Frustrated Lewis pair–cyano dual-mediated ternary crystalline carbon nitride homojunctions for highly enhanced visible-light-driven photocatalytic H2O2 production

Abstract

Hydrogen peroxide (H₂O₂) production via photocatalysis is highly desired as a sustainable alternative to energy-intensive industrial applications, and it fundamentally relies on the exploration of efficient photocatalysts. This work reports frustrated Lewis pair (FLP)–cyano dual-mediated ternary crystalline carbon nitride homojunction (UMTCN) photocatalysts, which are synthesized via alkali metal salt-assisted calcination. It is verified that the doped K⁺/Na⁺ ions form frustrated Lewis pairs (FLPs) with sp²-hybridized nitrogen atoms, accelerating isopropanol adsorption and deprotonation to supply protons. Meanwhile, the assembled ternary homojunction establishes a triple type-II carrier migration pathway with staggered band alignment, thus enhancing the spatial charge separation efficiency and achieving superior visible-light-driven photocatalytic H₂O₂ production performance. Moreover, the abundant –CN groups provide more active sites for the adsorption and activation of O₂, accelerating the surface reaction kinetics. The “three birds one stone” strategy-enabled UMTCN photocatalysts deliver an outstanding H₂O₂ production rate of 12.3 mmol g⁻¹ h⁻¹ under visible light (λ > 420 nm) with 90.3% selectivity for the two-electron oxygen reduction reaction, surpassing most reported carbon nitride-based analogues. This study underscores the synergistic mechanism of FLPs, –CN, and BIEF for enhanced photocatalytic performance, offering a new avenue for efficient CN-based photocatalysts toward solar-driven H₂O₂ synthesis.