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The formation of an electric double‐layer (EDL) is an important phenomenon for many research areas, including energy storage technology. Although EDL is well‐known in electrochemistry, most of the studies involve the characterization of liquid electrolyte/electrode interfaces, and only a limited number of studies in solid‐solid contacts, such as solid electrolyte/electrode interface are available. This paper employed electrochemical impedance spectroscopy (EIS) to systematically investigate the influence of experimental factors in the interfacial capacitance arising from the electrode polarization in a lithium disilicate glass/gold electrode interface. It analyzed the influence of a.c. input voltage amplitude, samples' roughness (mechanical and chemomechanical polishing) and thickness, range of applied frequency and temperature, and the number of impedance cycles. In short, it was found that an input voltage range of 15–60 mV is indicated to minimize potential electrochemical processes during electrode polarization, where the data is reproducible from the second measurement cycle onward. Smoother surfaces closely approximated ideal electrode spike behavior, with surface treatment exhibiting influence on interfacial capacitance values. Moreover, as expected, we observed an increase in relative permittivity values with increasing thickness, accompanied by decreased capacitance values. Finally, by employing optimal experimental conditions and analyzing the inflection frequency (finflection${{f}_{inflection}}$) of the ε′$\varepsilon ^{\prime}$ versus log(f$f$) curve, we determined that the ratio between effective charge carriers (ne${{n}_e}$) and the total number of charge carriers (nt${{n}_t}$) nent$\frac{{{{n}_e}}}{{{{n}_t}}}$ falls within the range of 5–12% between 130°C and 280°C. [ABSTRACT FROM AUTHOR]

Diffusion equations play a crucial role in various scientific and technological domains, including mathematical biology, physics, electrical engineering, and mathematics. This article presents a new formulation of the diffusion equation in the context of electrical engineering. Specifically, the behaviour of the physical quantity of charge carriers (such as concentration) is examined within semiconductor materials. The primary focus of this work is to solve the two-dimensional, time-fractional, nonlinear drift reaction–diffusion equation by applying an appropriate numerical scheme. In recent years, researchers working on nonlinear diffusion equations have proposed several numerical methods, with the shifted airfoil collocation method being one such efficient technique for solving nonlinear partial differential equations. This collocation approach effectively reduces the considered two-dimensional, time-fractional, nonlinear drift reaction–diffusion equation to a system of algebraic equations. The efficiency and effectiveness of the proposed method are validated through an error analysis, comparing the exact solution and the proposed numerical solution for a specific form of the considered mathematical model. The variations in the concentration of charge carriers, driven by the effects of drift and reaction terms, are displayed graphically as the system transitions from a fractional order to an integer order. [ABSTRACT FROM AUTHOR]

Diamond is emerging as an attractive third‐generation wide‐bandgap semiconductor for future on‐chip nonlinear photonics and quantum optics due to its unique thermal, optical, and mechanical properties. However, the light‐driven current under below‐band gap excitation from the second‐order nonlinear optical effect in diamond is still challenging. Herein, a giant second‐order nonlinear photocurrent is observed in the chemical vapor deposition (CVD) diamond by utilizing terahertz (THz) emission spectroscopy. This ultrafast photocurrent originates from the photon drag effect (PDE), during which the momentum transfer from the incident photons to the charge carriers at the rich grain boundaries of the CVD diamond after the exclusive subgap π–π* transition upon femtosecond laser excitation. Especially, the interplay between circular and linear PDE to the THz generation is clarified and distinguished under elliptically polarized light excitation. Furthermore, the picosecond ultrafast dynamics of these charge carriers are also verified by infrared spectroscopy. Owing to the giant photon‐drag‐induced ultrafast photocurrent, the CVD diamond presents the highest THz emission efficiency compared with the reported carbon allotropes, which expands the new functionality of diamond nonlinear photonics into on‐chip THz devices. [ABSTRACT FROM AUTHOR]

Aqueous batteries with high safety and cost efficiency usually employ metallic cations as charge carriers. Recently, ammonium (NH4+) ion batteries using the nonmetal NH4+ as a charge carrier exhibit distinct electrochemical features from conventional aqueous batteries. Herein, the electrochemical performances of a bimetallic hydroxide material are systematically studied with different charge carriers in the electrolytes, including NH4+, as well as the conventional monovalent metallic cations K+ and Na+, respectively. Electrochemical results indicate that the charge storage process using NH4+ as the working ions exhibits a higher discharge plateau, smaller electrochemical polarization, and larger discharge capacity than that using conventional metallic charge carriers. Experimental characterizations and theoretical calculations suggest that the strong interaction between NH4+ and the electrode material, as well as the low NH4+‐ion diffusion barrier lead to these superior electrochemical features. The assembled NH4+‐ion battery exhibits a good energy density of 123 Wh kg(cathode+anode)−1 at the power density of 480 W kg(cathode+anode)−1. These fundamental findings are important for developing good safety, low‐cost, and high‐energy aqueous batteries with sustainable NH4+ charge carriers. [ABSTRACT FROM AUTHOR]

[Display omitted] Tricobalt tetroxide (Co 3 O 4) has been developed as a promising photocatalyst material for various applications. Several reports have been published on the self-modification of Co 3 O 4 to achieve optimal photocatalytic performance. The pristine Co 3 O 4 alone is inadequate for photocatalysis due to the rapid recombination process of photogenerated (PG) charge carriers. The modification of Co 3 O 4 can be extended through the introduction of doping elements, incorporation of supporting materials, surface functionalization, metal loading, and combination with other photocatalysts. The addition of doping elements and support materials may enhance the photocatalysis process, although these modifications have a slight effect on decreasing the recombination process of PG charge carriers. On the other hand, combining Co 3 O 4 with other semiconductors results in a different PG charge carrier mechanism, leading to a decrease in the recombination process and an increase in photocatalytic activity. Therefore, this work discusses recent modifications of Co 3 O 4 and their effects on its photocatalytic performance. Additionally, the modification effects, such as enhanced surface area, generation of oxygen vacancies, tuning the band gap, and formation of heterojunctions, are reviewed to demonstrate the feasibility of separating PG charge carriers. Finally, the formation and mechanism of these modification effects are also reviewed based on theoretical and experimental approaches to validate their formation and the transfer process of charge carriers. [ABSTRACT FROM AUTHOR]

Hydrogen gas sensing of Co 1- x Zn x Fe 2 O 4 (x = 0–0.45) nanoparticles synthesized by a simple hydrothermal process has been investigated. An n→p crossover in the electrical conductivity toward hydrogen gas was observed. However, no such charge carrier reversal is noticed at higher x values. In both cases, the related mechanisms are proposed. It has been found that reversal is temperature and doping ratio dependent. In this regard, the more compatible and realistic model is presented which explains the nature of our observations. By analyzing the adsorption kinetics of the surface, it is identified that at a higher percentage of Zn (x = 0.45) the sensor response deviates from the Freundlich isotherm and falls under the category of the Langmuir adsorption model toward H 2 gas exposure. These strong correlations between the results of gas sensing measurements and those calculated based on the DC electric resistivity would pave the way for further investigation of the gas sensors from a fundamental point of view. Deposition of Palladium nano-structures (possibly island-like) on the surface of the CoFe 2 O 4 sensor appeared to be effective in speeding up the response time and increasing the sensitivity. The remarkable response time, as low as 3 s, is obtained after modifying the sensor surface with the palladium deposition. • The cobalt ferrite nanoparticles doped with Zinc elements are synthesized by means of the hydrothermal method. • An n→p crossover in the electrical conductivity toward hydrogen gas was observed by Zinc doping. • The strong correlations were observed between the gas sensing and DC electric resistivity. • We found an increase in the gas response and response time by Pd deposition on the surface of ferrite sensor. [ABSTRACT FROM AUTHOR]

Single phase lead tin sulfide (PbSnS) thin films have been successfully deposited on ITOcoated glass substrates using a 3-electrode electrochemical cell having graphite as the counter electrode and Ag/AgCl as the reference electrode. In this single-step electrodeposition, the PbSnS precursor thin film was directly electrodeposited on the conductive substrate from the electrolytic bath solution which contained Pb(NO3)2, SnCl2.2H2O and Na2S2O3. This was followed by annealing in air at 250 °C for an hour to improve the crystallinity. The annealed films were characterized by a variety of techniques. Powder X-ray diffraction revealed peaks which were indexed to the orthorhombic phase of PbSnS with preferred orientation along the (112) plane. Seebeck coefficient studies confirmed the type of charge carrier of the film. SEM micrographs showed a compact morphology composed of spherically shaped well defined grains covering the entire substrate. EDAX analysis of the film was consistent with the formation of PbSnS. Optical absorption measurements revealed the existence of a direct transition with an estimated band gap of 1.68 eV. [ABSTRACT FROM AUTHOR]

Many of the studies on the entropy‐stabilized oxide (Mg0.2Co0.2Ni0.2Cu0.2Zn0.2)O have been heavily application‐based. Previous works have studied effects of cation stoichiometry on the entropy‐driven reaction to form a single phase, but a fundamental exploration of the effects of anion stoichiometry and/or redox chemistry on electrical properties is lacking. Using near‐edge X‐ray absorption fine structure (NEXAFS) and electrical measurements, we show that oxidizing thin film samples of (Mg0.2Co0.2Ni0.2Cu0.2Zn0.2)O affects primarily the valence of Co, leaving the other cations in this high‐entropy system unchanged. This oxidation increases electrical conduction in these thin films, which occurs via small polaron hopping mediated by the Co valence shift from 2+ to a mixed 2+/3+ state. In parallel, we show that bulk samples sintered in an oxygen‐rich atmosphere have a lower activation energy for electrical conduction than those equilibrated in a nitrogen (reducing) atmosphere. Combining feasible defect compensation scenarios with electrical impedance measurements and NEXAFS data, we propose a self‐consistent interpretation of Co redox‐mediated small polaron conduction as the dominant method of charge transfer in this system. [ABSTRACT FROM AUTHOR]

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We showed two demonstrations of the local charge carrier dynamics measurements of photocatalytic materials using our recently developed time-resolved phase-contrast microscopic technique combined with the clustering analyses. In this microscopic time-resolved technique, we observed the charge carrier dynamics via the refractive index change instead of the luminescence or absorption change, where we could often observe non-radiative charge carrier processes such as charge carrier trapping and non-radiative relaxation. By the clustering analyses of all the pixel-by-pixel responses, we could extract various different charge carrier dynamics because photocatalytic materials have inhomogeneity on surfaces and the charge carrier behavior depends on the local structure and species. Even for typical photocatalytic materials, titanium oxide and hematite, we could recognize various charge carrier dynamics, which cannot be differentiated by the general fitting procedure for the averaged time response. We could categorize the surface-trapped charge carriers (holes and electrons) and bulk carriers in the nanosecond to millisecond order, which indicates that this analytical procedure will play an important role in understanding the charge carrier dynamics for various photocatalytic materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Internal electric fields enhance free-carrier density and NIR absorption. • Interfacial junctions intensify absorption of silica in full solar spectrum. • CrO x –SiO 2 absorbs light intensely over the full solar spectrum. • Heterojunctions boost photocurrent and photothermal performance of Co 2 SiO 4 and SiO 2. • CrO x –SiO 2 –Mg(OH) 2 enables light–heat–energy storage in one-step. Strong absorption of near-infrared (NIR) light is essential for efficient solar energy applications. NIR absorption primarily depends on the surface plasmon resonance of incident light with free charge carriers (FCCs). We demonstrated that S-scheme interfacial junctions (IJs) can substantially enhance FCC density, light-harvesting, photocurrent intensity, long lifetime of the charge carriers and photothermal effects, paving a way for novel light-material design. Abundant S–scheme IJs are constructed in CrO x –SiO 2 nanoparticles, which increase the FCCs outstandingly and enhance light absorption exceptionally over the entire solar spectrum. IJs' construction enables silica to harvest solar energy strongly. Doped with multifunctional CrO x –SiO 2 nanoparticles, the photothermal-dehydration conversion and the stored heat of Mg(OH) 2 can be improved by 7.0- and 5.1-times upon 30-min irradiation, respectively. The reversibility of the photothermal charge–discharge cycles of Mg(OH) 2 improves 19.3 times. The thermal-storage kinetics is substantially improved owing to the reduction of the dehydration activation energy (−15.2 %). Mg(OH) 2 –CrO x –SiO 2 composite is an excellent one-step system of light–heat–storage. [ABSTRACT FROM AUTHOR]

[Display omitted] • Efficient photocatalytic self-Fenton system (PSFs) constructed in-situ by TpPa-1 loaded Ti 3 C 2. • The regulation of free radicals has achieved efficient degradation and deep mineralization of SMX. • The synergistic effect between H 2 O 2 production and pollutant mineralization has been revealed. The photocatalytic self-Fenton technology has demonstrated unique advantages in the low-cost and efficient removal of environmental pollutants. Designing an efficient photocatalytic self-Fenton system (PSFs) to enhance the synergistic effect between photocatalytic H 2 O 2 production and pollutant mineralization processes, as well as understanding the regulatory mechanism of free radical reactions in this process, are crucial for advancing this technology. In this study, an efficient PSFs was developed by coating COFs (TpPa-1) onto the surface of MXene (Ti 3 C 2). Under visible light irradiation, the generation rate of H 2 O 2 reached 983.9 μmol·g−1·h−1, which is 9 times that of pure TpPa-1. Additionally, this led to a significant increase in the removal rate of sulfamethoxazole (SMX) from 25 % to 92 % within 100 min. Photoelectrochemical tests and density functional theory (DFT) calculations confirmed that the incorporation of Ti 3 C 2 not only facilitates efficient charge carrier transport but also enhances the generation of hydroxyl radicals (·OH) and the production of H 2 O 2 , thereby improving the photocatalytic self-Fenton removal efficiency of SMX. This research is expected to have a positive impact on the development of efficient PSFs. [ABSTRACT FROM AUTHOR]

Charge carriers have been studied for use in applications such as fuel cells, redox flow batteries, and electrochemical CO2 reactors for conversion to value-added products. Here, transient-based equilibrium models are developed for two well-known charge carriers: methyl viologen (MV) and ethyl viologen (EV). The models are simulated using Butler-Volmer kinetics until steady-state is reached. EV is favored over MV due to lower dimerization, and enabling over 2 × production of reduced EV+ over MV+. MV and EV products do not appear to significantly change, except only under sufficiently acidic conditions (pH < 4). Charge and energy input requirement are used to assess total system efficiency and potential for system scale-up via chronoamperometry. The charge and energy analysis performed with EV as the charge carrier reveals that optimal charging voltage is around − 0.8 to − 0.85 V vs. Ag/AgCl, which is above the minimum reduction voltage (around − 0.6 to − 0.7 V vs. Ag/AgCl) and suggest more favorable conditions for performing such charge carrier reductions. [ABSTRACT FROM AUTHOR]

In this work, the growth of extended tri-s-triazine units (melem units) on g-C3N4 (CN) by hydrothermal treatment and its effect on the photodegradation efficiency of tetracycline hydrochloride (TC) is investigated. The CN-180-x and CN-200-6 samples were prepared using different hydrolysis times and temperatures, and they were characterized by multiple physicochemical techniques. In addition, their photodegradation performance was evaluated under visible light irradiation. Compared to the CN, CN-180-6 possesses remarkable photocatalytic degradation efficiency at 97.17% towards TC removal in an aqueous solution. The high visible-light-induced photo-reactivity of CN-180-6 directly correlates to charge transfer efficiency, numerous structural defects with a high specific surface area (75.0 m2 g−1), and sufficient O-functional groups over g-C3N4. However, hydrothermal treatment at a higher temperature or during a longer time additionally induces the growth of extended melem units on the surface of g-C3N4, resulting in the inhibition of the charge transfer. In addition, the superoxide radical is proven to be generated from photoexcited reaction and plays a key role in the TC degradation. [ABSTRACT FROM AUTHOR]

Multivalent ion batteries have emerged as promising solutions to meet the future demands of energy storage applications, offering not only high energy density but also diverse socio-economic advantages. Among the various options for cathodes, quinone-based organic compounds have gained attention as suitable active materials for multivalent ion batteries due to their well-aligned ion channels, flexible structures, and competitive electrochemical performance. However, the charge carriers associated with anions that are often exploited in multivalent ion battery systems operate by way of a "non-rocking-chair" mechanism, which requires the use of an excess amount of electrolyte and results in a significant decrease in the energy density. In this review, by categorizing the various charge carriers exploited in previous studies on multivalent ion batteries, we summarize recently reported quinone-based organic cathodes for multivalent ion batteries and emphasize the importance of accurately identifying the charge carriers for calculating the energy density. We also propose potential future directions toward the practical realization of multivalent ion batteries, in link with their efficient energy storage applications.

Abstract This review discusses how halide ion species have been used as charge carriers in both anion rocking‐chair and dual‐ion battery (DIB) systems. The anion rocking‐chair batteries based on fluoride and chloride have emerged over the past decade and are garnering increased research interest due to their large theoretical energy density values and the natural abundance of halide‐containing materials. Moreover, DIBs that use halide species as their anionic charge carrier are seen as one of the promising next‐generation battery technologies due to their low cost and high working potentials. Although numerous polyatomic anions have been studied as charge carriers, the use of single halide ions (i.e., F− and Cl−) and metal‐based superhalides (e.g., [MgCl3]−) as anionic charge carriers in DIBs has been considerably less explored. Herein, we provide an overview of some of the key advances and recent progress that has been made with regard to halide ion charge carriers in electrochemical energy storage. We offer our perspectives on the current state of the field and provide a roadmap in hopes that it helps researchers toward making new advances in these promising and emerging areas.

Abstract Growing attention to the development of sustainable solar‐to‐energy conversion applications has resulted in the synthesis of promising and environment‐friendly nanomaterials as energy harvesters. Among various carbon nanomaterials, carbon dots (CDs) have received significant attention due to their excellent light absorption capability, broad absorption region, and superior photostability with enormous potential for solar energy applications. Therefore, utilizing and modulating the charge carriers generated from CDs is critical for achieving a high energy conversion efficiency of CDs. Herein, we focus on the distinct characteristics of CDs as energy converters from charge excitation to charge separation and transfer for various solar‐to‐energy applications, including photovoltaic cells, photocatalysts, and photoelectrocatalysts. We anticipate that this review will offer insight into the synthesis and design of novel nanocomposites with a fundamental analysis of the photochemical properties and future development of energy conversion devices.

ZnO (ZO), Fe2O3 (FO), and graphene oxide (GO)/ZO/FO/ZnFe2O4 (ZFO) composite photocatalysts have been synthesized successfully via a simple sol–gel method and low-temperature technology. The phase structure and microstructural analysis confirmed that the GO/ZO/FO/ZFO magnetic separation photocatalyst is composed of GO, hexagonal ZnO, rhombohedral Fe2O3, and spinel ZnFe2O4 without any other impurities. The GO/ZO/FO/ZFO composite photocatalysts have a high visible light optical absorption coefficient and photocatalytic activity for degrading dyes, refractory pollutants, and antibiotics. The degradation percentages of methyl orange, tetrabromobisphenol A, and oxytetracycline hydrochloride by the GO/ZO/FO/ZFO magnetic separation photocatalyst were 98% for 180 min, 99% for 150 min, and 85% for 180 min, respectively. The special synthesis path leads to the formation of a special heterojunction between GO, ZnO, Fe2O3, and ZnFe2O4, which does not change the optical band gap value of the main lattice Fe2O3, and enhances the surface defects of the GO/ZO/FO/ZFO magnetic separation photocatalyst, resulting in high charge carrier transfer and separation efficiency of the catalyst and then enhanced the photocatalytic activity of the GO/ZO/FO/ZFO magnetic separation photocatalyst.

Photocatalysis, as an alternative for treating persistent water pollutants, holds immense promise. However, limitations hinder sustained treatment and recycling under varying light conditions. This comprehensive review delves into the novel paradigm of metal and non-metal doping to overcome these challenges. It begins by discussing the fundamental principles of photocatalysis and its inherent limitations. Understanding these constraints is crucial for developing effective strategies. Band gap narrowing by metal and non-metal doping modifies the band gap, enabling visible-light absorption. Impurity energy levels and oxygen vacancies influenced the doping energy levels and surface defects. Interfacial electron transfer and charge carrier recombination are the most important factors that impact overall efficiency. The comparative analysis of nanomaterials are reviewed on various, including nanometal oxides, nanocarbon materials, and advanced two-dimensional structures. The synthesis process are narratively presented, emphasizing production yields, selectivity, and efficiency. The review has potential applications in the environment for efficient pollutant removal and water purification, economic cost-effective and scalable production and technological advancement catalyst design, in spite of its challenges in material stability, synthesis methods and optimizing band gaps. The novelty of the review paper is on the proposal of a new paradigm of heterojunctions of doped metal and non-metal photocatalysts to promise highly efficient water treatment. This review bridges the gap between fundamental research and practical applications, offering insights into tailored nano photocatalysts. [Display omitted] • Characterization of metal and non-metal-doped heteroatom photocatalysts. • Compare doped heteroatom nanomaterials in photocatalysis. • Future challenges in heteroatom-doped nanomaterials. [ABSTRACT FROM AUTHOR]

We showed two demonstrations of the local charge carrier dynamics measurements of photocatalytic materials using our recently developed time-resolved phase-contrast microscopic technique combined with the clustering analyses. In this microscopic time-resolved technique, we observed the charge carrier dynamics via the refractive index change instead of the luminescence or absorption change, where we could often observe non-radiative charge carrier processes such as charge carrier trapping and non-radiative relaxation. By the clustering analyses of all the pixel-by-pixel responses, we could extract various different charge carrier dynamics because photocatalytic materials have inhomogeneity on surfaces and the charge carrier behavior depends on the local structure and species. Even for typical photocatalytic materials, titanium oxide and hematite, we could recognize various charge carrier dynamics, which cannot be differentiated by the general fitting procedure for the averaged time response. We could categorize the surface-trapped charge carriers (holes and electrons) and bulk carriers in the nanosecond to millisecond order, which indicates that this analytical procedure will play an important role in understanding the charge carrier dynamics for various photocatalytic materials.

We constructed quantum-scale catalytic regions on the surfaces of TiO 2 nanoparticles by loading TiO 2 quantum dots (QDs) with a two-step method. The removal rate and mineralization efficiency of toluene were measured and then used in evaluating the oxidation performance of the prepared samples. A home-built atmospheric surface photovoltage spectrometer and X-ray photoelectron spectrometer were used in analyzing band alignment across the interface between TiO 2 QD and TiO 2 particle and the transfer of charge carriers at the surface. Results showed that an upward band bending formed from the TiO 2 particle to the TiO 2 QD and promoted the accumulation of holes at the QD side. Moreover, the QD and surrounding substrate TiO 2 formed a quantum-scale catalytic region, improving the reaction probability of electron-hole pairs and corresponding intermediates. The mineralization efficiency of toluene in QD-loaded TiO 2 reached 95.8%. The synthetic method is green and simple, showing potential in scale production and industrial application. [ABSTRACT FROM AUTHOR]

Growing attention to the development of sustainable solar‐to‐energy conversion applications has resulted in the synthesis of promising and environment‐friendly nanomaterials as energy harvesters. Among various carbon nanomaterials, carbon dots (CDs) have received significant attention due to their excellent light absorption capability, broad absorption region, and superior photostability with enormous potential for solar energy applications. Therefore, utilizing and modulating the charge carriers generated from CDs is critical for achieving a high energy conversion efficiency of CDs. Herein, we focus on the distinct characteristics of CDs as energy converters from charge excitation to charge separation and transfer for various solar‐to‐energy applications, including photovoltaic cells, photocatalysts, and photoelectrocatalysts. We anticipate that this review will offer insight into the synthesis and design of novel nanocomposites with a fundamental analysis of the photochemical properties and future development of energy conversion devices. [ABSTRACT FROM AUTHOR]

This review discusses how halide ion species have been used as charge carriers in both anion rocking‐chair and dual‐ion battery (DIB) systems. The anion rocking‐chair batteries based on fluoride and chloride have emerged over the past decade and are garnering increased research interest due to their large theoretical energy density values and the natural abundance of halide‐containing materials. Moreover, DIBs that use halide species as their anionic charge carrier are seen as one of the promising next‐generation battery technologies due to their low cost and high working potentials. Although numerous polyatomic anions have been studied as charge carriers, the use of single halide ions (i.e., F− and Cl−) and metal‐based superhalides (e.g., [MgCl3]−) as anionic charge carriers in DIBs has been considerably less explored. Herein, we provide an overview of some of the key advances and recent progress that has been made with regard to halide ion charge carriers in electrochemical energy storage. We offer our perspectives on the current state of the field and provide a roadmap in hopes that it helps researchers toward making new advances in these promising and emerging areas. [ABSTRACT FROM AUTHOR]

Graphdiyne (GDY), which features a highly π‐conjugated structure, direct bandgap, and high charge carrier mobility, presents the major requirements for photocatalysis. Up to now, all photocatalytic studies are performed without paying too much attention on the GDY bandgap (1.1 eV at the G0W0 many‐body theory level). Such a narrow bandgap is not suitable for the band alignment between GDY and other semiconductors, making it difficult to achieve efficient photogenerated charge carrier separation. Herein, for the first time, it is demonstrated that tuning the electronic bandgap of GDY via H‐substitution (H‐GDY) promotes interfacial charge separation and improves photocatalytic H2 evolution. The H‐GDY exhibits an increased bandgap energy (≈2.5 eV) and exploitable conduction band minimum and valence band maximum edges. As a representative semiconductor, TiO2 is hybridized with both H‐GDY and GDY to fabricate a heterojunction. Compared to the GDY/TiO2, the H‐GDY/TiO2 heterojunction leads to a remarkable enhancement of the photocatalytic H2 generation by 1.35 times under UV–visible illumination (6200 µmol h−1 g−1) and four times under visible light (670 µmol h−1 g−1). Such enhancement is attributed to the suitable band alignment between H‐GDY and TiO2, which efficiently promotes the photogenerated electron and hole separation, as supported by density functional theory calculations. [ABSTRACT FROM AUTHOR]

[Display omitted] • Heavy monovalent and trivalent doping achieved in single crystals of MAPbI 3 and MAPbBr 3. • Monovalent doping forms microstrains and enhances electrical conductivity by 10 ∼ 100 times. • Trivalent doping with Bi3+ and Sb3+ significantly enhances electrical conductivity by 105. • Bi3+ doping oxidizes the deep defect state Pb0 to form Bi+ and Pb2+ and also substitutes Pb0. • Enhanced ZT of 100 times the best previous reports on MAPbBr 3 single crystals achieved. Organic-inorganic hybrid metal halide perovskites have emerged as a promising candidate for low-temperature thermoelectric conversion. However, challenges remain in heavily doping bulk perovskite single crystals without phase segregation or self-doping compensation issues to increase the carrier concentration. Previous efforts to enhance their thermoelectric performance rely on photoexcitation or surface/interface doping, which is not suitable for bulk devices to work in dark. This study achieves high monovalent and trivalent doping concentrations of up to 5 % in bulk single crystals of MAPbI 3 and MAPbBr 3 without phase segregation or defect formation. For monovalent doping, K+ and Li+ are incorporated into the perovskite lattice as interstitials. The resulting lattice distortion/microstrain enhances the electrical conductivity by 10 ∼ 100 times of undoped samples at 420 K. Trivalent doping using SbCl 3 , BiBr 3 , and BiI 3 significantly enhances the carrier concentration and electrical conductivity, up to 1012 cm−3 and 0.038 S m−1 for MAPbBr 3 with 10 % BiI 3 at 465 K, respectively, which is 105 times of the undoped samples and 10 times of the best reports on doped MAPbBr 3. Interestingly, the Bi3+ dopant oxidizes the deep defect state Pb0, resulting in Bi+ and Pb2+ formation and contributing to the enhanced electrical conductivity. Enhanced thermoelectric figure of merit (ZT) is achieved in MAPbBr 3 with 5 % BiI 3 at 315 K, almost 100 times of the best reports on doped MAPbBr 3. This study provides fundamental understanding of doping-modulated microstructural, charge carrier, and thermoelectric properties of hybrid halide perovskites, offering potential doping strategies to realize the theoretically predicted promising thermoelectric properties in their bulk single crystals for practical thermoelectric devices. The doping-modulated carrier transport will also guide the optimization of optoelectronic applications of halide perovskites for solar cells, light emitters, and photodetectors. [ABSTRACT FROM AUTHOR]

In this work, the growth of extended tri-s-triazine units (melem units) on g-C3N4 (CN) by hydrothermal treatment and its effect on the photodegradation efficiency of tetracycline hydrochloride (TC) is investigated. The CN-180-x and CN-200-6 samples were prepared using different hydrolysis times and temperatures, and they were characterized by multiple physicochemical techniques. In addition, their photodegradation performance was evaluated under visible light irradiation. Compared to the CN, CN-180-6 possesses remarkable photocatalytic degradation efficiency at 97.17% towards TC removal in an aqueous solution. The high visible-light-induced photo-reactivity of CN-180-6 directly correlates to charge transfer efficiency, numerous structural defects with a high specific surface area (75.0 m2 g−1), and sufficient O-functional groups over g-C3N4. However, hydrothermal treatment at a higher temperature or during a longer time additionally induces the growth of extended melem units on the surface of g-C3N4, resulting in the inhibition of the charge transfer. In addition, the superoxide radical is proven to be generated from photoexcited reaction and plays a key role in the TC degradation.

Metal oxide (MO) nanoparticles (NPs) are widely applied to medicine, agriculture, industry, and other fields, however, their potential toxicity is often concerned. Various toxicological studies are carried out to investigate the toxicity and underlying mechanism of MO NPs. A series of physicochemical properties of MO NPs, such as primary size, charge, solubility, crystal structure, crystalline phase, etc., are correlated with their induced toxicity. Recently, electronic properties of MO NPs have exhibited intense correlation with the oxidative injury in cells and mice. The overlap between the conduction band energy (Ec) of MO NPs and the biological redox potential range (-4.12 to -4.84 eV) of biological systems shows increasing evidence in causing the oxidative injury. Charge carrier types (hole or electron) of MO NPs are further found to potentiate or alleviate these injuries. Based on this knowledge, safer MO NPs can be prepared through regulation of energy edges of MO NPs. Herein, the relationship between the electronic properties of MO NPs and their induced oxidative injury is summarized, and the new safe-by-design approach for preparing safer MO NPs is introduced. [ABSTRACT FROM AUTHOR]

Cellulose insulation polymer material is widely used in oil immersed bushing. Moisture is one of the important reasons for the deterioration of cellulose polymer insulation, which seriously threatens the safe and stable operation of bushing. It is significant to study the polarization and depolarization behavior of oil-immersed cellulose polymer insulation with different moisture condition under higher voltage. Based on polarization/depolarization current method and charge difference method, the polarization/depolarization current, interfacial polarization current and electrical conductivity of cellulose polymer under different DC voltages and humidity were obtained. Based on molecular-dynamics simulation, the effect of moisture on cellulose polymer insulation was analyzed. The results show that the polarization and depolarization currents become larger with the increase in DC voltage and moisture. The higher applied voltage will accelerate the charge carrier motion. The ionization of water molecules will produce more charge carriers. Thus, high DC voltage and moisture content will increase the interface polarization current. Increased moisture content results in more charge carriers ionized by water molecules. In addition, the invasion of moisture will reduce the band width of cellulose polymer and enhance its electrostatic potential, so as to improve its overall electrical conductivity. This paper provides a reference for analyzing the polarization characteristics of charge carriers in cellulose polymer insulation.

• Perovskite solar cells based on sputtered all-metal-oxide charge transport layers have been successfully developed. • An enhanced power conversion efficiency (16.51%) was achieved by adjusting the properties of NiO x and ZnO layers. • The PSCs showed greatly improved stability under ambient condition. Despite the great advance in power conversion efficiency (PCE), the poor stability of perovskite solar cells in ambient condition becomes a tremendous obstruction for real application. Solution-processed all-metal-oxide charge transport layers exhibit remarkable improvement in stability in ambient air according to the previous report. However, the solution process is confined to the limited effective area and morphology of the substrate. Here we report the magnetron sputtered charge transport layers, of which Cu doped NiO x (Cu:NiO x) acts as the hole transport layer and ZnO as the electron transport layer, respectively. We precisely control their properties on unlimited substrates without post-annealing for balanced charge transport efficiency in both interfaces, which demonstrates better power conversion efficiency. The all-metal-oxide based devices also demonstrate excellent stability in ambient condition when compared to the control devices based on conventional organic transport layers. [ABSTRACT FROM AUTHOR]

Electrons and holes as charge carriers appear when a molecular system is exposed to external electric field. For nonsymmetric molecules, the distribution of charge carriers is also nonsymmetric. Although symmetric distribution of charge carriers is expected when the molecular system is symmetric, as the present work shows, they are not symmetric unexpectedly; that is, electrons and holes are not each other's mirror images. In this respect, asymmetric deformation density analysis is introduced to measure the extent of asymmetric distribution of electrons and holes as charge carriers when the symmetric system is exposed to symmetric external potential. Segments of (5,0) carbon nanotubes with different lengths are selected as symmetric systems, and a linear electric field is applied along the principal axis as symmetric potential. Results show that, at high electric fields, electrons tend to localize at the ends, while holes tend to occupy the middle area of carbon nanotube segments. While charge carriers play a vital role in molecular conductivity, asymmetric distribution of electrons and holes in symmetric systems has not yet been reported. [ABSTRACT FROM AUTHOR]

Organic semiconductors (OSCs) materials are currently under intense investigation because of their potential applications such as organic field‐effect transistors, organic photovoltaic devices, and organic light‐emitting diodes. Inspired by the selenization strategy can promote anisotropic charge carrier migration, and selenium‐containing compounds have been proved to be promising materials as OSCs both for hole and electron transfer. Herein, we now explore the anisotropic transport properties of the series of selenium‐containing compounds. For the compound containing SeSe bond, the SeSe bond will break when attaching an electron, thus those compounds cannot act as n‐type OSCs. About the different isomer compounds with conjugated structure, the charge transfer will be affected by the stacking of the conjugated structures. The analysis of chemical structure and charge transfer property indicates that Se‐containing materials are promising high‐performance OSCs and might be used as p‐type, n‐type, or ambipolar OSCs. Furthermore, the symmetry of the selenium‐containing OSCs will affect the type of OSCs. In addition, there is no direct relationship between the R groups with their performance, whether it or not as p‐type OSCs or n‐types. This work demonstrates the relationship between the optoelectronic function and structure of selenium‐containing OSCs materials and hence paves the way to design and improve optoelectronic function of OSCs materials. [ABSTRACT FROM AUTHOR]

Charge carrier mobility in organic semiconductors is not a constant value unambigously characterizing some particular material, but depends on the electric field, temperature and even on time after it was generated or injected. The time dependence is particularly important for the thin-film devices where charge carriers pass the organic layer before mobility reaching its stationary value. Here we give a review of experimental techniques with ultrafast timeresolution enabling one to address the mobility kinetics and analyse properties of the time-dependent mobility in conjugated polymers and organic solar cells. We analyse kinetics during the charge carrier generation and extraction of free charge carriers. The mobility typically decreases by several orders of magnitude on a picosecond-nanosecond time scale; however, its kinetics also depends on the investigation technique. The mobility kinetics in blends for bulk heterojunction solar cells strongly depends on the stoichiometric ratio of donor and acceptor materials. [ABSTRACT FROM AUTHOR]

Due to its enormous development potential, research on perovskite solar cells (PSCs) is progressing rapidly worldwide. Among numerous hole transport materials (HTMs), an organic molecule spiro-OMeTAD emerged victorious. Spiro's application in PSCs is constrained to its weak hole mobility and low conductivity. Here, an inexpensive, ecologically friendly inorganic oxidant iodine pentoxide (I 2 O 5) is used to aid in quick and manageable oxidation of Spiro. I 2 O 5 -modified Spiro as HTM improves the charge carrier transportation. Meanwhile, trap-states density and trap-assisted recombination are decreased. Additionally, the modification adjusts the HTM's energy level to match the perovskite layer properly. As a result, the I 2 O 5 -modified PSC achieves a champion power conversion efficiency of 22.80%, while the pristine device gets an efficiency of 20.65%. [Display omitted] • Iodine pentoxide (I 2 O 5) is introduced to spiro-OMeTAD hole transport layer. • I 2 O 5 -introduction adjusts Spiro oxidation rate and increase carrier concentration. • I 2 O 5 -modification decreases defect density and trap-assisted recombination. • I 2 O 5 -treated PSC achieves an efficiency of 22.80%, pristine device gets 20.65%. [ABSTRACT FROM AUTHOR]