Photothermal conversion materials are critical in the development of solar-driven interfacial evaporation techniques; however, achieving a high energy conversion efficiency remains challenging owing to the high cost and instability of light-absorbing materials, in addition to the difficulties of simultaneously improving light absorption while suppressing heat loss. A black silicon (Si) powder with a porous structure was prepared by chemical etching of a low-cost commercial micron-sized Al–Si alloy, and a flexible Janus black Si photothermal conversion membrane was constructed. The partially broken spherical particles and porous structure obtained after etching enhanced the refraction of light from the Si powder, imparting the prepared membrane with an average light absorption rate of 95.95% over the solar spectrum. Evaporation from the membrane increased the intermediate water content and reduced the equivalent evaporation enthalpy. The thermal conduction loss was inhibited through a one-dimensional water transport structure, and the membrane achieved a water evaporation rate of 2.17 kg m^–2 h^–1 and a photothermal efficiency of 94.95% under 1 sun illumination. Benefiting from the broadband absorption and high photothermal efficiency of black Si powder, surface modification of hydrophobic polydimethylsiloxane, and directional salt-out structure design, the evaporation rate of the Janus black Si membrane-based system in a 10% NaCl solution was maintained >2.10 kg m^–2 h^–1 after 7 days of continuous evaporation cycles. The removal rate of metal ions from simulated seawater and from practical wastewater containing complex heavy metals reached >99.9%, indicating the promising potential of black Si membrane for application in solar-driven interfacial water purification.

中文翻译：

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用于高效太阳能驱动界面水净化的柔性 Janus 黑硅光热转换膜


光热转换材料对于太阳能驱动界面蒸发技术的发展至关重要；然而，由于光吸收材料的高成本和不稳定性，以及同时提高光吸收和抑制热损失的困难，实现高能量转换效率仍然具有挑战性。通过化学刻蚀低成本商用微米级铝硅合金制备了具有多孔结构的黑硅（Si）粉末，并构建了柔性Janus黑硅光热转换膜。蚀刻后获得的部分破碎的球形颗粒和多孔结构增强了硅粉对光的折射，使制备的膜在太阳光谱范围内的平均光吸收率为95.95%。从膜中蒸发增加了中间水含量并降低了当量蒸发焓。通过一维水传输结构抑制热传导损失，膜在高温下实现了2.17 kg m ^–2 h ^–1 的水蒸发速率和94.95%的光热效率。 1 太阳光照。受益于黑硅粉末的宽带吸收和高光热效率、疏水性聚二甲基硅氧烷的表面改性以及定向盐析结构设计，Janus黑硅膜基体系在10% NaCl溶液中的蒸发速率保持>2.10 kg m ^–2 h ^–1 连续蒸发循环 7 天后。模拟海水和含复杂重金属的实际废水中金属离子去除率均达到>99。9%，表明黑硅膜在太阳能驱动的界面水净化中的应用前景广阔。