Ultrafast Electron Transfer Coupled with a Proton Relay in an Anisotropic Dual S‐Scheme Heterojunction for Overcoming Kinetics Mismatch in H 2 O 2 Photosynthesis

ABSTRACT The kinetic mismatch between electron transfer and proton diffusion fundamentally limits the efficiency of photocatalytic H 2 O 2 production. To address this, an anisotropic dual S‐scheme heterojunction (C 3 N 4 /SubPc‐1/C 3 N 5 ) is constructed to achieve spatiotemporal synergy between charge and proton transport. This multidimensional design establishes a tridirectional (lateral, vertical, and internal) charge transfer network, enabling ultrafast electron migration. Simultaneously, the ─CONH─ bridge acts as a dual channel for concurrent electron and proton transfer. Coupled with a Yeager‐type oxygen adsorption configuration that preferentially activates a dual‐pathway 2e − oxygen reduction reaction (ORR), the optimized catalyst achieves an exceptional H 2 O 2 production rate of 2048.7 µmol·g − 1 ·h −1 and an apparent quantum yield of 16.28% at 400 nm. A combination of synchrotron radiation X‐ray photoelectron spectroscopy (SI‐XPS), femtosecond transient absorption spectroscopy (fs‐TAS), and multiscale theoretical calculations —including density functional theory (DFT), time‐dependent density functional theory (TDDFT), and molecular dynamics (MD) simulations— collectively reveals that the <1 ps anisotropic dual S‐scheme electron transfer mechanism works synergistically with the proton relay function to efficiently drive charge separation and reactant activation. This study provides a universal interfacial engineering paradigm for managing complex proton‐coupled electron transfer (PCET) processes in artificial photosynthesis.