A facile solution-based technique was developed to grow vertically aligned TiO 2 nanowires with predominantly anatase phase on arbitrary substrates of stainless steel, glass, silicon wafer and carbon cloth at the low temperature of 80 C and in an open atmosphere.

radiative cooling requires a radiator with spectral selectivity, which refers to high absorptivity/emittance only in the atmospheric window (8-13 µm) and an extremely high solar reflectance (0.3-2.5 µm). [2] Traditional solutions combine a shielding layer and a radiative layer [3] or a radiative layer and a reflective metal layer. [2b,4] However, conventional materials and their combinations have a limited cooling effect because of their inability to satisfy the stringent requirements for selectivity. In 2014, Raman et al. [4b] reported an advanced 1D nanophotonic device that can reflect 97% of solar irradiance and allow selective radiation in atmospheric windows. It is the first device to achieve absolute cooling, that is, ≈4.9 °C sub-ambient temperature at a solar intensity (I solar ) of 850 W m −2 . Subsequently, many precision photonic devices have been used for PDRC, such as 1D photonic films [5] and metasurfaces, [6] as well as the product of their combination. [1a,7] These photonic devices have resulted in high efficiencies in PDRC applications. Nonetheless, large-scale applications of these devices remain to be a challenge owing to the demand for manufacturing processes.Recently, PDRC designs based on porous polymer structures have attracted considerable attention because of their high cooling performance, simplicity, applicability, and economic efficiency. [8] For example, Yang et al. [8a] reported a porous poly (vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP) coating that exhibit an average solar reflectance (R solar , 0.24-2.5 µm) and long-wave IR (LWIR) emittance (ε LWIR , 8-13 µm) of ≈96% and ≈97.3%, respectively, allowing for a sub-ambient temperature drops of ≈6 °C at a I solar of 890 W m −2 . Wu et al. [9] reported a hierarchically porous array polymethyl methacrylate film with a porosity of 60% and a close-packed micropore array on the surface combined with abundant random nanopores inside, which demonstrated excellent R solar (95%) and ε LWIR (98%), with sub-ambient cooling of ≈5.5 to ≈8.9 °C. The excellent sunlight reflection originates from the bimodal pore size distribution with nanopores centered at hundreds of nanometers and micropores centered at several microns and/or high porosity. However, there is a certain distance away from perfect spectral selectivity, [9,10] especially the less reflectivity in the mid-wave

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A new quaternary phosphonium modified hierarchically macro/mesoporous silica (named HPS-P) was prepared by a sol−gel method accompanied by phase separation by using PEG-10000 as surfactant and tetramethoxysilane as silicon source, followed by reacting with quaternary phosphonium. The resultant HPS-P containing large macroporous skeleton with an average diameter of 0.67 μm and mesopores with an average diameter of 10.3 nm has a specific area of ca. 254.7 m 2 g −1 . The adsorption of HPS-P for ReO 4 − was investigated, and the adsorption equilibrium could be achieved within 1 min; the adsorption isotherm data for ReO 4− could be well fitted with a modified Langmuir model. Moreover, HPS-P has excellent adsorption selectivities toward ReO 4 − with competing anions, including NO 3, and Cl − . The ΔH Θ and ΔS Θ of the Cl − /ReO 4 − ion-exchange reaction of HPS-P were calculated to be −4.5 kJ mol −1 and 12.6 J mol −1 K −1 , respectively, indicating that the adsorption of ReO 4 − onto HPS-P is a spontaneous physical adsorption process. In dynamic column experiment, HPS-P could be recycled by 2.2 mol L −1 HNO 3 with a good performance within 3 min. IR and XPS analysis confirmed that the adsorption mechanism is ion-exchange.