ZnCl2 Solution Research Articles

Comparison of acidic leaching using a conventional and ultrasound-assisted method for preparation of magnetic-activated biochar

Four magnetic biochars (MBs) were prepared from two mixtures of Sappeli sawdust with NiCl2 solution or Sappeli sawdust with NiCl2 plus ZnCl2 solutions. These mixtures formed two pastes that were dried and further pyrolyzed at 700 °C under nitrogen flow. The pyrolyzed material was leached out with 0.1 M HCl under conventional reflux (AL- 80 °C, 2 h) or assisted by ultrasound-leaching (US- 15 min, 600 W), obtaining four biochars: SNiAL, SNiUS, SNiZnAL, SNiZnUS. The biochars were characterized by VSM, XRD, FTIR, isotherms of adsorption and desorption of nitrogen, pHpzc, hydrophobically characteristics (HI), TGA, elemental analysis (CHN/O). The data show that using the leaching process assisted by ultrasound can obtain biochars that present good magnetization saturation, with a lower leaching time than conventional leaching. The four biochar were tested as adsorbents to remove ten emerging contaminants and four dyes of aqueous effluents. It was observed that the impregnation of zinc chloride in the samples led to an increase in the surface areas of the magnetic biochars, which influenced the most of sorption capacities of the adsorbents for the different sorbing species. Making a ratio of sorption capacities of SNiAL/SNiZnAL and SNiUS/SNiZnUS, it was obtained the values, respectively, of 0.9761, and 0.9710 (Acid Red 1), 2.057, and 3.030 (Reactive Blue 4), 4.192, and 1.971 (Basic Violet 3), 3.359, and 1.129 (Basic Green 1), 1.673, and 1.835 (Paracetamol), 3.612, and 3.779 (Propranolol), 5.871, and 5.171 (Sodium Diclofenac), 1.457, and 1.607 (Nicotinamide), 1.094 and 1.093 (Caffeine), 1.167, and 2.398 (4-chloroaniline), 1.009 and 0.9965 (2-nitrophenol), 1.156 and 1.341 (Resorcinol), 1.299 and 1.331 (Hydroquinone), 0.9975 and 1.019 (4-bromophenol).

A Highly Electroactive Poly(aniline-co-thionine) for Rechargeable Zinc Batteries

A novel conductive polymer poly(aniline-co-thionine) (PANTHI) was prepared via electrochemical polymerization by introducing redox-active thionine into the polyaniline skeleton to extend its cable length, and then explored as a cathode active material for aqueous zinc-polymer batteries in a mixed solution of ZnCl2 and NH4Cl. Due to that thionine is a phenothiazine derivative without methyl groups, it increases the degree of conjugation of copolymer chains and the Zn-copolymer battery exhibits greatly enhanced discharge specific capacity, energy density, and excellent cycle stability at pH 4.8, compared to Zn-polyaniline batteries. The Zn-PANTHI battery delivers a high specific capacity and energy density of 157.8 Ah kg−1 and 173.6 Wh kg−1, respectively, and retains the coulomb efficiency of about 95.3% over 200 consecutive cycles at a current density of 200 mA g−1. The copolymerization strategy provided an effective method towards synthesizing new conductive aniline-based polymers with other organic redox-active groups for rechargeable batteries, supercapacitors and sensors.

Improved osteogenesis in rat femur segmental defects treated with human allograft and zinc adjuvants.

Bone allograft is widely used to treat large bone defects or complex fractures. However, processing methods can significantly compromise allograft osteogenic activity. Adjuvants that can restore the osteogenic activity of processed allograft should improve clinical outcomes. In this study, zinc was tested as an adjuvant to increase the osteogenic activity of human allograft in a Rag2 null rat femoral defect model. Femoral defects were treated with human demineralized bone matrix (DBM) mixed with carboxy methyl cellulose containing ZnCl2 (0, 75, 150, 300 µg) or Zn stearate (347 µg). Rat femur defects treated with DBM-ZnCl2 (75 µg) and DBM-Zn stearate (347 µg) showed increased calcified tissue in the defect site compared to DBM alone. Radiograph scoring and µCT (microcomputed tomography) analysis showed an increased amount of bone formation at the defects treated with DBM-Zn stearate. Use of zinc as an adjuvant was also tested using human cancellous bone chips. The bone chips were soaked in ZnCl2 solutions before being added to defect sites. Zn adsorbed onto the chips in a time- and concentration-dependent manner. Rat femur defects treated with Zn-bound bone chips had more new bone in the defects based on µCT and histomorphometric analyses. The results indicate that zinc supplementation of human bone allograft improves allograft osteogenic activity in the rat femur defect model.

Sphalerite‐galena replacement in sodium chloride solution: A thermodynamic approach

AbstractConsidering the material balances of the constituents including solid phases, replacement reaction of the sphalerite‐galena pair in chloride solution is examined quantitatively under equilibrium conditions of 250°C, water saturation vapor pressure, and initial Cl concentration of 1 mol/L. NaCl+PbCl2 solution with solid sphalerite, dissolves and releases both total Zn and total S of 1.26 × 10−5 mol/L into the solution under without or lower PbCl2 concentration. If the PbCl2 concentration is higher than 1.32 × 10−6 mol/L, precipitation of galena as replacement occurs, suggesting that sphalerite has an ability to trap a lower concentration of Pb. If PbCl2 concentration of the solution is higher than 1.32 × 10−6 mol/L, the majority of Pb deposited as galena with using sulfur originated from solid sphalerite dissolved, and the amount of Zn from sphalerite equivalent to the amount of galena deposited releases into the solution. On the other hand, NaCl+ZnCl2 solution with solid galena under the same environmental conditions, dissolves and releases both total Pb and total S of 6.43 × 10−6 mol/L into the solution under without or lower ZnCl2 concentration. Over the ZnCl2 concentration of 6.40 × 10−5 mol/L in the solution, precipitation of sphalerite occurs, indicating that galena cannot trap a low concentration of Zn. Zinc would drain away from the hydrothermal depositional environment under the presence of only galena. These relationships are controlled mainly by the reaction of predominant metal chloride or metal hydroxide species in the solution. Sphalerite is a good scavenger for Pb, but galena is not for Zn.

Cellulose-based hydrogel beads: Preparation and characterization

Biopolymer-based hydrogel beads possessing intrinsic low-toxicity, biocompatibility and biodegradability have gained widespread utility in several applications. Among the biopolymers, cellulose is one of the most abundant renewable biomaterials. Herein cellulose hydrogel beads have been prepared by dissolving cellulose in 68% ZnCl2 solution and then crosslinking the polymer chains through calcium ions. The water and ethanol washing of the beads profoundly influences the beads architecture as characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray powder diffraction and Scanning electron microscopy. The total crystallinity index of the beads increases with the amount of calcium ions that is further enhanced by water washing. These beads, possessing a layer-like nanoporous structure, are capable of loading bovine serum albumin (BSA) and releasing in a sustained manner. The outcome promises a large-scale production of cellulose beads having the potential to be eco-friendly and inexpensive delivery carriers in food, pharmaceutical, medical and agriculture applications.

Fluorammonium method of titanium slag processing

Titanium dioxide is the most common titanium-containing product on the world market, and the demand for it is increasing. The global consumption of TiO2 is 7 – 7.5 million tons annually. Titanium dioxide is mainly obtained from ilmenite and rutile concentrates. The largest producers are China, USA, Germany, UK, Mexico, and Saudi Arabia. In addition to the natural resources of titan, there are man-made sources. This type of resource includes titanium-containing slags obtained as a result of pyrometallurgical processing of ores and concentrates containing titanium dioxide. These slags, in addition to titanium dioxide, contain silicon in the form of dioxide, silicates or aluminosilicates, whose chemical processing is difficult due to their high melting point (more than 2000 °C) and the chemical stability of these compounds in mineral acids (sulfuric, nitric, hydrochloric). Processing of such raw materials is carried out by “classical” chlorine and sulfuric acid methods. The use of fluorides in industry is realized in the production of aluminum, zirconium, uranium, beryllium, niobium, etc., which indicates the possibility of using fluoride methods for titanium slags processing. The article discusses a method for producing titanium dioxide based on the use of ammonium hydrodifluoride NH4HF2 , which has a high reactivity to a number of chemically resistant oxides (oxides of silicon, titanium, aluminum, etc.). The fluoroammonium method for processing titanium slag using NH4HF2 involves slag decomposition of in NH4HF2 melt followed by silicon admixture sublimation. Cleaning from iron, aluminum and other impurities is carried out using a solution of NH4HF2. Further precipitation of titanium with treatment of the precipitate by AlCl3 and ZnCl2 solutions followed by calcination allows to obtain a rutile modification of titanium dioxide.

Enhanced Performance of Ti3C2Tx (MXene) Electrodes in Concentrated ZnCl2 Solutions: A Combined Electrochemical and EQCM-D Study

The need for improved batteries and supercapacitors, which are not based on lithium compounds, promotes significant research efforts to find suitable alternative systems based on various mono and multivalent cations capable of delivering high energy and power density with good long-term stability. The progress in aqueous Zn-ion batteries and supercapacitors obtained over the past years lead to the development of new structures and compounds that enable revisable hosting of Zn-ions while keeping good structural integrity. Yet, as aqueous electrolytes involve also the generation and co-insertion of protons it is necessary to carefully define what is the charge storage mechanism in these Zn insertion compounds. In this work, the use of Ti3C2Tx as an anode for the Zn-ion system was evaluated for the first time in different ZnCl2 concentrations. Remarkable changes in the charge storage mechanism and the performance of the Ti3C2Tx electrodes were observed by moving from dilute Zn electrolytes (1 M) to higher concentrations. The high acidity of the concentrated ZnCl2 solutions results in an additional charge storage mechanism that arises from redox interactions between the MXene and the released protons and hence enhanced capacity values (60 mAh/g with good rate capability and capacity retention of 89.4% after 9000 cycles). In-situ EQCM-D measurements were employed to shed light on the charge storage mechanism of the Ti3C2Tx and the exact identity of the charge carrier inserted into the electrodes. The demonstrated EQCM-D based analysis provides precise quantification of the Zn-ion to proton ratio in the examined system and can be further applied for other aqueous Zn-ion electrodes and multivalent systems as well.

Density cleaning for some Turkish lignites

In the scope of this study, in order to determine the floatability characteristics of lignites, 5 samples were collected from various lignite reserves of Turkey namely Dursunbey, Çayırhan, Ilgın, Ermenek, and Gürmin-Merzifon. Collected samples were analyzed in terms of float and sink analysis. As regards to float and sink analysis, the original samples were floated and sinked in 2 different ZnCl2 solutions of densities 1.40 and 1.60 g cm-3. Proximate analysis of each original sample for the corresponding lignite was carried out in the beginning of this study. In terms of proximate analysis performed, Dursunbey lignite sample has the lowest ash content of 24.86 % while Gürmin Merzifon lignite sample has the highest ash content of 45.02 %, respectively. Accordingly, 5 float and sink analysis graphic obtained and they would help one to understand and easily figure out the optimum medium density for cleaning.

Test conditions can significantly affect the results of in vitro cytotoxicity testing of degradable metallic biomaterials

In vitro cytotoxicity testing is an indispensable part of the development of new biomaterials. However, the standard ISO 10993-5 enables variability in the testing conditions, which makes the results of the test incomparable. We studied the influence of media composition on the results of the cytotoxicity test. Solutions of ZnCl2 served as simulated extracts and we also used extracts of three types of Zn-based and Mg-based degradable metals. We incubated the cells with the solutions prepared in two types of media with two concentrations of serum (5 and 10%). We compared the toxic effect of the extracts on L929 murine fibroblast-derived cell line, which is recommended by ISO standard and on “osteoblast-like cells” U-2 OS. We also compared two methods of exposition: solutions were added either to a sub-confluent layer or to the cell suspension. We evaluated the metabolic activity of the cells using the resazurin test. We found out that in vitro cytotoxicity is dramatically influenced by the concentration of serum and by the type of the medium as well as by the type of exposition and type of cells. Therefore, when performing in vitro cytotoxicity testing of biomaterials, the authors should carefully specify the conditions of the test and comparison of different studies should be carried out with caution.

KESETIMBANGAN ADSORPSI LOGAM BERA T (Zn) DENGAN ADSORBEN PASIR YANG DILAPISI BESI OKSIDA

Sorption to iron-oxide coated sand is a promising technology for removal of dissolved heavy metal fraction in aqueous solution waste industry due to the availability this material in Indonesia and economic considerations. The objective of this experiment was to study the effect of temperature upon equilibrium constant using lsoterm Langmuir adsorption model and lsoterm Freundlich adsorption model. This experiment was started by determining equilibrium time as a basic time running this experiment. Adsorption experiment was conducted at stirred glass tank by making 5 mg!L ZnCl2 solutions. This solution was added with iron oxide coated sand as adsorbent. A few minutes before equilibrium time, sample was drawn and the remaining concentration was measured by AAS. The results showed that the adsorption temperature had significant effect to adsorption Zn2+onto iron oxide coated sand as adsorbent. The effect of temperature upon equilibrium constant using lsoterm Langmuir model followed the equation b [-831.41] = 0.22452exp T with relative error 6.98%. The effect of temperature upon equilibrium constant using lsoterm Freundlich model followed the equation kF = 0.05797 1 exp (-0. 003 T) and n = 3 with relative errors respectively 6. 57% and 4. 52%.

Synthesis of ZnO/FA composite for methylene blue decolorization

In this research, a ZnO/FA composite was successfully synthesized for the photocatalytic treatment of methylene blue. ZnO was obtained from Zn-C battery waste by precipitation method. Zinc metal from battery waste was separated, cleaned, and dissolve in hydrochloric acid to get the ZnCl2 solution. After adding some base until pH = 10, white precipitation was formed. This precipitate was filtered out and calcinated at 400 °C for 4 hours to obtained ZnO. Fly Ash (FA) was obtained from coal combustion waste. Fly ash was cleaned and drying at 105 °C for 3 hours. Synthesis of ZnO/FA composite was synthesized by a solid dispersion method using acetone as a medium with a various composition of ZnO: FA = 20:80; 40:60; 60:40; 80,20 in percentage. The XRD data show that the ZnO/FA composite was successfully synthesized. The SEM photo’s show that different morphology where more ZnO in the composite, the FA particles will be increasingly encased with ZnO particles. Photocatalytic performance studies of ZnO/FA composites for decolorization of methylene blue were carried out in various compositions, exposure times, substrate concentrations, and mass composites. The optimum decolorization was found in 40:60 composition, 3 hours irradiation time, 5 ppm concentration of methylene blue, and 150 mg of photocatalyst mass.

Excimer ultraviolet-irradiated carbon nanofibers with ZnO interlayer for strong binding to lithium polysulfides

Lithium–sulfur (Li–S) batteries have attracted significant attention due to their high theoretical specific capacity (1675 mAh g−1) and energy density (2600 Wh kg−1) as well as abundant natural reserves. However, polysulfide shuttling, low conductivity of sulfur species and low cell energy densities hinder the practical applications of these batteries. Herein, carbon nanofiber (CNF) is subjected to excimer ultraviolet (EUV) irradiation in ZnCl2 solution affording ZnO grains attached to the CNF (denoted as EUV-ZnO/CNF) as an interlayer for Li–S batteries. EUV-ZnO/CNF shows strong chemical anchoring and physical block effects on the polysulfides as CNF provide a conductive network allowing the fast transmission of electrons, and ZnO particles provide active sites to adsorb the polysulfide intermediate. The electrode with the EUV-ZnO/CNF interlayer exhibits a high initial discharge capacity of 1388.3 mAh g−1, and a capacity of 780.4 mAh g−1 is retained after 200 cycles with S loading of 1.55 mg cm−2. Our work demonstrates an effective and environmentally friendly method to prepare EUV-ZnO/CNF as an interlayer for high performance Li–S batteries.

An optimized procedure for extraction and identification of microplastics in marine sediment

Microplastics (MPs) in sediment environments have been widely reported. As the number of samples increases, establishing a reliable and effective method becomes increasingly urgent for the rapid extraction and identification of MPs in sediments. Herein, we proposed a system with continuous density flotation of NaBr-ZnCl2 (mixture of NaBr and ZnCl2) solution for extracting MPs in a sediment sample, combined with micro-Fourier transform infrared (μ-FT-IR) imaging scanning for identification of MPs. The recoveries of MPs were estimated for four different sizes, shapes, and ten different types of polymers. The results indicated NaBr-ZnCl2 solution showed a high recovery rate from 88.33% to 100.00% for extracting these different MPs. The μ-FT-IR imaging scanning allows for the detection of plastic down to the size of 6.25 μm in filed samples, and merely takes about 3 min, which was validated by testing of sediments from Jiaozhou Bay, China and its adjacent estuaries.

Synthesis and characterization of Ag@AgCl-reinforced cellulose composites with enhanced antibacterial and photocatalytic degradation properties

In the present work, Ag@AgCl-reinforced cellulose composites with enhanced antibacterial and photocatalytic degradation properties were successfully synthesized via oil bath heating method. During the process, zinc chloride (ZnCl2) solution was used as both Cl− resource to form AgCl and the solvent to dissolve cellulose. The samples were synthesized with different temperatures, times, and concentrations of ZnCl2 solution. The morphology, microstructure and phase of the as-prepared samples were analyzed with X-ray powder diffraction (XRD), fourier transform infrared (FTIR) spectrometry, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), photocatalytic activity studies and inhibition zone experiments. Results showed that dye solution could be completely degraded by the materials in 1 h, and higher concentrations of ZnCl2 solution favored for larger inhibition zones (higher to 10.8 mm). This synthetic strategy displayed here offers more possibilities to high value-added applications of cellulose.

Lamina Cell Shape and Cell Wall Thickness Are Useful Indicators for Metal Tolerance-An Example in Bryophytes.

Bryophytes are widely used to monitor air quality. Due to the lack of a cuticle, their cells can be compared to the roots of crop plants. This study aimed to test a hypothetical relation between metal tolerance and cell shape in biomonitoring mosses (Hypnum cupressiforme, Pleurozium schreberi, Pseudoscleropodium purum) and metal sensitive species (Physcomitrium patens, Plagiomnium affine). The tolerance experiments were conducted on leafy gametophytes exposed to solutions of ZnSO4, ZnCl2, and FeSO4 in graded concentrations of 1 M to 10−8 M. Plasmolysis in D-mannitol (0.8 M) was used as a viability measure. The selected species differed significantly in lamina cell shape, cell wall thickness, and metal tolerance. In those tested mosses, the lamina cell shape correlated significantly with the heavy metal tolerance, and we found differences for ZnSO4 and ZnCl2. Biomonitoring species with long and thin cells proved more tolerant than species with isodiametric cells. For the latter, “death zones” at intermediate metal concentrations were found upon exposure to ZnSO4. Species with a greater tolerance towards FeSO4 and ZnSO4 had thicker cell walls than less tolerant species. Hence, cell shape as a protoplast-to-wall ratio, in combination with cell wall thickness, could be a good marker for metal tolerance.

ZnO nanoparticles effect on pollen grain germination and pollen tube elongation

Plant germ cells, such as pollen grains, can be affected by exposure to metal nanoparticles (NPs) that have diffused into the environment. The germination and tube elongation of pollen grain (Lilium longiflorum) exposed to low-solubility NPs was observed. The germination rate of pollen grain exposed to 100 mg L−1 ZnO NP dispersion decreased significantly from controls and exposure of the other NPs. On the other hand, when pollens were exposed to ionic solutions in which particles were removed from the 100 mg L−1 ZnO NP dispersion, the germination rates were equivalent to those in the control pollens. On the contrary, decrease of the germination rate compared to controls was small in the exposure to ZnCl2 solution, which contained a larger amount of water-soluble Zn2+ than ZnO NP dispersion. From these results, it was concluded that fine ZnO NP may adhere to pollens, due to the cohesive property of nanoparticles, and Zn2+ dissolved at the interface may be continuously absorbed by pollens. When pollen was exposed to ZnO NP, a spot with a high Ca2+ local concentration was observed at the tip of the pollen tube. On the contrary, simultaneous exposure to antagonistic ZnO NP and CaCl2 resulted in no decrease in the germination rate. From the above, it is considered that upon exposure to ZnO NP, cells absorb Zn2+ depending on the specific solubility of ZnO NP. Despite the low solubility of zinc oxide nanoparticle, pollen cell-attached particles inhibited germination and elongation of pollen tube by continuous Zn2+ dissolution from particles and Zn2+ absorption by the cell.

Kinetic analysis and pyrolysis mechanism of raw and impregnated almond shells

Nowadays, lignocellulosic agro-wastes, as rice husks, walnut shells, almond shells, woody wastes, etc., are considered on the one hand as a serious environmental concern and on the other hand as a source of highly concentrated carbon, which can be transformed into energy and value-added products through a suitable thermochemical process. Respectively, pyrolysis is described as an appropriate thermochemical process of agro-waste conversion due to a significant reduction in the volume/mass ratio of agro-wastes, thus limiting the problem associated with their disposal or waste storage, in addition to producing value-added products. Various approaches and modifications of “classical” pyrolysis are sought as well in order to direct biomass pyrolysis process to a greater extent to one or another product or to obtain a product with certain characteristics. In this regard, thermal decomposition reactions studies are important, firstly to fundamentally clarify the mechanisms, i.e. the mechanism of reactions, the parameters that affect them and respectively the consequences on the yield and characteristics of the final products, and secondly to implement industrially the developed thermochemical technologies, which require in depth understanding of the kinetics of thermal decomposition. In the current study the thermal stability and kinetic parameters of pyrolysis of virgin and impregnated with ZnCl2 almond shells were investigated and compared. Unequivocally the treatment with ZnCl2 solution of initial almond shells leads to changes in the matrix of almond shells, which affects both, i.e. the process of pyrolysis and the final characteristics of the obtained pyrolytic products. The impregnation alters the thermal decomposition mechanism and it appears that the activation energy of pyrolysis does not depend on the conversion degree and is lower for preliminary untreated almond shells. Based on kinetic parameters, the thermodynamic functions describing the formation of activated complex were determined as well. It appears that preliminary treatment of almonds shells with ZnCl2 solution leads to higher speed proceeding pyrolysis and yields of pyrolytic solid product (char) with well-developed porosity. However pyrolysis of ZnCl2 solution treated shells requires higher energy consumption.

Carbon obtained from waste polyethylene terephthalate (PET) containers as potential sorbent of radionuclides from the contaminated aqueous solutions

Waste polyethylene terephthalate (PET) beverage containers have been carbonized in a nitrogen stream and chemically treated to obtain activated carbon. The potential sorbent has been physico-chemically characterized and tested for use in the solidification of liquid radioactive waste (LRW). For this purpose, we have determined main factors describing adsorption of the selected radioactive metals. It was found that adsorption process fulfils Freundlich and kinetic pseudo-second-order models. It has been also shown that activation of the raw PET carbon with using the ZnCl2 solution leads to the best adsorption results of the radionuclides. Activated carbon obtained within this work appeared to be a potential candidate for a low-cost, chemically stable adsorbent for water decontamination. Procedures for the carbonization and activation need, however, to be improved. Activated carbon obtained from waste polyethylene terephthalate (PET) beverage containers appeared to be a potential candidate for a low-cost, chemically stable adsorbent for water decontamination and the management of radioactive liquid wastes (LRW).

ZnCl2 regulated flax-based porous carbon fibers for supercapacitors with good cycling stability

We systemically control the specific surface area and pore structure of flax-based carbon fibers by impregnating with zinc chloride (ZnCl2) solution. The results show that ZnCl2 affects the microstructure and the specific capacitance.

Enhanced oxygen reduction and evolution in N-doped carbon anchored with Co nanoparticles for rechargeable Zn-air batteries

In this study, a facile surface treatment on polypyrrole (PPy) nanofiber with ZnCl2 solution is employed to fabricate N-doped carbon anchored with metallic Co (denoted as Co/N-CZn) via gas-transport approach. Structural characterizations reveal that the intrinsic structure of Co/N-CZn in terms of its morphology, pore structure and defects have been greatly modulated by such a surface treatment, resulting in a higher loading amount of metallic Co, larger surface area and increased pyridinic N and Co-N species as efficient active sites. Benefiting from the structural modulation, Co/N-CZn exhibits outstanding ORR activity and kinetics with a positive half-wave potential of 0.88 V vs. RHE, a high kinetic current density (Jk) value of 36.6 mA cm−2 at 0.85 V vs. RHE, and a small Tafel slope of 55.9 mV dec−1, which even outperforms commercial Pt/C. Moreover, enhanced OER performance is also achieved in Co/N-CZn, with an overpotential of 280 mV at 10 mA cm−2, surpasses that of commercial RuO2 (295 mV). Finally, Co/N-CZn shows promise for substitution of commercial Pt/C and RuO2 to drive both liquid and solid-state rechargeable Zn-air batteries with high peak power densities of 196 mW cm−2 and 130 mW cm−2.