Role of plasmonic Au nanoparticles embedded in the diamond-like carbon overlayer in the performance of CuFeO2 solar photocathodes

Delafossite CuFeO2 (CFO) has attracted much attention as a candidate p-type photocathode for photoelectrochemical (PEC) solar hydrogen production. In this paper first, a detailed electrochemical study was carried out in order to determine the best potential range for the potentiostatic deposition of nanostructured CFO on FTO glass. The structural and morphological properties of prepared samples were characterized by XRD and FESEM. Optical and photoelectrochemical investigations show that the sample prepared at - 0.7 V exhibits the best optical properties, charge separation, and charge transfer among prepared samples. We also provided direct evidence of surface states as charge trapping centers cause carrier recombination and limit photovoltage and charge transfer at SCLJ (semiconductor/liquid junction). Deposition of plasmonic Au nanoparticles (NPs) embedded in the diamond-like carbon (DLC) scaffold on the surface of CuFeO2 not only improved optical properties but also passivated these surface states and enhanced the PEC performance, consequently.