Solar steam generation (SSG) has been a promising solution to water scarcity by evaporating seawater at a low cost and in an eco-friendly way. However, small molecule-based photothermal materials utilized for SSG interfacial layers have been limited owing to their narrow absorption and low solar-thermal conversion. In this work, three neutral d⁸ transition-metal (nickel, palladium, and platinum) bis(dithiolene) complexes with an intervalence charge-transfer that induces the second near-infrared (NIR-II) absorption and square-planar geometries favoring intermolecular stacking were synthesized and identified. The metal complex-adsorbed SSG interfacial layer exhibits broad absorption from visible to NIR-II regions for effective solar-light harvesting as well as a high photothermal conversion temperature ranging 155–186 °C under 1064 nm of laser irradiation for 16 s via advancing nonradiative heat release. Among them, the best solar energy-to-vapor conversion efficiency of 95.64% and a water evaporation rate of 1.406 kg m⁻² h⁻¹ under one sun irradiation were achieved for nickel complex-based SSG devices. This study provides a strategy for designing solar-thermal conversion materials based on NIR-II organometallic complexes and further successfully advancing them into high-performing solar-driven evaporation applications.

中文翻译：

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具有间隔电荷转移跃迁的中性 d8 金属配合物可触发有效的 NIR-II 光热转换，用于太阳能驱动的海水淡化

太阳能蒸汽发电（SSG）通过以低成本和环保的方式蒸发海水，成为解决水资源短缺问题的一种有前途的解决方案。然而，用于SSG界面层的小分子光热材料由于其窄吸收和低太阳热转换而受到限制。在这项工作中，三种中性 d ⁸过渡金属（镍、钯和铂）双（二硫烯）配合物具有间隔电荷转移，可诱导第二次近红外（NIR-II）吸收和有利于分子间相互作用的方形平面几何形状堆积进行了合成和鉴定。金属络合物吸附的 SSG 界面层表现出从可见光到 NIR-II 区域的广泛吸收，可有效收集太阳光，并且通过先进的非辐射技术，在 1064 nm 激光照射下 16 s 的光热转换温度范围为 155-186 ° C热量释放。其中，镍配合物基SSG装置的最佳太阳能-蒸汽转换效率为95.64%，一次太阳照射下水蒸发率为1.406 kg m ^-2 h ^{-1 。}这项研究提供了一种设计基于 NIR-II 有机金属配合物的光热转换材料的策略，并进一步成功地将其推进到高性能太阳能驱动蒸发应用中。