Design of Solar Energy Harvesting Reactor From 2D to 3D Structures for Solar Thermal Conversion

ABSTRACT Solar energy utilisation is pivotal for advancing sustainable and renewable energy solutions, yet the rational design of high‐efficiency photothermal conversion devices remains a critical challenge. This paper systematically examines the evolution of photothermal reactor architectures from two‐dimensional (2D) to 3D structures, emphasising their respective roles in overcoming performance limitations. We highlight the superior spectral selectivity and enhanced high‐intensity irradiation absorption of 2D materials, alongside the advantages of 3D configurations in optimising temperature distribution and energy transfer efficiency. Two fundamental design strategies are critically evaluated: enhancement of intrinsic photothermal material properties and engineering of optical structures for improved light management. Key material considerations, including fabrication techniques, incidence angle dependence, light absorption bandwidth and application‐specific performance, are comprehensively discussed. Our analysis reveals that advanced 2D photothermal reactor design increasingly relies on extending optical path lengths and transcending inherent material constraints, accompanied by growing complexity in optical effect integration. This review provides a roadmap for the synergistic design of 2D and 3D photothermal reactors, aiming to accelerate their commercial viability and contribute to the next generation of solar energy utilisation technologies.