Ferritin‐Inspired Encapsulation and Stabilization of Gold Nanoclusters for High‐Performance Photothermal Conversion

Abstract Gold nanoclusters (AuNCs) are highly promising for applications in photothermal conversion due to their exceptional surface area and optical properties. However, their high surface energy often leads to aggregation, compromising stability and performance. To address this, we developed a ferritin‐inspired covalent organic cage with a near‐enclosed cavity to physically stabilize AuNCs. This superphane cage coordinates with Au 3 ⁺ ions, forming highly stable and uniform AuNCs upon reduction. The encapsulated AuNCs exhibit broad absorption (250–2500 nm) and achieve remarkable photothermal conversion efficiency of 92.8% under 808 nm laser irradiation. At low power densities (0.5 W/cm 2 ), temperatures reach 150 °C, and under one‐sun illumination (1 kW/m 2 ), the solar‐to‐vapor generation efficiency reaches 95.1%, with a water evaporation rate of 2.35 kg m −2 h −1 . Even after 20 seawater desalination cycles, the system maintains a stable evaporation rate of 2.24 kg m −2 h −1 , demonstrating excellent salt tolerance and durability. This ferritin‐inspired strategy offers a robust platform for enhancing the stability and performance of AuNCs, advancing sustainable energy and water purification technologies.