Free H2O Research Articles

Weak solvation effects and molecular-rich layers induced water-poor Helmholtz layers boost highly stable Zn anode

The advancement of aqueous Zn-based energy storage systems encounters major challenges due to the occurrence of side reactions and the growth of dendrites caused by the highly active nature of water in the aqueous electrolyte. Herein, a zwitterion additive named sulfonated amphoteric betaine (referred to as DMAPS) regulates the Zn2+ electrolyte environment through a weak solvation effect to promote highly stable Zn anodes. The inherently occurring anionic (-SO3-) and cationic (-NR4+) counterions in the DMAPS chain can be effectively separated under an external electric field to enable the creation of distinct ion migration pathways, thereby significantly enhancing the transportation of electrolyte ions. Moreover, DMAPS can be adsorbed onto the surface of Zn anode to form a H2O-poor Helmholtz layer, which can serve as a protective barrier to suppress corrosion of the Zn anode by free H2O and inhibits the formation of differential electric field to facilitate the directional deposition of Zn2+. In addition, density functional theory (DFT) and molecular dynamics (MD) further assisted in demonstrating the intrinsic mechanism of the reconstruction of the solvated sheath structure of Zn2+ by DMAPS. As a result, the Zn//Zn symmetric cell in ZnSO4+DMAPS solution can be cycled steadily for 2100 h at a current density of 1 mA cm-2 and 1 mAh cm-2. The assembled Zn ion hybrid capacitor with ZnSO4+DMAPS electrolyte was stably cycled for 20,000 cycles with 90% capacity retention at 5 A g-1.

Dissolved ammonia catalyzes proto-dolomite precipitation at Earth surface temperature

Marine carbonate rocks are the major reservoir of carbon through CaCO3 and CaMg(CO3)2 precipitation extracting CO2/HCO3- from the atmosphere/oceans; hence dolomite is one of the major sinks in the global carbon cycle. Most ancient dolomite has been considered as mainly precipitated under Earth surface conditions. Previous studies have demonstrated that microbes can mediate dolomite formation. However, the “microbial dolomite” model is not sufficient to explain the dolomite that shows no or little evidence of a microbial origin. Although attempted for decades, the synthesis of inorganically-produced dolomite at normal temperatures (<50 °C) has been relatively unsuccessful. Hence, this "dolomite enigma" has been one principal research focus this century. Here we demonstrate that NH3 catalyzes proto-dolomite precipitation inorganically with higher Mg/Ca molar ratios and CO32- activity at normal temperatures of 30 °C and 40 °C. NH3 dissolution increases the alkalinity of the solution and transformes into NH4+ ions, which prefer to bond with H2O on Mg[(H2O)6]2+ rather than free H2O, thus releasing Mg2+ to facilitate proto-dolomite nucleation. Furthermore, the low dielectric constant and low dipole moment allow NH4+ absorbed on crystal surfaces to lower the energy barrier of Mg[(H2O)6]2+ dehydration, promoting proto-dolomite nucleis growth. The system for proto-dolomite precipitation in our experiments closely simulates the natural aqueous environment. This study brings new insights to understanding the mechanisms of dolomite precipitation in natural waters.

Ultra-Microporous Fe-MOF with Prolonged NO Delivery in Biological Media for Therapeutic Application.

Nitric oxide (NO), a key element in the regulation of essential biological mechanisms, presents huge potential as therapeutic agent in the treatment and prevention of chronic diseases. Metal-organic frameworks (MOFs) with open metal sites are promising carriers for NO therapies but delivering it over an extended period in biological media remains a great challenge due to i) a fast degradation of the material in body fluids and/or ii) a rapid replacement of NO by water molecules onto the Lewis acid sites. Here, a new ultra-narrow pores Fe bisphosphonate MOF, denoted MIP-210(Fe) or Fe(H2O)(Hmbpa) (H4mbpa = p-xylenediphosphonic acid) is described that adsorbs NO due to an unprecedented sorption mechanism: coordination of NO through the Fe(III) sites is unusually preferred, replacing bound water, and creating a stable interaction with the free H2O and P-OH groups delimiting the ultra-narrow pores. This, associated with the high chemical stability of the MOF in body fluids, enables an unprecedented slow replacement of NO by water molecules in biological media, achieving an extraordinarily extended NO delivery time over at least 70h, exceeding by far the NO kinetics release reported with others porous materials, paving the way for the development of safe and successful gas therapies.

Multifunctional Interface Layer Constructed by Trace Zwitterions for Highly Reversible Zinc Anodes

The inhomogeneous plating/stripping of Zn anode, attributed to dendrite growth and parasitic reactions at the electrode/electrolyte interface, severely restricts its cycling life‐span. Here, trace zwitterions (trifluoroacetate pyridine, TFAPD) are introduced into the aqueous electrolyte to construct a multifunctional interface that enhances the reversibility of Zn anode. The TFA− anions with strong specific adsorption adhere onto the Zn surface to reconstruct the inner Helmholtz plane (IHP), preventing the hydrogen evolution and corrosion side reactions caused by free H2O. The Py+ cations accumulate on the outer Helmholtz plane (OHP) of Zn anode with the force of electric field during Zn2+ plating, forming a shielding layer to uniformize the deposition of Zn2+. Besides, the adsorbed TFA− and Py+ promote the desolvation process of Zn2+ resulting in fast reaction kinetics. Thus, the Zn||Zn cells present an outstanding cycling performance of more than 10000 hours. And even at 85% utilization rate of Zn, it can stably cycle for over 200 hours at 10 mA cm−2 and 10 mAh cm−2. The Zn||I2 full cell exhibits a capacity retention of over 95% even after 30000 cycles. Remarkably, the Zn||I2 pouch cells (95 mAh) deliver a high‐capacity retention of 99% after 750 cycles.

Multifunctional Interface Layer Constructed by Trace Zwitterions for Highly Reversible Zinc Anodes.

The inhomogeneous plating/stripping of Zn anode, attributed to dendrite growth and parasitic reactions at the electrode/electrolyte interface, severely restricts its cycling life-span. Here, trace zwitterions (trifluoroacetate pyridine, TFAPD) are introduced into the aqueous electrolyte to construct a multifunctional interface that enhances the reversibility of Zn anode. The TFA- anions with strong specific adsorption adhere onto the Zn surface to reconstruct the inner Helmholtz plane (IHP), preventing the hydrogen evolution and corrosion side reactions caused by free H2O. The Py+ cations accumulate on the outer Helmholtz plane (OHP) of Zn anode with the force of electric field during Zn2+ plating, forming a shielding layer to uniformize the deposition of Zn2+. Besides, the adsorbed TFA- and Py+ promote the desolvation process of Zn2+ resulting in fast reaction kinetics. Thus, the Zn||Zn cells present an outstanding cycling performance of more than 10000 hours. And even at 85% utilization rate of Zn, it can stably cycle for over 200 hours at 10 mA cm-2 and 10 mAh cm-2. The Zn||I2 full cell exhibits a capacity retention of over 95% even after 30000 cycles. Remarkably, the Zn||I2 pouch cells (95 mAh) deliver a high-capacity retention of 99% after 750 cycles.

An Ion-Pumping Quasi-Solid Electrolyte Enabled by Electrokinetic Effects for Stable Aqueous Zinc Metal Batteries.

The practical application of aqueous zinc (Zn) metal batteries (ZMBs) is hindered by the complicated hydrogen evolution, passivation reactions, and dendrite growth of Zn metal anodes. Here, an ion-pumping quasi-solid electrolyte (IPQSE) with high Zn2+ transport kinetics enabled by the electrokinetic phenomena to realize high-performance quasi-solid state Zn metal batteries (QSSZMBs) is reported. The IPQSE is prepared through the in situ ring-opening polymerization of tetramethylolmethane-tri-β-aziridinylpropionate in the aqueous electrolyte. The porous polymer framework with high zeta potential provides the IPQSE with an electrokinetic ion-pumping feature enabled by the electrokinetic effects (electro-osmosis and electrokinetic surface conduction), which significantly accelerates the Zn2+ transport, reduces the concentration polarization and overcomes the diffusion-limited current. Moreover, the Zn2+ affinity of the polymer and hydrogen bonding interactions in the IPQSE changes the Zn2+ coordination environment and reduces the amount of free H2O, which lowers the H2O activity and inhibits H2O-induced side reactions. Consequently, the highly reversible and stable Zn metal anodes are achieved. The assembled QSSZMBs based on the IPQSE display excellent cycling stability with high capacity retention and Coulombic efficiency. The high-performance quasi-solid state Zn metal pouch cells are demonstrated, showing great promise for the practical application of the IPQSE.

High-Capacity spatial confined deposition/stripping enabled by biphasic modulation strategy for highly reversible zinc anodes

The development of aqueous zinc ion batteries (AZIBs) faces two major challenges: dendrites Zn and parasitic reaction, which originates from the random zinc deposition at the anode interface and the abundant free H2O activity of the solvation structure. Here, we report a biphasic modulation strategy (anode interface construction and solvation structure regulation) to solve these two issues simultaneously. Through introducing trace dynamic molecular additives, the rampant alkaline zincate byproducts at the anode interface are in situ converted to three-dimensional (3D) interconnected zinc deposition/stripping templates, while the solvation structure is effectively tailored to inhibit the overactivity of electrolyte. In situ Raman and molecular dynamics simulations verify that the Zn2+ flux during the electrochemical cycles is regulated in an orderly manner, hydrogen evolution reactions (HER) and dendrites zinc growth are effectively prevented. Zinc metal deposition/stripping is effectively confined to the 3D host space by solvation structure modulation and templates guidance, thus optimizing the crystallographic and zinc metal utilization rate during electrochemistry cycling. Even under extreme conditions, such as a high (dis)charge capacity of 10 mAh cm−2, symmetrical cells assembled based on a biphasic modulation strategy maintain long-term stability of over 1000 h.

Regulating solvation structure and enhancing anion-derived solid electrolyte interphase with N, N'-Dimethylpropyleneurea Co-solvent for long-term and dendrite-free Zn metal anodes

Aqueous zinc-ion batteries (ZIBs) are troubled by conventional weak acidic electrolyte, triggering undesirable side reactions and detestable dendrites, thus leading to low Coulombic efficiency (CE) and poor cycle stability. Herein, an organic solvent, N, N′- Dimethylpropyleneurea (DMPU), is introduced as an additive and co-solvent to achieve high-performance ZIBs. As a co-solvent, DMPU can coordinate with Zn2+to replace partial water (H2O) in solvation sheath and limit free H2O activity by H-bond interaction. As an additive, meanwhile, it possesses high Zn absorbability to form a stable inorganic/organic shielding layer for remodeling Zn surface, thus enhancing Zn2+ de-solvation kinetics and restraining unwanted reactions. Distinctly, DMPU regulates non-dendritic Zn plating/stripping behaviors, thus achieving a high CE of 99.3 % and a long cycling life of 2760 h (h) at 2 mA cm−2 and 2 mA h cm−2. The Zn//NaV3O8·1·5H2O (NVO) full cell with DMPU can operate stably for 5850 cycles with a retention of 80.6 % at 3 A g−1. This strategy represents a good point to choose organic co-solvent for practical high-performance ZIBs.

Geochemical Evidence of Water-Fluxed Crustal Melting in the Northern Colombian Andes

Abstract The compositions of crustal magmas are powerful tools for understanding the formation and differentiation of continents. However, the geochemical fingerprints that distinguish the two dominant mechanisms of crustal melting, namely dehydration and water-fluxed melting, are still controversial. To provide new insights into this problem, we discuss the petrogenesis of the Paipa Volcanic Complex (PVC), an isolated Quaternary volcanic field in the Colombian Eastern Cordillera. The PVC is characterized by peraluminous trondhjemite-like rhyolites with exceptionally high Na2O contents (~6 wt %), super-chondritic Nb/Ta (~27), elevated Sr/Y ratios (~120), spoon-shaped REE patterns, and enriched isotopic compositions that overlap with those of the local basement. They also exhibit high pre-eruptive H2O contents (~up to 9.5 wt %) and abundant Paleozoic zircon inheritances. We demonstrate that these characteristics are inconsistent with a process of intra-crustal differentiation from a mafic or intermediate mantle-derived precursor. Instead, we propose that the origin of the PVC is best explained by melting the local (meta)sedimentary basement under H2O-saturated conditions, at middle-crustal pressures (~1.3 GPa) and relatively low temperatures (~690–740°C), following the complete breakdown of plagioclase and biotite, and the formation of reactive peritectic amphibole. This scenario differs from the high-temperature dehydration melting conditions that have been widely proposed for the Andes and globally, which result in the production of water undersaturated magmas in equilibrium with anhydrous lithologies rich in plagioclase and/or garnet. Accordingly, we speculate that an external H2O flux was ultimately sourced from a buoyant, cold, and hydrated mantle wedge that was extensively metasomatized by fluids derived from the Nazca and Caribbean flat-slab fronts. These conditions depressed the asthenospheric mantle potential temperature, likely inhibiting mantle melting. In turn, they facilitated the infiltration and ascent of mantle-derived H2O through pre-existing crustal faults and shear zones. Our results indicate that water-fluxed melting could be a plausible mechanism for generating crustal magmas in orogenic regions where the availability of free H2O has been difficult to confirm.

Highly Reversible Zn Metal Anode Securing by Functional Electrolyte Modulation

AbstractThe stability of the Zn metal anode is significantly affected by the various parasitic reactions during plating/stripping. Here, sodium 4‐aminobenzenesulfonate (SABS) is a functional electrolyte additive to modulate the electrode/electrolyte interface to protect the Zn metal. An electrical double layer (EDL) reconstruction of the interface is affected by providing hydrogen bond sites through nitrogen and oxygen elements with lone pair electrons in SABS molecules. These strong hydrogen bonds not only limit the corrosion of free H2O molecules on the surface of Zn anode but also promote the desolvation process. Besides, the SABS can be further in situ decomposed into a solid electrode/electrolyte interface (SEI) layer to regulate the plating/stripping behavior of Zn2+. As a result, based on the synergism of organic–inorganic hybrid SEI layer and the EDL reconstruction, the Zn//Zn symmetric cells exceptionally survive lasting for 6500 hours at 1 mA cm−2 and 1 mAh cm−2, and over 900 cycles even at 40 mA cm−2 and 10 mAh cm−2. The Zn‐I2 full cell maintains excellent cycle stability of 92.4% after 20000 cycles. Remarkably, the pouch cell maintains a capacity retention of over 99.1% (63 mAh) for 820 cycles at 5 mA cm−2.

Improving the rate and cycle performance of V-based cathodes through regulation of the Zn2+ desolvation process

The large-scale application of vanadium in AZIBs has been hampered by its inferior rate performance and cycling stability, arising from the desolvation penalty of Zn2+ and the dissolution of vanadium. To address this issue, hydroxymethyl zinc phosphates Zn(O3PCH2OH) (ZnOPC) have been innovatively employed as a cathode electrolyte interphase (CEI) material to enhance the electrochemical performance of V2O5·nH2O (VO) cathode. The organized path structure of ZnOPC, coupled with its numerous hydroxyl groups, significantly reduces the desolvation penalty of Zn[H2O]62+ by forming new hydrogen bonds with the solvent-shell water molecules. More importantly, ZnOPC effectively mitigates vanadium dissolution by immobilizing free H2O which comes from the desolvation of Zn[H2O]62+. Consequently, the modified VO cathode exhibits superior rate performance and extraordinary cycling life, maintaining a specific capacity of 202.7 mAh/g after 7000 cycles at 10 A/g and 238.1 mAh/g at the high current of 20 A/g. These results offer a new prospect for designing high electrochemical performance vanadium-based cathode for AZIBs.

Achieving Highly Stable Zn Metal Anodes at Low Temperature via Regulating Electrolyte Solvation Structure.

Zinc metal is an attractive anode material for rechargeable aqueous Zn-ion batteries (ZIBs). However, the dendrite growth, water-induced parasitic reactions, and freezing problem of aqueous electrolyte at low temperatures are the major roadblocks that hinder the widely commercialization of ZIBs. Herein, tetrahydrofuran (THF) is proposed as the electrolyte additive to improve the reversibility and stability of Zn anode. Theoretical calculation and experimental results reveal that the introduction of THF into the aqueous electrolyte can optimize the solvation structure which can effectively alleviate the H2O-induced side reactions and protect the Zn anode from corrosion. Moreover, THF can act as a hydrogen bond acceptor to interact with H2O, which can greatly reduce the activity of free H2O in electrolytes and improve the low-temperature electrochemical performance of Zn anode. As a result, the Zn anodes demonstrate high cyclic stability for 2800h at 27°C and over 4000h at -10°C at 1.0mA cm-2 /1.0mAhcm-2. The full cell exhibits excellent cyclic stability and rate capability at 27 and -10°C. This work is expected to provide a new approach to regulate the aqueous electrolyte and Zn anode interface chemistry for highly stable and reversible Zn anodes.

The Construction of Anion-Induced Solvation Structures in Low-concentration Electrolyte for Stable Zinc Anodes.

Aqueous zinc-ion batteries (ZIBs) are promising large-scale energy storage devices because of their low cost and high safety. However, owing to the high activity of H2O molecules in electrolytes, hydrogen evolution reaction and side reactions usually take place on Zn anodes. Herein, additive-free PCA-Zn electrolyte with capacity of suppressing the activity of free and solvated H2O molecules was designed by selecting the cationophilic and solventophilic anions. In such electrolyte, contact ion-pairs and solvent-shared ion-pairs were achieved even at low concentration, where PCA- anions coordinate with Zn2+ and bond with solvated H2O molecules. Simultaneously, PCA- anions also induce the construction of H-bonds between free H2O molecules and them. Therefore, the activity of free and solvated H2O molecules is effectively restrained. Furthermore, since PCA- anions possess a strong affinity with metal Zn, they can also adsorb on Zn anode surface to protect Zn anode from the direct contact of H2O molecules, inhibiting the occurrence of water-triggered side reactions. As a result, plating/stripping behavior of Zn anodes is highly reversible and the coulombic efficiency can reach to 99.43 % in PCA-Zn electrolyte. To illustrate the feasibility of PCA-Zn electrolyte, the Zn||PANI full batteries were assembled based on PCA-Zn electrolyte and exhibited enhanced cycling performance.

Enhancing thermoelectric conversion efficiency of hydrogel-based supercapacitors by the three-dimensional ion channels hydration

Ionic thermoelectric (i-TE) supercapacitors are capable of converting low-grade heat directly into electricity, which has enormous potential for wearable power sources and the Internet of Things. However, the low thermoelectric conversion efficiency limits their applications. Here, we report a method for forming polar corona in a three-dimensional (3D) network based on chitosan-polyacrylamide‑silicon dioxide (PACS) hydrogel, significantly increasing the maximum thermogalvanic power density of 187.2 mW m−2 at a temperature difference (ΔT) of 5 K. The abundant functional groups on PACS confine free H2O molecules to the polymer network, forming polar corona, reducing the volume of thermally diffused ions, and enabling rapid conduction of lithium ions (Li+) in unsaturated coordination. In addition, demonstrating an impressive ionic conductivity of 50.2 mS cm−1 as well as a maximum thermal charging voltage of 200 mV (ΔT of 8 K), this work provides a new strategy for broadening applications of ionic thermally chargeable supercapacitors in harvesting low-grade heat and wearable devices.

Inorganic intumescing alkali silicate particles

New generation intumescent coatings apply self-intumescing particles to induce expansion in a controlled manner. Various studies have investigated alkali silicate-based coatings due to their inherent expansion with the release of H2O. The presented work investigated the self-intumescing concept of alkali silicates as particles. A thorough study of inorganic alkali silicate particles as potential intumescent ingredients in passive fire protection systems was carried out by applying HSDM, TGA, FTIR, XRD, and SEM. Herein, particles of lithium-, sodium-, and potassium silicates were synthesized with varying silica-to-alkali oxide molar ratios and curing humidity. Subsequently, the hydration chemistry and thermal behavior were examined. The results revealed increased expansion potential with decreasing SiO2/M2O molar ratio (M = Na, Li, or K) in the range 3.1–7.4 and increasing curing humidity in the range 35, 50, and 90% RH. Previous studies have emphasized the effect of solid-bound H2O to induce intumescence. In this study, the influence of the softening of the silicate matrix and H2O release is highlighted to allow increased expansion potential. Here, the coupling of thermal analysis with microscopy suggests an intumescence mechanism in the order of 1) initial shrinkage due to loss of free and physical bound H2O, 2) sphere formation to minimize surface energy, 3) expansion as a result of H2O evolution and viscoelastic melt formation, and 4) second shrinkage due to sintering before 5) melting. The sodium alkali silicate particles with a SiO2/M2O molar ratio of 3.4 exhibited a timely softening of the silicate matrix from about 155 °C to provide a distinct spherical particle followed by ionic H2O evolution. As a result, hereof, hollow, spherical particles with relative solid expansions of up to 550% were obtained and maintained until a second shrinkage at 650 °C with a subsequent melting at 950 °C. In comparison, the imbalance in viscoelastic melt formation and H2O release of lithium- and potassium silicate particles resulted in less expansion. Considering the expansion potential and thermal behavior of the alkali silicate particles, it is suggested as a possible, sustainable intumescence ingredient.

New types of open-framework vanadium borophosphates with photocatalytic properties.

The exploration of new open-framework polyoxometalates is very significant in structural chemistry and materials science. Herein, three new organic hybrid three-dimensional vanadium borophosphates (H3O)7(H2aeae)3{[Cd(H2O)3]2[H3O⊃(V2BP2O12)6]}·15H2O (1, aeae = 2-(2-aminoethylamino)ethanol) and (H3O)5(H2aeae)3{[TM(H2O)2.5(H2aeae)0.5]2[H3O⊃ (V2BP2O12)6]}·9H2O [TM = Mn(2), Co(3)] were hydrothermally prepared and structurally characterized. The three vanadium borophosphates contain similar 12-member ring crown-shaped clusters [(V2BP2O12)6]18- based on the linkage of six [V2O8] dimers and six [BP2O10] units. The [(V2BP2O12)6]18- cluster is further bridged by the unsaturated [Cd(H2O)3]2+ or [TM(H2O)2.5(H2aeae)0.5]3+ complexes to build new types of open-framework vanadium borophosphates with pores and cavities retained by the protonated H2aeae2+, H3O+ and free H2O. Surprisingly, the monodentate H2aeae2+ ligand coordinating with a metal center was observed in 2 and 3 for the first time as the aeae molecule acted as the trichelating ligand. Their optical absorption edges were determined to be in the range of 2.61-2.68 eV using solid-state UV-vis spectroscopy. 1-3 exhibited excellent photocatalytic activity towards methylene blue (MB) degradation under visible light irradiation, which presented the first example of organic hybrid open-framework vanadium borophosphates as the photo-catalysts for MB degradation.

3D self-assembled polar vs. non-polar NiO nanoparticles nanoengineered from turbostratic Ni3(OH)4(NO3)2 and ordered β-Ni(OH)2 intermediates.

A surfactant-free ammonia and carbamide precursor-modulated engineering of self-assembled flower-like 3D NiO nanostructures based on ordered β-Ni(OH)2 and turbostratic Ni3(OH)4(NO3)2 nanoplate-structured intermediates is reported. By employing complementary structural and spectroscopic techniques, fundamental insights into structural and chemical transformations from intermediates to NiO nanoparticles (NPs) are provided. FTIR, Raman and DSC analyses show that the transformation of intermediates to NiO NPs involves subsequent loss of NO3- and OH- species through a double-step phase transformation at 306 and 326 °C corresponding to the loss of free interlayer ions and H2O species, respectively, followed by the loss of chemically bonded OH- and NO3- ions. Transformation to NiO NPs via the ammonia route proceeds as single-phase transition, accompanied with a loss of OH- species at 298 °C. The full transformation to NiO NPs of both intermediates is achieved at 350 °C through annealing in the air atmosphere. Ammonia-derived NPs maintain nanoflower morphology by self-assembling into nanoplates, which is enabled by H2O-mediated adhesion on the NiO NPs' {100} neutral surfaces. Structural transformations of turbostratic Ni3(OH)4(NO3)2 nanoplates result in the formation of NiO NPs dominantly shaped by inert polar OH-terminated (111) atomic planes, leading to the loss of the initial self-assembled 3D structure. DFT calculations support these observations, confirming that H2O adsorbs dissociatively on polar {111} surfaces, while only physisorption is energetically feasible on {100} surfaces. NiO NPs obtained via two different routes have overall different properties: carbamide-derived NPs are 3 times larger (15.5 vs. 5.4 nm), possess a larger band gap (3.6 vs. 3.2 eV) and are more Ni deficient. The intensity ratio of surface optical (SO) modes to transversal and longitudinal optical modes is ∼40 times higher in the NiO NPs obtained from β-Ni(OH)2 compared to Ni3(OH)4(NO3)2-derived NPs. The SO phonon lifetime is an order of magnitude shorter in NiO obtained from β-Ni(OH)2, reflecting a much smaller NP size. The choice of a precursor defines the size, morphology, crystallographic surface orientations and band gap of the NiO NPs, with Ni deficiency providing pathways for utilizing them as p-type materials, allowing for the precise nanoengineering of polar and neutral surface-dominated NiO NPs, which is of exceptional importance for use in catalysis.

A common polar dye additive as corrosion inhibitor and leveling agent for stable aqueous zinc‐ion batteries

AbstractThe industrial application of zinc‐ion batteries is restricted by irrepressible dendrite growth and side reactions that resulted from the surface heterogeneity of the commercial zinc electrode and the thermodynamic spontaneous corrosion in a weakly acidic aqueous electrolyte. Herein, a common polar dye, Procion Red MX‐5b, with high polarity and asymmetric charge distribution is introduced into the zinc sulfate electrolyte, which can not only reconstruct the solvation configuration of Zn2+ and strengthen hydrogen bonding to reduce the reactivity of free H2O but also homogenize interfacial electric field by its preferentially absorption on the zinc surface. The symmetric cell can cycle with a lower voltage hysteresis (78.4 mV) for 1120 times at 5 mA cm−2 and Zn//NaV3O8·1.5H2O full cell can be cycled over 1000 times with high capacity (average 170 mAh g−1) at 4 A g−1 in the compound electrolyte. This study provides a new perspective for additive engineering strategies of aqueous zinc‐ion batteries.

A Urea Modified Ternary Aqueous Electrolyte with Tuned Intermolecular Interactions and Confined Water Activity for Highly Stable Zinc-Ion Batteries

Aqueous zinc-ion batteries (ZIBs) have gained attention as potential energy storage devices due to their high safety.1 However, the narrow electrochemical window and unfavorable side reactions (i.e., hydrogen and oxygen evolution reactions) induced by water decomposition restrict their development.2,3 Thus, constraining water activity is necessary to enhance stability and enlarge electrochemical window. In this study, we prepare a 2.9 m (mol kgsolvent −1) Zn(ClO4)2−CO(NH2)2−H2O ternary aqueous electrolyte with restricted water activity at room temperature. Raman, Fourier transform infrared (FTIR), and nuclear magnetic resonance (NMR) characterization techniques suggest strong intermolecular interactions between CO(NH2)2 and H2O, which decrease the free H2O molecules and reduce their associated activity to suppress the parasitic reactions at the electrodes. Density functional theory (DFT) calculations substantiate the strong hydrogen bonds between urea and water. Compared with eutectic electrolyte and water-in-salt electrolyte, this aqueous electrolyte exhibits a high ionic conductivity (6.83 mS cm−1) as conventional aqueous electrolytes without sacrificing the voltage window (2.5 V). Furthermore, DFT computations reveal the preferential adsorption of urea molecules onto the zinc surface, mediating zinc deposition process. The reduction of urea generates a robust organic solid electrolyte interphase (SEI), promoting homogeneous zinc deposition on the anode and hindering parasitic reactions. Consequently, this ternary aqueous electrolyte not only imparts Zn/Zn symmetric cells with prolonged cycling stability exceeding 1000 h at various current densities but also endows zinc−vanadium batteries a capacity of 250 mAh g−1 for 400 cycles at 1 A g−1. This finding highlights a promising approach for the development of stable aqueous zinc-ion batteries with an expanded electrochemical window.Reference A. Konarov et al. ACS Energy Letters 2018, 3 (10), 2620–2640.C. Li et al. Joule 2022, 6 (8), 1733–1738.J. Zhou et al. Advanced Materials 2021, 33 (33), 2101649. Figure 1

Perspective on the interfacial engineering for electrocatalytic N2 to NH3 conversion from catalysts to systems

AbstractAmmonia (NH3) has received significant attention due to its increasing demand as a key commodity for industrial chemical production, a green fuel, and a hydrogen (H2) carrier. Electrochemical nitrogen (N2) reduction reaction (ENRR) emerges as the most attractive pathway to produce NH3. The process utilizes H2O as a proton source under mild temperature and pressure, which can reduce CO2 emissions and energy input compared to the traditional Haber‐Bosch process. However, ENRR is severely insufficient for practical applications due to its kinetically sluggish steps compared to its competitive hydrogen evolution reaction. Also, the imbalanced reactant concentrations of N2 and H2O, resulting from the low N2 solubility, and oppositely, free H2O accessibility toward catalysts, cause the ineffective three‐phase‐boundary that acts as active sites for ENRR. To overcome these challenges, it is essential to perform interfacial engineering for each part of the catalyst and reaction environment. In this perspective, recent advances in interfacial engineering are examined and critically reviewed, and further research directions are proposed to develop ENRR significantly. The sections cover catalytic active site modification, hydrophobic/hydrophilic control, electrolyte engineering, and system design. The insights and prospects in this perspective will be effective for developing ENRR in a scientific and practical manner.