Graphdiyne as a Hole-Transport Channel in Carbon Nitride Heterojunctions for Synergistic CO2 Reduction and γ-Butyrolactone Synthesis.

Coupling photocatalytic CO2 reduction with organic oxidation promises enhanced solar energy conversion and atom economy but remains challenging due to the difficulty in orchestrating selective redox transformations while suppressing side reactions. Here, we report a metal-free graphdiyne (GDY)/polymeric carbon nitride (PCN) heterojunction that achieves exceptional bifunctional performance in CO2 reduction coupled with tetrahydrofuran oxidation to γ-butyrolactone. The optimized composite delivers a CO production rate of 55 µmol·h-1·g-1 with 95% selectivity, and a γ-butyrolactone yield of 54% with near-unity selectivity (> 99%) under mild photothermal conditions, representing 2.9-fold and 6.8-fold enhancements over thermally treated PCN, respectively. Mechanistic investigations reveal that GDY serves as a hole-transport layer, generating a built-in electric field that drives spatial separation of charge carriers. This configuration confines electrons on PCN for CO2 reduction while directing holes to GDY for tetrahydrofuran activation. Moreover, the metal-free heterojunction suppresses over-oxidation pathways that plague metal-loaded systems, enabling remarkable selectivity control. This work establishes the GDY/PCN heterojunction as a powerful platform for cooperative photoredox catalysis and provides a blueprint for designing metal-free heterojunctions toward sustainable synthesis.