Full-Spectrum-Responsive Au@CuS-Decorated Monoclinic TiO Nanowires for Solar Hydrogen Production.

Developing photocatalysts that can efficiently capture light across a broad spectrum, from ultraviolet to near-infrared, is crucial for maximizing solar energy utilization. Such broad-spectrum responsiveness enhances solar energy utilization in photocatalysis, enabling a more sustainable and efficient pathway for hydrogen production. The limited availability of photocatalysts capable of responding to near-infrared irradiation underscores the urgent need for the development of versatile near-infrared-responsive photocatalysts. In this work, TiO nanowires in the monoclinic phase, a less common crystallographic form of TiO, were synthesized, followed by a decoration with Au particles surrounded by a hollow CuS shell. The resulting TiO-Au@CuS heterostructure nanowires exhibited remarkable properties conducive to efficient solar hydrogen production. The band structure alignment among TiO, Au, and CuS induced a Z-scheme charge separation mechanism, which boosted both the carrier utilization efficiency and redox powers. Furthermore, incorporating Au@CuS significantly broadened the absorption capability of TiO into the visible and near-infrared spectral ranges. This enhancement arose primarily from the inherent bandgap absorption of CuS, as well as the plasmonic properties of Au and CuS components. Additionally, the hydrophilic surface of TiO-Au@CuS enhanced the water accessibility, which promoted interactions between water molecules and the photocatalyst surface. By integrating these characteristics, TiO-Au@CuS heterostructure nanowires demonstrated noteworthy efficiency in solar hydrogen production across a wide spectral region, achieving notable apparent quantum yields of 10.51% at 300 nm, 4.38% at 450 nm, 4.17% at 800 nm, and 3.66% at 1800 nm. Notably, TiO-Au@CuS surpassed all of the near-infrared-responsive TiO-based photocatalysts ever reported in hydrogen production. The findings can provide a practical strategy to design a full-spectrum-responsive TiO-based photocatalyst for widespread use in photocatalytic processes.