Bridging Copper-Oxygen-Titanium Bonds for Methanol Photoreforming to Hydrogen on Zero-Dimensional/Two-Dimensional CuxO/TiO2 Heterojunctions.

Solar-driven hydrogen (H2) evolution from liquid organic hydrogen carriers (LOHCs) by using rationally designed heterojunctions represents a transformative approach toward carbon neutrality. However, practical implementation is hindered by inefficient charge separation and transport, predominantly due to suboptimal interfacial engineering in conventional heterostructures. Here, dense Cu-O-Ti bonds are created between zero-dimensional (0D) CuxO nanocrystals (2-3 nm) and two-dimensional (2D) TiO2 architectures via a mechanism mediated by unsaturated oxygen atoms, which serve as electron mobility highways to ease excited-state relaxation and recombination. The optimized heterostructure achieves a record-high H2 evolution activity (64 mmol·g-1·h-1) from methanol photoreforming, outperforming pristine TiO2 and commercial TiO2 by 9-fold and 428-fold, respectively. Dynamic Cu2+/Cu+ redox cycling not only contributes to durability in extracting protons from methanol to H2 but also activates water molecules, promoting methanol oxidation into formic acid. This work points to a feasible path to overcome the quantum mechanical barriers for methanol photoreforming, powering an efficiency leap for solar-to-H2 conversion.