The energy efficiency in solar steam generation by 2D photothermal materials has approached its limit. In this work, we fabricated 3D cylindrical cup-shaped structures of mixed metal oxide as solar evaporator, and the 3D structure led to a high energy efficiency close to 100% under one-sun illumination due to the capability of the cup wall to recover the diffuse reflectance and thermal radiation heat loss from the 2D cup bottom. Additional heat was gained from the ambient air when the 3D structure was exposed under one-sun illumination, leading to an extremely high steam generation rate of 2.04 kg m⁻² h⁻¹. The 3D structure has a high thermal stability and shows great promise in practical applications including domestic wastewater volume reduction and seawater desalination. The results of this work inspire further research efforts to use 3D photothermal structures to break through the energy efficiency limit of 2D photothermal materials.

二维光热材料生产太阳能蒸汽的能效已接近极限。在这项工作中，我们制作了混合金属氧化物的3D圆柱杯形结构作为太阳能蒸发器，由于杯壁能够回收太阳光，该3D结构在一次阳光照射下可产生接近100％的高能效。二维杯底部的漫反射率和热辐射热量损失。当3D结构在阳光照射下暴露时，会从环境空气中获得更多热量，从而导致2.04 kg m ^-2 h ^-1的极高蒸汽产生率。3D结构具有很高的热稳定性，并在包括生活废水减少和海水淡化在内的实际应用中显示出广阔的前景。这项工作的结果激发了进一步的研究努力，以使用3D光热结构突破2D光热材料的能效极限。