Mengyuan He

Hydrogen has garnered considerable attention as a promising energy source for addressing contemporary environmental degradation and energy scarcity challenges. Electrocatalytic water splitting for hydrogen production has emerged as an environmentally friendly and versatile method, offering high purity. However, the development of cost-effective electrocatalytic catalysts using abundant and inexpensive materials is crucial. In this study, we successfully synthesized nitrogen-doped Co₆Mo₆C supported on nitrogen-doped graphene (N-Co₆Mo₆C/NC). The catalyst exhibited high performance and durability in alkaline electrolytes (1.0 M KOH) for hydrogen evolution, showcasing an overpotential of 185 mV at a current density of 100 mA cm⁻² and a Tafel slope of 80 mV dec⁻¹. These findings present a novel avenue for the fabrication of efficient bimetallic carbide catalysts.

Hydrogen atoms can enter into metallic materials through penetration and diffusion, leading to the degradation of the mechanical properties of the materials, and the application of hydrogen barrier coatings is an effective means to alleviate this problem. Zirconia coatings (ZrO₂) have been widely studied as a common hydrogen barrier coating, but zirconia undergoes a crystalline transition with temperature change, which can lead to volumetric changes in the coating and thus cause problems such as cracking and peeling of the coating. In this work, ZrO₂ coating was prepared on a Q235 matrix using a sol-gel method, while yttria-stabilized zirconia (YSZ) coatings with different contents of rare earth elements were prepared in order to alleviate a series of problems caused by the crystal form transformation of ZrO₂. The coating performances were evaluated by the electrochemical hydrogen penetration test, pencil hardness test, scratch test, and high-temperature oxidation test. The results show that yttrium can improve the stability of the high-temperature phase of ZrO₂, alleviating the cracking problem of the coating due to the volume change triggered by the crystalline transition; improve the consistency of the coating; and refine the grain size of the oxide. The performance of YSZ coating was strongly influenced by the yttria doping mass, and the coating with 10 wt% yttria doping had the best hydrogen barrier performance, the best antioxidant performance, and the largest adhesion. Compared with the matrix, the steady-state hydrogen current density of the YSZ coating decreased by 72.3%, the antioxidant performance was improved by 65.8%, and the ZrO₂ coating hardness and adhesion levels were B and 4B, respectively, while YSZ coating hardness and adhesion were upgraded to 2H and 5B. With the further increase in yttrium doping mass, the hardness of the coating continued to improve, but the defects of the coating increased, resulting in a decrease in the hydrogen barrier performance, antioxidant performance, and adhesion. In this work, the various performances of ZrO₂ coating were significantly improved by doping with the rare earth element, which provides a reference for further development and application of oxide coatings.

Epoxy coatings are popular due to their strong adhesion, low cost, and superior thermal and electrical insulation. Unfortunately, surface defects in epoxy resin lead to surface cracks, limiting the long-term use of epoxy resin coatings in humid marine environments. In this study, modified kaolin (Kaolin) was added to an epoxy resin (EP) to enhance its corrosion resistance, and a silane coupling agent 3-aminopropyltriethoxysilane (APTES), tetraethyl orthosilicate (TEOS), and 8-hydroxyquinoline (8-HQ) were chosen as modifiers. This resulted in the composite 8-hydroxyquinoline/silica/amino kaolin (8-HQ@SiO2@AK), and the structural makeup, loading, hydrophobic characteristics, surface roughness, and corrosion resistance of 8-HQ@SiO2@AK and 8-hydroxyquinoline/silica/amino kaolin/epoxy resin composite coating (8-HQ@SiO2@AK/EP) was investigated. Based on these findings, the maximum contact angle of the hydrophobic composite coating was 88°, its roughness Ra was 3.09 nm, and the hardness and adhesion were unaltered compared to silica-modified kaolin/epoxy composite coatings (SiO2@AK/EP). The impedance modulus |Z|0.01 Hz of the composite was 3.662×109 Ω • cm2 after 30 days of immersion, which indicated significantly enhanced corrosion resistance.