Augmenting the Photocatalytic Activity of Nitrogen Vacancy‐Engineered Na/K‐Co‐Doped g‐C ₃ N ₄ for Efficient H ₂ O ₂ Generation and Ciprofloxacin Degradation

ABSTRACT The present study represents the successful Na/K co‐doping of g‐C 3 N 4 (NKCN), which significantly enhances the photocatalytic H 2 O 2 generation under visible‐light irradiation and ciprofloxacin (CIP) degradation compared to the bulk and single‐doped g‐CN. The concurrent exchange of Na + and K + ions into the g‐CN framework effectively tailors their electronic structure, increases visible‐light absorption, and reduces the recombination rate of charge carriers to accelerate photocatalysis. NKCN exhibited a much higher rate of H 2 O 2 production (1920 µmol g −1 h −1 with solar‐to‐chemical conversion (SCC) efficiency of 0.13%), alongside CIP degradation (92% in 1 h) in wastewater. The vacancy and charge transfer dynamics are evaluated through x‐ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), and trapping test. Moreover, the underlying mechanism of active species (•O 2 − and •OH) is also confirmed and explained vividly, while the CIP mineralization pathway was elucidated using LC–MS analysis. The stability and reusability of NKCN were also evaluated over five consecutive cycles, maintaining nearly 90% of its initial degradation efficiency, demonstrating its excellent structural stability and practical applicability for wastewater treatment. This study offers a promising approach for developing scalable and sustainable photocatalysts for sustainable energy production and wastewater treatment.