Z-Scheme Tungsten Copper Oxide for Photocatalytic Water Splitting

Abstract

A significant limitation in energy technology is the challenge of large-scale energy storage, which hinders the widespread adoption of renewable energy sources. To transition from the current reliance on fossil-fuel-generated power, which is highly predictable, there must be a cost-effective solution for large-scale energy storage. One promising technology is the direct use of sunlight to split water into hydrogen and oxygen, which is known as photoelectrochemical (PEC) water splitting. This eco-friendly method has garnered significant attention for producing renewable hydrogen. The efficiency of PEC water-splitting cells, which convert solar energy to hydrogen, largely depends on the semiconductor materials used, demonstrating that they are a promising technology for the production of green hydrogen. We developed a PEC cell for water splitting that utilizes sunlight to drive the chemical reaction, separating water molecules into hydrogen and oxygen gas. This approach allows hydrogen gas to be stored and used as a reliable power source, similar to fossil fuels but without generating greenhouse gases. We have prepared a nanostructured heterostructure of WO_2.9 using the hot wire chemical vapor deposition (HWCVD) method on an oxidized copper substrate. The resulting WO_2.9/Cu₂O/Cu nanostructures are rod-shaped with an average diameter of 50 ± 8 nm. The photocatalyst demonstrates excellent hydrogen production activity under visible light, achieving a solar-to-hydrogen (STH) efficiency of approximately 1% without any applied bias potential. This study highlights a promising pathway for creating high-performance, low-cost photocatalysts for green hydrogen production.