Investigation of Cu-Deficient Copper Gallium Selenide Thin Film as a Photocathode for Photoelectrochemical Water Splitting

Abstract

Polycrystalline thin films of CuGaSe2-related Cu-deficient materials were prepared by vacuum co-evaporation. The composition was adjusted in order to prepare copper gallium selenide, abbreviated as CGSe, with an optimal band gap and valence band maximum position for photoelectrochemical water splitting. The effect of the Ga/Cu ratio on the photoelectrochemical properties of CGSe was also studied. With increasing Ga/Cu ratio, the band gap of CGSe became larger, and the valence band maximum position became deeper against the vacuum level. However, an analysis of the photocurrent and onset potential indicated that the Ga/Cu ratio should be less than 3.5 for optimal performance. A Pt-deposited CGSe electrode with a Ga/Cu ratio of 3 showed an onset potential of about 1.1 V vs RHE and an energy conversion efficiency of 0.35% under AM 1.5G light illumination in a 0.1 M Na2SO4 solution with pH 9.5.

An Optically and Electrochemically Decoupled Monolithic Photoelectrochemical Cell for High-Performance Solar-Driven Water Splitting

“…Photosynthetic cells based on a semiconductor/liquid interface, also known as photoelectrochemical (PEC) cells, produce value-added chemicals and fuels such as hydrogen and various hydrocarbons by photodriven electrolysis such as water electrolysis and CO 2 reduction. − In a photosynthetic cell, photoexcited electron–hole pairs in a semiconductor drive a desired (photo)­electrolysis at a semiconductor/liquid interface. Because most of the semiconductors for photosynthetic cells have poor catalytic properties for photodriven electrolysis, the semiconductors are usually enhanced with cocatalysts to reduce the overpotential for a high solar-driven electrolysis efficiency. − For instance, the metal particles such as Pt, Ir and Ru, and Au and Cu are used to enhance PEC reactions on semiconductors for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) and for the CO 2 reduction reaction (CO 2 RR), respectively. − However, those metals are opaque and therefore, can block light absorption in the underlying photoelectrode if the size and distribution of the metal particles are poorly controlled. This limits the surface area of a cocatalyst on a photoelectrode and, thus, limits cocatalysts to using costly novel metals with excellent electrocatalytic performances.…”

Covalent Organic Framework Nanoplates Enable Solution-Processed Crystalline Nanofilms for Photoelectrochemical Hydrogen Evolution

“…Indeed, developing donor polymer:TPB-MeOTP-NP or TPB-MeOTP-NP:inorganic nanoparticle bulk-heterojunction structure-based COF photoelectrodes , is currently ongoing in our laboratory. Nevertheless, it is noteworthy that only a few photocathodes, including both organic and inorganic semiconductor-based ones, have so far been reported with a similarly positive onset potential (>+1 V RHE ). − Our results thus indicate that COF photoelectrodes hold great promise for tandem devices to achieve unbiased solar-to-fuel conversion, especially after gaining a higher J ph with further optimization.…”

Effect of charge selective contacts on the quasi Fermi level splitting of CuGa3Se5 thin film photocathodes for hydrogen evolution and methylviologen reduction

“…1). [4][5][6][7][8][9][10][11][12][13][14][15] For this use, the copper-poor phase CuGa 3 Se 5 (CGSe) has emerged as a champion. 13,14 Its structure is obtained from the zinc blende (ZnS) crystal structure by replacing Zn atoms with equal amounts of Cu and Ga (Fig.…”