Zn Substrate Research Articles

Improved the deposition rate of polydopamine on the biodegradable pure Zn via ZnO coating for cardiovascular stent application

Metal zinc due to its rapid degradation rate and good absorption in the body is suitable for the clinical requirements of cardiovascular stents. Biomimetic polydopamine (PDA) as a high-efficient surface coating can adhere to Zn substrate tightly, improving the biocompatibility of zinc biodegradable cardiovascular sent. However, traditional PDA deposition method requires accurate pH and long immersion time, resulting in a low growth rate of coating. Herein, ZnO layers coat on the Zn surface, which produces the transition from the valence band to conduction band under UV irridation (UVZnO). Forming of photo-induced electron-hole (e−-h+) pair generates transfer energy, which can catalyze H2O and O2 to produce active oxygen species (ROS). The abundant ROS accelerates the deposition of PDA on Zn substrate, which shortens the polymerization time to 30 min at pH 8.5. The polymerization rate of PDA increases about two orders of magnitude. ZnO nano-layer can control the release of Zn2+ ions, which enhances endothelial cells (ECs) proliferation. It is promising to improve the re-endothelialization and avoid re-stenosis in sent and neointimal hyperplasia. In addition, the UVZnO/PDA/PLGA layer increases the corrosion resistance of Zn substrate after long-term immersion. The Zn/UVZnO/PDA/PLGA is promising for the treatment of cardiovascular diseases.

Mass-producible in-situ amorphous solid/electrolyte interface with high ionic conductivity for long-cycling aqueous Zn-ion batteries

Although aqueous Zn-ion batteries (aZIBs) have garnered significant attention, they are yet to be commercialized due to severe corrosion and dendrite growth on Zn anodes. In this work, an artificial solid-electrolyte interface (SEI) with amorphous structure was created in-situ on the anode by immersing Zn foil in ethylene diamine tetra(methylene phosphonic acid) sodium (EDTMPNA5) liquid. This facile and effective method provides the possibility for Zn anode protection in large-scale applications. Experimental results, combined with theoretical calculations, indicate that the artificial SEI remains intact and adheres tightly to the Zn substrate. The negatively-charged phosphonic acid groups and disordered inner structure offer adequate sites for rapid Zn2+ transference and facilitate [Zn(H2O)6]2+ desolvation during charging/discharging. Due to the synergistic effect of the aforementioned advantages, the artificial SEI endows high Coulombic efficiency (CE, 99.75%) and smooth Zn deposition/stripping under the SEI. The symmetric cell exhibits a long cycling life of over 2400 h with low-voltage hysteresis. Additionally, full cells with MVO cathodes demonstrate the superiority of the modified anodes. This work provides insight into the design of in-situ artificial SEI on the Zn anode and self-discharge suppression to expedite the practical application of aZIBs.

Hydrated Eutectic Electrolytes Stabilizing Quasi-Underpotential Mg Plating/Stripping for High-Voltage Mg Batteries.

Aqueous rechargeable Mg batteries (ARMBs) usually fail from severe anode passivation, alternatively, executing quasi-underpotential Mg plating/stripping chemistry (UPMC) on a proper heterogeneous metal substrate is a crucial remedy. Herein, a stable UPMC on Zn substrate is initially achieved in new hydrated eutectic electrolytes (HEEs), delivering an ultralow UPMC overpotential and high energy/voltage plateau of ARMBs. The unique eutectic property remarkably expands the lower limit of electrochemical stability window (ESW) of HEEs and undermines the competition between hydrogen evolution/corrosion reactions and UPMC, enabling a reversible UPMC. The UPMC is carefully revealed by multiple characterizations, which shows a low overpotential of 50 mV at 0.1 mA cm-2 over 550 h. With sulfonic acid-doped polyaniline (SPANI) cathodes, UPMC-based full cells show high energy/power densities of 168.6 Wh kg-1 /2.1 kWh kg-1 and voltage plateau of 1.3 V, far overwhelming conventional aqueous systems.

Hydrated Eutectic Electrolytes Stabilizing Quasi‐Underpotential Mg Plating/Stripping for High‐Voltage Mg Batteries

AbstractAqueous rechargeable Mg batteries (ARMBs) usually fail from severe anode passivation, alternatively, executing quasi‐underpotential Mg plating/stripping chemistry (UPMC) on a proper heterogeneous metal substrate is a crucial remedy. Herein, a stable UPMC on Zn substrate is initially achieved in new hydrated eutectic electrolytes (HEEs), delivering an ultralow UPMC overpotential and high energy/voltage plateau of ARMBs. The unique eutectic property remarkably expands the lower limit of electrochemical stability window (ESW) of HEEs and undermines the competition between hydrogen evolution/corrosion reactions and UPMC, enabling a reversible UPMC. The UPMC is carefully revealed by multiple characterizations, which shows a low overpotential of 50 mV at 0.1 mA cm−2 over 550 h. With sulfonic acid‐doped polyaniline (SPANI) cathodes, UPMC‐based full cells show high energy/power densities of 168.6 Wh kg−1/2.1 kWh kg−1 and voltage plateau of 1.3 V, far overwhelming conventional aqueous systems.

Oxygen Adsorption on Polar and Non-Polar Zn:ZnO Heterostructures from First Principles.

Zn:ZnO nanostructures have been studied extensively due to their potential use in many applications, such as oxygen scavengers for food packaging applications. Under atmospheric conditions, ZnO grows on the surface of Zn via an oxidation process. The mechanisms governing Zn oxidation are still not fully understood, with classical oxidation models, such as the Cabrera Mott, underestimating the oxide thickness of Zn:ZnO core-shell structures. In this work, Ab initio DFT calculations were performed to assess the adsorption properties of oxygen molecules on Zn:ZnO heterostructures to help elucidate the mechanisms involved in the growth of a ZnO film on a Zn substrate. Results suggest that the charge transfer mechanism from the Zn:ZnO heterostructures to the adsorbed oxygen layer can be promoted by two different processes: the electronic doping of ZnO due to the formation of the Zn:ZnO interface and the excess surface charge due to the presence of dangling bonds on the as cleaved ZnO.

Regulation of Released Alkali from Gel Polymer Electrolyte in Quasi-Solid State Zn-Air Battery.

Gel polymer electrolyte (GPE) in quasi-solid state Zn-air battery (QSZAB) will release alkali during cycling, resulting in gradual dehydration of GPE, corrosion of Zn electrode, Zn dendrites growth, and therefore inferior performance. Here, hollow Sn microspheres are prepared on Zn substrate by the technique of colloidal self-assembly. The inner surfaces of hollow Sn microspheres are modified by 2-hydroxypropyl-β-cyclodextrin (hollow Sn-inner HPβCD) to regulate the released alkali at GPE|anode interface. The hollow Sn-inner HPβCD can lessen the leakage of released alkali, make stored alkali diffuse back to GPE during the charging process, and mitigate the loss of soluble Zn(OH)4 2- to suppress Zn dendrites growth. Resultantly, GPE in QSZAB with hollow Sn-inner HPβCD exhibits a high retention capacity for alkaline solution. The cell also exhibits a long cyclic lifespan of 127h due to the effective regulation of released alkali, which outperforms QSZAB without hollow Sn-inner HPβCD by 7.94 times. This work rivets the regulation of released alkali at GPE|anode interface, providing new insight to improve QSZABs' performance.

An Ion-Sieving Janus Separator toward Planar Electrodeposition for Deeply Rechargeable Zn-Metal Anodes.

The irregular and random electrodeposition of zinc has emerged as a non-negligible barrier for deeply rechargeable aqueous zinc (Zn)-ion batteries (AZIBs), yet traditional texture regulation of the Zn substrate cannot continuously induce uniform Zn deposition. Here, a Janus separator is constructed via parallelly grown graphene sheets modified with sulfonic cellulose on one side of the commercial glass fiber separator through the spin-coating technique. The Janus separator can consistently regulate Zn growth toward a locked crystallographic orientation of Zn(002) texture to intercept dendrites. Furthermore, the separator can spontaneously repel SO4 2- and anchor H+ while allowing effective transport of Zn2+ to alleviate side reactions. Accordingly, the Zn symmetric cell harvests a long-term lifespan over 1400h at 10mA cm-2 /10 mAh cm-2 and endures stable cycling over 220h even at a high depth of discharge (DOD) of 56%. The Zn/carbon nanotube (CNT)-MnO2 cell achieves an outstanding capacity retention of 95% at 1 A g-1 after 1900 cycles. Furthermore, the Zn/NH4 V4 O10 pouch cell with a Janus separator delivers an initial capacity of 178 mAh g-1 and a high capacity retention of 87.4% after 260 cycles. This work provides a continuous regulation approach to achieve crystallographic homogeneity of the Zn anode, which can be suitable for other metal batteries.

An efficient approach to endow TiNbTaZr implant with osteogenic differentiation and antibacterial activity in vitro

Osteogenic differentiation and antibacterial property are two-core requirements for bone implants, but typically they are not compatible. Zinc (Zn) as a common bioactive material is widely used in the medical field. A balance between antibacterial and osteogenic activity can be achieved at appropriate Zn concentration. In this study, the TNTZ/Zn micro/nano-composites were prepared by doping Zn nanoparticles onto Ti-35Nb-2Ta-3Zr (TNTZ) surface through the friction stir processing (FSP) technique. The results of material characterization revealed the homogeneous distribution of Zn, the presence of α″ martensite, and the increase in microhardness in the stir zone. Due to the solid metallurgical bonding between Zn NPs and substrate, Zn ions were released slowly and may be biologically responsive through body fluid corrosion. In terms of biological activity, the expression of adhesion-related protein vinculin and osteogenic differentiation genes were up-regulated by TNTZ/Zn, which improved the early adhesion and osteogenic differentiation of bone marrow stromal stem cells. Besides, TNTZ/Zn presented excellent antibacterial properties, and direct contact with the fine grain surface containing Zn NPs may be the dominant mechanism. TNTZ/Zn micro/nano-composites have excellent mechanical properties, osteogenic differentiation and antibacterial properties, providing an efficient strategy for titanium alloy surface modification and showing tremendous potential in dental applications.

Solid-Solution-Based Metal Coating Enables Highly Reversible, Dendrite-Free Aluminum Anode

Aluminum-ion batteries have attracted great interest in the grid-scale energy storage field due to their good safety, low cost and the high abundance of Al. However, Al anodes suffer from severe dendrite growth, especially at high deposition rates. Here, we report a simple strategy for constructing a highly reversible, dendrite-free, Al-based anode through directly introducing a solid-solution-based metal coating to a Zn foil substrate. Compared with Cu foil substrates and bare Al, a Zn foil substrate shows a lower nucleation barrier of Al deposition due to the intrinsic, definite solubility between Al and Zn. During Al deposition, a thin, solid-solution alloy phase is first formed on the surface of the Zn foil substrate and then guides the parallel growth of flake-like Al on Zn substrate. The well-designed, Zn-coated Al (Zn@Al) anode can effectively inhibit dendrite growth and alleviate the corrosion of the Al anode. The fabricated Zn@Al–graphite battery exhibits a high specific capacity of 80 mAh·g−1 and an ultra-long lifespan over 10,000 cycles at a high current density of 20 A·g−1 in low-cost molten salt electrolyte. This work opens a new avenue for the development of stable Al anodes and can provide insights for other metal anode protection.

Osteogenic and angiogenic bioactive collagen entrapped calcium/zinc phosphates coating on biodegradable Zn for orthopedic implant applications.

Zinc is becoming one of the leading candidate materials for biodegradable orthopedic implants owing to its attractive properties in terms of degradation behavior and mechanical properties. However, the insufficient surface bio-activities postpone its clinical application. In this study, an organic-inorganic collagen entrapped calcium/zinc phosphates coating was constructed on Zn surface to lessen Zn2+ releasing rate and to leverage the surface osteogenic and angiogenic properties. Collagen molecules were immobilized onto Zn substrate and subsequently coordinated with calcium and zinc ions to promote the CaZnP inorganic phase growth, ensuing an intertwined collagen-CaZnP hybrid system. Consequently, the hybrid coating was highly coalesced and compact. Such high quality warranted the contained Zn2+ releasing in a tolerable rate favorable for cells viability. The collagen-CaZnP coated Zn showed remarkedly stronger osteogenicity as compared to the untreated Zn, ascertained by the MC3T3-E1 osteoblast cell proliferation and differentiation assays, such as alkaline phosphatase expression and calcium nodule formation results. In addition, this hybrid coating supported human umbilical vein endothelial cells (HUVECs) migration and tube formation. The enhanced osteogenic and angiogenic properties could be ascribed to the nature of collagen and calcium/zinc phosphate components, the hybrid micro/nano-structure as well as the ability of controlling the Zn2+ release of Zn substrate into a suitable concentration range. Our strategy provides a new avenue to surface modification of biodegradable metals for bone regenerative perspective.

An accurate and general local electronic structural descriptor for oxygen reduction on metal surface alloys: Potential of breaking scaling relationship and application to PtZn ones with superior activity

Metal alloys and metal surface alloys are important ways to improve oxygen reduction activity and reduce economic costs. Due to the decline of symmetry of alloys, prediction of surface catalytic site activity by traditional structural and electronic descriptors faces a great challenge. Thus, it is important and urgent to develop a suitable and general descriptor to quickly identify the catalytic activity of surface sites for designing novel alloy catalysts and improving the computational efficiency. Herein, oxygen reduction on PtZn surface alloys with Zn substrate is selected as an example to search for suitable descriptors and high ORR activity materials. A local electronic structural descriptor for surface alloys, which includes charge states of the active sites and the nearby sites is developed. In addition, the contribution of each part of charge states to the adsorption intensity can be clearly known according to the descriptor. Comparing with traditional descriptors, this descriptor exhibits superior accuracy in predicting the binding strength of *OH and *OOH and ORR activity of PtZn surface alloys. Accordingly, the ORR activity of PtZn surface alloys at different Zn concentrations in sublayer (Pt@Pt1−xZnx@), are systematically examined. Both DFT and descriptor predication prove its high ORR activity in a large range of Zn concentrations: Pt@Pt1-xZnx@ shows better or comparable activity than Pt(111) at x = 1/9 ∼ 4/9, or 5/9 ∼ 7/9, respectively, and the corresponding calculated exchange current rate constants are 0.84 ∼ 7.69, 0.10 ∼ 0.60 mA cm−2, respectively. Combining with their stability verified by formation energy, vacancy formation energy, segregation energy and AIMD, the PtZn surface alloy will be a promising ORR catalyst. Furthermore, our proposed descriptor also indicates the broken of scale relationship for ORR, implying possible extremely high ORR activity in other metal alloys and its popularity application.

Enhanced corrosion resistance and cytocompatibility of zinc by Zn-Al layered double hydroxide films

Zinc (Zn) is promising candidate to construct biodegradable medical devices. However, the poor corrosion resistance limits its clinical application. Herein, Zn-Al layered double hydroxide (LDH) films were constructed. Results showed that Zn-Al LDHs films could effectively enhance the anti-corrosion ability and biocompatibility of the Zn substrate, which provided new insights in the surface modification of Zn.

Hydrophobic Electrode Design for CO2 Electroreduction in a Microchannel Reactor.

Microchannel reactor is a novel electrochemical device to intensify CO2 mass transfer with large interfacial areas. However, if the catalyst inserted in the microchannel is wetted, CO2 is required to diffuse across the liquid film to get access to reaction sites. In this paper, a hydrophobic polytetrafluoroethylene (PTFE)-doped Ag nanocatalyst on a Zn rod was synthesized through a facile galvanic replacement of 2Ag++Zn → 2Ag + Zn2+. The catalyst layer, which was PTFE incorporated into the Ag matrix, was detected to distribute uniformly on the Zn substrate with a thickness of 77 μm. Consequently, the PTFE-doped electrode demonstrated enhanced activity with an optimal 96.19% CO faradaic efficiency (FECO) in the microchannel reactor. Typically, the catalyst could maintain over 90% FECO even at the current density of 24 mA cm-2, which was nearly 30% higher than that of a similar catalyst without PTFE. In addition, influences of the concentration of PTFE and deposition time were also investigated, determining that 1 vol % of PTFE and 30 min of coating yielded best electrocatalytic efficiency. To achieve a further breakthrough of CO2 mass transfer limitations, reactions were applied under relatively high pressures (3-15 bar) in a single-compartment high-pressure cell. The maximum CO partial current density (jCO) can reach 106.76 mA cm-2 at 9 bar.

In-situ grown porous protective layers with high binding strength for stable Zn anodes

Zinc (Zn) metal is a promising anode material for aqueous batteries. Unfortunately, undesirable issues such as dendrite growth, intricate side reactions, and limited reversibility restrict its large-scale applications. Herein, a porous ZIF-8 protecting layer is in-situ constructed on the Zn surface (named as Zn@ZIF8) to effectively manipulate the Zn plating/stripping behavior. The in-situformation of porous ZIF-8 layer not only shows excellent bonding strength with Zn substrate but also affords low nucleation overpotential and uniform Zn2+ electrolyte flux and reduces intricate side reactions, thus leading to homogeneous Zn plating/stripping behavior. These merits enable substantially stable symmetric Zn cells and Zn-based electrochemical energy storage devices. In detail, the Zn ion capacitor based on Zn@ZIF8 anodes demonstrates superior cycling stability (∼100% capacity retention after 20 000 cycles), much better than those with bare Zn anodes. This work presents a facile and effective approach for manipulating Zn dendrites growth and realizing ultra-stable Zn-based batteries.

Corrosion and Biocompatibility of Pure Zn with a Micro-Arc-Oxidized Layer Coated with Calcium Phosphate

Recent studies have indicated a great demand to optimize the biocompatibility properties of pure Zn as an implant material. For this purpose, CaZn2(PO4)2·2H2O (CaZnP) was prepared using hydrothermal treatment (HT) combined with micro-arc oxidation (MAO) on pure Zn substrate to generate biodegradable implants. The polarization test and electrochemical impedance spectroscopy indicated that the MAO1−HT coating could modulate the corrosion behavior of MAO1 by filling the crevice between the coating and the substrate. Immersion test evaluation revealed that the osteogenic properties of MAO1−HT coating were better than that of pure Zn substrate, as evidenced by the molar ratio of Ca and P, which increased after soaking in simulated body fluid (SBF) for up to 10 days. In addition, L-929 cells cultured in the 100%, 50%, and 25% extracts of MAO1−HT coated samples exhibited excellent cytocompatibility. Meanwhile, cell adhesion was promoted on the surface with high roughness generated during MAO and HT processes. In summary, the calcified coatings improved biocompatibility and adjusted the degradation rates of pure Zn, broadening the application of Zn alloys.

Stacked Lamellar Matrix Enabling Regulated Deposition and Superior Thermo‐Kinetics for Advanced Aqueous Zn‐Ion System under Practical Conditions

AbstractZinc anodes have attracted widespread attention for their intrinsic safety, low cost, and abundant resources, but still suffer from severe irreversibility due to spontaneous corrosion and nonplanar dendrite formation in aqueous electrolytes. In this work, a 3D stacked lamellar matrix (SLM) composed of ZnF2/Zn3(PO4)2/CFX is elaborately designed on a Zn substrate via simple chemical/electrochemical reactions, delivering enhanced thermodynamic stability and rapid zinc ions transport kinetics. The abundant ion conduction channels in SLM could also redistribute Zn2+ ions flux and further suppress the dendrite growth. With these synergetic effects, the SLM‐Zn anodes enable exceptional performance, including a high depth of discharge (90%) in a Zn|Zn symmetrical cell for 187 h, steady charge/discharge process (94.1% retention of SLM‐Zn|MnO2 full cell for 1000 cycles at a harsh rate of 15 C), and low negative/positive capacity ratio (≈3.3) in SLM‐Zn|AC hybrid supercapacitor with limited Zn anode (10 µm) and high‐load cathode (≈1.77 mA h cm−2), which greatly promotes the application of aqueous Zn‐ion energy system under practical conditions.

Effect of Ni-interlayer on zinc-assisted liquid-metal-induced-embrittlement susceptibility of 22MnB5 galvanized steel

In this study, in-situ heat treatment and high-temperature tensile tests were performed to investigate the effect of an Ni-interlayer on the zinc-assisted liquid-metal-induced-embrittlement (LMIE) susceptibility of 22MnB5 galvanized steel. The heat treatment results indicated that the Ni-interlayer delays the diffusion between liquid Zn and steel substrate, and it can modify the phase composition of the coating. The high-temperature tensile test results showed that the strength and ductility of the 22MnB5 galvanized steel increased as the Ni-electroplating time increased, indicating that the Ni-interlayer could improve the strength and ductility of the 22MnB5 galvanized steel. The fracture type of the galvanized steel was brittle, while that of the Ni-interlayer galvanized steel was ductile, additionally, a U-shaped crack extending to the steel substrate was observed near the fracture of the galvanized steel, whereas no cracks extending to the steel substrate were observed near the fracture of the Ni-interlayer galvanized steel. In general, the Ni-interlayer can reduce the susceptibility of zinc-assisted LMIE; moreover, when the Ni layer was electrodeposited for 8 min, the property of the Ni-interlayer galvanized steel was found to be comparable to those of bare steel.

Influence of bovine serum albumin on biodegradation behavior of pure Zn.

Zinc is emerging as a promising biodegradable metal for temporary implant applications. In this work, we investigate the influence of bovine serum albumin (BSA)-the most abundant blood protein in simulated body fluid (SBF) on degradation of pure Zn via electrochemical measurements and long-term immersion. Electrochemical experiments indicate a decrease of the corrosion rate of bare Zn with increasing BSA concentration in solution for short-term exposures. Samples were characterized with scanning electron microscope (SEM) (including energy dispersive spectroscopy [EDS], X-ray photoelectron spectroscopy [XPS], Fourier transform infrared spectroscopy [FTIR], and time-of-flight secondary ion mass spectrometry [TOF-SIMS]) after immersion up to 21 days. Presence of BSA in the electrolyte, decrease the amount of Ca-phosphate precipitation on Zn surface. However, a more compact surface layer formed in the presence of BSA in solution. Most noteworthy, in long-term exposures, BSA enhances localized corrosion of Zn-such detrimental localized attack was not observed in BSA-free solution. We suggest that a sealed space forming between the Zn substrate and a protein adsorption layer restricts mass transport, thus triggering localized corrosion of Zn.

Corrosion Behavior and Biocompatibility of Diamond-like Carbon-Coated Zinc: An In Vitro Study.

Owing to the desirable degradation rate and good biocompatibility, zinc (Zn) and Zn alloys are promising biodegradable implant metals in orthopedic and cardiovascular applications. Surface modification, such as deposition of coatings, is frequently implemented to further enhance their biological properties. In this study, diamond-like carbon (DLC) films are deposited on Zn by magnetron sputtering. The DLC films do not change the surface morphology of Zn but alter the hydrophobic properties with a contact angle of approximately 90°. Electrochemical and in vitro immersion tests reveal that the corrosion resistances of the DLC-coated Zn decrease unexpectedly, which is possibly due to galvanic corrosion between the DLC film and Zn substrate. Furthermore, the uncoated and coated Zn samples show hemolysis ratios less than 1%. The cells cultured in the Zn extract exhibit higher viability than those cultured in the extract of the DLC-coated Zn, suggesting that the DLC films decrease the cytocompatibility of Zn. The lower corrosion resistance has little influence on the hemolysis ratio, suggesting that hemolysis is not an obstacle for the design of Zn-based biomaterials. Our results show that the traditional concept of protection with DLC films may not be applicable universally and decreased corrosion resistance and cytocompatibility are actually observed in DLC-coated Zn.

Early electrochemical characteristics and corrosion behaviors of pure zinc in simulated body fluid

• QCM technique was used to monitor the early mass change of Zn in SBF. • Pitting and preferential dissolution occurred along grain boundaries. • Localized corrosion and the corrosion rate were affected by CPF. The demand for zinc (Zn) in medical applications is continuously increasing, due to its excellent biodegradation performance; however, the early electrochemical characteristics and early corrosion behaviors of pure Zn remains unclear. In this study, pure Zn in simulated body fluid (SBF) was investigated via electrochemical measurement and quartz crystal microbalance (QCM) measurement. The results indicated that the corrosion resistance of pure Zn sharply decreased during the early 8 h of immersion and then gradually stabilized as the immersion time increased. According to the corrosion morphologies of Zn after different immersion times, the Zn substrate showed preferential dissolution along the grain boundary and pitting corrosion characteristic. Moreover, the corrosion products formed on the surface affected the electrochemical reaction and corrosion process of pure Zn, which significantly promoted the localized corrosion and electrochemical corrosion rate.