Ali Asghar, Qasim Muhammad, Piatkowski Piotr A, Boltaev Ganjaboy, Reddy Andra N K, Alnaser Ali S
Materials Science and Engineering Program, College of Arts and Sciences, American University of Sharjah Sharjah 26666 United Arab Emirates
Department of Physics, American University of Sharjah Sharjah 26666 United Arab Emirates.
Nanoscale Adv. 2025 May 19. doi: 10.1039/d5na00249d.
Interfacial solar desalination relies on enhanced optical absorbance, heat localization at the air/water interface, and effective water management on photothermal evaporators. However, its commercialization is hindered by marginal vaporization rates, processing challenges, and unacceptable stability. This study presents a novel substoichiometric molybdenum oxide (MoO ) solar absorber with a unique nanochannel-on-microchannel architecture, designed to enhance broadband absorbance, concentrate heat within thin layers of water, and promote superwicking. For the first time, a tightly focused, non-diffracting Bessel laser beam is employed to create nanochannels layered over hierarchically designed open microchannels. The nanochannels promote cluster evaporation by distributing water in very thin layers, while the hierarchical morphology and rough oxide microchannels contribute to strong broadband absorbance and generate capillary forces that enable superwicking on the surfaces at any angle. Outdoor tests demonstrated exceptional performance, with evaporation rates of 4.21 kg m h under 1 sun and 19.3 kg m h under 3 suns, outperforming existing evaporators. Comparison of these rates with indoor rates under controlled lab conditions suggests that ∼50% of the total evaporation rate was contributed by wind and ambient temperature. Moreover, the impact of water salinity on interfacial evaporation is revealed by performing experiments and comparing results from both saline and deionized water. Salt ions that are specifically adsorbed at the solution/MoO interface are found to inhibit direct contact between MoO and the secondary water, thereby enhancing evaporation by lowering the adsorption energy. A comprehensive analysis of hydrogen bonding states, the electrical double layer, temperature measurements, vaporization enthalpy, and efficiency calculations corroborates the performance improvements. Our findings demonstrate significant potential for large-scale solar desalination and provide new possibilities for advancing interfacial solar desalination.
界面太阳能海水淡化依赖于增强光吸收、在空气/水界面处的热局域化以及光热蒸发器上有效的水管理。然而，其商业化受到蒸发速率低、加工挑战和稳定性不佳的阻碍。本研究提出了一种具有独特的纳米通道-微通道结构的新型亚化学计量氧化钼（MoO ）太阳能吸收器，旨在增强宽带吸收、在薄层水中集中热量并促进超芯吸作用。首次采用紧密聚焦、非衍射的贝塞尔激光束在分层设计的开放微通道上创建纳米通道层。纳米通道通过将水分布在非常薄的层中来促进簇状蒸发，而分层形态和粗糙的氧化物微通道有助于实现强宽带吸收，并产生毛细作用力，使表面在任何角度都能实现超芯吸作用。户外测试展示了卓越的性能，在1个太阳光照下蒸发速率为4.21 kg m h，在3个太阳光照下为19.3 kg m h，优于现有蒸发器。将这些速率与受控实验室条件下的室内速率进行比较表明，总蒸发速率的约50%由风和环境温度贡献。此外，通过进行实验并比较盐水和去离子水的结果，揭示了水盐度对界面蒸发的影响。发现特异性吸附在溶液/MoO 界面的盐离子会抑制MoO 与二次水之间的直接接触，从而通过降低吸附能来增强蒸发。对氢键状态、双电层、温度测量、汽化焓和效率计算的综合分析证实了性能的提升。我们的研究结果表明大规模太阳能海水淡化具有巨大潜力，并为推进界面太阳能海水淡化提供了新的可能性。
