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With the development of wearable and wireless electronic devices, the triboelectric nanogenerator (TENG) is attracting interest as a candidate for portable power. Many studies are conducted to increase the surface charge density of the TENG, such as external charge pumping or external electron excitation strategies. However, there are limitations in that another additional external energy source is required. Here, a TENG–capacitor (TC) coupling system that can maximize energy generation and storage efficiency within a limited volume is proposed. Density functional theory calculations indicate that the electric field induced on capacitor increases the fermi energy of positive triboelectric material, resulting in more charge transfer between two triboelectric materials. TC coupling system enhances TENG output performance and the capacitor charging rate in a virtuous cycle. This study provides new insights into TENG structural design and an important guideline for the use of TENG as a portable power source for wearable and wireless applications. [ABSTRACT FROM AUTHOR]

The development of highly tribopositive materials is crucial for realizing high‐performance triboelectric nanogenerators. In this study, a novel protocol to maximize the number of non‐bonding electrons with local dipoles for designing highly tribopositive materials is introduced, and nitrogen‐based dimethylol urea, diazolidinyl urea, and imidazolidinyl urea as promising tribopositive materials are suggested. The mechanism by which nitrogen‐based materials provide highly tribopositive properties is investigated using calculations based on density functional theory. Highly electronegative atoms, such as nitrogen and oxygen, attract electrons from neighboring atoms, resulting in the formation of negative local dipoles in the highest occupied molecular orbital band composed of non‐bonding electrons, thereby creating an electron‐donating environment. The proposed design protocol is confirmed by quantitatively investigating the triboelectric properties of nitrogen‐based materials, and analyzing the charge transfer characteristics of dimethylol urea based on dipole interactions. [ABSTRACT FROM AUTHOR]

Improvement of the sluggish kinetics of the overall water splitting catalyst through N-doping and the formation of a carbon shell makes it possible to achieve carbon neutrality and to synthesize catalysts that can replace noble metals. Surprisingly, in Ni3FeN@NC catalysts, transition metals received an extra electron due to doping with the nitrogen element, and thus the electron distribution probability at the Fermi energy level increased. In addition, pyridinic-N in the N-doped carbon shell can contribute to the improvement of catalyst performance. Density functional theory (DFT) calculations demonstrated the electrical performance by specifying the model of Ni3FeN@NC and were able to elucidate the mechanism of the catalytic reaction (OER and HER). The OER and HER overpotentials of the synthesized Ni3FeN@NC were confirmed to be 246 mV and 181 mV at 10 mV cm−2 in 1.0 M KOH. It was proved that 98% of the performance was maintained even in overall water splitting performed for 24 h. [ABSTRACT FROM AUTHOR]

Overcoating layers deposited on the surface of heterogeneous catalysts using atomic layer deposition (ALD) have been shown to increase catalyst activity, lifetime, and selectivity. In this study, we performed Al2O3 ALD and Pd ALD in a commercial fluidized bed reactor on high surface area mesoporous powder supports to create overcoated catalysts with high precursor utilization. We investigated the reaction mechanism for both Al2O3 ALD and Pd ALD using in situ mass spectrometry and developed a mathematical model to understand the precursor saturation behaviors. We characterized the catalyst samples using a variety of techniques to measure the surface area, porosity, composition, and surface chemistry of the overcoated catalysts. Finally, we used propane dehydrogenation as a probe reaction to evaluate the performance of the catalysts prepared by fluidized bed ALD. [ABSTRACT FROM AUTHOR]

The need for advanced energy conversion and storage devices remains a critical challenge amid the growing worldwide demand for renewable energy. Metal fluoride thin films are of great interest for applications in lithium-ion and emerging rechargeable battery technologies, particularly for enhancing the stability of the electrode-electrolyte interface and thereby extending battery cyclability and lifetime. Reported within, sodium fluoride (NaF) thin films were synthesized via atomic layer deposition. NaF growth experiments were carried out at reactor temperatures between 175 and 250 °C using sodium tert-butoxide and HF-pyridine solution. The optimal deposition temperature range was 175–200 °C, and the resulting NaF films exhibited low roughness (Rq ≈ 1.6 nm for films of ∼8.5 nm), nearly stoichiometric composition (Na:F = 1:1.05) and a growth per cycle value of 0.85 Å/cycle on SiO2 substrates. These results are encouraging for future applications of NaF thin films in the development of improved energy capture and storage technologies. [ABSTRACT FROM AUTHOR]

Mo-doped BiVO4 electrodes were prepared by an electrochemical route for use as photoanodes in a photoelectrochemical cell. The purpose of Mo-doping was to improve the electron transport properties, which in turn can increase the electron–hole separation yield. The poor electron–hole separation yield was known to be one of the main limiting factors for BiVO4-based photoanodes. The electrochemical route provided an effective way of doping BiVO4, and the optimally doped sample, BiV0.97Mo0.03O4, increased the electron–hole separation yield from 0.23 to 0.57 at 0.6 V vs. RHE, which is a record high separation yield achieved for BiVO4-based photoanodes. As a result, BiV0.97Mo0.03O4 generated impressive photocurrents, for example, 2 mA cm−2 at a potential as low as 0.4 V vs. RHE for sulfite oxidation, which has fast oxidation kinetics and, therefore, the loss of holes by surface recombination is negligible. For photooxidation of water, BiV0.97Mo0.03O4 was paired with FeOOH as an oxygen evolution catalyst (OEC) to improve the poor catalytic ability of BiV0.97Mo0.03O4 for water oxidation. The resulting BiV0.97Mo0.03O4/FeOOH photoanodes generated a significantly improved photocurrent for water oxidation compared to previous reported results, but the photocurrent of BiV0.97Mo0.03O4/FeOOH for water oxidation could not reach the photocurrent of BiV0.97Mo0.03O4 for sulfite oxidation. In order to examine the cause, the effects of Mo-doping on the interaction between BiVO4 and FeOOH and the effects of FeOOH on the electron–hole separation yield of BiV0.97Mo0.03O4 were investigated in detail, which provided new insights into semiconductor–OEC interactions. [ABSTRACT FROM AUTHOR]

Monodisperse yolk-shell SiO2-TiO2 microspheres were synthesized using core-shell silica microspheres as templates. In the absence of prior surface modifications, a uniform coating of the TiO2 layer on the core-shell silica was achieved through a sol-gel route. Mesoporous silica shells between the outer TiO2 shell and the SiO2 core were selectively removed by using a weak base, yielding yolk-shell SiO2-TiO2 microspheres (ys-SiO2@TiO2). Using the same templates, we synthesized Pt-encased microspheres (SiO2@Pt-TiO2), in which Pt nanoparticles are embedded between the SiO2 core and the TiO2 shell. Selective etching of the silica shells in SiO2@Pt-TiO2 yields Pt-encased yolk-shell SiO2-TiO2 microspheres (ys-SiO2@ ${ \char60 {\rm{Pt}} \char62 }$TiO2), which contain void spaces suitable for use as nanoreactors. The ys-SiO2@ ${ \char60 {\rm{Pt}} \char62 }$TiO2 catalyst shows enhanced hydrogen production from water under UV-light irradiation presumably as a result of multiple reflections within the void spaces and can be reused without losing their activity. Moreover, this core-shell template method is effective for the synthesis of other yolk-shell microspheres with different metal oxides. [ABSTRACT FROM AUTHOR]

Abstract: A hexapod robot was developed to explore an agricultural field and gather agronomical information such as soil nutrients and plant growth. In addition, a sensor device for the robot to track a gas source was developed. The sensor device consisted of a CO2 gas sensor and an anemoscope. The gas sensor detected the concentration of CO2 in the surroundings, and the anemoscope indicated the upwind direction from the robot. An indoor test was conducted during which the hexapod robot tracked windward direction using the sensor device. According to the results, the hexapod robot with the sensor device successfully localized a CO2 source that was in the upwind direction. The robot paused on the spot under windless conditions, and walked windward as soon as the wind started blowing again. [Copyright &y& Elsevier]

A solid hydrazine was isolated as a crystalline powder by reacting aqueous hydrazine with supercritical CO2. Its structure determined by single crystal X-ray diffraction shows a zwitterionic form of NH3+NHCO2−. The solid hydrazine is remarkably stable but is as reactive as liquid hydrazine even in the absence of solvents. [ABSTRACT FROM AUTHOR]

Copper nitride nanoparticles supported on a mesoporous superparamagnetic silica microsphere exhibit superior activity toward the Huisgen cycloaddition of azides and alkynes. The nitride catalyst offers significant advantages over homogeneous Cu catalysts. [ABSTRACT FROM AUTHOR]

The energetically favorable formation of atomically precise clusters, known as magic size clusters, in the solution phase enables a precision nanoscale synthesis with exquisite uniformity. We report the synthesis of magic size clusters via vapor infiltration of atomic layer deposition precursors directly in a polymer thin film. Sequential infiltration of trimethylindium vapor and hydrogen sulfide gas into poly(methyl methacrylate) leads to the formation of clusters with uniform properties consistent with a magic size cluster─In 6 S 6 (CH 3 ) 6 . While an increase in cluster size might be expected with additional sequential infiltration cycles of the reactive In and S precursors, uniform properties consistent with magic size clusters form in multiple polymers under a range of processing conditions. Ultraviolet-visible absorption spectra of In 6 S 6 (CH 3 ) 6 are largely independent of the number of sequential infiltration cycles and exhibit air stability, both of which are attributed to an energetically favorable synthetic pathway that is evaluated with density functional theory.

Highly efficient water splitting electrocatalyst for producing hydrogen as a renewable energy source offers potential to achieve net-zero. However, it has significant challenges in using transition metal electrocatalysts as alternatives to noble metals due to their low efficiency and durability, furthermore, the reliance on electricity generation for electrocatalysts from fossil fuels leads to unavoidable carbon emissions. Here, a highly efficient self-powered water splitting system integrated is designed with triboelectric nanogenerator (TENG) and Ni 3 FeN@Fe 24 N 10 catalyst with improved catalytic activity and durability. First, the durability of the Ni 3 FeN catalyst is improved by forming N, P carbon shell using melamine, polyetherimide, and phytic acid. The catalyst activity is improved by generating Fe 24 N 10 in the carbon shell through the Kirkendall effect. The synthesized Ni 3 FeN@Fe 24 N 10 catalyst exhibited excellent bifunctional catalytic activity (η OER = 261.8 mV and η HER = 151.8 mV) and remarkable stability (91.7% in OER and 90.5% in HER) in 1 m KOH. Furthermore, to achieve ecofriendly electricity generation, a rotation-mode TENG that sustainably generate high-performance is realized using butylated melamine formaldehyde. As a result, H 2 is successfully generated using the integrated system composed of the designed TENG and catalyst. The finding provides a promising approach for energy generation to achieve net-zero., (© 2024 Wiley‐VCH GmbH.)

Airborne pathogens retain prolonged infectious activity once attached to the indoor environment, posing a pervasive threat to public health. Conventional air filters suffer from ineffective inactivation of the physics-separated microorganisms, and the chemical-based antimicrobial materials face challenges of poor stability/efficiency and inefficient viral inactivation. We, therefore, developed a rapid, reliable antimicrobial method against the attached indoor bacteria/viruses using a large-scale tunneling charge-motivated disinfection device fabricated by directly dispersing monolayer graphene on insulators. Free charges can be stably immobilized under the monolayer graphene through the tunneling effect. The stored charges can motivate continuous electron loss of attached microorganisms for accelerated disinfection, overcoming the diffusion limitation of chemical disinfectants. Complete (>99.99%) and broad-spectrum disinfection was achieved <1 min of attachment to the scaled-up device (25 square centimeters), reliably for 72 hours at high temperature (60°C) and humidity (90%). This method can be readily applied to high-touch surfaces in indoor environments for pathogen control.

Electrochemical synthesis conditions using nonaqueous solutions were developed to prepare highly transparent (T > 90%) and crystalline ZnO and Al-doped ZnO (AZO) films for use in solar energy conversion devices. A focused effort was made to produce pinhole-free films in a reproducible manner by identifying a key condition to prevent the formation of cracks during deposition. The polycrystalline domains in the resulting films had a uniform orientation (i.e., the c-axis perpendicular to the substrate), which enhanced the electron transport properties of the films. Furthermore, electrochemical Al doping of ZnO using nonaqueous media, which was demonstrated for the first time in this study, effectively increased the carrier density and raised the Fermi level of ZnO. These films were coupled with an electrodeposited p-type Cu 2 O to construct p-n heterojunction solar cells to demonstrate the utilization of these films for solar energy conversion. The resulting n-ZnO/p-Cu 2 O and n-AZO/p-Cu 2 O cells showed excellent performance compared with previously reported n-ZnO/p-Cu 2 O cells prepared by electrodeposition. In particular, replacing ZnO with AZO resulted in simultaneous enhancements in short circuit current and open circuit potential, and the n-AZO/p-Cu 2 O cell achieved an average power conversion efficiency (η) of 0.92 ± 0.09%. The electrodeposition condition reported here will offer a practical and versatile way to produce ZnO or AZO films, which play key roles in various solar energy conversion devices, with qualities comparable to those prepared by vacuum-based techniques.

This review focuses on introducing and explaining electrodepostion mechanisms and electrodeposition-based synthesis strategies used for the production of catalysts and semiconductor electrodes for use in water-splitting photoelectrochemical cells (PECs). It is composed of three main sections: electrochemical synthesis of hydrogen evolution catalysts, oxygen evolution catalysts, and semiconductor electrodes. The semiconductor section is divided into two parts: photoanodes and photocathodes. Photoanodes include n-type semiconductor electrodes that can perform water oxidation to O2 using photogenerated holes, while photocathodes include p-type semiconductor electrodes that can reduce water to H2 using photoexcited electrons. For each material type, deposition mechanisms were reviewed first followed by a brief discussion on its properties relevant to electrochemical and photoelectrochemical water splitting. Electrodeposition or electrochemical synthesis is an ideal method to produce individual components and integrated systems for PECs due to its various intrinsic advantages. This review will serve as a good resource or guideline for researchers who are currently utilizing electrochemical synthesis as well as for those who are interested in beginning to employ electrochemical synthesis for the construction of more efficient PECs.

The major limitation to investigating a variety of ternary oxides for use in solar energy conversion is the lack of synthesis methods to prepare them as high-quality electrodes. In this study, we demonstrate that Bi-based n-type ternary oxides, BiVO4, Bi2WO6, and Bi2Mo3O12, can be prepared as high-quality polycrystalline electrodes by mild chemical and thermal treatments of electrodeposited dendritic Bi films. The resulting oxide films have good coverage, adhesion, and electrical continuity, allowing for facile and accurate evaluation of these compounds for use in solar water oxidation. In particular, the BiVO4 electrode retained the porosity and nanocrystallinity of the original dendritic Bi film. This feature increased the electron-hole separation yield, making this compound more favorable for use as a photoanode in a photoelectrochemical cell.

Mo-doped BiVO4 electrodes were prepared by an electrochemical route for use as photoanodes in a photoelectrochemical cell. The purpose of Mo-doping was to improve the electron transport properties, which in turn can increase the electron-hole separation yield. The poor electron-hole separation yield was known to be one of the main limiting factors for BiVO4-based photoanodes. The electrochemical route provided an effective way of doping BiVO4, and the optimally doped sample, BiV(0.97)Mo(0.03)O4, increased the electron-hole separation yield from 0.23 to 0.57 at 0.6 V vs. RHE, which is a record high separation yield achieved for BiVO4-based photoanodes. As a result, BiV(0.97)Mo(0.03)O4 generated impressive photocurrents, for example, 2 mA cm(-2) at a potential as low as 0.4 V vs. RHE for sulfite oxidation, which has fast oxidation kinetics and, therefore, the loss of holes by surface recombination is negligible. For photooxidation of water, BiV(0.97)Mo(0.03)O4 was paired with FeOOH as an oxygen evolution catalyst (OEC) to improve the poor catalytic ability of BiV(0.97)Mo(0.03)O4 for water oxidation. The resulting BiV(0.97)Mo(0.03)O4/FeOOH photoanodes generated a significantly improved photocurrent for water oxidation compared to previous reported results, but the photocurrent of BiV(0.97)Mo(0.03)O4/FeOOH for water oxidation could not reach the photocurrent of BiV(0.97)Mo(0.03)O4 for sulfite oxidation. In order to examine the cause, the effects of Mo-doping on the interaction between BiVO4 and FeOOH and the effects of FeOOH on the electron-hole separation yield of BiV(0.97)Mo(0.03)O4 were investigated in detail, which provided new insights into semiconductor-OEC interactions.

Climate changes and continuous population growth increase water demands that will not be met by traditional water resources, like surface and ground water. To handle increased water demand, treated municipal wastewater is offered to farmers for agricultural irrigation. This study aimed to enhance the effluent quality from worn-out sewage treatment facilities in rural villages, retreat effluent to meet water quality criteria for irrigation, and assess any health-related and environmental impacts from using retreated wastewater irrigation on crops and in soil. We developed the compact wastewater retreatment and reuse system (WRRS), equipped with filters, ultraviolet light, and bubble elements. A pilot greenhouse experiment was conducted to evaluate lettuce growth patterns and quantify the heavy metal concentration and pathogenic microorganisms on lettuce and in soil after irrigating with tap water, treated wastewater, and WRRS retreated wastewater. The purification performance of each WRRS component was also assessed. The study findings revealed that existing worn-out sewage treatment facilities in rural villages could meet the water quality criteria for treated effluent and also reuse retreated wastewater for crop growth and other miscellaneous agricultural purposes.

Monodisperse yolk-shell SiO(2) -TiO(2) microspheres were synthesized using core-shell silica microspheres as templates. In the absence of prior surface modifications, a uniform coating of the TiO(2) layer on the core-shell silica was achieved through a sol-gel route. Mesoporous silica shells between the outer TiO(2) shell and the SiO(2) core were selectively removed by using a weak base, yielding yolk-shell SiO(2) -TiO(2) microspheres (ys-SiO(2) @TiO(2) ). Using the same templates, we synthesized Pt-encased microspheres (SiO(2) @Pt-TiO(2) ), in which Pt nanoparticles are embedded between the SiO(2) core and the TiO(2) shell. Selective etching of the silica shells in SiO(2) @Pt-TiO(2) yields Pt-encased yolk-shell SiO(2) -TiO(2) microspheres (ys-SiO(2) @< Pt >TiO(2) ), which contain void spaces suitable for use as nanoreactors. The ys-SiO(2) @< Pt >TiO(2) catalyst shows enhanced hydrogen production from water under UV-light irradiation presumably as a result of multiple reflections within the void spaces and can be reused without losing their activity. Moreover, this core-shell template method is effective for the synthesis of other yolk-shell microspheres with different metal oxides., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A solid hydrazine was isolated as a crystalline powder by reacting aqueous hydrazine with supercritical CO(2). Its structure determined by single crystal X-ray diffraction shows a zwitterionic form of NH(3)(+)NHCO(2)(-). The solid hydrazine is remarkably stable but is as reactive as liquid hydrazine even in the absence of solvents., (This journal is © The Royal Society of Chemistry 2011)