Augmenting Light‐to‐Heat Conversion Through 3D Scalable Palm Fiber for Energy Efficient Photothermal Solar Steam Generation

Tackling water scarcity is a pressing challenge, propelling recent advancements in solar steam generation (SSG). Recently, 3D photoabsorbers have outperformed their 2D counterparts in recovering light and minimizing heat losses, enabling a surge in exploring 3D materials and designs. Herein, 3D structures are fabricated using polydopamine (PDA) functionalized carbonized palm fibers (PDA c‐fiber) to shed light on the degree of improvement in SSG efficiency compared to their 2D counterpart. Specifically, two 3D models, a cone, and a cylindrical cup, are chosen for their inherent features, including a hollow cavity, circular base, and curved surface. These architectural elements play a crucial role in trapping light, facilitating reflections, and efficiently converting solar energy to heat through the photothermal effect. Scaling palm fibers from 2D to 3D significantly boosts SSG efficiency, from 67.9% to 103.7%, with water evaporation rate enhanced from 1.171 kg m −2 h −1 to 1.869 kg m −2 h −1 . Substantially, the 3D cup demonstrates superior photothermal performance primarily attributed to its heat recovery feature of the cup wall structure and circular basal area, enabling prolonged light‐to‐heat conversion. These findings provide valuable insights and foundation for developing efficient solar‐driven 3D upcycled photoabsorbers in the future.