Fossil fuels have been used for several decades and have resulted in increased greenhouse gases and pollutants. Currently, clean and renewable energy is in demand. Hydrogen appears to be a good candidate for clean energy because the only product of its reaction with oxygen is water. Water splitting by solar energy is a potential method for the generation of hydrogen in future applications. This study investigates the use of a CdTe quantum-dot-sensitized ZnO:N nanowire arrays for water splitting. The proposed method resulted in considerably enhanced photocurrent and stability. The electronic structures of the ZnO:N materials are also determined by O K-edge X-ray absorption spectroscopy. The incorporation of nitrogen into the ZnO nanostructure is determined by X-ray photoelectron spectroscopy and Zn K-edge X-ray absorption spectroscopy; the nitrogen incorporation changes the electronic state and, thus, increases the water-splitting performance.