Precise construction of high-density single-atom active centers on polymeric semiconductors, together with concurrent regulation of their interfacial charge-transfer behavior, remains a central challenge for both photocatalytic energy conversion and neuromorphic electronics. Yet conventional wet photodeposition routes suffer from solvent-induced coordination distortion, defect formation, and limited metal dispersion. Here, we report a solvent-free dry-state in-situ photoreduction strategy that anchors atomically dispersed Pt onto highly crystalline carbon nitride (AD-Pt-HCCN), achieving a Pt precursor conversion efficiency of 70.5%, which is 5.5 times higher than that of wet photodeposition. HAADF-STEM, XPS, and XAFS collectively confirm uniformly distributed Pt single atoms coordinated in a quasi-fivefold configuration within triazine-heptazine frameworks. This coordination environment suppresses the formation of a classical nanoparticle-induced Schottky-type barrier and promotes ultrafast interfacial charge extraction, as supported by fs-TA, PL, TRPL, and EIS analyses. As a result, a photocatalytic H₂ evolution rate of 5.8 mmol/g/h is achieved, outperforming the counterpart prepared by conventional wet photodeposition (3.8 mmol/g/h), owing to the synergistic contributions of the increased Pt loading efficiency and the enhanced interfacial charge transfer induced by atomically dispersed Pt sites. Remarkably, the same atomic Pt sites serve as efficient charge-modulation centers in neuromorphic transistors, enabling pronounced excitatory postsynaptic current (EPSC)/inhibitory postsynaptic current (IPSC) responses, robust long-term potentiation/depression (LTP/LTD), and linear, hardware-relevant synaptic weight updates. Integrating experimentally extracted conductance states into an artificial neural network (ANN) framework yields high recognition accuracy of 98.6%, highlighting the broad potential of AD-Pt-HCCN as a multifunctional building block for energy-intelligence convergence.

Carbon nitride (CN) has attracted intensive attention as a visible light photocatalyst, but the rapid recombination of photogenerated charge carriers limits its photocatalytic activity. Herein, we develop a new strategy to construct both homojunction and ohmic junction into CN via selectively introducing metallized CN (MCN), which leads to rapid separation and transfer of photogenerated charge carriers. The polymerization of urea in the presence of KOH creates CN homojunction with amino and cyano groups. The subsequent molten salt treatment induces a new type of cyano-terminated CN that can be converted to MCN through photodoping, forming homojunction and ohmic contact coexisting CN (HOCN). The formed HOCN photocatalyst exhibits a high photocatalytic H₂ evolution rate of 18.5 mmol·g⁻¹·h⁻¹ under visible light irradiation, 45-fold higher than that of bulk CN. This strategy provides a new idea for designing ohmic contact between semiconductor and metal, and realizing efficient photocatalysis by improving charge separation and transfer.