Metal-based co-catalysts in semiconductor CdS hybrid nanostructures for enhanced photocatalysis: material design, mechanisms, and emerging trends
Walker MacSwain, Dekun Ma, Zhi Jun Li, Hanjie Lin, Yue‐Ling Bai, Xia Hu, Weiwei Zheng
Abstract
Photocatalytic chemical transformations, such as water splitting for hydrogen generation and CO₂ reduction, provide a sustainable strategy to address the ongoing energy crisis by enabling the production of next-generation fuels. Achieving efficient solar-to-fuel conversion requires photocatalysts with strong visible light absorption and effective charge separation. However, pristine semiconductors like cadmium sulfide (CdS) suffer from rapid charge recombination after photoexcitation, which limits their photocatalytic performance. Incorporating co-catalysts into nanoscale CdS-based systems not only enhances visible light absorption but also mitigates charge recombination. Many metals possess suitable Fermi levels to facilitate reductive photocatalysis via electron transfer (eT) from CdS. Additionally, metal-CdS coupling can also have energy transfer (ET) processes which can promote exciton separation enhanced photocatalysis. Noble metals, in particular, exhibit localized surface plasmon resonance (LSPR), which can enhance light absorption and promote charge separation through hot electron injection or ET mechanisms. This review provides a comprehensive overview of hybrid metal–CdS and metal oxide–CdS heterojunctions for photocatalytic applications. Emphasis is placed on the diverse chemistry of CdS, which enables the formation of efficient heterojunctions with a wide range of metal-based co-catalysts for redox reactions. Special attention is given to emerging and underexplored metals and metal compounds/complexes, highlighting their potential to significantly enhance the performance of CdS-based photocatalysts and guide the development of next-generation systems.