Lu Zhu,Yousen Zhu,Xuanru Ren,Ping Zhang,Jianghao Qiao,Peizhong Feng
MoSi 2 -MoB-ZrO 2 composite powders are one-step synthesized prepared by self-propagating high-temperature synthesis (SHS), which are further utilized to prepare the oxidation protective coatings by spark plasma sintering (SPS) method on molybdenum substrate. Microstructure and properties of the coatings were investigated and determined. Oxidation behavior of the coatings at high temperature was also studied. The results showed that the composite coating is dense and crack-free due to the addition of ZrO 2 , which is beneficial for the decrease of mismatch in coefficient of thermal expansion, and no void exists in the diffusion layer owing to the diffusion of Si, which is inhibited by adding MoB. Compared with the pure MoSi2 coating, the high hardness of the composite coating is enhanced by about 20% while the fracture toughness of the composite coating is improved by about 25%, which makes the occurrence of intergranular fracture , crack deflection and crack bridging. After oxidation at 1400 °C for 80 h, MoSi 2 coating failed while xMoSi 2 -MoB-3ZrO 2 (x = 3, 4, 5) composite coating still kept its protective effect. Only a little substrate is consumed during oxidation and improved oxidation resistance is gained by MoSi 2 -MoB-ZrO 2 composite coating. 3MoSi 2 -MoB-3ZrO 2 coating shows the relatively best oxidation resistance due to the formation of crack-free oxide film on the surface of the coating.
Li-CO₂ batteries promise ultrahigh theoretical energy densities but face efficiency limitations owing to the sluggish decomposition of stable Li 2 CO 3 . Redirecting the redox pathway toward Li 2 C 2 O 4 overcomes this challenge, but its metastability leads to facile conversion to Li 2 CO 3 during discharge. Herein, subsurface electronic confinement is engineered in Mo-based catalysts, leveraging electron-deficient boron (B) as electron traps in the subsurface atomic layers to tailor their interfacial electronic landscapes. This design elevates the Mo d-band and intensifies the hybridization between the Mo d-orbitals and O p-orbitals of oxalate. Strengthening the Mo-O interaction stabilizes Li 2 C 2 O 4 against decomposition. The highly reversible and stable redox chemistry enabled by MoB results in an exceptional cycling stability and energy efficiency across a wide temperature range, with an expanded practical viability. At 70 µA cm −2 , the MoB-based battery is cycled for >1400 h with a high energy efficiency of >85%. The energy efficiency even remains at >90% for ≈150 h at a high temperature (90 °C). This study pioneers a material design framework for use in stabilizing metastable products within Li-CO 2 batteries, advancing their applicabilities in extreme environments, such as deep-earth exploration, by revealing the role of subsurface charge redistribution in steering reaction pathways.
Mainstream anaerobic treatment has the potential to capture organic energy, and represents a sustainable development trend, but with the problems of low biogas quality and dissolved methane emissions. In this study, methane-driven ammonia recovery of anaerobic effluent was proposed. A 380-day long-term experiment, which was divided into four phases according to different aeration modes, was conducted. The ammonia conversion and microbial characteristics shows that ammonia oxidizing bacteria (AOB) were constrained during Phases 2 (DO: <0.2 mg L −1 ) and 4 (DO: 0.1–1.6 mg L −1 ), and were active during Phase 3 (DO: 2–4 mg L −1 ). During phase 4, when the intermittent aeration was used, the total nitrogen removal rate was higher than during Phases 2 and 3, and nearly 100% ammonia was removed. Methylomonas , a genus of methane oxidizing bacteria (MOB), was enriched during Phase 4. The serum bottle experiment confirmed that the ammonia removal occurred through the MOB assimilation. The protein content in the CH 4 -added group was 35.5%, which was higher than in the group without CH 4 (23.3%). The powerful ammonia assimilation and protein synthesis capabilities of MOB give a meaning to the anaerobic effluent for ammonia recovery and protein production. Intermittent aeration could be used to constrain AOB and improve ammonia recovery efficiency.
危险品化学品经营许可证（带存储）