CoGa-Layered double hydroxides modified tin-doped hematite photoanode for efficient solar water splitting

In this paper, a CoGa-Layered Double Hydroxides Modified Tin-Doped Hematite Photoanode was prepared and utilized for highly efficient solar water splitting. [Display omitted] •CoGa-LDH cocatalyst grown in situ on tin doped hematite photoanode was prepared by a simple hydrothermal method.•The CoGa-LDH/Sn-Fe2O3 exhibits a significantly improved photocurrent density compared to that of α-Fe2O3.•The CoGa-LDH/Sn-Fe2O3 has excellent stability and the lower onset potential.•The reasons and mechanisms for efficient water splitting in CoGa-LDH/Sn-Fe2O3 have been studied and clearly revealed. Hematite suffers from low carrier concentration, limited hole diffusion distance, intricate surface states, and sluggish kinetic process of water oxidation, resulting in its inadequate performance for photoelectrocatalytic (PEC) water oxidation. This paper presents a method that combines tin doping and in situ growth of cobalt-gallium layered hydroxide co-catalysts to enhance the performance of the α-Fe2O3 photoanodic oxygen evolution reaction (OER). The optimal CoGa-LDH/Sn-Fe2O3 exhibits a significantly improved photocurrent density of 1.08 mA/cm2 at 1.23 V vs. RHE, representing an 86 % enhancement compared to that of Sn-Fe2O3, and it demonstrates remarkable stability. Additionally, the cathodic displacement of CoGa-LDH/Sn-Fe2O3 is observed to be 80 mV relative to the onset potential of Sn-Fe2O3. Systematic studies have demonstrated that tin doping significantly enhances the density of carriers in hematite and reduces the charge migration impedance of hematite, while the utilization of CoGa-LDH co-catalysts mitigates the complexation of photogenerated electron-hole pairs and reduces the transport resistance of photogenerated holes at the photoanode-electrolyte interface, consequently promoting the mobility of holes.