Hybrid artificial photosynthetic systems constructed using quantum dots and molecular catalysts for solar fuel production: development and advances

The construction of artificial photosynthetic (AP) systems for the hydrogen evolution reaction (HER) and carbon dioxide reduction reaction (CRR) is one of the hottest topics in the field of energy and sustainability. A typical AP system is composed of three key components, a photosensitizer (PS) for visible light harvesting, a catalyst for redox reactions, and a sacrificial electron donor (SED) for consuming holes generated in the PS. Among these three components, the PS and catalyst affect the photocatalytic performance much. There are two main types of AP systems, heterogeneous systems using inorganic materials and homogeneous systems using molecules. In addition to these, a compromise strategy of using inorganic luminescent nanoparticles as photosensitizers and molecular metal complexes as catalysts to construct hybrid AP systems has been developed. Inorganic luminescent nanoparticles, such as colloidal quantum dots (QDs) and carbon quantum dots (CQDs), have advantages of robust photostability, multiple excitation, and easy preparation. Molecular catalysts feature high activity, modifiable structures, and atom economy. Research on the combination of these two different types of materials to construct hybrid systems for solar fuel production is blooming. In the last decade, a large number of hybrid AP systems have been reported, and various strategies for system construction were developed. Obvious improvements in the photocatalytic efficiency of solar fuel production were witnessed. This review focuses on hybrid AP systems for the HER and CRR. The mechanism, composition, system design, and photocatalytic performances of the reported hybrid AP systems are reviewed. The advances and challenges in this field are discussed.