Unleashing Platinum-Sulfur Synergy in Ultranano-Structured Conjugated Porous Polymers Based on Thiazole for Efficient Hydrogen Generation.

The molecular design of conjugated porous polymers (CPPs) offers a powerful strategy to control their optoelectronic properties and interactions with semiconductor and metallic cocatalyst interfaces. Here, we develop an ultrananostructured thiazolo[5,4-d]thiazole (TzTz)-based CPP (UN_IEP-48), whose sulfur-containing units provide favourable sites for interaction with Pt. High-performance microfluidic processing enables its intimate integration with TiO2, yielding an optimized UN_IEP-48@T3 hybrid containing only 3 wt.% polymer. Photoluminescence and transient absorption spectroscopy reveal efficient charge separation consistent with a direct Z-scheme mechanism, directing the reduction pathway toward the CPP. Remarkably, photodeposition of only 0.5 wt.% Pt increases the H2 evolution rate from 3.0 to 94.3 mmol g-1 h-1, corresponding to a 30-fold enhancement and a photonic efficiency of 34.91%. Increasing Pt loading to 1 wt.% provides essentially no further improvement, highlighting efficient noble-metal utilization. Microscopy reveals preferential Pt localization on polymer-rich regions, while FTIR, XPS, and electrochemical impedance measurements support strong Pt-TzTz interactions and facilitated electron transfer. These results demonstrate how molecular engineering of CPPs can couple nanoscale heterojunction formation with cocatalyst interfacial chemistry, maximizing photocatalytic H2 production while minimizing noble-metal loading.