Hydrogen Evolution Reaction Catalyzed By Plasmoinic Photo-Electrodes Under Visible Light Illumination

Abstract

From the environmental point of view, the efficient control of the visible light driven hydrogen evolution reaction is one of the promising issue. For that, the semiconductor electrode can be regarded as the sufficient material but various semiconductor electrodes cannot be used for the visible light driven reactions due to their wide band gap energy. Recently, plasmoic photoelectric conversion system, which is the introduction of the plasmon active metal nano-structures onto the surface of the semiconductor substrate, has been received much attention due to its wide range photo response abilities. In this system, the electrons are excited and injected into the conduction band of the n-type semiconductor under visible light illuminations. Up to now, various plasmon-induced chemical reactions, even the water splitting, have been established. However, although well-established systems have been reported, the direct control of the reduction reaction at the metal-semiconductor interface using the excited electrons has not been well examined because the almost plasmonic photoconversion systems consist of the n-type semiconductor electrode and used the generated holes for the reactions. In this study, we have tried to establish the plasmon-induced hydrogen evolution system by using p-type semiconductor substrate and plasmon active nano-structures. By the fabrication of the plasmonic Ag dimer structures, we have observed the generation of the photo-current derived from the hydrogen evolution reactions under visible light illumination. Through the photocurrent measurements and the incident photon to current conversion efficiency obtained under different pH conditions, we have confirmed the pH dependence of the photo current value and the photo response characters. In addition to these, as the very interesting point for the current study, we have found the very unique catalytic property for the plasmonic hydrogen evolution especially under specific pH condition. Through the various photoelectrochemical measurements including isotropic selectively, we are sure that our plasmonic hydrogen evolution system could be one of the good candidate for future light energy conversion system.