Frustrated Lewis pairs-cyano dual-mediated ternary crystalline carbon nitride homojunction 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, which fundamentally relies on the exploration of efficient photocatalysts. This work reports the frustrated Lewis pairs (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⁺ form frustrated Lewis pairs (FLPs) with sp²-hybridized nitrogen atoms accelerate the isopropanol adsorption and deprotonation for proton supply. Meanwhile, the assembled ternary homojunction establishes a triple type-II carrier migration pathway with staggered band alignment, thus enhancing the spatial charge separation efficiency with superior visible-light-driven photocatalytic H2O2 production performance. Moreover, the abundant –C≡N groups provide more active sites for the adsorption and activation of O2, accelerating the surface reaction kinetics. The “three birds one stone” strategy awarded 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, –C≡N, and BIEF for boosted photocatalytic behaviors, offering a new avenue for efficient CN-based photocatalysts toward solar-driven H2O2 synthesis.