Carbon‐Based Metal‐Free Catalysts for Energy Storage and Environmental Remediation

Owing to their high earth‐abundance, eco‐friendliness, high electrical conductivity, large surface area, structure tunability at the atomic/morphological levels, and excellent stability in harsh conditions, carbon‐based metal‐free materials have become promising advanced electrode materials for high‐performance pseudocapacitors and metal–air batteries. Furthermore, carbon‐based nanomaterials with well‐defined structures can function as green catalysts because of their efficiency in advanced oxidation processes to remove organics in air or from water, which reduces the cost for air/water purification and avoids cross‐contamination by eliminating the release of heavy metals/metal ions. Here, the research and development of carbon‐based catalysts in supercapacitors and batteries for clean energy storage as well as in air/water treatments for environmental remediation are reviewed. The related mechanistic understanding and design principles of carbon‐based metal‐free catalysts are illustrated, along with the challenges and perspectives in this emerging field.     

Strength degradation of Si3N4---SiC-based ceramics in salt environments

The mechanism and kinetics of molten salt corrosion of reaction-sintered Si₃N₄---SiC-based ceramics, as well as the effect of these salts on its strength and fracture toughness at 20°C and 1200°C, were investigated. It was found that this material is highly resistant to corrosion in NaCl and sea salt up to 1100°C but degrades easily in Na₂SO₄ being a strong oxidant. Molten salt corrosion and salt-assisted oxidation cause mechanical properties' deterioration. Thus, NaCl effects involve up to 25% and 30% strength decrease at room temperature and at 1200°C, respectively. The results are explained by the etching of grain boundaries and by the formation of sodium silicate glassy layer during oxidation with it further cracking after cooling.     

Acoustic emission in the deformation and failure of corundum refractories

Conclusions A machine making it possible to simultaneously record strain and acoustic emission curves in bending of corundum refractories has been developed. It is shown that the Kaiser effect is not observed for CZ and MZ refractories with loads close to failure, which is the result of significant damage of the material in the preceding loading. The characteristic features of the strain curves of CZ and MZ refractories determined by recording of the acoustic emission process were established.Translated from Ogneupory, No. 4, pp. 15–19, April, 1986.     

Corundum-graphite materials for steel casting

Conclusions The new technology for corundum-graphite refractories with a pitch-ethyl silicate bond means we can exclude the harmful action of the volatile components of the pitch, A rise in firing temperature contributes to a greater yield of silicon carbide, and consequently to the production of a material with a greater strength and resistance to oxidation. The synthesis of silicon-carbide bond in the newly developed refractories greatly improves the properties of the refractory compared with the clay bond. Study of the corundum-graphite refractory materials shows that they are sufficiently deformative, and have a relatively high breakdown strength.Translated from Ogneupory, No. 2, pp. 14–17, February, 1984.     

Inkjet Printing of Self‐Assembled 2D Titanium Carbide and Protein Electrodes for Stimuli‐Responsive Electromagnetic Shielding

2D titanium carbides (MXene) possess significant characteristics including high conductivity and electromagnetic interference shielding efficiency (EMI SE) that are important for applications in printed and flexible electronics. However, MXene‐based ink formulations are yet to be demonstrated for proper inkjet printing of MXene patterns. Here, tandem repeat synthetic proteins based on squid ring teeth (SRT) are employed as templates of molecular self‐assembly to engineer MXene inks that can be printed as stimuli‐responsive electrodes on various substrates including cellulose paper, glass, and flexible polyethylene terephthalate (PET). MXene electrodes printed on PET substrates are able to display electrical conductivity values as high as 1080 ± 175 S cm^?1, which significantly exceeds electrical conductivity values of state‐of‐the‐art inkjet‐printed electrodes composed of other 2D materials including graphene (250 S cm^?1) and reduced graphene oxide (340 S cm^?1). Furthermore, this high electrical conductivity is sustained under excessive bending deformation. These flexible electrodes also exhibit effective EMI SE values reaching 50 dB at films with thicknesses of 1.35 µm, which mainly originate from their high electrical conductivity and layered structure.