Bridging Copper-Oxygen-Titanium Bonds for Methanol Photoreforming to Hydrogen on Zero-Dimensional/Two-Dimensional Cu<sub><i>x</i></sub>O/TiO<sub>2</sub> Heterojunctions.

Xu, Jian; Fu, Ce; Zhu, Qianqian; Zou, Haiyan; Wang, Linlin; Yang, Ruijie; Chen, Zhangxing; Zhao, Heng · ACS Nano · 2025

basic_science · Level V

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Abstract

Solar-driven hydrogen (H<sub>2</sub>) 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) Cu<sub><i>x</i></sub>O nanocrystals (2-3 nm) and two-dimensional (2D) TiO<sub>2</sub> 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 H<sub>2</sub> evolution activity (64 mmol·g<sup>-1</sup>·h<sup>-1</sup>) from methanol photoreforming, outperforming pristine TiO<sub>2</sub> and commercial TiO<sub>2</sub> by 9-fold and 428-fold, respectively. Dynamic Cu<sup>2+</sup>/Cu<sup>+</sup> redox cycling not only contributes to durability in extracting protons from methanol to H<sub>2</sub> 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-H<sub>2</sub> conversion.