Photothermal Catalytic Conversion Based on Single Atom Catalysts: Fundamentals and Applications

To achieve the stated goal of carbon neutrality, solar energy is regarded as the most promising alternative to traditional fossil fuels as a sustainable and clean resource. The key prerequisite for improving the efficiency of solar conversion is to maximize solar energy utilization. As a promising technology, photothermal catalysis can harness full-spectrum sunlight to activate photocatalysis and thermocatalysis through hot carrier generation and local heating. These synergistic catalytic effects driven by both light and heat can overcome the challenges associated with the low catalytic efficiency of photocatalysis and high energy consumption of thermocatalysis as well as modulate the reaction pathways to achieve desirable activity and selectivity. To achieve outstanding catalytic performance, photothermal materials should meet the requirements for sufficient electron-hole separation, efficient solar thermal generation, and abundant exposed active sites. Common fabrication strategies are based on the integration of materials with photo -active and photothermal conversion capabilities that often suffer from buried active sites, high temperature-induced deactivation, and complicated synthetic procedures. Single-atom catalysts (SACs) with isolated single atoms uniformly dispersed on a solid surface are advantageous for 100% atomic utilization and excellent catalytic activity. Therefore, these materials have received increasing attention for a wide range of applications. Many SAC substrates are endowed with hot carrier generation and photothermal conversion abilities under illumination. The strong chemical interaction between metal atoms and supports or surface lattice reconstruction can also prevent catalyst sintering even in long-term high-temperature environments. These unique features make SACs highly suitable for photothermal catalytic processes. Therefore, it is important to summarize recent advances in this field and provide in-depth insights into SACs-based photothermal catalysis to accelerate solar conversion technology development. Herein, the fundamental mechanisms and characteristics of photocatalysis, thermocatalysis, and photothermal catalysis are introduced and three photothermal catalysis modes categorized by driving force (including photo-driven thermocatalysis, thermal-assisted photocatalysis, and photo-thermal co-catalysis) are described and compared along with representative examples. The photothermal properties of SACs supported by carbon, semiconductors, and plasmonic materials are reviewed and pioneering studies for different applications are discussed in detail. Finally, the challenges and future research directions are proposed. This review aims to give a comprehensive understanding of photothermal catalytic processes driven by solar energy based on SACs and provide accessible guidelines for future development to achieve carbon neutrality targets.