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ZnO/PVA/CHI composite electrode with internal pore structure has been successfully prepared by cross-linking polymerization of polyvinyl alcohol (PVA) and chitosan (CHI). The resulting composite electrode exhibits a maximum anode dissolution current of 0.34A, 4.86 times higher than that of the pure ZnO electrode (0.07A).More importantly, the Rct of the composite electrode is 1.01Ω·cm2 for the composite electrode, which is lower than that of pure ZnO electrode (2.805Ω·cm2), attesting that the composite electrode possess a more favorable reaction rate. Moreover, the rechargeable battery assembled with composite electrode demonstrates a great improvement in charge/discharge efficiency and cycle stability. It remains over 80% of capacity retention even after 100 cycles, while that of pure electrode can only maintain this level less than 40 cycles. This proposed composting strategy herein may pay a way for the exploration of novel zinc anode for rechargeable zinc-air batteries with superior electrochemical performance.

Developing novel techniques to convert lignin into sustainable chemicals and functional materials is a critical route toward the high-value utilization of lignocellulosic biomass. Lignin-derived carbon materials hold great promise for applications in energy and chemical engineering, catalysis and environmental remediation. In this review, the state-of-art sciences and technologies for controllable synthesis of lignin-derived carbon materials are summarized, pore structure engineering, crystalline engineering, and morphology controlling methodologies are thoroughly outlined and critically discussed. Green chemical engineering with cost-effectiveness and precise carbonization tuning microstructure are future research trends of lignin-derived carbon materials. Future research directions that could be employed to advance lignin-derived carbon materials toward commercial applications are then proposed.

Although direct glucose fuel cell (DGFC) is widely regarded as one of the most promising energy systems, the low catalytic activity and inferior instability of most anode catalysts during electro-oxidation of glucose has greatly hampered its potential applications. In this work, an efficient and durable anode catalyst of nanoporous bismuth (Bi) for the alkaline electro-oxidation of glucose was proposed just by a simple de-alloying method. The microstructure and catalytic performance of nanoporous bismuth could be finely tuning through actively controlling the composition of precursor Mg–Bi alloy. A three-dimension structure was formed after de-alloying Mg–Bi precursor, giving rise to an increased specific surface area and correspondingly resulting in an enhanced electro-catalytic performance. It has intimated that the optimal nanoporous Bi catalyst with an open, bi-continuous interpenetrating pore-to-ligament structure was constructed based on Mg65Bi35 alloy etching and exhibited an enhanced current density (as high as 8.04 mA/cm2) during alkaline electro-oxidation of glucose, together with the lowest poisoning rate of 5.6 × 10−3%. The remarkable electrochemical performance of the nanoporous Bi catalyst, coupling with facile dealloying strategy may facilitate design and development of renewable energy device.

Electrocatalytic water splitting (EWS) is a promising route to produce hydrogen in a sustainable and environment-benign manner. To realize the large-scale hydrogen production, it is paramount to develop desirable electrocatalysts with engineered structure, high catalytic activity, facile accessibility, low cost, and good durability. Of late, boride-based materials, especially transition-metal borides (TMBs), are emerging as promising candidates for the EWS process. However, so far, little attempt has been made to provide a comprehensive summary on these findings. Herein, this review provides the up-to-date status on upgrading the catalytic performance of TMB-based nanomaterials by regulating the internal and external characteristics. The conventional synthetic techniques are first presented for the preparation of TMB-based catalysts. Afterwards, the advanced strategies are summarized to enhance the catalytic performance of TMBs, including morphology control, component regulation, phase engineering, surface oxidation and hybridization. Then, the design principles of TMB-based electrocatalysts for high-performance EWS are outlined. Lastly, the current challenges and future directions in the development of TMB-based materials are proposed. This review article is expected to envisage insights into the TMBs-based water splitting and to provide strategies for design of the next-generation TMB-based electrocatalysts.

This communication reports nickel hydroxide nanoplates grown on nickel foam (NF) by one-step water bath treatment of NF in nitric acid solution. The reaction temperature and duration were critical to the formation of nanoplates. Moreover, the Ni(OH)2 electrode on nickel foam (Ni(OH)2/NF) exhibited high performance and prominent stability toward the hydrogen evolution reaction (HER) in an alkaline solution. The mentioned finding will be expected to broaden the development of Ni(OH)2-based binder-free electrodes for electrochemical applications.

The development of low-cost electrocatalysts with high performance toward the hydrogen evolution reaction (HER) is crucial for large-scale and clean hydrogen production. Herein, we report a facile synthesis of Co/CoO hybrids with oxygen vacancies on carbon cloth (CC) via the calcination treatment of a Co3O4 precursor in a reducing atmosphere (H2/Ar). Moreover, to avoid delamination and cracks during heat treatment and catalyst abscission during the HER test, the precursor of Co(OH)2 was stabilized on CC by the anion intercalation method, resulting in robust adhesion between the film and substrate. The as-prepared Co/CoO hybrids rooted on the CC substrate possessed good charge transfer properties, favorable kinetics, abundant active sites, and robust adhesion. A suitable reducing atmosphere was crucial for high catalytic activity. By optimizing, the sample obtained in a 30% H2/Ar atmosphere (Co/CoO-30) possessed an optimal balance between Co/CoO and oxygen vacancies, exhibiting optimum HER performance with the smallest overpotential of 158 mV at 10 mA cm−2 and Tafel slope of 68.1 mV dec−1 as well as good stability, operating for at least 24 h.

The MnFe2O4/C catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) were prepared by a facile microwave sintering method, and the MnFe2O4/C electrode showed good performance for both ORR and OER. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to analyze the phase and morphology of the product. The current density of the MnFe2O4/C electrode was 141.8 mA cm−2 at −0.2 V (vs. Hg/HgO) and 92.5 mA cm−2 at 0.6 V (vs. Hg/HgO) in 6 mol L−1 KOH electrolyte at room temperature. A primary zinc-air battery was assembled using MnFe2O4/C electrode, the discharge voltage could reach up to 816 mV at a high current density of 80 mA cm−2.

Manganese(II)/Manganese(III) with a standard electrode potential of 1.51 V has been identified as a potential positive electrode for redox flow cells. The current work is to evaluate the use of methane sulfonic acid (MSA) as a solvent for Manganese(II)/Manganese(III) electric pairs as cathode materials applied to redox flow batteries (RFB). The electrochemical behavior of the MSA medium in Manganese(II)/Manganese(III) was studied by linear scanning voltammetry and cyclic voltammetry. The results show that the reaction of Manganese(II)/Manganese(III) on the graphite electrode is a quasi reversible single electron transfer step. The diffusion coefficient of Mn2+ was identified as 0.982 × 10−6 cm2 s−1 in 1 M MSA. As the concentration of MSA increases from 2 to 5 M, Mn3+ would be more stable, and the electrochemical kinetics of Manganese(II)/Manganese(III) couple would be better. When the MSA concentration reached 5 M, reduction kinetics of oxidized species Mn3+ decreased obviously. The results support the selecting of 4 M MSA. When the current density was 20 mA cm−2, the average energy efficiency and coulomb efficiency of the battery were 74.0% and 92.2% respectively. The average discharge voltage was 1.91 V and the average energy efficiency was 59%, which was higher than the total V cell. At the same time, the battery got a good charging and discharging cycle performance, which indicates that the zinc manganese oxide redox battery has a wide application prospect.

The Mn/C catalysts for oxygen reduction reaction (ORR) were prepared by a facile method, the as-prepared material synthesized at 300 °C for 2 h exhibits splendid catalytic activity for ORR along with ascendant long-term durability, the current density of the Mn-300-2/C electrode is 119 mA cm−2 at −0.2 V (vs. Hg/HgO) in 6 mol L−1 KOH electrolyte. A primary Zn-air battery was assembled using Mn-300-2/C electrode, the discharge voltage could reach up to 1.17 V at 50 mA cm−2 and 1.07 V at a high current density of 75 mA cm−2.

The Pd ZnO/C catalytic material for ethanol oxidation reaction is prepared by microwave heating-glycol reduction method. Pd ZnO is well polymerized and dispersed on XC72. The results demonstrate that Pd ZnO/C has better electro catalytic activity and stability for ethanol oxidation reaction than Pd/C at room temperature. ZnO/C shows no catalysis for ethanol oxidation. The oxidation peak potential of Pd ZnO/C electrode is shifted negatively to 0.21 V. The current density of Pd ZnO/C electrode is 145 mA cm−2, while that of the Pd/C electrode is 60 mA cm−2. Moreover, single cell discharge test shows that discharge voltage of the Pd ZnO/C electrode reaches to 0.41 V at 30 mA cm−2. In summary, ZnO as a co-catalyst significantly improves the activity of Pd ZnO/C catalyst for ethanol oxidation reaction.

The perovskite-type oxide La0.2Sr0.8CoO3 was prepared by sol-gel process, which particle was irregular cube with particle size between 50 and 60 nm. A novel air electrode for oxygen evolution reaction prepared by using La0.2Sr0.8CoO3 as a catalyst has a current density of 152 mA cm−2 when the potential is 0.7 V (vs. Hg/HgO) in an alkaline medium (6 mol L−1 KOH) under the air atmosphere. The research results show that n (C6H8O7): n (M) = 1:1, pH = 9, calcination temperature 800 °C, 5 h calcination time is the best preparation process conditions.

The La0.5Sr0.5CoO3/C was synthesized by sol-microwave process, which has globular particle with size range of 15–25 nm and distributed evenly. The electrode prepared with this catalyst has a current density of 141 mA·cm−2 at 0.7 V (vs. Hg/HgO) in an alkaline medium (6 mol·L−1 KOH). La0.5Sr0.5CoO3/C has excellent catalytic performance for oxygen evolution, which is superior to RuO2/C catalyst and can replace noble metal catalytic materials. The polarization curves of oxygen evolution for La0.5Sr0.5CoO3/C electrode and RuO2 (20%)/C electrode are shown. At 0.7 V (vs. Hg/HgO), the oxygen evolution current density is 141 and 135 mA·cm−2, respectively. The results show that perovskite-type oxide La0.5Sr0.5CoO3/C prepared by sol-microwave method has better catalytic performance than RuO2(20%)/C.

A new electrocatalyst Co–N/C complex for oxygen reduction reaction (ORR) was prepared by different cobalt salts using ethylenediamine as a nitrogen source. The Co5.47N/C was prepared by sintering at 1000 °C for 2 h in a hydrogen atmosphere. The Co–Ac–N/C catalyst that prepared by cobalt acetate was the best catalyst for oxygen reduction and the current density of Co–Ac–N/C electrode at 0.75 V (vs. RHE) was 128 mA cm−2 in 6 mol L−1 KOH electrolyte. A zinc–air battery using Co–Ac–N/C electrode was successfully assembled and the discharge voltage reached to 0.99 V under the high current density of 80 mA cm−2. Furthermore, the Co–N/C electrodes showed superior methanol crossover tolerance for ORR.

Achieving a good match between strength and conductivity is a challenge of the development of the high-performance Cu-Cr-Nb alloy for aerospace and fusion energy. The effect of heat treatment on Cr2Nb phase, strength and conductivity of spark plasma sintered (SPSed) Cu-2Cr-1Nb (at%) alloy was investigated. The results illustrated that Cr2Nb phase of Cu-2Cr-1Nb alloy can be regulated by heat treatment, multi-scale Cr2Nb phase with sizes of 0.10&ndash, 0.50 &mu, m, 30&ndash, 100 nm and less than 30 nm was obtained, and the strength and conductivity were significantly increased after heat treatment at 500 &deg, C for 2 h, the room temperature tensile strength and conductivity were 332 MPa and 86.7% IACS, 2.5% and 34.8% higher than those of as-SPSed alloy, the tensile strength at 700 &deg, C was 76 MPa. Increasing heat treatment temperature and time, the tensile strength of the alloy was reduced by 1.5%, 4.3% and 12.3% after heat treatment at 500 &deg, C, 700 &deg, C and 950 &deg, C for 72 h. The good match between strength and conductivity of Cu-Cr-Nb alloy was obtained by reducing the content of alloying elements (Cr and Nb) and microstructure regulation. This approach can be used to prepare structural/functional materials with excellent strength and conductivity.

The hematite type Fe2O3/C catalyst for oxygen evolution reaction (OER) was prepared using a facile urea combustion method. The Fe2O3/C electrode showed excellent electrocatalytic ability towards OER in alkaline medium. The phase and morphology of the product were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The sintering temperature is 600 °C, and the calcination time is 3 h, which is the best preparation process condition. The particles were irregular spherical with the size of 10–30 nm and dispersed uniformly. The current density of the Fe2O3/C electrode was 147 mA cm−2 at 0.6 V (vs. HgO/Hg) in 6 mol L−1 KOH electrolyte at room temperature.

Achieving a good match between strength and conductivity is a challenge of the development of the high-performance Cu-Cr-Nb alloy for aerospace and fusion energy. The effect of heat treatment on Cr2Nb phase, strength and conductivity of spark plasma sintered (SPSed) Cu-2Cr-1Nb (at%) alloy was investigated. The results illustrated that Cr2Nb phase of Cu-2Cr-1Nb alloy can be regulated by heat treatment, multi-scale Cr2Nb phase with sizes of 0.10–0.50 μm, 30–100 nm and less than 30 nm was obtained, and the strength and conductivity were significantly increased after heat treatment at 500 °C for 2 h, the room temperature tensile strength and conductivity were 332 MPa and 86.7% IACS, 2.5% and 34.8% higher than those of as-SPSed alloy; the tensile strength at 700 °C was 76 MPa. Increasing heat treatment temperature and time, the tensile strength of the alloy was reduced by 1.5%, 4.3% and 12.3% after heat treatment at 500 °C, 700 °C and 950 °C for 72 h. The good match between strength and conductivity of Cu-Cr-Nb alloy was obtained by reducing the content of alloying elements (Cr and Nb) and microstructure regulation. This approach can be used to prepare structural/functional materials with excellent strength and conductivity.

This paper aims to investigate the constituent phytochemicals and biological activities of six Lithocarpus litseifolius (Hance) Chun (L. litseifolius) cultivars. Processed by UPLC-MS/MS and untargeted metabolomics analysis software (MS-DIAL and MS-FINDER), components of different L. litseifolius cultivars were analyzed qualitatively and quantitatively. By conducting a comprehensive analysis of spectra, MS/MS fragmentation, and retention time, 40 compounds (including 6 phenolic glycosides and 34 flavonoids) were identified rapidly and accurately. Moreover, the total phenolic content (TPC), total flavonoid content (TFC), antioxidant, antimicrobial effects, and pheochromocytoma (PC12) cell viability of different L. litseifolius varieties were evaluated. Purple small leaf (PSL) was found to be the most superior variety with the highest antioxidant activities (8.27, 10.09, and 10.80 mg TE/g for DPPH, ABTS, and FRAP assays, respectively), broad-spectrum antimicrobial activity, and lowest cell cytotoxicity. The results showed that these bioactivities were closely related to phytochemicals among the six cultivars. PRACTICAL APPLICATIONS: L. litseifolius is well known as an important folk drink in the Southern China folklore for its specific efficacy in preventing diabetes. However, there is still a paucity of information on L. litseifolius, as other active components and bioactivities of it remain to be investigated. The wide range of flavonoids discovered in L. litseifolius provides abundant natural health-promoting agents for further applications in medicine and functional food.

The thermal decomposition behavior of NiFe layered double hydroxide (LDH) was investigated by thermogravimetric analysis-differential scanning calorimetry (TG-DSC). The calcined product at 500 °C was mainly NiO/FeOx composite oxide, of which FeOx was amorphous oxide; the calcined product at 650 °C was mainly NiO/NiFe2O4 composite oxide. The polarization curves and chronopotentiometry stated that the NiO/FeOx and NiO/NiFe2O4 showed good electrocatalytic OER and ORR activity; the OER activity of NiO/FeOx was better than that of NiO/NiFe2O4; the ORR activity of NiO/NiFe2O4 was better than that of NiO/FeOx.

Beta-cyclodextrin (β-CD) was first ground among the single stranded linear polyethylene glycol (PEG), and then the ZnO/PVA/β-CD/PEG composite electrode was prepared by chemical crosslinking method. From the SEM diagram of the composite electrode after 80 cycles, it can be seen that the internal and surface of the electrode was distributed a large number of holes within the average diameter of 150 μm. These holes have formed the interpenetrated three-dimensional framework with the active ZnO embedded in and no dendrite formation. The results show that the discharge capacity of the composite electrode is reduced to 80% of the maximum capacity after 130 cycles, which indicates that the cycle life of the composite electrode is longer than that of the blank electrode. The results of polarization curve test shows that the maximum dissolution current of the composite electrode was increased from 60 to 280 mA·cm−2 after 80 cycles, indicating that the activity of the composite electrode was still good after 80 cycles. Compared with it, the blank electrode had few activities after 80 cycles.

The capacity utilization of zinc anode is usually very low in alkaline solution because of extreme dissolution and the passivation of zinc surface. This problem can be substantially overcome by using the composite electrode of Zn-PCH (PVA chemical hydrogel). In this work, PCH hydrogel film coated on the surface of the ZnO particles can reduce the solubility of the zinc and the concentration of the Zn(OH)42−. The cell with the Zn-PCH electrode reached 150 cycles before its capacity fell below 90% of the initial capacity, while the standard cell failed after 150 cycles. Based on the scanning electron microscopy observation of the Zn-PCH electrode, it shows a distribution of big spherical particles to form a loose and porous structure rather than a dense and compact film, which can help zinc electrode to stay in a loose and porous structure. Such texture is definitely in favor of the diffusion of OH− ions, facilitating the utilization of active material. Therefore, the Zn-PCH electrode can effectively improve the cycle performance of the secondary Zn-air battery.

Male infertility has become a global health problem. Currently, the diagnosis of male infertility depends on the results of semen quality or requires invasive surgical intervention. The process is complex and time-consuming. Metabolomics is an emerging platform with unique advantages in disease diagnosis and pathological mechanism research. In this study, ultra-performance liquid chromatography-electrospray ionization-ion trap-time of flight mass spectrometry (UPLC-ESI-IT-TOFMS) combined with chemometrics methods was used to discover potential biomarkers of male infertility based on non-targeted plasma metabolomics. Plasma samples from healthy controls (HC, n = 43) and various types of infertile patients, i.e., patients having oligozoospermia (OS, n = 36), asthenospermia (AS, n = 56) and erectile dysfunction (ED, n = 45) were analyzed by UPLC-ESI-IT-TOFMS. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were performed. The results of OPLS-DA showed that HCs could be discriminated from infertile patients including OS (R2 = 0.903, Q2 = 0.617, AUC = 0.992), AS (R2 = 0.985, Q2 = 0.658, AUC = 0.999) or ED (R2 = 0.942, Q2 = 0.500, AUC = 0.998). Some potential biomarkers were successfully discovered by variable selection methods and variable important in the projection (VIP) in combination with the T-test. Statistical significance was set at p < 0.05; the Benjamini–Hochberg false discovery rate was used to reduce type 1 errors resulting from multiple comparisons. The identified biomarkers were associated with energy consumption, hormone regulation and antioxidant defenses in spermatogenesis. To elucidate the pathophysiology of male infertility, relative metabolic pathways were studied. It was found that male infertility is closely related to disturbed phospholipid metabolism, amino acid metabolism, steroid hormone biosynthesis metabolism, metabolism of fatty acids and products of carnitine acylation, and purine and pyrimidine metabolisms. Plasma metabolomics provides a novel strategy for the diagnosis of male infertility and offers a new insight to study pathogenesis mechanism.

Exploring cost-effective and high-efficiency noble-metal free electrocatalysts for oxygen evolution reaction (OER) are of critical importance to the area of renewable energy storage and conversion systems. Herein, Ni–Fe–Mo films were fabricated via electrodeposition method with a very high current density. The film exhibits excellent activity towards OER with a overpotentials of 306 mV at current density of 10 mA·cm−2 and a lower Tafel slope of 77.1 mV·dec−1 under alkaline conditions (30 wt.% KOH). The synergistic effect of the Mo, Ni, and Fe contribute the improved catalytic activity for OER.

A new type of composite electrocatalyst was designed and prepared with NiFe layered double hydroxides (LDHs) for oxygen evolution reaction (OER) and CoPc for oxygen reduction reaction (ORR) supported on carbon nanotubes (CNTs). The NiFe LDH–CoPc/CNT composite exhibits higher electrocatalytic activity and stability than the commercial precious metal catalyst Pd/C + Ru/C in 6 M KOH electrolyte. The resulting rechargeable Zn–air battery showed high discharge voltage at 195 mW cm−2. The discharge voltage is around 1.08~0.95 V and the charge voltage is lower, 2.07 V, after the cycle of 300 h at 80 mA cm−2, indicating that zinc–air battery possessed high reversibility and durability over long charge and discharge cycles.

A ZnO/PVA/PAADDA composite electrode for rechargeable zinc-air battery was prepared by chemical cross-linked PVA (polyvinyl alcohol) with poly(acrylamide-co-diallyldimethylammonium chloride) (PAADDA). Fourier transform infrared spectra (FT-IR), scanning electron microscopy (SEM), and transmission microscopy (TEM) studies reveal that the PVA/PAADDA polymer had a well-connected three-dimensional network structure. Linear sweep voltammetry, cyclic voltammetry (CV), electrochemical impedance spectroscopies (EIS), and charge/discharge cycling tests were carried out on the ZnO/PVA/PAADDA electrode, which shows much better electrochemical activity and capacity stability comparing with the bare ZnO electrode without polymer.

Increasing the number of active sites is critical for developing N-doped carbon electrocatalysts towards oxygen reduction reaction (ORR) in fuel cells and metal-air batteries applications. Herein, we prepared N-doped carbon nanotubes (N-CNT) with enriched pyridinic N and abundant defects resulted from the etching of KMnO4 of the precursor (polypyrrole). It was observed that the content of pyridinic N could be well controlled by regulating the etching time. The resultant catalyst displayed a superior ORR activity compared commercial Pt/C in an alkaline solution, which was further confirmed by home-made Zn-air batteries. Density functional theory (DFT) computations showed that the superior catalytic activity originated from the second nearest carbon atom to the pyridinic-N at the edge. This work provides a simple etching approach to alter the N configuration and the amount of defects in N-doped CNT, which can be extended to many other energy conversion materials.

A core/shell polyaniline (PANI)/MnO2 composite (denoted as “PANI@MnO2”) was prepared and evaluated as electrode material for supercapacitor applications. In the composite, α-MnO2 showed chrysanthemum-like and spherical structure, which were coated in situ with PANI. In this process, α-MnO2 serves as a scaffold and also acts as an oxidant to induce aniline polymerization. Scanning electron microscopy and transmission electron microscopy images clearly showed the core/shell structure of the PANI@MnO2 composite, which was further characterized by X-ray powder diffraction, Fourier transformation infrared spectroscopy and Raman spectroscopy. In addition, the thermo-gravimetric analysis illustrates that the composite has a good thermal stability and the mass ratio of PANI and MnO2 is 0.11. Electrochemical properties of the composite and its components were evaluated using cyclic voltammetry, electrochemical impedance spectra and chronopotentiometry. The specific capacitance of the high-mass loading PANI@MnO2 electrode is 75 Fg−1, 1.1 times higher than that of MnO2 electrode (67 Fg−1), at a current density of 0.1Ag−1. Moreover, the composite electrode retains 90% of the initial capacitance after 3000 cycles, while this is only 75% for α-MnO2. The improved electrochemical performance may be attributed to the synergistic effect between PANI and α-MnO2.

The main barrier preventing the commercial application of alkaline aluminum-air battery is the severe self-corrosion of Al anode. Herein, three kinds of novel inorganic-organic hybrid corrosion inhibitors are constructed, which containing ZnO and organic acids (acetic acid, citric acid and EDTA). Electrochemical tests demonstrate that the combination of ZnO and organic acid effectively suppresses the self-corrosion of Al foam anode in alkaline solution. Among them, the Al-air battery exhibits a high voltage platform (1.13 V), a high specific capacity (1902 mA h g−1) and a high anode utilization (58.23%) within 0.3 M ZnO+0.03 M citric acid hybrid inhibitors system. Surface analyses confirm that the organic acid greatly boosts the formation of uniform and dense Zn film on Al surface. A combined experimental research and theory computation reveal that the corrosion inhibition mechanism of ZnO + organic acid hybrid system is: the phase-forming corrosion inhibitor (ZnO) deposit on the Al surface to form Zn protective film and cover the active sites of hydrogen evolution; the active sites of organic acids are the O atoms of carbonyl groups, which adsorbing on the surface of Zn protective film and Al foam, thereby forming the composite protective films of RCOO-Al and RCOO-Zn.

Zinc electrode with polyvinyl alcohol(PVA)/poly(diallyldimethylammonium chloride) (PDDA) film coated ZnO was prepared by a chemical cross-linking method. The PVA/PDDA polymer film has an interpenetrating network structure where PVA works as polymer matrix and PDDA as anion charge carriers. Fourier transform infrared spectra (FT-IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies reveal that a polymer film with well-connected three dimensional network structure is formed around ZnO nanoparticles. Linear sweep voltammetry, cyclic voltammetry (CV) and charge/discharge cycling tests were carried out on the ZnO/PVA/PDDA composite electrode, which exhibits higher electrochemical activity and dramatically superior cycle stability than the bare ZnO electrode without polymer films. The ZnO/PVA/PDDA electrode showed remarkably lower solubility during cycling.

The ethanol electrooxidation behaviors on Rh/C in alkaline media were studied compared with that on Pd/C. The Rh/C and Pd/C catalysts were synthesized by a microwave heating-glycol reduction method and characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The electrocatalytic activities of the catalysts were investigated by cyclic voltammetry (CV), chronoamperometry (CA), electrochemical impedance spectroscopy (EIS) and single cell discharge testing methods. The results showed that Rh/C presented higher activity and better stability toward ethanol oxidation than Pd/C. On the CV plots, it was observed that the onset potential of oxidation on Rh/C shifted negatively and the backward peak current on Rh/C decreased as compared to that of Pd/C. Intermediate species are produced during the oxidation process, as revealed by the complex impedance spectra. Rh/C presented higher tolerance for surface poisoning than Pd/C, which can be reflected by the negative impedance on the Pd/C electrode. The selectivity for ethanol oxidation to CO2 (existing as CO32− in alkaline media) on Rh/C and Pd/C electrodes were determined to be as low as 10.07% and 2.18%, respectively. Nevertheless, the ability of Rh for breaking the C–C bond in ethanol is still slightly higher than that of Pd under the same conditions.

It goes without saying that the oxygen reduction reaction (ORR) on Pt-based catalyst is one of the most significant cathode reactions in fuel cells. Although high price and low stability, Pt-based catalyst still enjoys its widespread researches for its relatively high activity. Recently, there has been some impressive progress in strategies like alloying, single atoms, morphology and component regulation. This paper aims to introduce the preparation strategies of Pt-based catalyst and further expound its inactivation mechanism and the essence of active sites. It also shows some challenges as well as methods applying in fuel cells, which provides some reference for the practical application in the future.