Tree‐Inspired Ultralong Hydroxyapatite Nanowires‐Based Multifunctional Aerogel with Vertically Aligned Channels for Continuous Flow Catalysis, Water Disinfection, and Solar Energy‐Driven Water Purification

Abstract

Water pollution and freshwater shortage have deteriorated the global water crisis. Developing sustainable methods to alleviate contaminated water has become an urgent affair. Herein, inspired by water transportation and transpiration of natural trees, the authors report an ultralong hydroxyapatite nanowires‐based biomimetic aerogel with vertically aligned channels and multiple functions for continuous flow catalysis, water disinfection, solar energy‐driven water purification, and seawater desalination. Ultralong hydroxyapatite nanowires act as carriers to immobilize catalyst nanoparticles and serve as building blocks to assemble with chitosan to form the biomimetic aerogel with structure‐function integration. Benefiting from the interconnected cellular structure, unidirectional aligned channels, nanowire‐interwoven networked pore wall, and evenly distributed catalyst nanoparticles, the biomimetic aerogel exhibits high catalytic activity (97.6% treatment efficiency) and permeability (1786 L m−2 h−1), excellent recyclability and stability in continuous flow catalytic degradation of methylene blue solely driven by gravity. The biomimetic aerogel exhibits excellent performance for bacteria removal and anti‐biofouling. The superior photothermal conversion and heat confinement properties enable the biomimetic aerogel with a high efficiency (86.7%) for solar energy‐driven seawater desalination and wastewater purification under one sun irradiation. The multifunctional biomimetic aerogel has promising applications in catalytic reactions, wastewater remediation, and environmental engineering.

Protein-Based Flexible Conductive Aerogels for Piezoresistive Pressure Sensors

“…During freezing, the protein materials (and PEDOT-S) are accumulated among the side of ice crystals. 64 The gel-network will be deformed during the growth of ice crystals and a stronger gel will able to counteract severe mechanical deformation. As observed during rheological measurements, addition of PEDOT-S leads to an increased gel strength, which is likely to be the origin of the large difference in microstructure observable between gels made with and without PEDOT-S. Gels with added PEDOT-S are able to withstand severe deformation of growing ice crystals and as a result form a network structure ( Figure 5 b,e).…”

Fibrous Aerogels for Solar Vapor Generation

“…Copyright (2018) American Chemical Society. Reprinted with permission from ( Xiong et al, 2021 ). Copyright (2021) WILEY VCH.…”

“…Hydroxyapatite (HAP) is a mineral predominantly found in our bones and teeth ( Farokhi et al, 2018 ). Ultralong flexible HAP nanowires could be prepared by hydrothermal method and used as substrate for SVG ( Figure 5B ; Xiong et al, 2021 ). HAP nanowires have diameters of 10–20 nm and lengths of hundred micrometers.…”

“…During the process, adequate water supply is critical for improving the evaporator performance and achieving higher efficiency, the pathway used to transport water differs among evaporators( Zhang Y. et al, 2020 ). The water pathways can be divided into three categories on the basis of thermal management design: 1D array, 2D lamella, and 3D porous structure ( Li et al, 2016 ; Li et al, 2017b ; Xiong et al, 2021 ; Figures 9A–C ). The 1D array is a narrow path for water to climb up to the surface of system, mainly intended to reduce heat loss.…”

“…(C) Water supply provided by 3D porous channel that is directly soaking in water. Reprinted with permission from ( Xiong et al, 2021 ). Copyright (2021) WILEY VCH.…”