Synergistic Defect and Hole Engineering in K–Doped Cyano–Rich Porous Graphitic Carbon Nitride to Boost Photocatalytic Hydrogen Peroxide Production

ABSTRACT Photocatalytic conversion of H ₂ O and O ₂ into H ₂ O ₂ provides a promising sustainable ambient–condition route alternative to energy–intensive anthraquinone processes for on–site H ₂ O ₂ production. Herein a series of K–doped cyano–rich g–C ₃ N ₄ with porous structure (g–PC ₃ N ₄ K) have been successful synthesized by a molten salt assisted pyrolysis with subsequent secondary pyrolysis under the assistance of sublimated sulfur. Experimental and theoretical results demonstrate that the synergistic effects of K─N electron channels and the introduction of ─C≡N as well as porous structure is beneficial to the exposure of catalytically activity sites and the rapid separation and transfer of photogenerated electron–hole pairs, which contributes to the improved photocatalytic performance for H ₂ O ₂ production. As expected, the optimal g–PC ₃ N ₄ K exhibits a 14.05–fold higher H ₂ O ₂ yield than pristine g–C ₃ N ₄ and high H ₂ O ₂ yield of 1625 µ M and high solar–to–chemical conversion (SCC) efficiency of 5.93% can be also achieved within one hour under sunlight illumination, indicating its excellent performance and potentially practical application for photocatalytic H ₂ O ₂ synthesis.