Effects of Ag doping on LaMnO3 photocatalysts for photoelectrochemical water splitting

Abstract

As a redox material, perovskite is considered one of the most efficient photovoltaic materials for producing hydrogen via water splitting reactions. This study used a wet chemical method to synthesize La1−xAgxMnO3 nanoparticles (0.00 ≤ x ≤ 0.09). The formation, chemical composition, and morphology of samples were examined by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), and high-resolution transmission electron microscopy (HR-TEM). The optical properties were examined by ultraviolet visible (UV) diffuse reflectance spectroscopy. XRD demonstrated that the samples had a rhombohedral hexagonal structure with a space group R overline{3 } c. The pore volume, pore size, and surface area were calculated and examined. The prepared samples were used as a photoanode in alkaline media for water splitting, and the photocurrent was measured. The photocurrent density recorded (14.01, 12.02, 11.67, and 10.28 μA/cm2) for x = (0.09, 0.06, 0.03, and 0.00) at 1 V vs. Ag/AgCl, respectively. The smaller impedance of the sample (x = 0.09) photoanodes than the sample (x = 0.00), which displayed a considerable decrease in charge transfer resistance. The electron lifetime (τ) increased with increasing Ag concentration, where x = 0.09 has the largest electron lifetime (τ) = 10.04 ms. Therefore, the electron–hole recombination rate of La0.91Ag0.09MnO3 is lower than LaMnO3. The samples demonstrated long-term stability for 1 h and enhanced photoelectrochemical performance.