Black titania/graphene oxide nanocomposite films with excellent photothermal property for solar steam generation
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lar steam generation is an efficient and green technology for desalination and drinking water purification, however, impeded by high cost, low efficiency, and complicated process. Black titania is expected to exhibit excellent solar steam performance due to its outstanding light absorption properties, chemical stability, low cost, and innocuity. Herein, we design a high absorbing and efficient solar steam generation system based on a black titania/graphene oxide nanocomposite film affixed to airlaid paper wrapped over the surface of expandable polyethylene foam; the system possesses several important criteria required for the ideal solar steam generator: wide-spectrum absorption, adequate water supply, reduced heat loss for localized water heating, and porous structure for steam flow. Remarkably, we realized a solar thermal conversion efficiency of 69.1% under illumination of 1 kW/m2 without solar concentration, and the device delivered remarkable cycle stability.
I. INTRODUCTION
The world is facing a very serious problem of water shortages.1 With the growth of population and the expansion of industrialization, more frequently, agricultural activities and environmental pollution result in more urgent problem of water purification.2 Various technological solutions have been developed to meet the increasing demand for fresh water,3 among which desalination and water reuse are developed to obtain freshwater.4–6 However, these methods result from high cost, low efficiency, and complicated process. Solar steam generation is an efficient and green technology for desalination systems and drinking water purification. Earlier solar thermal conversion techniques basically depend on highly absorbing materials and optical concentration to heat bulk liquid,7 such as charcoal,8 black cloth,9 and solar still.10,11 Even if these materials have excellent absorption properties, their photothermal conversion efficiency is still at a very low level,12 and it unavoidably results in unnecessary heat loss due to the energy transfer to the nonevaporative portion of bulk water. The conventional bulk heating of water is not a rational choice for water evaporation, and thus there is a need for a solar energy acquisition system with low optical concentration and high conversion efficiency. Contributing Editor: Xiaobo Chen a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2018.25
However, solar steam technology can directly convert liquid water into vapor through surface plasmon resonance effects without heating bulk water.13–16 Many plasmonic nanoparticles have been studied to generate solar steam, such as Au nanoparticles,17,18 3D selfassembly of Al nanoparticles,19 Ag polyhedron nanoparticles,20 graphene,21 and black gold membranes with ultrabroadband plasmonic.22 Although the photothermal conversion efficiency is improved to a great extent, the dispersed particles are easily aggregated and deposited at high temperature, and the price of Au is high, so that it is not practical for large-scale production. To solve
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