Yunhong Liang

The Ti-6Al-4V alloy produced by laser powder bed fusion (LPBF) is severely limited in its service life in extreme aerospace environments due to insufficient high-temperature oxidation resistance and corrosion resistance. This study prepared Ti64-xMo alloys (x = 0, 0.05, 0.5, 5 wt.%) using LPBF technology, aiming to enhance their corrosion resistance at wide temperature range through the regulation of non-equilibrium microstructures. The results indicate that the addition of Mo induces a transition from a typical 'basket-like' structure to a fine 'lava-like' structure, characterized by distinct β grain boundaries and an increased volume fraction of the β phase. The corrosion current density of the Ti64-5Mo alloy at 25°C decreased by four orders of magnitude (from 10-2 to 10-6 A/cm2), and its corrosion resistance at 800°C was significantly improved, reducing the corrosion rate by approximately 50%. This material exhibits excellent corrosion resistance over a wide temperature range, attributed to the presence of molybdenum, which aids in the formation of a stable bimodal structure and promotes the development of secondary 'β' phase boundaries. This facilitates the generation of a dense protective layer on the surface and enhances the adhesion of the oxide layer, effectively preventing its spalling and achieving outstanding high-temperature protective performance.

Electrocatalytic synthesis of ammonia (NH₃) from nitrate (NO₃^-) is an effective approach for reducing nitrate pollutants in the environment and a promising method for ammonia synthesis under mild conditions. However, current catalyst synthesis is costly, and their application in real wastewater remains underexplored. Herein, we prepared high-efficiency copper-based single-atom-nanoparticle synergistic sites on carbon felt (Cu_SA/NP@C) from copper-containing wastewater. Trace Cu²⁺ in wastewater enables efficient nitrate reduction reaction (NO₃RR), and the effect of different Cu²⁺ concentrations was also investigated. The optimized Cu_SA/NP@C, with synergy between single atoms and nanoparticles, shows excellent activity: maximum Faraday efficiency of ~100% (at -0.3 V vs. RHE) and NH₃ yield of ~10 mg cm^-2. Theoretical calculations reveal that Cu single-atoms and nanoparticles synergistically act on the NO₃* and H* intermediates to promote nitrate hydrogenation to NH₃. A membrane electrode assembly with the Cu_SA/NP@C cathode achieves NH₃ synthesis at an industrial current density of 200 mA cm^-2 for over 90 hours. This “treating waste with waste” strategy offers new paths for nitrate wastewater recycling and green NH₃ synthesis advancement.