Realizing Textured Zinc Metal Anodes through Regulating Electrodeposition Current for Aqueous Zinc Batteries.

Crystallography modulation of zinc (Zn) metal anode is promising to promote Zn reversibility in aqueous electrolytes, but efficiently constructing Zn with specific crystallographic texture remains challenging. Herein, we report a current-controlled electrodeposition strategy to texture the Zn electrodeposits in conventional aqueous electrolytes. Using the electrolytic cell with low-cost Zn(CH3 COO)2 electrolyte and Cu substrate as a model system, the texture of as-deposited Zn gradually transforms from (101) to (002) crystal plane as increasing the current density from 20 to 80 mA cm-2 . Moreover, the high current accelerates the Zn nucleation rate with abundant nuclei, enabling uniform deposition. The (002) texture permits stronger resistance to dendrite growth and interfacial side reactions than the (101) texture. The resultant (002)-textured Zn electrode achieves deep cycling stability and supports the stable operation of full batteries with conventional V/Mn-based oxide cathodes.

In-Situ Integration of a Hydrophobic and Fast-Zn2+ -Conductive Inorganic Interphase to Stabilize Zn Metal Anodes.

The irreversible issues of Zn anode stemming from dendrite growth and water-induced erosion have severely hindered the commercialization of rechargeable aqueous Zn batteries. Herein, a hydrophobic and fast-Zn2+ -conductive zinc hexacyanoferrate (HB-ZnHCF) interphase layer is in situ integrated on Zn by a rapid room-temperature wet-chemistry method to address these dilemmas. Different from currently proposed hydrophilic inorganic cases, the hydrophobic and compact HB-ZnHCF interphase effectively prevents the access of water molecules to Zn surface, thus avoiding H2 evolution and Zn corrosion. Moreover, the HB-ZnHCF with large internal ion channels, strong zincophilicity, and high Zn2+ transference number (0.86) permits fast Zn2+ transport and enables smooth Zn deposition. Remarkably, the resultant HB-ZnHCF@Zn electrode delivers unprecedented reversibility with 99.88 % Coulombic efficiency over 3000 cycles, realizes long-term cycling over 5800 h (>8 months, 1 mA cm-2 ) and 1000 h (10 mA cm-2 ), and assures the stable operation of full Zn battery with both coin- and pouch-type configurations.

Different effects of selenium speciation on selenium absorption, selenium transformation and cadmium antagonism in garlic.

Currently, planting selenium-rich crops using inorganic selenium such as selenate and selenite is used to address human selenium deficiency problems. In this paper, besides the above two traditional inorganic selenium speciation, we chose a new organic selenium speciation of potassium selenocyanoacetate to investigate the different effects of selenium speciation on selenium absorption, selenium transformation and cadmium antagonism via foliar application. Plantingexperiments showed that the selenium content of garlic bulbs treated with organic selenium was 1.8-3.9 times higher than that of inorganic selenium. Additionally, the absorption and transformation efficiency of organic selenium in garlic was also the highest, reaching over 95 %. Importantly, it was noteworthy that the cadmium content in bulbs treated with organic selenium was significantly lower than the Chinese food safety standard (0.2 mg/kg). Hence, this study provides an efficient organic selenium speciation which is beneficial to meet human selenium requirements and ensure safe utilization of cadmium-contaminated soils.

Colloidal iron species driven enhanced H2O2 decomposition into hydroxyl radicals for efficient removal of methylene blue from water.

Colloids are wide-spread in natural waters and colloid-facilitated transport via adsorption was established as the most important mechanism for the mobilization of aqueous contaminants. This study reports another possible, but reasonable, role of colloids for the contaminants driven by redox reactions. Under the same conditions (pH 6.0, 0.3 ml 30% H2O2, and 25 °C), the degradation efficiencies of methylene blue (MB) at 240 min over Fe colloid, Fe ion, Fe oxide and Fe(OH)3 were 95.38%, 42.66%, 4.42% and 9.40%. We suggested that, Fe colloid can promote the H2O2 based in-situ chemical oxidation process (ISCO) compared with other iron species such as Fe(Ⅲ) ion, Fe oxide and Fe(OH)3 in natural water. Furthermore, the MB removal via adsorption by Fe colloid was only 1.74% at 240 min. Hence, the occurrence, behavior and fate of MB in Fe colloid containing natural water system mainly depends on the reduction-oxidation rather than adsorption-desorption process. Based on the mass balance of colloidal iron species and characterization of iron configurations distribution, Fe oligomers were the active and dominant components for Fe colloid-driven enhanced H2O2 activation among three types of Fe species. The quick and steady conversion of Fe(III) to Fe(II) was proven to be reason why Fe colloid can efficiently react with H2O2 to produce hydroxyl radicals.

Boric Acid Functional Fluorescent Covalent-Organic Framework for Sensitive and Selective Visualization of CH3Hg.

Methylmercury (CH3Hg+) recognition remains a challenging and imperative task due to its high toxicity and wide existence in the ecosystem. Herein, a novel fluorescent covalent-organic framework containing a boric acid functional group (COF-BA) was prepared by a postmodification strategy for CH3Hg+ detection. COF-BA served as a sensing platform for CH3Hg+ with fluorescence static quenching accompanied by fluorescence color changing from intense blue to colorless, and the detection limit was determined as 1.68 µM in a relatively narrow concentration range. COF-BA also exhibited superior selectivity toward CH3Hg+ detection. Furthermore, the spiked and recovery test in real water samples showed its efficient detection practicality. The detection mechanism of COF-BA toward CH3Hg+ was investigated. The recognitive boric acid group in COF-BA was first replaced by CH3Hg+. Then, the quinoline structure that served to limit the rotation of the imine bond was disrupted, leading to dramatic fluorescence quenching. The boric acid functional COF fluorescent probe can be a promising sensing platform for the detection of methylmercury and also provides new ideas for the construction of new fluorescent COF materials.

Orientational Electrodeposition of Highly (002)-Textured Zinc Metal Anodes Enabled by Iodide Ions for Stable Aqueous Zinc Batteries.

Regulating the crystallographic texture of the zinc (Zn) metal anode is promising to promote Zn reversibility in aqueous electrolytes, but the direct fabrication of specific textured Zn still remains challenging. Herein, we report a facile iodide ion (I-)-assisted electrodeposition strategy that can scalably fabricate highly (002) crystal plane-textured Zn metal anode (H-(002)-Zn). Theoretical and experimental characterizations demonstrate that the presence of I- additives can significantly elevate the growth rate of the Zn (100) plane, homogenize the Zn nucleation, and promote the plating kinetics, thus enabling the uniform H-(002)-Zn electrodeposition. Taking the electrolytic cell with the conventional ZnSO4-based electrolyte and commercial Cu substrate as a model system, the Zn texture gradually transforms from (101) to (002) as the increase of NaI additive concentration. In the optimized 1 M ZnSO4 + 0.8 M NaI electrolyte, the as-prepared H-(002)-Zn features a compact structure and an ultrahigh intensity ratio of (002) to (101) signal without containing the (100) signal. The free-standing H-(002)-Zn electrode manifests stronger resistance to interfacial side reactions than the conventional (101)-textured Zn electrode, thus delivering a high efficiency of 99.88% over 400 cycles and ultralong cycling lifespan over 6700 h (>9 months at 1 mA cm-2) and assuring the stable operation of full Zn batteries. This work will enlighten the efficient electrosynthesis of high-performance Zn anodes for practical aqueous Zn batteries.

Non-flammable, dilute, and hydrous organic electrolytes for reversible Zn batteries.

Rechargeable Zn batteries hold great practicability for cost-effective sustainable energy storage but suffer from irreversibility of the Zn anode in aqueous electrolytes due to parasitic H2 evolution, corrosion, and dendrite growth. Herein, we report a non-flammable, dilute, and hydrous organic electrolyte by dissolving low-cost hydrated Zn(ClO4)2·6H2O in trimethyl phosphate (TMP), which homogenizes plating/stripping and enables in situ formation of a Zn3(PO4)2-ZnCl2-rich interphase to stabilize the Zn anode. A dilute 0.5 m Zn(ClO4)2·6H2O/TMP electrolyte featuring a H2O-poor Zn2+-solvation sheath and low water activity enables significantly enhanced Zn reversibility and a wider electrochemical window than the concentrated counterpart. In this formulated electrolyte, the Zn anode exhibits a high efficiency of 99.5% over 500 cycles, long-term cycling for 1200 h (5 mA h cm-2 at 5 mA cm-2) and stable operation at 50 °C. The results would guide the design of hydrous organic electrolytes for practical rechargeable batteries employing metallic electrode materials.

Integration of T7 exonuclease-triggered amplification and cationic conjugated polymer biosensing for highly sensitive detection of microRNA.

A novel and highly sensitive method for detection of microRNA (miRNA) was developed by integration of T7 exonuclease-triggered amplification and cationic conjugated polymer (CCP) biosensing. First, a fluorescein-labeled probe was designed with the complementary sequence to the target miRNA. When target miRNA was absent in the solution, the fluorescence probe interacted with CCP through the strong electrostatic interactions, leading to the highly efficient fluorescence resonance energy transfer (FRET) from CCP to fluorescein. In the presence of target miRNA, the probe hybridized with the miRNA to form DNA/miRNA duplex hybrids. Then, T7 exonuclease digested cyclically the fluorescence probes in hybrids and triggered the enzyme amplification reaction, generating a large number of single nucleotides. Owing to the weak electrostatic interaction between CCP and the single nucleotide, the FRET from CCP to fluorescein would not take place, which effectively reduced the background and significantly enhanced the sensitivity and the dynamic range of miRNA detection. The linear range of the assay was 0.2-100 pM and the detection limit 0.08 pM was 58 times lower than that of the endonuclease-based assay. The method is simple, cost-effective, and with no need for the sophisticated instrument, and has broad application prospects for miRNA detection and early diagnosis.