Superior Catalytic Performance of Nickel-Doped Graphitic Carbon Nitride Toward Visible-Light-Mediated Synthesis of Functionalized 4 H -Chromenes: A Green and Sustainable Approach

Among the diverse photocatalyst, nickel-doped graphitic carbon nitride (Ni@g-C3N4) has become a focus of extensive research as an efficient photocatalyst due to its excellent chemical stability, favorable band structure, and ease of synthesis. In this report, we have documented the synthesis of functionalized 4H-chromene using Ni@g-C3N4 as a heterogeneous photocatalyst. Various spectroscopic techniques were employed to characterize the catalyst. The photocatalytic activity of the synthesized Ni@g-C3N4 was examined for the synthesis of 4H-chromene derivatives in an aqueous medium. Ni@g-C3N4 showcased much better catalytic activity than g-C3N4 itself. Moreover, it demonstrated excellent recyclability, retaining its catalytic efficiency and affording consistently high product yield over five cycles without any distinct decline in efficiency. Gram-scale synthesis of the reaction illustrates the industrial applicability of the present protocol. Additionally, high product yields, wide functional group tolerance, operational simplicity, and facile catalyst recovery contribute to the process toward green and sustainable development.