Advances on Single‐Atom‐Based Dual‐Site Photocatalysts: Fundamentals, Mechanisms, and Applications

Abstract

Single‐atom catalysts (SACs) have emerged as leading‐edge research in the field of photocatalysis due to outstanding photocatalytic performance, maximum atomic utilization efficiency, and well‐defined catalytic active sites. However, the singular functionality of active sites in SACs restricts their applications in complex redox reactions involving multiple intermediates and reaction pathways. To circumvent this limitation, a second site comprising single atoms (SA), alloys, clusters, or nanoparticles is proposed to establish SA‐based dual‐site photocatalysts (SA DSPs). While maintaining 100% atomic utilization, the second site and site–site collaboration endow SA DSPs with superior photocatalytic activities to surpass those of SACs. In this review, the latest investigations on SA DSPs featuring diverse compositions, electronic and geometric configurations, site–site collaboration, and metal–support interactions are summarized. Thereafter, the mechanisms underlying enhanced photocatalytic activities are elucidated regarding the roles of the dual sites in charge‐carrier dynamics and surface reactivity. Furthermore, the state‐of‐the‐art applications in photocatalytic hydrogen evolution, CO2 reduction, and methane oxidation, etc., over SA DSPs are discussed. It is anticipated that this review will offer insights into precise control and design of dual sites in photocatalysts, thereby advancing photocatalysis toward commercial viability.