Layered hydrated vanadium oxide as highly reversible intercalation cathode for aqueous Zn-ion batteries

Aqueous Zn-ion batteries(ZIBs)hold great potential in large-scale energy storage systems due to the merits of low-cost and high safety.However,the unstable structure of cathode materials and sluggish(de)intercalation kinetics of Zn2+pose challenges for further development.Herein,highly reversible aqueous ZIBs are constructed with layered hydrated vanadium oxide as a cathode material.The electrochemical performances are further tested with the optimized electrolyte of 3M Zn(CF3SO3)2 and a cut-off voltage of 0.4 to 1.3 V,exhibiting a remarkable capacity of 290mAh g−1 at 0.5Ag−1,and long-term cycling stability at high current density.Furthermore,the Zn2+storage mechanism of V3O7⋅H2O is recognized as a highly reversible(de)intercalation process with good structural stability,implying the potential application in the field of large-scale energy storage.

Unsaturated transport properties of water molecules and ions in graphene oxide/hydrated calcium silicate nanochannels:from basic principles to complex environmental performance effects

The problems of traditional concrete such as brittleness,poor toughness and short service life of concrete engineering under acid rain or marine environment need to be solved urgently.Hydrated calcium silicate(C-S-H)is a key component to improve the mechanical properties and durability of concrete.However,the traditional method of concrete material design based on empirical models or comparative tests has become a bottleneck restricting the sustainable development of concrete.The synthesis method,molecular structure and properties of C-S-H were systematically described in this paper;The interface structure and interaction of graphene oxide/calcium silicate hydrate(C-S-H/GO)were discussed.On this basis,the saturated and unsaturated transport characteristics of ions and water molecules in C-S-H/GO nanochannels under the environment of ocean and acid rain were introduced.The contents of this review provide the basis for improving the multi-scale transmission theory and microstructure design of concrete.It has important guiding significance for analyzing and improving the service life of concrete in complex environment.

Structure and oxygen-defect regulation of hydrated vanadium oxide for enhanced zinc ion storage via interlayer doping strategy

Hydrated vanadium oxide(VOH)is a promising cathode candidate for the aqueous zinc-ion batteries(AZIBs),due to the large interlayer spacing and high capacity.However,severe pulverization and structure collapse upon cycling limit its practical application.Herein,preintercalation strategy with higher positive charge of Cr^(3+) is proposed to regulate the structure and oxygen defect of the VOH-O_(d).The VOH-O_(d) with moderated amount of Cr^(3+) incorporation(M-CrVOH-O_(d)),showing a flower-like hierarchical structure assembled with thin nanosheets,can expand the interlayer spacing and increase the oxygen defect,inducing an enhanced high-rate cycling capability.As a result,M-CrVOH-O_(d) delivers a high capacity of 405 mAh·g^(−1)at 0.5 A·g^(−1),high capacity retention of 120%over 3,500 cycles,as well as an extraordinary energy output(297.3 Wh·kg^(−1)at 355.9 W·kg^(−1)).The density functional theory(DFT)calculations can prove the enhanced reaction kinetics with narrower bandgap and lower Zn^(2+) adsorption energy after the Cr-preintercalation.Meanwhile,based on the ex-situ X-ray diffraction(XRD)analysis,synergistic intercalation of the Zn^(2+)/H^(+)into the interlayers of M-CrVOH-O_(d) can bring the high specific capacity.This work could help us understand the enhanced performance of VOH from the point of the chemical reactions.

Antimony(V) removal from water by hydrated ferric oxides supported by calcite sand and polymeric anion exchanger

We fabricated and characterized two hybrid adsorbents originated from hydrated ferric oxides （HFOs） using a polymeric anion exchanger D201 and calcite as host. The resultant adsorbents （denoted as HFO-201 and IOCCS） were employed for Sb（V） removal from water. Increasing solution pH from 3 to 9 apparently weakened Sb（V） removal by both composites, while increasing temperature from 293 to 313 K only improved Sb（V） uptake by IOCCS. HFO-201 exhibited much higher capacity for Sb（V） than for IOCCS in the absence of other anions in solution. Increasing ionic strength from 0.01 to 0.1 mol/L NaNO3 would result in a significant drop of the capacity of HFO-201 in the studied pH ranges; however, negligible effect was observed for 1OCCS under similar conditions. Similarly, the competing chloride and sulfate pose more negative effect on Sb（V） adsorption by HFO-201 than by IOCCS, and the presence of silicate greatly decreased their adsorption simultaneously, while calcium ions were found to promote the adsorption of both adsorbents. XPS analysis further demonstrated that preferable Sb（V） adsorption by both hybrids was attributed to the inner sphere complexation of Sb（V） and HFO, and Ca（II） induced adsorption enhancement possibly resulted from the formation of HFO-Ca-Sb complexes. Column adsorption runs proved that Sb（V） in the synthetic water could be effectively removed from 30 μg/L to below 5μg/L （the drinking water standard regulated by China）, and the effective treatable volume of IOCCS was around 6 times as that of HFO-201, implying that HFO coatings onto calcite might be a more effective approach than immobilization inside D201.

Synthesis of novel hydrated ferric oxide biochar nanohybrids for efficient arsenic removal from wastewater

Hydrated ferric oxide(HFO)has high adsorption efficiency for As(Ⅲ).However,its high self-aggregation usually reduces the efficiency and limits the scaledup application.Herein,biochar(BC),with large surface area and amounts of surface functional groups was used to tune the loading and distribution of HFO to prepare an efficient adsorbent(HFO/BC)via in-situ synthesis method.The influence of the mass ratio of iron salt to BC on HFO/BC morphology was investigated,and the mechanism was discussed.The results showed that novel HFO was formed and distributed uniformly on the surface of BC when the mass ratio of iron salt to BC was 5:1.The adsorption kinetics and isotherms studies show that the novel HFO/BC(5:1)composite can fast treat As(Ⅲ)with a high adsorption capacity of 104.55 mg·g^(-1),indicating that it is a potential material for removing arsenic from polluted water.

Pre-potassiated hydrated vanadium oxide as cathode for quasi-solid-state zinc-ion battery

Zinc-ion batteries(ZIBs),in particular quasi-solid-state ZIBs,occupy a crucial position in the field of energy storage devices owing to the superiorities of abundant zinc reserve,low cost,high safety and high theoretical capacity of zinc anode.However,as divalent Zn^(2+)ions experience strong electrostatic interactions when intercalating into the cathode materials,which poses challenges to the structural stability and higher demand in Zn^(2+)ions diffusion kinetics of the cathode materials.Here,a microwave-assisted hydrothermal method is adopted to prepare pre-potassiated hydrated vanadium pentoxide(K_(0.52)V_(2)O_(5)·0.29H_(2)O,abbreviated as KHVO)cathode material,in which the potassium ions preinserted into the interlayers can act as“pillars”to stabilize the lamellar structure,and crystal water can act as“lubricant”to improve the diffusion efficiency of Zn^(2+)ions.Consequently,the KHVO displays high electrochemical properties with high capacity(∼300 mAh/g),superior rate capability(69 mAh/g at 5 A/g)and ultralong cycling performance(>1500 cycles at 2 A/g)in quasi-solid-state ZIBs.These superior Zn storage properties result from the large diffusion coefficient and highly stable and reversible Zn^(2+)(de)intercalation reaction of KHVO.

Cr^(3+)pre-intercalated hydrated vanadium oxide as an excellent performance cathode for aqueous zinc-ion batteries

Rechargeable aqueous zinc-ion batteries(ZIBs)are regarded as the next promising large scale energy storage systems owing to their low cost,high safety and environmental friendliness.Vanadium-based materials are one of the most important cathodes of ZIBs due to their high abundance and multielectron transfer of various oxidations of vanadium.Nevertheless,the strong electrostatic interaction between Zn^(2+)and cathodes,intrinsic poor electronic conductivity and solubility of vanadium-based cathodes in electrolytes bring about inferior electrochemical performance.In this work,we introduce aliovalent Cr^(3+)into the interlayer of hydrated vanadium oxide(Cr-VOH)as pillar to significantly increase the structural stability and electrochemical reversibility.The pre-intercalation of Cr^(3+)also provides an enhanced electronic conductivity and fast Zn^(2+)diffusion dynamics,enabling superior Zn2+storage performance of the Cr-VOH cathode.As a result,the Cr-VOH cathode exhibits a high reversible discharge capacity of~380 mAh g^(−1)at 50 mA g^(−1),excellent rate capacity of 166 mAh g^(−1)at 8 A g^(−1)and prolonged cycling stability over 500 cycles.Furthermore,it displays a high energy density of 273.6 W h kg^(−1)at 0.05 A g^(−1)and the power density of 4960 W kg^(−1)at 8 A g^(−1),contributing to the practical application potential of aqueous ZIBs.

Validation of polymer-based nano-iron oxide in further phosphorus removal from bioeffluent： laboratory and scaled- up study

The efficient removal of phosphorous from water is an important but challenging task. In this study, we validated the applicability of a new commercially available nanocomposite adsorbent, i.e., a polymer-based hydrated ferric oxide nanocomposite （HFO-201）, for the further removal of phosphorous from the bioefftuent discharged from a municipal wastewater treatment plant, and the operating parameters such as the flow rate, temperature and composition of the regenerants were optimized. Labora- tory-scale results indicate that phosphorous in real bioeffluent can be effectively removed from 0.92 mg· L^-1 to 〈 0.5 mg· L^-1 （or even 〈 0.1 mg·L^-1 as desired） by the new adsorbent at a flow rate of 50 bed volume （BV） per hour and treatable volume of 3500-4000BV per run. Phosphorous removal is independent of the ambient temperature in the range of 15℃-40℃. Moreover, the exhausted HFO-201 can be regenerated by a 2% NaOH ＋ 5% NaC1 binary solution for repeated use without significant capacity loss. A scaled-up study further indicated that even though the initial total phosphorus （TP） was as high as 2 mg·L^-1, it could be reduced to 〈 0.5 mg·L^-1, with a working capacity of 4.4-4.8 g·L^-1 HFO- 201. In general, HFO-201 adsorption is a choice method for the efficient removal of phosphate from biotreated waste effluent.

Effect of hydration on the surface basicity and catalytic activity of Mg-rare earth mixed oxides for aldol condensation

Magnesium and rare earth mixed oxides（Mg3 REOx（RE=La, Y. Ce）） were prepared and characterized by Xray diffraction（XRD）, N_2 adsorption-desorption, infrared spectra and microcalorimetry of CO_2. The results reveal that the Mg_3 CeO_x catalyst is present in the form of Mg-Ce-O solid solution,while the Mg3 LaOx and Mg_3 YO_x catalysts are probably rare earth oxides dispersed on MgO surface. As a result, among the calcined Mg_3 REO_x catalysts, the Mg_3 CeO_x catalyst presents the highest rate constant for acetone aldolization, which is well correlated to its more homogeneous distribution of basic sites. In contrary, the Mg_3 YO_x catalyst exhibit the lowest catalytic activity for acetone aldolization. Upon hydration pre-treatment, the basic properties on the surface of the Mg_3 REO_x catalysts were changed markedly. The Mg_3 YO_x catalyst after hydration treatment shows the highest amount of basic sites on catalyst surface, and then exhibits the highest activity among the hydrated Mg_3 REO_x catalysts. These results make it possible to fine-tune basic sites for acetone aldolization.