High‐performance water purification and desalination by solar‐driven interfacial evaporation and photocatalytic VOC decomposition enabled by hierarchical TiO ₂ ‐CuO nanoarchitecture

Abstract

Solar-driven interfacial evaporation for clean water generation has drawn significant attention as a promising and environmentally friendly avenue to tackle the global issue of water scarcity. The collected condensate can be free from most pollutants and impurities of diverse undrinkable water sources, such as heavy metals, organic dyes, minerals, and salts. However, when water is contaminated by volatile organic compounds (VOCs), this approach is ineffective because VOCs also evaporate and even can be enriched in the condensate. Here, we demonstrate TiO 2 -loaded CuO nanowire-covered Cu foam (TiO 2 -CuO-Cu foam ) for efficient solar-driven interfacial evaporation and synchronous removal of VOCs via photocatalytic degradation. The TiO 2 -CuO-Cu foam nanoarchitecture possesses high solar absorption, quasi-onedimensional water pathway, super-hydrophilicity for ultrafast water transport, long-term stability, and potential for cost-effective and scalable production for both VOC removal and desalination, meeting World Health Organization potable water standards. Our TiO 2 -CuO-Cu foam evaporator simultaneously demonstrates high solar evaporation efficiency of 86.6% and efficiency of 80.0% for the removal of VOCs under one sun (i.e., 1 kW m À2 ). This result may open new opportunities for energy-efficient, clean water generation from real-world water sources using solar energy. Novelty StatementTiO 2 -loaded CuO nanowire-covered Cu foam (TiO 2 -CuO-Cu foam ) was obtained through the facile and green synthesis process. The TiO 2 -CuO-Cu foam nanoarchitecture possesses high solar absorption due to surface nanostructuring, quasi-one-dimensional water pathway for localized thermal management, superhydrophilicity for ultrafast water transport, TiO 2 -CuO heterojunction for enhanced photodegradation of VOCs without consumption of chemical reagents, Yikuan Tian and Huachao Yang contributed equally to this work.

Enhancing solar absorbance using a 2D graphene oxide/CuO composite film for efficient solar desalination

“…9c summarizes the performance of various evaporators prepared using GO or CuO. 28,31,40–49 Clearly, GO/CuO-2 demonstrated an exceptional evaporation rate and efficiency, making a promising candidate for high-performance ISSG.…”

Systematic Review of Material and Structural Design in Interfacial Solar Evaporators for Clean Water Production

“…Black TiOx/stainless steel mesh [303] 0.8012 50.3% TiO 2 /CuO/Cu foam [275] 1.28 86.6% TiO 2 has been studied in harvesting solar energy due to economic access, good stability, and nontoxicity. [278] However, relatively wide bandgap (3.2 eV) makes it difficult to be triggered by light with wavelength higher than 400 nm and also excited electrons and holes with larger bandgap favor to emit photons and lower the solar thermal conversion efficiency.…”

“…[ 1,260,270–273 ] Another advantage of semiconductors applied the interfacial solar evaporation is that photocatalysis could be introduced at the same time to efficiently degrade pollutants in wastewater and with the assistance of temperature increase on the materials, the performance of thermal photodegradation could be further enhanced. [ 273–275 ]…”

“…[1,260,[270][271][272][273] Another advantage of semiconductors applied the interfacial solar evaporation is that photocatalysis could be introduced at the same time to efficiently degrade pollutants in wastewater and with the assistance of temperature increase on the materials, the performance of thermal photodegradation could be further enhanced. [273][274][275] The detailed summary of semiconductor-based interfacial solar evaporators is given in Table 9, including using MoS 2 , [261,263,273,276,277] MoC, [267,269] TiO 2 , [278][279][280][281][282] CuO, [264][265][266] g-C 3 N 4 , [283] bimetal semiconductors, [284,285] and hybrids with carbon materials such as PDA [265,284] and rGO [286,287] on various kinds of substrates such as foam/aerogel, hydrogel, membrane, mesh, wood, and textile. For instance, Xiao et al [262] fabricated a MoS 2 /sodium alginate hydrogel on the melamine sponge by simple dipping and drying followed by crosslinking method.…”

Progress on TiO2-based materials for solar water interfacial evaporation

“…Due to these properties, the microporous hydrogel-based evaporator had 77.39% evaporation efficiency with a 1.853 Kg m −2 h −1 evaporation rate. In addition, Tian et al (2022) fabricated TiO 2 -loaded CuO nanowire-covered Cu foam (TiO 2 -CuO-Cu foam ) simultaneously, demonstrating a high solar evaporation efficiency of 86.6% with about 80.0% VOCs removal efficiency under 1 Sun irradiation. Yuan et al (2021) presented a hierarchical 1D/2D TiO 2 @ MoS 2 core-shell network on a Ti mesh, which had efficient solardriven interfacial water evaporation and pollutant removal with a high light absorption of 96.5% and a water evaporation rate of 1.42 kg m −2 h −1 under 1 Sun.…”