• Synthesis and Investigation of Tungsten–Copper Oxide Composites for Enhanced Photocatalytic Applications

A major challenge in energy technology is the limitation of large-scale energy storage technologies, which greatly impedes the widespread adoption of many renewable energy sources due to their non-constant and commonly unpredictable energy generation rates. Thus, for society to move away from its current dependence on fossil fuels, a cost-effective solution for large-scale energy storage is essential. One promising technology is hydrogen generation through photoelectrochemical (PEC) water splitting, which uses sunlight to split water into hydrogen and oxygen gas. This method allows hydrogen gas to be stored and utilized as an on-demand energy source utilizing existing technologies, thus providing a green energy source with the flexibility of fossil fuels. Previous studies on single-catalyst PECs are greatly limited by only being able to harvest a fraction of the solar spectrum or have band edges that do not facilitate the evolution of both hydrogen and oxygen gases. In order to overcome this barrier, we have identified WO_2.9 and Cu₂O as co-catalysts for direct Z-scheme device geometry. We have prepared the WO_2.9/Cu₂O heterostructures by synthesizing WO_2.9 nanostructures using hot wire chemical vapor deposition on Cu₂O thin films that were grown in situ on Cu substrates. The resulting WO_2.9 nanostructures are rod-shaped with an average diameter of 50 nm. The photocatalyst shows excellent hydrogen production activity under visible light, achieving a solar-to-hydrogen (STH) efficiency of approximately 1% without any applied bias potential. Here we will discuss these results along with their potential for utilization in high-performance, low-cost photocatalysts for green hydrogen production applications.