Support-Modulated Synergy in Dual-Atom Catalysts: Toward Rational Design and Enhanced Mechanisms for CO2 Photoreduction

With the escalating global energy crisis and intensifying greenhouse effect, solar-driven photocatalytic CO2 reduction technology for producing high-value chemicals or fuels has emerged as a highly promising and crucial strategy to address energy shortages and environmental issues simultaneously. Dual-atom catalysts (DACs), owing to ultrahigh atom utilization, flexibly tunable electronic structures, and unique dual-site synergistic effects, exhibit significant advantages in overcoming the activity limitations of conventional single-atom catalysts (SACs) and optimizing the reaction kinetics of CO2 reduction. As an indispensable component of DACs, the support not only stabilizes the bimetallic active sites and prevents agglomeration, but also modulates the electronic states and coordination environments of the active sites through metal-metal and metal-support interactions, thereby enhancing CO2 adsorption and activation, accelerating charge separation and transfer, and regulating reaction pathways. In this review, we systematically summarize recent advances in DACs for photocatalytic CO2 reduction. Firstly, the design and synthesis strategies alongside advanced characterization techniques, particularly operando spectroscopies and machine learning, for DACs are discussed. Secondly, the synergistic mechanisms between dual atoms and the regulatory effects of various supports, including carbon-based materials, carbon nitride, oxides, sulfides, metal-organic frameworks (MOFs), and covalent organic frameworks (COFs), are detailed in steering CO2 reduction pathways. Finally, the core challenges currently faced by DACs in this field are analyzed, and future development directions are prospected by integrating cutting-edge research trends. This review aims to provide theoretical guidance and technical references for the rational design and development of high-performance DACs toward efficient CO2 photoreduction through a systematic review of existing research and exploration of mechanisms.