Reconstructing Interunit Photogenerated Charge Transport Pathways: Replacement of Hydrogen Bond Tunneling with Pt−N Covalent Electron Channels and Reverse Blocking Verification

To address the issue of slow carrier migration in photocatalysis, an innovative strategy of constructing covalent bonds as “directed highways” between isolated units to replace conventional weak hydrogen-bond migration pathways was proposed. Using hydrogen-bonded melon-based graphitic carbon nitride (MGCN) as a model system, different hydrogen-bond densities were achieved by adjusting the pyrolysis process. It was found that as the amino group content increased, the density of the hydrogen-bond network enhanced, leading to a significant improvement in charge carrier transport behavior. After further loading Pt single atoms, a −N−Pt− covalent bridging structure was successfully constructed between the chains, thereby replacing the weak hydrogen-bond electron pathway with a high-speed covalent electron channel and broadening the interchain charge transport route. The proportion of this structure increased from 21% to 45% with a rising amino group content. This covalent channel effectively promoted rapid interchain charge migration, enabling MGCN-600-Pt to achieve optimal photocatalytic hydrogen evolution activity (18.0 mmol g −1 h −1 ). The reliability of this mechanism was confirmed by a reverse experiment involving simultaneous blocking of hydrogen and covalent bonds via a cyanation reaction. Theoretical calculations revealed that the interchain −N−Pt−N 4 sites coupled with intrachain Pt−N 4 sites to form a synergistic hydrogen spillover channel between intrachain and interchain Pt. This study provides an in-depth exploration of the structure−activity relationship between the two types of interactions, achieving a transformative shift from hydrogen-bond tunneling to high-speed covalent-bond transport.