Atmospheric Water Harvesting (AWH) represents a feasible technological approach for mitigating water shortages, offering a potential strategy for the global issue of water scarcity. This study uses ether extraction to explore the synthesis of keggin-type Heteropolyacid Phosphomolybdenum tungstic Acid (HPA). The unique properties of this heteropolyacid, such as strong acidity, high specific surface area combined with a hierarchical pore architecture, and electrostatic interactions, make it highly effective for water adsorption. By modifying the HPA, a new class of copolymer monomers (HPAs) was developed and then copolymerized with acrylic acid, resulting in the creation of a multifunctional polymeric material (HPAs-PAA) that has excellent biphasic water adsorption capacity to adsorb both water vapor and liquid water. The synthesized material has significant performance characteristics, with an adsorbent capacity of 1837 g/g of water vapor, a wide hygroscopic range (25 % RH-90 % RH), and a maximum water vapor adsorption capacity of 1381.8 mg/g at 90 % RH. Furthermore, under standard solar irradiation conditions of 1 kW/m2, the material demonstrates a desorption rate of 0.29 kg/m2/h, showcasing exceptional desorption performance. After 30 adsorption-desorption cycles, the HPAs-PAA retains 84.57 % of its initial capacity (from 951.6 mg/g to 804.8 mg/g), indicating remarkable water vapor adsorption-desorption cycle stability. Furthermore, the material exhibits excellent moisture retention capabilities and holding properties, rendering it an ideal adsorbent for AWH in arid environments. It also provides a new approach to developing sustainable water harvesting materials.