Single Copper Atoms Enhance Photoconductivity in g-C₃N₄

Graphitic carbon nitride (g-C₃N₄) and its doped analogues have been studied over the past decade in part due to their promising applications in heterogeneous photocatalysis; however, the effect of doping on the photoconductivity is poorly understood. Herein, we investigate Cu doped g-C₃N₄ (Cu-g-C₃N₄) and demonstrate via extended X-ray absorption fine structure that Cu⁺ incorporates as an individual ion. Time-resolved optical pump terahertz probe spectroscopy was utilized to measure the ultrafast photoconductivity in response to a 400 nm pump pulse and showed that the Cu⁺ dopant significantly enhances photoconductivity of the as-prepared powdered sample, which decays within 10 ps. Furthermore, a film preparation technique was applied that further enhanced the photoconductivity and induced a longer-lived photoconductive state with a lifetime on the order of 100 ps. This study provides valuable insight into the ultrafast photoconductivity dynamics of g-C₃N₄ materials, which is essential toward developing efficient g-C₃N₄ photocatalysts.