Copper as a single metal atom based photo-, electro- and photoelectrochemical catalyst decorated on carbon nitride surface for efficient CO <sub>2</sub> reduction: A review
Jinli Qiao, Nabeel Khan Niazi, Jianan Zhang, Lulu Li, Israr Masood ul Hasan, Ruinan He, Luwei Peng, Nengneng Xu, Farwa Farwa
Abstract
The processes of photocatalytic CO<sub>2</sub> reduction (pCO<sub>2</sub>R) and electrochemical CO<sub>2</sub> reduction (ECO<sub>2</sub>R) have attracted considerable interest owing to their high potential to address many environmental and energy-related issues. In this aspect, a single Cu atom decorated on a carbon nitride (CN) surface (Cu–CN) has gained increasing popularity because of its unique advantages, such as excellent atom utilization and ultrahigh catalytic activity. CN—particularly graphitic CN (g-C<sub>3</sub>N<sub>4</sub>)—is a photo- and electrocatalyst and used as an important support material for single Cu atom-based catalysts. These key functions of Cu–CN-based catalysts can improve the catalytic performance and stability in the pCO<sub>2</sub>R and ECO<sub>2</sub>R during the application process. In this review, we focus on Cu as a single metal atom decorated on CN for efficient photoelectrochemical CO<sub>2</sub> reduction (pECO<sub>2</sub>R), where ECO<sub>2</sub>R increases the electrocatalytic active area and promotes electron transfer, while pCO<sub>2</sub>R enhances the surface redox reaction by efficiently using photogenerated charges and offering integral activity as well as an active interface between Cu and CN. Interactions of single Cu atom-based photo-, electro-, and photoelectrochemical catalysts with g-C<sub>3</sub>N<sub>4</sub> are discussed. Moreover, for a deeper understanding of the history of the development of pCO<sub>2</sub>R and ECO<sub>2</sub>R, the basics of CO<sub>2</sub> reduction, including pCO<sub>2</sub>R and ECO<sub>2</sub>R over g-C<sub>3</sub>N<sub>4</sub>, as well as the structural composition, characterization, unique design, and mechanism of a single atom site are reviewed in detail. Finally, some future prospects and key challenges are discussed.