Design, Synthesis, and Applications of Atomically Precise Photocatalysts

ConspectusPhotocatalysis represents a cornerstone of sustainable chemistry. It provides a promising green and highly efficient catalytic pathway for harnessing solar energy to drive crucial chemical reactions, including water splitting, CO2 reduction, and pollutant degradation. Nevertheless, the widespread industrial deployment of this technology still encounters considerable challenges. The main limitations include the inherently low density of accessible catalytic active sites on conventional photocatalyst surfaces. In addition, the rapid and undesired recombination of photogenerated electron–hole pairs significantly diminishes quantum efficiency before these charge carriers can engage in surface reactions. As fundamental research in photocatalysis has advanced, the underlying mechanisms governing light absorption, charge generation, separation, migration, and surface reactions have been progressively elucidated. As a result, research is now focused on band structure engineering and recombination suppression to enhance photocatalytic performance.In this context, single-atom catalysts (SACs) have emerged as a particularly suitable and revolutionary approach. SACs feature isolated metal atoms anchored onto a supporting substrate, achieving near 100% atomic utilization efficiency. The unique and strong interactions formed between the dispersed metal atoms, the support material, and the reactants can lead to the creation of novel, highly active catalytic sites. Crucially, these interactions exert a profound influence on the electronic properties of the host photocatalyst. SACs can effectively modulate the band gap, tailoring light absorption characteristics, and, more importantly, significantly reduce the recombination rate of photogenerated electrons and holes by acting as efficient electron traps or facilitating rapid charge transfer pathways. Furthermore, the distinct spatial geometric configuration and unique electronic features intrinsic to SACs, arising from the quantum confinement effect and the specific coordination environment of the single atoms, often enhance the intrinsic activity of the original catalytic sites on the photocatalyst surface, leading to superior reaction kinetics.In this Account, we summarize our group’s recent progress over the past decade in the synthesis of single-atom catalysts (SACs), with a focus on the underlying design principles and synthetic methodologies. We systematically analyze the conceptual frameworks and synthetic strategies employed in our studies. Furthermore, we highlight two future research directions in photocatalysis proposed by our group: photocatalytic CO2 conversion and photocatalytic organic synthesis. We argue that the inherent green and sustainable characteristics of photocatalytic reactions, when combined with their unique ability to harness solar energy, an abundant yet intermittent natural resource, position them as highly promising technologies for addressing some of the most pressing global challenges. These include environmental remediation, carbon neutrality, and the advancement of sustainable chemical manufacturing.