Superhydrophobic Cobalt–Graphene Composite for the Corrosion Protection of Copper Bipolar Plates in Proton Exchange Membrane Fuel Cells

Superhydrophobic cobalt and cobalt–graphene films were fabricated on copper bipolar plates (BPPs) using potentiostatic electrodeposition to improve their corrosion resistance and surface conductivity. A scanning electron microscope (SEM) was used to study the surface morphology of the prepared superhydrophobic films. The results show that the cobalt film modified by stearic acid (Co-SA) and cobalt–graphene composite modified by stearic acid (Co–G-SA) exhibit micro–nano structures. The results of the Fourier transforming infrared (FTIR) spectrophotometer confirm that the copper substrate was coated by Co-SA and Co–G-SA films. The wettability results of the prepared superhydrophobic films demonstrate that the films display superhydrophobicity, where the fabricated Co-SA and Co–G-SA films have contact angles (CAs) of 159 deg and 165 deg, respectively. Chemical stability, mechanical abrasion resistance, surface conductivity, and corrosion resistance in a simulated proton exchange membrane fuel cells (PEMFCs) environment are significantly higher for copper coated by Co–G-SA film. Because the copper coated with Co–G-SA has a low interfacial contact resistance (ICR) value and a high corrosion resistance, it is thought to be a good choice for PEMFC bipolar plates.

Mesoporous N-P Codoped Carbon Nanosheets as Superior Cathodic Catalysts of Neutral Metal-Air Batteries

Development of high-efficiency oxygen reduction reaction (ORR) catalysts under neutral conditions has made little research progress. In this work, we synthesized a three-dimensional porous N/P codoped carbon nanosheet composites (CNP@PNS) by high-temperature thermal treatment of dicyandiamide, starch, and triphenylphosphine and subsequent porous structure-making treatment using the NaCl molten salt template. In the neutral solution, the electrocatalytic performance of the CNP@PNS-4 catalyst exhibits an onset potential of 0.98 V (vs reversible hydrogen electrode) and a half-wave potential of 0.91 V for ORR, which greatly surpasses commercial Pt/C (40%). Three kinds of neutral metal-air batteries (Zn-air, Al-air, and Fe-air) using the prepared samples as cathodic catalysts were constructed, corresponding to the maximum power density of 120.2, 78.3, and 18.9 mW·cm^-2, respectively. Also, they reveal outstanding discharge stability under different current densities. The density functional theory calculation depicts the reduction of the free energy of the determining step and subsequent decline of the overpotential for ORR.

The State of Research Regarding Ordered Mesoporous Materials in Batteries

Ordered mesoporous materials, porous materials with a pore size of 2-50 nm which are prepared via the sol-gel process using surfactant molecular aggregates as a template to assemble channels through the interfacial action of organic and inorganic substances, have recently triggered a heated debate. In addition to applications in the catalytic cracking of heavy oils and residues, the manufacturing of graft materials, the purification of water, the conversion of automobile exhaust, biochips, and the treatment of environmental pollutants via photocatalysts, ordered mesoporous materials have drawn substantial attention in the field of electrochemical energy storage due to advantages such as large specific surface area, uniform and continuously adjustable pore size, and orderly arrangement. Here, a general summary and appraisal of the study of ordered mesoporous materials for batteries in recent years is given, including the synthesis methods, meso/nanostructural features, and electrochemical capabilities of such materials.

High performance composites of spinel LiMn2O4/3DG for lithium ion batteries

A highly crystalline nanosized spinel LiMn₂O₄/3DG composite cathode material for high rate lithium ion batteries was successfully prepared by mixing spinel LiMn₂O₄ particles with reduced graphene oxide (3DG). Spinel LiMn₂O₄ and reduced three-dimensional graphene oxide were synthesized using a hydrothermal method and freeze-drying technology, respectively. The structure, morphology and electrochemical performance of the synthesized materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge–discharge techniques. The results showed that the LiMn₂O₄/3DG composites exhibited excellent rate capability and stable cycling performance. The discharge capacity was 131 mA h g⁻¹ and the capacity remains at 89.3% after 100 cycles at a 0.5 C rate, while the discharge capacity was 90 mA h g⁻¹ at 10 C. Compared with spinel LiMn₂O₄ materials, the LiMn₂O₄/3DG composites showed obvious improvement in electrochemical performance.

3DG/LiMn₂O₄ composites exhibit a high specific capacity and excellent rate performance.

Enhancement in graphitization of coal tar pitch by functionalized carbon nanotubes

In this study, the influence of the addition of carbon nanotubes (CNTs) and carbon black (CB) on the graphitization temperature and microstructure of coal tar pitch (CTP) are investigated.

Recent advances in the fabrication and structure-specific applications of graphene-based inorganic hybrid membranes

The preparation and applications of graphene (G)-based materials are attracting increasing interests due to their unique electronic, optical, magnetic, thermal, and mechanical properties. Compared to G-based hybrid and composite materials, G-based inorganic hybrid membrane (GIHM) offers enormous advantages ascribed to their facile synthesis, planar two-dimensional multilayer structure, high specific surface area, and mechanical stability, as well as their unique optical and mechanical properties. In this review, we report the recent advances in the technical fabrication and structure-specific applications of GIHMs with desirable thickness and compositions. In addition, the advantages and disadvantages of the methods utilized for creating GIHMs are discussed in detail. Finally, the potential applications and key challenges of GIHMs for future technical applications are mentioned.

Formation of a protective nitride layer by electrochemical nitridation on 316L SS bipolar plates for a proton exchange membrane fuel cell (PEMFC)

In the present study, an attempt has been made to increase the corrosion resistance of 316L stainless steel (SS) bipolar plates (Bp) through electrochemical nitridation using a nitrate bearing electrolyte solution of 0.1 M HNO₃ and 0.5 M KNO_3.