in-situ hydrothermal method. BiFeO3/Na2Ti3O7 (BFT) nanocomposite, forming a p-n heterojunction due to the equilibrium of Fermi level, exhibits exceptional blue-light-driven photo-oxidation activity with an exceptional benzyl alcohol conversion rate of 29.64 mmolproduced BAD·g−1 h−1. The outstanding performance originates from the promotion of photogenerated charge separation and effective inhibition of charge recombination due to internal electric field of p-n heterojunction. Density functional theory calculations combined with femtosecond transient absorption spectroscopy distinctly confirms the efficient separation and transfer of photogenerated carriers to be S-scheme charge transfer mechanism over the p-n heterojunctions. Furthermore, in-situ infrared spectroscopy combined with XPS results demonstrate the strong adsorption of benzyl alcohol and weak adsorption of benzaldehyde on BFT, which facilitates the transformation of reactant and desorption of product. This study provides a simple and effective approach to enhance photocatalytic selective oxidation reactions.

Photoelectron marginalization effect in ZnO/WO3/graphene-like composites: Study of alternating strong-low photocatalytic hydrogen production performance and mechanism

ZnO/WO3/graphene-like composite photocatalysts are prepared by in-situ deposition and successfully utilized for alternating strong-low light catalytic decomposition of water to produce hydrogen. Additionally, the study details the microscopic morphology and optoelectronic properties of the ZnO/WO3/graphene-like composite. The results indicate that an internal electric field is generated between the ZnO/WO3 heterostructure and the graphene-like material. This induced electric field leads to a large amount of ordered electron transfer from ZnO/WO3 to the graphene-like material, resulting in the electron marginalization effect, which ensures the prerequisite for alternating strong-low photocatalytic splitting of water into hydrogen. When the mass fraction of the graphene-like material in the WO3/ZnO/graphene-like composite photocatalyst is 30 %, the photocatalytic hydrogen production rate reaches the maximum value of 820 times that of intrinsic ZnO. Therefore, this work provides a new perspective for alternating strong-low light catalytic water splitting to produce hydrogen.

Tribo-hygro-electric generator: Harnessing mechanical energy with liquid-infused porous cellulose for multiple sensing and DC power generation

This study introduces the Tribo-Hygro-Electric Generator (THEG), a novel device that harvests ambient mechanical and water-enabled energies for highly sensitive, self-powered multi-sensing. THEG employs a simple design using liquid-infused porous cellulose (LIPC), created by absorbing functional liquids such as water into porous cellulose, and metal contacts with distinct work functions (e.g., Al and Cu) to generate triboelectric charges through friction. It operates via a three-step process: generating triboelectric charges through sliding motion, establishing an internal electric field across Al/LIPC/Cu interfaces for charge separation, and directing charges to create unidirectional output electron transfer, producing direct current (DC) outputs. The principle behind THEG emphasizes the critical role of the single Schottky contact at the Al/LIPC interface in separating and directing charge transfer, as well as the conductive path formed by the hydrogen-bonded network of water molecules and cellulose’s functional groups. THEG can harvest DC power with a current density of up to 3.4 A/m² and 0.5 V, which can be increased to 2 V with four cells in series. THEG demonstrates impressive multiple-sensing capabilities, with robust linear relationships (correlation coefficients > 0.99) between output current density and stimuli such as pressure, velocity, water absorption, and ion concentration. Demonstrating practical utility, the generated energy powers devices like a commercial calculator. This technology advances mechanical energy harvesting and multiple sensing, reducing dependence on external power and enabling transformative IoT applications.

Thermovoltaic response in two-layered thin-film zinc oxide structures

A method of measuring the thermovoltaic effect in heterogeneous media with gradient doping impurity distributions producing gradient carrier distributions has been proposed. Iron doped zinc oxide specimens have been produced using ion beam sputtering on thin foil tantalum substrates for thermovoltaic effect measurements, glass-ceramic substrates for Hall measurements and silicon substrates for structural study. The doping impurity concentration хFe in the specimens has been varied from 0.34 to 4.18 at.%. X-ray phase analysis has shown that all the specimens have a hexagonal zinc oxide crystal structure. The films have preferential [002] orientation. The carrier concentration in the experimental specimen layers according Hall data obtained on an ECOPIA 5500 measurement system in a 0.5 T DC magnetic field has varied in the 1016–1020 cm-3 range. The specimens have an n-type conductivity. Thermovoltaic measurements have been carried out for two-layered iron doped zinc oxide specimens with different carrier and iron doping impurity concentrations using the method proposed. The maximum thermovoltaic response (U ~ 80 μV) has been observed in the two-layered thin-film specimen with the carrier concentration difference between the layers (Δn ≈ 2∙103 cm-3). The observed saturation of the thermovoltaic response has been attributed to the establishment of dynamic equilibrium between carrier diffusion from the high carrier concentration layer to the low carrier concentration layer and carrier drift due to internal electric field.

Construction of Z‐type heterojunction Bi4Ti3O12/g‐C3N4 with pyroelectric effect for enhanced photocatalytic performance

AbstractPhotocatalytic technology has been widely studied, discussed, and tested as a feasible wastewater degradation technology. The present study demonstrated the preparation of g‐C3N4 material using solid‐state sintering method and the construction of Bi4Ti3O12/g‐C3N4 heterostructure via hydrothermal method. This direct contact Z‐type heterojunction improves the wide bandgap of Bi4Ti3O12 monomer, enhances its photoresponsiveness, and thus improves its photocatalytic performance. During the process of photocatalytic experiments, an environment of cold and hot fluctuations were created, and the pyroelectric effect was utilized to induce self‐polarization of the material and formed an internal electric field. It improves the transport ability of electron–hole pairs and suppresses their recombination in the transport path. According to the degradation experiment results, the degradation efficiency of pyroelectric synergistic heterojunction photocatalysis reached 88.7%, which was 2.27 times that of Bi4Ti3O12. It proves that the photocatalysis by pyroelectric synergistic heterojunction has good application prospects.

A Photovoltaic Self-Powered Volatile Organic Compounds Sensor Based on Asymmetric Geometry 2D MoS2 Diodes

Transition metal dichalcogenides have gained considerable interest for vapour sensing applications due to their large surface-to-volume ratio and high sensitivity. Herein, we demonstrate a new self-powered volatile organic compounds (VOC) sensor based on asymmetric geometry multi-layer molybdenum disulfide (MoS2) diode. The asymmetric contact geometry of the MoS2 diode induces an internal built-in electric field resulting in self-powering via a photovoltaic response. While illuminated by UV-light, the sensor exhibited a high responsivity of ∼60% with a relatively fast response time of ∼10 sec to 200 ppm of acetone, without an external bias voltage. The MoS2 VOC diode sensor is a promising candidate for self-powered, fast, portable, and highly sensitive VOC sensor applications.

Broadband self-powered MoS2/PdSe2/WSe2 PSN heterojunction photodetector for high-performance optical imaging and communication

Two-dimensional (2D) semi-metal transition metal dichalcogenides (TMDs) have drawn significant attention for their distinctive physical properties. However, the inherent high dark current of these materials and the single structure of detectors hinder the further development of photodetectors with high performance. Here, we construct a PSN (p-type semiconductor/semi-metal/n-type semiconductor) architecture by sandwiching 2D semi-metal between two semiconductor layers. In this architecture, the top and bottom layers generate an internal built-in electric field, while the middle layer serves as an absorption layer for low-energy photons and facilitates the dissociation of photo-generated carriers. As a result, the heterojunction device demonstrates a wide spectrum optical response from visible to infrared light (405 nm to 1550 nm) without requiring an external voltage. Working in self-powered mode at room temperature, the device achieves a responsivity of 0.56 A/W, a detectivity of 5.63 × 1011 Jones, and a rapid response speed of 190/74 µs. Additionally, the device shows potential for applications in fast optical communication and multi-wavelength optical imaging. This work presents a novel approach for developing a new type of broadband, self-powered, high-performance miniaturized semi-metal-based photodetector.

Enhancing the Photocatalytic Performance for Norfloxacin Degradation by Fabricating S-Scheme ZnO/BiOCl Heterojunction

Construction of S-scheme heterojunctions can effectively limit the recombination of photogenerated e− and h+, thus improving photocatalytic activity. Therefore, S-scheme ZnO/BiOCl (molar ratio = 1:2) n–n heterojunctions were synthesized via a hydrothermal–hydrolysis combined method in this study. The physical and chemical properties of the ZnO/BiOCl heterojunctions were characterized by XRD, XPS, SEM, TEM, DRS, N2 adsorption–desorption and ESR. Additionally, the photoelectric performances of ZnO/BiOCl heterojunctions were investigated with TPR, M–S plot and EIS. The results show that photocatalytic degradation of NOR by ZnO/BiOCl reached to 94.4% under simulated sunlight, which was 3.7 and 1.6 times greater than that of ZnO and BiOCl, respectively. The enhanced photodegradation ability was attributed to the enhancement of the internal electric field between ZnO and BiOCl, facilitating the active separation of photogenerated electrons and holes. The radical capture experiments and ESR results illustrate that the contribution of reactive species was in descending order of ·OH > h+ > ·O2− and a possible mechanism for the photodegradation of NOR over S-scheme ZnO/BiOCl heterojunctions was proposed.

Internal Electric Fields and Structural Instabilities in Insulating Transition Metal Compounds: Influence on Optical Properties

AbstractThis work reviews new ideas developed in the last two decades which play a key role for understanding the optical properties of insulating materials containing transition metal (TM) cations. Initially, this review deals with compounds involving d4 and d9 ions where the local structure of the involved MX6 complexes (M=dn cation, X=ligand) is never cubic but distorted, a fact widely ascribed to the Jahn‐Teller (JT) effect. Nevertheless, that assumption is often wrong as the JT coupling requires an orbitally degenerate ground state in the initial geometry a condition not fulfilled even if the lattice is tetragonal. For this reason, the equilibrium geometry of d4 and d9 complexes in low symmetry lattices, is influenced by two factors: (i) The effects, usually ignored, of the internal electric field, ER, due to the rest of lattice ions on the active electrons localized in the MX6 unit. (ii) The existence of structural instabilities driven by vibronic interactions that lead to negative force constants. As first examples of these ideas, we show that the equilibrium structure, electronic ground state of KZnF3:Cu2+, K2ZnF4:Cu2+ and K2CuF4 obey to different causes and only in KZnF3:Cu2+ the JT effect takes place. These ideas also explain the local structure and optical properties of CuF2, CrF2 or KAlCuF6 compounds where the JT effect is symmetry forbidden and those of layered copper chloroperovskites where the orthorhombic instability explains the red shift of one d−d transition under pressure. In a second step, this review explores stable systems involving d3, d5 or d9 cations, where the internal electric field, ER, is responsible for some puzzling phenomena. This is the case of ruby and emerald that surprisingly exhibit a different color despite the Cr3+‐O2− distance is the same. A similar situation holds when comparing the normal (KMgF3) and the inverted (LiBaF3) perovskites doped with Mn2+ having the same Mn2+‐F distance but clearly different optical spectra. The role of ER is particularly remarkable looking for the origin of the color in the historical Egyptian Blue pigment based on CaCuSi4O10.

Construction of a In2O3/ultrathin g-C3N4 S-scheme heterojunction for sensitive photoelectrochemical aptasensing of diazinon

A single semiconductor-based photoelectrochemical (PEC) aptasensor usually faces a challenge of low sensitivity due to poor solar energy utilization and a high photogenerated carrier recombination rate. Herein, an ultra-thin carbon nitride nanosheet-coated In2O3 (In2O3/CNS) S-type heterojunction-based PEC aptasensor has been established to achieve highly sensitive detection of diazinon (DZN) pesticide in water environment. Construction of S-type heterojunction induces a band shift and an electric field effect, enhancing light utilization and accelerating directional transmission of carriers, leading to outstanding PEC performance. The creation of internal electric field at interface ensures stable carrier transport. Additionally, ultrathin CNS structure can effectively shorten the transport path of carriers. The close coating of In2O3 and CNS promotes the transfer of charge. The synergistic effects amplify the sensor’s response, ultimately enabling the effective detection of DZN residue over a wide detection range (0.98 ∼ 980.0 pg mL−1), a low detection limit (0.33 pg mL−1, S/N = 3) and excellent accuracy in practical application (RSD < 5 %). This work provides a reference for the construction of a new S-type heterojunction-based PEC sensor.

Fabrication of CoTiO3/MgIn2S4 S–scheme heterojunctions with efficient charge separation to enhance the photocatalytic activities of hydrogen generation and formaldehyde removal

The efficient separation of photoinduced charge carriers is a primary factor in the catalytic performance of photocatalysts. Constructing S-scheme heterojunctions is a prospective strategy to efficiently and spatially separate photoinduced charges while retaining strong oxidation and reduction capacities of the catalyst system. Herein, CoTiO3/MgIn2S4 (abbreviated x% CTO/MIS, where x% represents the mass ratio of CTO-to-MIS; x = 5, 10, 15, 20, and 25) heterojunctions were successfully synthesized using a hydrothermal method. These heterojunctions exhibited highly efficient and reusable visible-light photocatalytic properties for hydrogen (H2) generation and formaldehyde (HCHO) degradation. Notably, the 15 % CTO/MIS demonstrated an admirable H2 evolution activity of 631.77 μmol·g−1·h−1, with AQE = 2.25 % at λ = 420 nm, and an HCHO degradation rate of 67.18 %. The intermediate products generated during HCHO removal were identified applying in situ diffuse reflectance infrared Fourier transform spectroscopy. The exceptional catalytic performance of the synthesized materials was attributed to the boosted light absorption and utilization, rapidly separation, and transfer of photoproduced charge carriers, which resulted from the internal electric field of the S-scheme mechanism. Moreover, the S-scheme electron transfer pathway for the CTO/MIS catalyst system during the photocatalytic process was confirmed using electron spin resonance spectroscopy, free-radical capturing tests, density functional theory calculations, in situ X-ray photoelectron spectroscopy, and semiconductor energy band theory. The study offers an innovative perspective for establishing S-scheme heterojunctions with highly efficient and stable photocatalytic activity for H2 generation and HCHO removal.

Heterointerface engineering in mesoporous g-C3N4@MnFe2O4 photocatalysts for superior hydrogen (H2) evolution

Surfaces and interfaces play a pivotal role in heterostructures-based photocatalysts, which regulate the transfer, separation, and migration of photogenerated charge carriers. In this study, p-type MnFe2O4 nanoparticles (NPs) with complementary band structures were purposefully integrated with n-type porous g-C3N4 nanosheets (NSs) through precise interface engineering. The synergies in the g-C3N4@MnFe2O4 nanocomposites (NCs), leading to performance enhancement and functionalities, arise from their optimized mass fractions within the composite. The heterojunction interface formed in NCs possesses uniformly distributed mesopores (<4 nm), abundant active sites, and a high specific surface area (116 m2/g). Mesoporous heterojunctions improve photocatalytic activity by promoting the transfer of photogenerated electrons and holes to the photocatalyst surface. Notably, the optimized NCs, containing 20 wt% MnFe2O4, display the highest hydrogen evolution rate of 3.17 mmol g⁻¹ h⁻¹ (with methanol) and 5.77 mmol g⁻¹ h⁻¹ (with triethanolamine), which is many folds higher than bare MnFe2O4 and porous g-C3N4, using 1.0 wt.% of Pt as co-catalyst. The enhanced performance is corroborated by the efficient separation of photoinduced charge carriers, facilitated by an induced internal electric field arising from the Fermi level differences between the semiconductors. This study provides new insights into the advantages of designing and constructing mesoporous Z-scheme heterojunction photocatalysts for hydrogen evolution.

Tailoring carbon intercalated α,β-FePc heterophase junction to boost electron transfer for 1O2-dominated photo-Fenton reaction

Construction of 1O2-dominated photo-Fenton reaction (PFR) is of great significance to enhance the compatibility to complicated water matrices, due to the selectivity of 1O2. Herein, a carbon intercalated heterophase junction (α,β-FePc@C) is constructed through a calcination-regulated strategy. The as-synthesized α,β-FePc@C exhibited high efficiency in tetracycline degradation with catalyst-dosage-normalized kinetic rate constant of 1.39 L min-1 g-1, outperforming most previously reported works. Importantly, H2O2 activation follows h+-meditated two-step oxidation, resulting in 1O2-dominated reaction with strong anti-interference performance. Experimental and theoretical evidences reveal that dual phases of α-FePc and β-FePc are strategically retained to form heterophase junction, creating internal electric field to propel the photogenerated carrier separation. Carbon intercalation not only optimizes band structure to promote electron transition but also boosts the electron transfer for H2O2 activation. In general, this work presents a facile strategy of constructing photocatalyst for 1O2-dominated PFR and sheds light on upgrading the adaptability of PFR to complex water matrices.

Oxygen Vacancies Regulated S-Scheme Charge Transport Route in BiVO4-OVs/g-C3N4 Heterojunction for Enhanced Photocatalytic Performance.

Oxygen vacancies (OVs) are widely considered as active sites in photocatalytic reactions, yet the crucial role of OVs in S-scheme heterojunction photocatalysts requires deeper understanding. In this work, OVs at hetero-interface regulated S-scheme BiVO4-OVs/g-C3N4 photocatalysts are constructed. The Fermi-level structures of BiVO4 and g-C3N4 lead to a redistribution of charges at the heterojunction interface, inducing an internal electric field at the interface, which tends to promote the recombination of photogenerated carriers at the interface. Importantly, the introduction of OVs induces defect electronic states in the BiVO4 bandgap, creating indirect recombination energy level that serves as crucial intermediator for photogenerated carrier recombination in the S-scheme heterojunction. As a result, the photocatalytic degradation rate on Rhodamine B (RhB) and tetracyclines (TCs) for the optimal sample is 10.7 and 11.8 times higher than the bare one, the photocatalytic hydrogen production rate is also improved to 558 µmol g-1 h-1. This work shows the importance of OVs in heterostructure photocatalysis from both thermodynamic and kinetic aspects and may provide new insight into the rational design of S-scheme photocatalysts.

Research on the Fabrication and X‐Ray Detection Performance of MAPbBr3‐Based 3D/2D Heterojunctions

Perovskite materials, renowned for their high mean atomic number, charge carrier mobility–lifetime product, and X‐ray absorption coefficient, have emerged as exceptional candidates for the fabrication of high‐sensitivity X‐ray detectors. Herein, a BA2PbBr4/MAPbBr3 heterojunction is epitaxially grown, with ion migration effectively suppressed through the passivation of surface defects of the 3D heterojunction. Additionally, the presence of an internal electric field within the heterojunction facilitated the extraction and accumulation of photoinduced charge carriers, further enhancing device sensitivity (5964.05 μC Gy−1 cm−2). The fabricated 2D/3D perovskite heterojunction devices show outstanding self‐driven X‐ray detection performance at 0 V mm−1 bias (1195.5 μC Gy−1 cm−2), surpassing that of α‐Se detectors (20 μC Gy−1 cm−2). The proposed method for the fabrication of self‐driven detectors is relatively simple and is therefore expected to contribute to the commercialization of perovskite‐based X‐ray detectors.

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.

Self-Powered Traffic Lights Through Wind Energy Harvesting Based on High-Performance Fur-Brush Dish Triboelectric Nanogenerators.

Traffic lights play vital roles in urban traffic management systems, providing clear directional guidance for vehicles and pedestrians while ensuring traffic safety. However, the vast quantity of traffic lights widely distributed in the transportation system aggravates energy consumption. Here, a self-powered traffic light system is proposed through wind energy harvesting based on a high-performance fur-brush dish triboelectric nanogenerator (FD-TENG). The FD-TENG harvests wind energy to power the traffic light system continuously without needing an external power supply. Natural rabbit furs are applied to dish structures, due to their outstanding characteristics of shallow wear, high performance, and resistance to humidity. Also, the grid pattern of the dish structure significantly impacts the TENG outputs. Additionally, the internal electric field and the influences of mechanical and structural parameters on the outputs are analyzed by finite element simulations. After optimization, the FD-TENG can achieve a peak power density of 3.275Wm-3. The portable and miniature features of FD-TENG make it suitable for other natural environment systems such as forests, oceans, and mountains, besides the traffic light systems. This study presents a viable strategy for self-powered traffic lights, establishing a basis for efficient environmental energy harvesting toward big data and Internet of Things applications.

Sensitive detection of Hg(II) on MoS2/NiS2 based on interfacial engineering to accelerate the Ni2+/Ni3+ cycle: Identification the role of atomic-level heterojunction-induced electron transfer in electroanalysis

The valence change of transition metal ions in nanomaterials can highly enhance the electrochemical detection performance toward heavy metal ions (HMIs), and how to further promote the valence change calls enormous concerns in electroanalysis. In this work, an interfacial engineering that combing the MoS2 and NiS2 together to form the MoS2/NiS2 complex is proposed. The density functional theory (DFT) results reveals that the novel atomic-level heterojunction between MoS2 and NiS2 will build an internal electric field (IEF), which leads to an enhanced conductivity and valence change behavior of Ni atoms in MoS2/NiS2 complex, resulting in a superior detection performance. In detail, the formation of atomic-level heterojunctions in the MoS2/NiS2 complex accelerates electron transfer due to the valence changes associated with Ni2+/Ni3+ cycling. The active Mo4+ species on MoS2 act as electron donors, facilitating the reduction of Ni3+ to Ni2+ on NiS2, thereby promoting Ni2+/Ni3+ cycling. As anticipated, the MoS2/NiS2 complex exhibits exceptional detection performance for Hg(II), with a sensitivity of 459.13 μA μM−1 cm−2, surpassing even that of other composite materials. In general, these findings are expected to significantly advance the application of electron transfer acceleration in electroanalysis based on the construction of heterojunction.