No abstract

In this study, hydrogen gas (H 2 ) and formic acid (HCOOH) are simultaneously generated through direct water photoelectrolysis and CO 2 reduction, respectively, by using Ag nanoparticles (Ag NP) decorated n-GaN films as photoelectrodes. Photoelectrochemical cells with CO 2 -containing NaCl aqueous solution as an electrolyte and n-GaN films as photoelectrodes offer an environmentally friendly system to generate energy under sunlight. The typical production rates of HCOOH and H 2 generated from the n-GaN photoelectrodes with TiO 2 /Ag NP composite layers are markedly higher than those for the n-GaN photoelectrodes without the TiO 2 /Ag NPs. The transmission spectra obtained from the TiO 2 /Ag NP/n-GaN photoelectrodes exhibited an additional visible light absorption band at around 550 nm due to localized surface plasmon resonance effect, except for the ultraviolet absorption with a wavelength of lower than 365 nm. However, the additional visible absorption was not the main cause of the enhancement of H 2 and HCOOH production rates. Instead, the enhancement was mainly due to the remarkable improvement in texture at the photoelectrode/TiO 2 interface.