Engineering pentacene excited-state pathways through Ti3C2Tx heterojunctions for efficient photocatalytic hydrogen evolution

π-Conjugated PAH@Ti 3 C 2 T x heterojunctions enable direct interfacial charge transfer for efficient solar-driven H 2  evolution. • Conductive Ti 3 C 2 T x shortens charge pathways, reduces transport resistance, and promotes photocarrier separation and utilization. • Ti 3 C 2 T x coupling regulates pentacene excited-state dynamics, favoring long-lived charge-separated states for enhanced H 2 evolution. Although photocatalytic hydrogen evolution shows great potential for environmental sustainability and solar-to-chemical energy conversion, its practical implementation remains hindered by low efficiency, limited catalyst selectivity and incomplete understanding of the reaction mechanisms. Herein, we report the rational construction of polycyclic aromatic hydrocarbon (PAH)-decorated Ti 3 C 2 T x MXene organic–inorganic heterojunctions for enhanced visible-light-driven photocatalytic H 2 production. Comprehensive characterizations, including UV–vis absorption spectroscopy, photoluminescence spectroscopy, electrochemical impedance spectroscopy, transient absorption spectroscopy, photocurrent measurements, and density functional theory calculations, were employed to elucidate the structure–property relationship and interfacial charge-transfer mechanism at the molecular level. Transient spectroscopic analysis further suggests that interfacial electron transfer in pentacene@Ti 3 C 2 T x competes with the intrinsic intersystem crossing process, thereby reducing triplet-state-related relaxation and enhancing charge utilization efficiency. This work clarifies the molecular-structure-dependent charge-transfer mechanism in PAH/MXene photocatalysts and provides a rational design strategy for developing efficient organic semiconductor-based systems for visible-light-driven hydrogen production. Download: Download high-res image (159KB) Download: Download full-size image