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Photoelectrochemical hydrogen production from water splitting using heterostructured nanowire arrays of Bi2O3/BiAl oxides as a photocathode
摘要： To date, most metal oxide-based photocathodes used in photoelectrochemical cells for water splitting contain copper cations in its composition, which can be reduced to metal Cu under cathodic bias leading to deactivation of the photoelectrode. Here, a Cu-free photocathode composed by a ternary heterostructure of Bi2O3/Al2Bi24O39/Al2Bi48O75 nanowires is reported with a narrow band gap energy (1.83 eV) and suitable conduction band edge potential (?0.98 VRHE) for water reduction to hydrogen. Photoelectrochemical measurements display that the highest photocurrent density of ?4.85 mA cm?2 at 0 VRHE under simulated sunlight is achieved by tuning the Bi:Al molar ratio of photocathode to 21:1. The photocurrent onset potential of the Bi2O3/BiAl oxides photoelectrode was estimated to be 0.57 VRHE at pH 7, which is comparable to that of silicon. Controlled potential photoelectrolysis at 0 VRHE showed a stable photocurrent of about ?2 mA cm?2 for 2 h of continuous operation. The H2 measured at this time was 696 μmol cm?2, which corresponds to a Faradaic efficiency of 93%. Finally, this work gives a new generation of Cu-free photocathodes and demonstrates a promising future of BiAl oxides in constructing photoelectrochemical devices for water splitting.
关键词： Oxides,Solar energy,PEC cells,Water reduction,Spray pyrolysis,Heterojunction
更新于2025-09-23 15:23:52
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Oxynitride Thin Films versus Particle-Based Photoanodes: a Comparative Study for Photoelectrochemical Solar Water Splitting
摘要： The solar water splitting process assisted by semiconductor photocatalysts attracts growing research interests worldwide for the production of hydrogen as a clean and sustainable energy carrier. Due to their optical and electrical properties several oxynitride materials show great promise for the fabrication of efficient photocatalysts for solar water splitting. This study reports a comparative investigation of particle- and thin films-based photocatalysts using three different oxynitride materials. The absolute comparison of the photoelectrochemical activities favors the particle-based electrodes due to the better absorption properties and larger electrochemical surface area. However, thin films surpass the particle-based photoelectrodes due to their more suitable morphological features that improve the separation and mobility of the photo-generated charge carriers. Our analysis identifies what specific insights into the properties of materials can be achieved with the two complementary approaches.
关键词： Oxynitride,pulsed laser deposition,photoelectrochemistry,thin films,solar water splitting,photoanode
更新于2025-09-23 15:23:52
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Rationally Designed Nanostructure Features on Superhydrophobic Surfaces for Enhancing Self-Propelling Dynamics of Condensed Droplets
摘要： Self-propelling ability towards achieving more efficient dropwise condensation intensively appeals to researchers due to its academic significance to explain some basic wetting phenomena. Herein we designed and fabricated the two types of microstructure superhydrophobic surfaces, i.e., sealed layered nanoporous structures (SLP-surface) and open nanocone structures (OC-surface). As a consequence, the resultant surfaces exhibit the robust water repellency, and the water droplet nearly suspends on the superhydrophobic surfaces (CA=158.8°±0.5°, SA=4°±0.5° for SLP-surface and CA=160.2°±0.4°, SA=1°±0.5° for OC-surface, respectively). Meanwhile, the impacting droplets can be rapidly rebounded off with shorter contact time of 11.2 ms and 10.4 ms (impact velocity V0 = 1 m/s). The excellent static-dynamic superhydrophobicity is mainly attributed to the air pockets captured by the both microscopic rough structures. Regarding the self-propelling ability of condensed droplets, it is found that the droplet microscopic pining effect of SLP-surface severely weakens dynamic self-propelling ability of condensed droplets. The capillary adhesive force induced by the sealed layered nanoporous structures is up to 16.0 μN. However, the open nanocone structures cause lower water adhesive force (~4.1 μN) under the action of flowing air pockets, producing higher dynamic self-propelling ability of condensed droplets. As a consequence, the open nanocone structure superhydrophobic surface displays a huge potential of inhibiting attachment of condensed droplets.
关键词： self-propelling ability,superhydrophobic,water adhesion force,designed nanostructures
更新于2025-09-23 15:23:52
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Electric field assisted ion adsorption with nanoporous SWCNT electrodes
摘要： The permeable single wall carbon nanotube (SWCNT) film electrodes of high electrical conductivity for filtration of ions are promising for future water treatment technology. The permeable SWCNT film electrodes were obtained by the use of the Zn/Al-based dispersant-aided SWCNT ink. The G band peak position and ID/IG value of Raman spectra do not change before and after the polarization of the SWCNT electrodes, showing the robustness of permeable SWCNT film electrodes. The analysis of N2 adsorption isotherms showed that microporosity and specific surface area of the SWCNT electrodes were larger than those of the pristine SWCNT, due to the debundling of SWCNTs and removal of the caps of SWCNT on the dispersion treatment. Application of the electric voltage above ?3 V to the SWCNT electrodes enhanced markedly the adsorption-mediated permeability of K+ ions, reaching the removability of 90%. The removability dependence of Na+ ions on the initial ion concentration showed that the SWCNT permeation electrodes filter was efficient for diluted Na+ ionic solution. The ions of smaller Stokes radius were adsorbed for the mixed ionic solution of Li+, Na+, K+, Rb+, and Cs+, suggesting that the inner tube space of SWCNT electrodes is important for adsorption of ions.
关键词： Permeable electrodes,Electrosorption,Electric field assistance,Ion adsorption,Water treatment,Single wall carbon nanotube
更新于2025-09-23 15:23:52
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Relationship of Water Content With Silicon and Fluorine Contents of Silicone-Hydrogel Contact Lens Materials
摘要： Objectives: The relationship between water (W) content and silicon (Si) content of silicone-hydrogel (SiHy) contact lens materials was inspected using identical methodologies, equipment, and operators for materials composing 16 types of commercially available SiHy contact lenses. Fluorine (F) content was included in the analysis for the three materials also containing a fluoropolymer. One type of lens consisted of a bulk SiHy material coated with thin layers of conventional hydrogel. Methods: SiHy materials were obtained in the form of 16 contact lens brands purchased on the open market in a common range of refractive powers from -3 to +6 D in single lots. All test lenses were equilibrated at room temperature in a standard saline recommended in the American National Standards Institute Z80.20-2016 and International Organization for Standardization (ISO) 18369-4:2017 standards. W content was obtained gravimetrically, in %, according to those standards for 16 lenses of each SiHy material. Si content was determined in % using inductively coupled plasma optical emission spectroscopy for four digested lenses of each material. F content was determined in % using an ion-selective electrode for four combusted lenses of each of the three fluorinated SiHy materials. W and Si contents of the bulk SiHy material of the coated lens were estimated by computational exclusion of the hydrogel layers. Results: The linear coefficients of determination (R2, n=16) were 0.7576 (relating mean dry Si content [n=4] to mean W content [n=16]) and 0.8819 (relating mean hydrated Si content [n=4] to mean W content [n=16]). When the 4 SiHy materials that were fluorinated or coated were excluded from the analysis, the R2 values (n=12) were 0.8869 and 0.9263, respectively. When F contents and the coating were added to the assessments, the linear coefficients of determination (R2, n=16) became 0.8948 (relating mean dry [Si+F] content to mean W content) and 0.9397 (relating mean hydrated [Si+F] content to mean W content). Conclusions: There is a fundamental negative linear relationship between Si and W contents for SiHy contact lens materials above 35% W content that is followed when F content and hydrogel coatings are empirically added to the analysis below 35% W content. The relationship was tightest for hydrated (Si+F) content and W content, for which the regression equation had an R2 of 0.9397: (Si+F)= -0.3073 (W)+22.148. The relationship between (Si+F) and W therefore seems to be based on composition rather than structure of available SiHy contact lens materials.
关键词： Water content,Contact lenses,Silicone,Silicon,Hydrogel,Fluorine
更新于2025-09-23 15:23:52
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Organic/inorganic nitride heterostructure for efficient photocatalytic oxygen evolution
摘要： Given the four-electron water oxidation reaction as the rate-limiting step for water splitting, highly efficient photocatalysts for oxygen evolution have been receiving increasing research attentions. In this study, an organic/inorganic g-C3N4/CoN nitride heterostructure was developed by a facile precipitation-nitridation two-step process. With the CoN loading amounts optimized, the obtained g-C3N4/CoN composite achieves more than 4-fold increase in photocatalytic activity for oxygen evolution, as compared to the pristine g-C3N4, with a highest oxygen evolution rate reaching 607.2 μmol h?1 g?1 under visible light (λ > 420 nm). It was demonstrated that the formed g-C3N4/CoN heterostructure could promote the interfacial charge carrier separation and the loaded CoN acting as an effective cocatalyst could accelerate the water oxidation reaction kinetics, which synergistically contributes to the great enhancement in photocatalytic activity for oxygen evolution. Interestingly, by physically mixing g-C3N4/CoN and g-C3N4/Ni, acting as oxygen and hydrogen production photocatalysts, respectively, the obtained composite could stably produce oxygen and hydrogen in the stoichiometric ratio from pure water under visible light (λ > 420 nm). Although the photocatalytic overall water splitting activity is still very low, this study demonstrates a facile and promising approach to develop visible-light active photocatalysts for simultaneous hydrogen and oxygen production from water, from the perspective of surface modification and bifunctional cocatalyst loading.
关键词： Oxygen evolution,g-C3N4,Photocatalytic water splitting,Heterostructures
更新于2025-09-23 15:23:52
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Constructing 3D sub-micrometer CoO octahedrons packed with layered MoS2 shell for boosting photocatalytic overall water splitting activity
摘要： A 3D architectures of CoO@MoS2 composite photocatalyst was prepared by coating MoS2 onto the (1 1 1) facts of sub-micrometer CoO octahedrons via a facile solvothermal method. The CoO@MoS2 composites show a significantly improved photocatalytic activity for overall water splitting. At an optimal ratio of 3 wt% MoS2, CoO@MoS2-3% composite can split pure water with the stoichiometric ratio production of H2 and O2 under visible light irradiation, meanwhile, presents the highest H2 production evolution (1.07 μmol/h), which is almost four times than that of pure CoO (0.26 μmol/h). Moreover, the CoO@MoS2 composite still remains good stability after three successive cyclings (over 72 h). The enhanced photocatalytic activity and stability can be attributed that the layered MoS2 shell not only promoted the photo-induced charge transfer at the interface of CoO due to the sufficient contact area between CoO and MoS2, but also protected the exposed the (1 1 1) facts of CoO from devastation. Our work offers more insights into the development of a simple synthesis of well-shaped 3D-based composite photocatalysts towards the energy- and environmental-related applications.
关键词： CoO octahedrons,MoS2,Overall water splitting,Core-shell,Visible light
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE Industry Applications Society Annual Meeting (IAS) - Portland, OR, USA (2018.9.23-2018.9.27)] 2018 IEEE Industry Applications Society Annual Meeting (IAS) - Performance Based Design of IMD for Single Stage PV Fed Water Pumping
摘要： This paper presents an improved designed induction motor, used for photovoltaic (PV) array fed water pumping system. The overall system is designed without a mechanical sensor to reduce both cost and complexity with simultaneous assurance of optimum power utilization of a PV array. The proposed system consists of an induction motor operated water pump, controlled by field-oriented control (FOC) with artificial neural network (ANN) current control technique. The MPPT (Maximum Power Point Tracking) as well as DC link voltage, is regulated by three-phase voltage source inverter (VSI). The estimation of motor speed eliminates the use of mechanical sensor and makes the system cheaper and robust. A new robust speed adaptive algorithm is presented, which is less dependent on parameters. A detailed study of various factors affecting the efficiency of the motor, is given to improve the behavior of the induction motor drive (IMD) for water pumping. The designed motor is tested on the developed prototype in the laboratory and its suitability is judged through various results under steady state and dynamic conditions of insolation variations.
关键词： Field-Oriented Control (FOC),Speed Adaptation,Finite Element Method,ANN Based Current Control,IMD (Induction Motor Drive),Water pump,PV Array,P&O Based MPPT Algorithm
更新于2025-09-23 15:23:52
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Diversity of TiO <sub/>2</sub> : Controlling the Molecular and Electronic Structure of Atomic-Layer-Deposited Black TiO <sub/>2</sub>
摘要： Visually black, electrically leaky, amorphous titania (am-TiO2) thin films were grown by atomic layer deposition (ALD) for photocatalytic applications. Broad spectral absorbance in the visible range and exceptional conductivity are attributed to trapped Ti3+ in the film. Oxidation of Ti3+ upon heat treatment leads to a drop in conductivity, a color change from black to white and crystallization of am-TiO2. ALD grown black TiO2, without any heat treatment, is subject to dissolution in alkaline photoelectrochemical conditions. The best photocatalytic activity for solar water splitting is obtained for completely crystalline white TiO2.
关键词： atomic layer deposition,photocatalysis,titanium dioxide,protecting overlayers,crystallization,oxide defects,water splitting
更新于2025-09-23 15:23:52
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A Comparative Study of Pressure Cooker, Ultra-Violet and RO Methods of Water Purification
摘要： In this work, the performances of the pressure cooker method, the ultra-violet method and RO method of water purification is studied. The performance of any method studied here relates to the production of potable water which meets the World Health Organization (WHO) standards. This comparative study is based on underground water obtained from a depth greater than 300 feet. The results showed that all these three methods yield same level of purity.
关键词： potable water,pressure cooker method,Water purification,reverse osmosis method,ultra-violet method
更新于2025-09-23 15:22:29