NaBr-Impregnated Graphene Aerogel for Ammonia-Based Adsorption Heat Pump Application

Abstract

Ammonia-based adsorption heat pumps (AAHPs) are receiving significant attention due to effective low-grade thermal energy usability, cost-effectiveness, and ecofriendliness. For AAHPs to be widely utilized, it is essential to develop adsorbent materials that meet all of the characteristics required by AAHPs, which has been very challenging. Although metal halides (MHs) have excellent ammonia adsorption performance, their practical application to AAHPs has been limited due to their conformational instability during the ammonia adsorption−desorption process. Here, the MHimpregnated graphene aerogel (GA-NaBr) is studied from the perspective of AAHPs. Due to the pore structure formed by strong and flexible graphene networks and the high NH 3 affinity of the scaffolded NaBr, the composite addressed the MHs' issues, showing much-improved adsorption rate and stability compared to pure NaBr, while maintaining equivalent adsorption capacity. With its structural stability and impressive adsorption performance, GA-NaBr could be a breakthrough adsorption structure in the field of AAHPs.

Solar-Responsive Interface Self-Assembled MOF-Derived Foam for Adaptive Indoor Humidity Regulation

“…To solve the above challenges, porous materials such as silica gels, zeolites, covalent organic frameworks, and metallic organic frameworks are used for water absorption in humid areas. , However, their limitation in releasing water molecules at room temperature restricts their effectiveness for passive humidity regulation. Recently, in combination with photothermal materials, solar-driven passive adsorption pump membranes have gained special interest in the field of indoor humidity regulation because they can capture excess moisture in the air, and the water in the adsorbent can be simply released by the irradiation of sunshine. ,, In terms of adsorption materials, metal–organic frameworks (MOFs) are expected to be a more efficient adsorbent owing to their rapid adsorption efficiency, satisfactory water-harvesting capacity, low desorption temperature, and long-term durability. , Among them, partial MOFs such as Al-fumarate, MOF-303, MIL-100­(Fe), and MIL-101­(Cr) have already been proven as promising desiccants for atmospheric water collection. , These MOF-based adsorbents need to be further processed into adsorption wheels with functional binders due to their powdery nature. As an early exploratory work, we proposed an MOF hygroscopic fiber device for atmospheric water harvesting.…”

“…Recently, in combination with photothermal materials, solar-driven passive adsorption pump membranes have gained special interest in the field of indoor humidity regulation because they can capture excess moisture in the air, and the water in the adsorbent can be simply released by the irradiation of sunshine. 8,12,13 In terms of adsorption materials, metal−organic frameworks (MOFs) are expected to be a more efficient adsorbent owing to their rapid adsorption efficiency, satisfactory water-harvesting capacity, low desorption temperature, and long-term durability. 14,15 Among them, partial MOFs such as Al-fumarate, MOF-303, MIL-100(Fe), and MIL-101(Cr) have already been proven as promising desiccants for atmospheric water collection.…”