Effect and Mechanism of Polyethylene Glycol (PEG) Used as a Phase Change Composite on Cement Paste

The use of phase change materials (PCMs) in the construction industry is one of the primary strategies for addressing the building industry’s present excessive energy usage. However, since PCMs must be enclosed before being used in construction, their efficiency is limited and their compatibility with concrete is poor. Thus, polyethylene glycol (PEG), a sequence of PCMs that may be put directly into concrete, is the target of this research. The fluidity, mechanical properties, thermal properties, hydration process, and hydration products of PEG-600 cement slurry were examined by TAM, XRD, FTIR, DSC, MALDI, etc., methods in this study. Furthermore, we tested the thermal properties of PEG-800 to confirm that the same depolymerization of PEG occurred in an alkaline environment. When PEG, with a molecular weight of 600 (PEG-600), dose was increased to 10%, both compressive and flexural strength fell by 19% and 18%, respectively. The phase change points of both PEG-600 cement paste and PEG-800 cement paste decreased to 10~15 °C, and the enthalpy of the phase change was about 6 J/g. Additionally, it was discovered that PEG entered the reaction during the hydration step. PEG underwent depolymerization and subsequently formed a complex with Ca2+. However, due to the large dose of PEG used in this investigation, a self-curing effect of PEG in concrete was not seen. The findings of this research suggest a novel use for PCMs: PEG may be directly applied to concrete to fulfill both mechanical and thermal requirements. Additionally, the number of hydration products and phase compositions remained almost constant

Green Chemistry: Advanced Electrocatalysts and System Design for Ammonia Oxidation

The hazards associated with handling hydrogen fuels have driven people to consider alternative clean and sustainable fuel types. Ammonia shows significant potential for this task as both a direct fuel and hydrogen carrier due to its unique features of facile transportation and low cost. Regarding this, electrochemical ammonia oxidation reaction (AOR) is the essential process for utilizing ammonia for energy applications, either for hydrogen production via ammonia splitting or energy generation via direct ammonia fuel cells, which is highly commercially promising. On this basis, the development of high‐performance and economic electrocatalysts for AOR is critical. In this review, the kinetics and mechanism of ammonia electrooxidation are first discussed to provide a foundation to understand the current issues associated with this technology, and then a comprehensive presentation on the different types of electrocatalysts for AOR is illustrated. Afterward, an outlook is presented and the possible research directions for AOR electrocatalysis are proposed, which is expected to shed light on the future development of this promising technology

Intravital Whole-Process Monitoring Thermo-Chemotherapy Via 2D Silicon Nanoplatform: A Macro Guidance and Long-Term Microscopic Precise Imaging Strategy

10.1002/advs.202101242Advanced Science816210124