Over 11 kg m^–2 h^–1 Evaporation Rate Achieved by Cooling Metal–Organic Framework Foam with Pine Needle-Like Hierarchical Structures to Subambient Temperature

Abstract

Solar steam generation has become a hot research topic because of its great potential to alleviate the drinking water crisis without extra energy input. Although some efforts focusing on designing spatial geometry have been made to multiply the evaporation performances of up-to-date three-dimensional evaporators, they still have some shortcomings, such as low material and space utilization efficiencies, complex spatial geometry, energy loss due to the hot solar absorption surface, and salt crystallization due to inefficient water supply. Herein, a biomimetic copper-based metal−organic framework (Cu−Cu(OH) 2 -MOF) foam sheet with interconnected pores and pine needle-like hierarchical structures consisting of Cu(OH) 2 nanowires and MOF nanowhiskers is fabricated. The pine needle-like hierarchical structures of Cu−Cu(OH) 2 -MOF foam contribute to absorbing solar energy and supplying sufficient water by trapping incident light and enhancing the capillary force, respectively. Inspired by drying clothes outside under solar irradiation, through exposing one end of the Cu−Cu(OH) 2 -MOF foam to air, the biface evaporator achieves a subambient evaporation surface temperature and an evaporation rate of up to 3.27 kg m −2 h −1 under only one sun illumination. Furthermore, when coupled with an air flow, the biface evaporator realizes an excellent evaporation rate of 11.58 kg m −2 h −1 with an energy efficiency of 160.07% even in seawater, ensuring its great application prospect to be used in drinking water production and seawater desalination.

An upcycled wood sponge adsorbent for drinking water purification by solar steam generation

“…62 Since the air-flow in an outdoor environment can result in an unsaturated state at the evaporator surface resulting in a higher rate of evaporation from the surface of the evaporator. 67 In addition, the outdoor light intensity was probably much higher than 1 sun during a sunny summer day. Based on the differential scanning calorimetry (DSC) measurement results for PVA-MWS-Hg 2+ (Fig.…”

Exhausted Cr(VI) Sensing/Removal Aerogels Are Recycled for Water Purification and Solar‐Thermal Energy Generation

“…[ 41 ] In addition, the air flow will cool the surface of the evaporator under the outdoor experiment, and the air with high humidity on the evaporator surface is continuously replaced by the new air with low humidity, which would provide an unsaturated state on the surface of the evaporator, thus leading to a high evaporation efficiency. [ 42 ] Subsequently, the leakage of Cr(VI) of the MS x ‐CPC aerogel in aqueous was also investigated. It can be seen that the MS x ‐CPC aerogel leaked ≈1.1 mg mL –1 of chromium ions after being immersed for 50 h in aqueous solution, which was far below the requirement of total chromium in wastewater (2 mg mL –1 ) (Figure S15, Supporting Information).…”

Structure Dependent Broadband Optical Absorption in Carbon Nanotubes

“…In addition, the low filling fraction (∼1.5%) of FCNTs also contribute in trapping and subsequent absorption of the incident light efficiently (see Figure d, d1, and d2). Being a small-size conductor, the hot electron effects in FCNTs may be exploited in the field of solar steam generation and photothermal conversion. − The synergistic effects of all of these contributions make FCNTs a near-perfect broadband absorber, having an absorption of more than 99.97% up to a 60° incident angle . It should be highlighted here that the depictions in Figure on the interaction of incident radiation with varying CNT structures is qualitative.…”