H2O Nanoparticles Research Articles

Tungsten based nanostructured hybrid electrocatalysts in neutral medium for hydrogen evolution reaction

Generating a clean and sustainable hydrogen using the naturally available electrocatalysts to split water is among the primary energy resources adopted by the global industries. Transition metal dichalcogenides such as tungsten disulfide (WS2) provide abundant active sites to foster hydrogen evolution reaction (HER). A simple hydrothermal process was employed to synthesize WO3·H2O (hydrated tungsten trioxide) and WO3 nanoparticles. The inclusion of WS2 into the oxide has enhanced the ionic movement, which has improved the catalytic performance of the composite. The hydrophilic nature of WO3 has facilitated the conversion of water molecules into adsorbed hydrogen, which was then spilled over the HER active sites of WS2 to produce hydrogen. Thus, the WO3·H2O/WS2 catalyst achieved a current density of 10 mA cm−2 at an overpotential of 383 mV with Tafel slope of 77 mV dec−1 under neutral conditions and a hydrogen evolution rate of 0.33 mmol h−1 cm−2 at −0.5 V versus RHE.

G-C3N4 tubes decorated with MnMoO4·H2O: Outstanding S-scheme photocatalyst for detoxification of water pollutants upon visible light

Recently, the utilization of heterogeneous photocatalysts has been proposed as an effective solution for environmental purification, as one of the solar energy conversion processes, under mild conditions. In this research, MnMoO4·H2O nanoparticles were anchored on tubular g-C3N4 (abbreviated as TGCN) by a one-pot hydrothermal route. The phase structure, electronic environment, spectroscopic characteristics, composition, morphology, surface area, and electrochemical properties of the resultant materials were explored using XRD, XPS, EDX, FESEM, HRTEM, FTIR, PL, photocurrent, EIS, and BET analyses. The photocatalytic activity of TGCN/MnMoO4·H2O (20 %) nanocomposite was 4.25, 5.36, 9.07, 12.4, and 8.84 times better than modified GCN, and 3.91, 2.77, 6.24, 10.9, and 6.82 times higher than MnMoO4·H2O in removals of tetracycline, rhodamine B, methylene blue, methyl orange, and fuchsine pollutants, respectively. The improved visible-light absorption and rapid charge migration/separation between TGCN and MnMoO4·H2O counterparts through S-scheme heterojunction route were the key reasons for the boosted photocatalytic performance. The biocompatibility of solution after decomposition of tetracycline via the growth of wheat seeds was verified. Finally, the stability of the binary TGCN/MnMoO4·H2O (20 %) heterostructure was measured by the stability test after four reuses.

FeF3·0.33H2O nanoparticles decorated Ti3C2 MXene as high-performance bifunctional sulfur host for lithium‑sulfur batteries

Lithium‑sulfur batteries are deemed as a potential next-generation energy storage system, but their development is hindered by the shuttle effect of lithium polysulfides. Design and synthesis of multifunctional sulfur host materials are expected to adsorb lithium polysulfides and catalyze their conversion during the lithiation process, thereby suppressing the shuttle effect. In this work, FeF3·0.33H2O nanoparticles is in situ grown on the surface of Ti3C2 nanosheets (FeF3@Ti3C2) and used as the bifunctional sulfur host for lithium‑sulfur batteries. Ti3C2 nanosheets not only provide two-dimensional (2D) conductive substrate for sulfur, but also strongly adsorb lithium polysulfides and suppress the shuttle effect. Meanwhile, FeF3 nanoparticles can accelerate the conversion reaction of lithium polysulfides, which also contributes to inhibiting the shuttle of lithium polysulfides. In addition, decorating Ti3C2 nanosheets with FeF3 nanoparticles can prevent the stacking of Ti3C2 nanosheets and enhance the interaction between Ti3C2 and lithium polysulfides. Therefore, sulfur-loaded FeF3@Ti3C2 (FeF3@Ti3C2@S) displays excellent electrochemical performance, such as a high reversible capacity of 687 mAh g−1 at 2C after 1000 cycles, and the capacity decay rate is only 0.023 %. This work paves a simple way for improving the performance of Ti3C2 as the sulfur host and expanding its application in lithium‑sulfur batteries.

Novel synthesis of FeF3·0.33H2O@hollow acetylene black nanosphere and its long-life electrochemical properties as a cathode for lithium-ion batteries

Iron (III) fluoride (FeF3), characterized by high voltage and high specific capacity and emerges as a promising candidate for the forthcoming generation of cathode materials in lithium-ion batteries. This study employs a novel methodology by introducing Fe3+ sources into hollow acetylene black particles through a vacuum impregnation method. This innovative approach results in the synthesis of a composite material comprising FeF3∙0.33H2O encapsulated within hollow acetylene black nanospheres, denoted as the FeF3∙0.33H2O @hollow acetylene black nanosphere composite material (FF@HCN). The composite exhibits a shell composed of highly graphitized carbon and a core containing FeF3∙0.33H2O particles in the range of 10–20 nm. The proportion of active materials is 75.56 %. The acetylene black has chain-like structure and high specific surface area, significantly enhances the material's conductivity, contributing 74.4 % to the pseudocapacitance at a scan rate of 1 mV s−1. The cavity graphite shell plays a crucial role in restricting the expansion and pulverization decay of FeF3∙0.33H2O nanoparticles, thereby markedly improving the cycle stability. The initial capacity of the FF@HCN composite is 224.4 mAh g−1, and after 1000 cycles at 0.1 C, it maintains a capacity of 162.3 mAh g−1, resulting in a capacity retention rate of 72.3 % and decay per cycle of 0.027 %.

Facile synthesis of FeF3•0.33H2O@3D N-doped carbon microspheres via self-assembly: An examination of electrochemical cathode dynamics in lithium-ion batteries

The theoretical capacity of FeF3 is 712 mAh g−1, making it a potential candidate as the next-generation cathode material of lithium-ion battery. However, FeF3 suffers from poor electronic/ion conductivity and poor kinetics. In this study, FeF3⋅0·33H2O@3D N-doped carbon nanofibrous microspheres (referred to as FF@CM) were prepared by EDTA self-assembly with chitosan fibers/Fe3+ sources, then carbonization and in-situ fluorination. The ultrafine FeF3⋅0.33H2O nanoparticles with an average diameter of 4.42 nm were found embedded in the 3D N-doped carbon microspheres. The FF@CM cathode delivers an initial discharge capacity of 353.57 mAh g−1 at 0.2C with a capacity decay rate of 6.77 % after 25 cycles, outperforming the bare FF cathode (with an initial discharge capacity of 263.92 mAh g−1 and a capacity decay rate of 35.95 %), the reversible capacities of the FF@CM and bare FF electrodes after 200 cycles at 0.2C are 96.29 and 4.75 mAh g−1, the pseudocapacitive contribution is up to 64 % for the FF@CM cathode at 1.0 mV s−1. The specific discharge capacities of FF@CM at 0.1, 0.2, 0.5, and 1C were 477.57, 432.15, 309.87 and 233.37 mAh g−1. Upon returning the rate to 0.1C, FF@CM recovered to the 79.23 % of the original capacity. The excellent electrochemical dynamics are attributed to its better electrolyte wettability and electronic conductivity of 3D porous microspheres, which have key contributions to advanced pseudo-capacitive behavior.

Nano-Ni/Co-PBA as high-performance cathode material for aqueous sodium-ion batteries

Prussian blue analogues (PBAs) are reliable and promising cathode materials for aqueous sodium-ion batteries (ASIBs) owing to their open three-dimensional frameworks, outstanding stability, and low production costs. However, PBAs containing only a single type of transition-metal ion often have limited charge-storage capacities in aqueous systems. This study reports the first example of K0.11Ni0.39Co0.79[Fe(CN)6]·2.04H2O nanoparticles (Ni/Co-PBA) being used as a high-capacity cathode material for ASIBs. Owing to multi-electron redox reactions involving Co and Fe ions, Ni/Co-PBA has an initial capacity of 65 mAh g−1 and a capacity retention rate of 80% after 1000 cycles at 1.0 A g−1, indicating its outstanding cycle performance and capacity retention. Ex-situ x-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and the galvanostatic intermittent titration technique were used to analyze the redox mechanisms and kinetics of Ni/Co-PBA. Ni/Co-PBA-based ASIBs are among the most promising energy-storage technologies for large-scale fixed energy-storage systems because of their outstanding electrochemical performance, low costs, and high efficiency.

Microwave assisted synthesis of iron fluoride/three dimensional graphene nanostructure composites for high-performance lithium-ion batteries

Three dimensional graphene nanostructure (3DGN) was used as a substrate to improve the electrochemical performance of FeF3·0.33H2O. FeF3·0.33H2O/3DGN composites were synthesized by an in-situ microwave assisted method. The amount of 3DGN plays an important role in the morphology and electrochemical performance of the composites. The composite presents high reversible capacities and good cycling stability when tested as the cathode materials of lithium ion batteries. It is able to give a reversible capacity of 199.1 mAh g−1 at 1 C after 100 cycles. The improved electrochemical performance is attributed to the synergistic effect of FeF3·0.33H2O nanoparticles and 3DGN.

Blackberry morphology inspired superhydrophobic poplar scrimber with superstrong UV-resistant, self-healing and reversible properties

Blackberry inspired superhydrophobic poplar scrimber with superstrong ultra-violet (UV) resistance, self-healing and reversible functional superhydrophobicity was fabricated via in-situ growth of Cu7Cl4(OH)10·H2O nano particles in the absence of low surface-free energy materials. Superhydrophobic poplar scrimber exhibited the best ultraviolet resistance over 1920 h of UV-irradiation at 340 nm, which could be the protection ascribed to UV light absorption by the hierarchical structure of Cu7Cl4(OH)10·H2O. More importantly, superhydrophobicity was reversed by a simply drying process under humid conditions. The results provider a novel strategy for preparing a simple, multifunctional, and reversibly superhydrophobic wood-based engineering material.

Constructing a hexagonal/orthorhombic WO3 phase junction for enhanced photochromism

Mixed-phase composites with an optimal phase ratio show greater light utilization than their monophasic counterparts. This approach can be applied to develop mixed-phase photochromic tungsten oxide (WO3), which shows a rapid photoresponse and high-contrast coloring. Therefore, this paper optimized the phase ratio of hexagonal WO3 (h-WO3·0.33H2O) and orthorhombic WO3·H2O (o-WO3·H2O) to form a homojunction. To enhance its photochromism, nanostructured WO3 was produced via a one-step hydrothermal strategy, in which its phase structure and morphology were controlled by regulating the reaction temperature during precursor synthesis. Various material characterization techniques were carried out to reveal the complex crystal nucleation and growth of phase junctions. h-WO3·0.33H2O nanoparticles dominated the systems, while o-WO3·H2O nanoblocks also appeared from 41.77 wt% to 56.50 wt% at a low hydrothermal synthesis temperature, producing a mixture of both polymorphs. The improved photochromic properties (from light yellow to black-green) of the mixed-phase WO3 composite compared with pure h-WO3·0.33H2O (from gray-white to dark gray) was attributed to the formation of a phase junction between h-WO3·0.33H2O and o-WO3·H2O. The photoelectrochemical results showed that this resulted in highly efficient charge carrier separation and transfer. The strong visual rendering of the black-green state may be useful for developing intelligent displays and similar devices.

Production of Graphene/Inorganic Matrix Composites through the Sintering of Graphene Oxide Flakes Decorated with CuWO4·2H2O Nanoparticles.

There is growing interest in graphene-reinforced inorganic matrix composites, but progress in this field is far behind that of polymer matrices due to difficulties in the processing of carbon materials in aggressive sintering environments, including oxidation and solubility in the host matrix. Copper-tungsten matrices are of particular interest in the power switching field but are difficult to produce due to the mutual insolubility of metals and poor wetting. Herein, composites were produced by decorating graphene oxide flakes with 8 nm diameter CuWO4·2H2O nanoparticles and then sintering them to form the final shape. The oxide nanoparticles were found to self-assemble into platelets on the surfaces of graphene flakes. Upon sintering, the presence of graphene was found to change the grain morphology from elongated needles to a polyhedral shape. It was found that, despite the nanosize of the CuWO4·2H2O particles used, the sintering conditions did not reduce the matrix to a pure metal; the sintered composites were found to be of mixed phase with copper tungstate and copper oxide present. Raman spectroscopy indicated that the graphene oxide became hydrogenated during the sintering process as a result of the reducing hydrogen atmosphere used.

Self-intercepting interference of hydrogen-bond induced flexible hybrid film to facilitate lithium extraction

Supported lithium-ion sieve (LIS) adsorbents have received widespread attention due to their excellent inherent adsorption potential toward lithium (Li) in the liquid Li source. However, LIS-based adsorbents still suffer from slow Li extraction rate and reduced Li selectivity caused by the embedding of the active sites and the adverse effects of high level of competing ions from the seawater/brine. Here, relying on the hydrogen bond (OMnO···HO) interaction, a LIS-based sandwich heterostructure is designed by the confinement of 0D MnO2·0.3H2O (HMO) nanoparticles into the interlayer of a flexible 2D MXene/1D cellulose nanofiber (MC) hybrid film (HMO@MC). Benefiting from the strong hydrogen bond interaction, the HMO@MC hybrid film achieves an excellent LIS utilization (up to 96 %) and a maximum Li adsorption capacity of 21.39 mg g−1, outperforming most LIS-based adsorbents. More impressively, the HMO@MC heavily reduces the Li migration barrier by self-intercepting interference through the steric hindrance effect of surface functional groups, thereby obtaining a fast Li adsorption rate (18.23 mg g−1 HMO, 12 h) and a super-high Li selectivity (e.g., Li/Na of 29231.8 and Li/Mg of 3605.9). This work offers a new adsorbent designing idea for Li extraction from liquid lithium source and will inspire more efforts in constructing LIS-based adsorbents for Li recovery.

Nitrogen vacancy defects in single-particle nanodiamonds sense paramagnetic transition metal spin noise from nanoparticles on a transmission electron microscopy grid.

Spin-active nanomaterials play a vital role in current and upcoming quantum technologies, such as spintronics, data storage and computing. To advance the design and application of these materials, methods to link size, shape, structure, and chemical composition with functional magnetic properties at the nanoscale level are needed. In this work, we combine the power of two local probes, namely, Nitrogen Vacancy (NV) spin-active defects in diamond and an electron beam, within experimental platforms used in electron microscopy. Negatively charged NVs within fluorescent nanodiamond (FND) particles are used to sense the local paramagnetic environment of Rb0.5Co1.3[Fe(CN)6]·3.7H2O nanoparticles (NPs), a Prussian blue analogue (PBA), as a function of FND-PBA distance (order of 10 nm) and local PBA concentration. We demonstrate perturbation of NV spins by proximal electron spins of transition metals within NPs, as detected by changes in the photoluminescence (PL) of NVs. Workflows are reported and demonstrated that employ a Transmission Electron Microscope (TEM) finder grid to spatially correlate functional and structural features of the same unique NP studied using NV sensing, based on a combination of Optically Detected Magnetic Resonance (ODMR) and Magnetic Modulation (MM) of NV PL, within TEM imaging modalities. Significantly, spin-spin dipole interactions were detected between NVs in a single FND and paramagnetic metal centre spin fluctuations in NPs through a carbon film barrier of 13 nm thickness, evidenced by TEM tilt series imaging and Electron Energy-Loss Spectroscopy (EELS), opening new avenues to sense magnetic materials encapsulated in or between thin-layered nanostructures. The measurement strategies reported herein provide a pathway towards solid-state quantitative NV sensing with atomic-scale theoretical spatial resolution, critical to the development of quantum technologies, such as memory storage and molecular switching nanodevices.

Molecular Compartments Created in Metal–Organic Frameworks for Efficient Visible-Light-Driven CO2 Overall Conversion

We report the construction of molecular compartments by the growth of narrow-band semiconductor nanoparticles, tungsten oxide and its hydrate, in the mesopores of a metal-organic framework (MOF), MIL-100-Fe. The location of these nanoparticles in pores and their spatial arrangement across the MOF crystal are unveiled by powder X-ray diffraction and small-angle neutron scattering, respectively. Such a composition with pore-level precision leads to efficient overall conversion of gas-phase CO2 and H2O to CO, CH4, and H2O2 under visible light. When WO3·H2O nanoparticles are positioned in 2.5 nm mesopores with 24 wt %, the resulting composite, namely, 24%-WO3·H2O-in-MIL-100-Fe, exhibits a CO2 reduction rate of 0.49 mmol·g-1·h-1 beyond 420 nm and an apparent quantum efficiency of 1.5% at 420 nm. These performances stand as new benchmarks for visible-light-driven CO2 overall conversion. In addition to the size and location of semiconductor nanoparticles, the coordinated water species in the crystal are found critical for high catalytic activity, an aspect usually overlooked.

Superhydrophobic Poplar Scrimber Via In Situ Synthesis of Cu7Cl4(OH)10·H2O Heterostructure Inspired by Pine Cone with Superultraviolet Resistance

Sustainable wood-based materials with versatile functions such as ultraviolet resistance, superhydrophobicity, self-cleaning/antifouling capability, etc. have great potential to be used in building fields for replacing non-biodegradable fossil-based materials due to their facile preparation, biodegradability, and durability as well as the increasing concerns on environmental impact. Herein, pine-cone-shaped Cu7Cl4(OH)10·H2O nanoparticles were in situ synthesized by a hydrothermal process on a radial section of a poplar scrimber surface. As expected, the superhydrophobic function had been endowed to all three sections of the poplar scrimber surface, which exhibited excellent mechanical durability, desirable chemical stability, and splendid self-cleaning and antifouling capabilities. It should be noted that the modified poplar scrimber kept the superhydrophobic state even after 624 h of exposure to 340 nm ultraviolet (UV) irradiation, which could be ascribed to the unique hierarchical structure of the pine-cone-shaped Cu7Cl4(OH)10·H2O nanoparticles toward providing abundant voids for absorption of UV light. More importantly, a model of crystalline cellulose before and after compression was proposed to explain the improvement of physical and mechanical properties of poplar scrimber. This work will provide a new path for the superhydrophobic modification on wood-based engineering materials, which has potential to be applied in the industrial production of superhydrophobic wood scrimber to promote the sustainable development of timber resources.

RGO–Encapsulated Co/Ni dual–doped FeF3·0.33H2O nanoparticles enabling a high-rate and long-life iron (III) fluoride–lithium battery

Conversion-type iron fluoride promises a high energy density and redox potential, which is considered an extremely promising candidate for next-generation high-specific-energy and low-cost Li-ion battery. Unfortunately, its commercialization is plagued by the poor rate capability and fast capacity degradation resulting from its inferior electronic conductivity and large volumetric expansion. Herein, a three-dimensional sandwich architecture of rGO-encapsulated Ni/Co dual‐doped FeF3·0.33H2O nanoparticles (NC-FF) is fabricated by co-precipitation and subsequent calcination. The results show that the flower-like Ni/Co dual‐doped FeF3·0.33H2O nanoparticles are firmly encapsulated within highly conductive rGO sheets through MOC bonding interaction, which constructs a robust electronic/ionic network and a buffer layer against the severe volume variation. The Ni-doping can facilitate to the capacity improvement by expanding the cell volume, and the Co-doping can promote the rate capability and cycling stability enhancement by accelerating Li+ migration. Benefiting from the synergies of Ni/Co dual-doping and encapsulation of rGO, the NC-FF exhibits a high-rate capability of 200.1 mAh g−1 at 5.0 C and good cycle stability of 177.8 mAh g−1 after 400cycles. Moreover, the NC-FF|Graphite symmetric-cell still shows a high reversible capacity of 396.2 mAh g−1 at 1.0C and good cycle stability of 247.5 mAh g−1 after 100cycles.

A versatile TiO2/ZrO2 nanocomposite coating produced on Ti-6Al-4V via plasma electrolytic oxidation process

In this work, ZrTiO4/TiO2 composite coatings were synthesized via plasma electrolytic oxidation process, representing multifunctional applications ranging from corrosion resistance to photocatalytic performance. We produced ceramic coatings on Ti-6Al-4V alloy under different current density conditions (2, 4, and 6 A/dm2) with an electrolyte containing Na3PO4.12H2O and ZrO2 nanoparticles. Prepared coatings were analyzed through SEM, XRD, AFM, and the sessile drop technique to measure contact angle. The cytotoxicity, electrochemical, and photocatalysis behavior of coatings were evaluated using MG63 cell, Hank's physiological, and methylene blue solution, respectively. The apatite forming ability in SBF (bioactivity behavior) and the release of Ti, Al, V, and Zr of composite coating were examined for optimum coating. The pore size, thickness, roughness, and porosity percentage increased with ascending the current density from 2 to 6 A/dm2, whereas the wettability of oxide coatings decreased moderately. ZrO2 nanoparticles were experienced reactive incorporation to the coating during PEO process, resulting in the formation of ZrTiO4 phases. The in vitro corrosion resistance and MG63 cell response indicated that the increment in current density has detrimental effects on electrochemical behavior and cell attachment of PEO-treated coatings. The apparent constant rate of MB photodegradation in the presence of the Zr3CD2 coating was about 3.15 times faster than the PEO coating without ZrO2 nanoparticles produced with 2 A/dm2 current density. Moreover, although the microstructure of PEO coating produced at the current density of 2 A/dm2 was fruitful for the apatite phase deposition, it accelerated the Al and V ion release rather than untreated sample.

Sonochemical synthesis of nanoparticles of Cd metal organic framework based on thiazole ligand as a new precursor for fabrication of cadmium sulfate nanoparticles

The current study reports the fabrication of a new Cd-MOF, [Cd (DPTTZ) (5-AIP)] (IUST-1), which was synthesized by the reaction of 5-Aminoisophthalic acid (5-AIP), 2, 5-di (pyridine-4-yl) thiazolo [5, 4-d] thiazole (DPTTZ) and cadmium nitrate tetrahydrate, via solvothermal and sonochemical methods. In comparison to the solvothermal route, which routinely takes 48 h, the ultrasound-assisted method improved faster synthesis with a reaction time of 1 h. Single crystal of IUST-1 was gained by solvothermal method and crystal structure characterized using X-ray crystallography and a range of spectroscopic techniques. The sonochemical method was utilized to synthesize IUST-1 nanoparticles as a precursor for the preparation of CdSO4·H2O nanoparticles. The calcination of IUST-1 at 600 °C under air atmosphere yields CdSO4·H2O nanoplates.

Exploration of Highly Porous Biochar Derived from Dead Leaves to Immobilize LiOH·H2O Nanoparticles for Efficient Thermochemical Heat Storage Applications

The inadequate utilization of low‐grade energy from industrial waste heat and solar energy calls for an efficient thermochemical heat storage material. The fabrication of a low‐cost but highly efficient composite comprising highly porous biochar and LiOH·H2O nanoparticles for heat storage applications is reported. The biochar is prepared by the KOH‐assisted pyrolysis of dead banyan leaves, and its microstructure and surface properties can be finely tuned by varying the KOH‐to‐biomass ratio. Such biochar can be mediated to possess a large specific surface area and total pore volume reaching as high as 1255.03 m2 g−1 and 3.65 cm3 g−1, respectively, superior to most previously reported biochar/biocarbon derived from different kinds of waste biomass. Besides, adequate functional groups and a hierarchical porous structure consisting of micropores and mesopores are demonstrated in the prepared biochar. The subsequent hydrothermal reaction with a short duration yields a biochar‐LiOH·H2O composite, where LiOH·H2O can be homogeneously immobilized with a nanoscale size within the porous biochar matrix. Thus, an enormous biochar/LiOH·H2O nanoparticles interface can be obtained, resulting in fast hydration reactions with water molecules. Consequently, a significant heat storage density of as high as 3089.6 kJ kg−1 is achieved within only 10 min, outstripping some recently reported thermochemical heat storage systems.

Boosted Thermal Storage Performance of LiOH·H2O by Carbon Nanotubes Isolated Multilayered Graphene Oxide Frames

Cellulose-originated three-dimensional graphene oxide CNT-modified LiOH·H2O (3D-GO-CNTs-LiOH·H2O) was synthesized by the hydrothermal method. LiOH·H2O nanoparticles (5–50 nm) were homogeneously dispersed inside the 3D-GO-CNTs frames. The composite showed enhanced heat storage density, excellent thermal conductivity, and greatly improved hydration rate due to both the hydrophilic reaction interface of 3D-GO-CNTs frames and reduced size of LiOH·H2O nanoparticles. LiOH·H2O content ratio of 23% (3D-GO-CNTs-LiOH·H2O-1) results in best heat storage performance with activation energy of 23.8 kJ/mol, thermal conductivity of 3.06 W/m·K, and heat storage capacity of 2800 kJ/kg. 3D-GO-CNTs-LiOH·H2O shows 4.2 folders heat storage capacity than that of pristine LiOH·H2O after the same hydration reaction. Other composite materials also show good performance: 3D-GO-CNTs-LiOH·H2O-2 (activation energy: 28.5 kJ/mol, thermal conductivity: 2.33 W/m·K, and heat storage capacity: 2051 kJ/kg.); 3D-GO-CNTs-LiOH·H2O-3 (activation energy: 32.3 kJ/mol, thermal conductivity: 2.01 W/m·K, and heat storage capacity: 1983 kJ/kg.). The addition of cellulose originated 3D-GO-CNTs was proved to be an excellent strategy to boost the heat storage performance of LiOH·H2O.

Enhanced Overall Water Splitting by a Zirconium‐Doped TaON‐Based Photocatalyst

AbstractSolar‐powered one‐step‐excitation overall water splitting (OWS) using semiconducting materials is a simple means of achieving scalable and sustainable hydrogen production. While tantalum oxynitride (TaON) is one of the few photocatalysts capable of promoting OWS via single‐step visible‐light excitation, the efficiency of this process remains extremely poor. The present work employed 15 nm amorphous Ta2O5⋅3.3 H2O nanoparticles as a new precursor together with Zr doping and an optimized nitridation duration to synthesize a TaON‐based photocatalyst with reduced particle sizes and low defect densities. Upon loading with Ru/Cr2O3/IrO2 cocatalysts, this material exhibited stoichiometric water splitting into hydrogen and oxygen, with an order of magnitude improvement in efficiency. Our findings demonstrate the importance of inventing/selecting the appropriate synthetic precursor and of defect control for fabricating active OWS photocatalysts.