Performance of photocatalytic water splitting for hydrogen production using kelp as a sacrificial agent

Abstract

The study investigated the influence of catalyst concentration, co-catalyst loading ratio, sacrificial agent concentration, irradiation time, irradiation intensity and different pretreatments of sacrificial agent on hydrogen production, using multistage porous Pd/TiO2 as the catalyst and kelp as the sacrificial agent. The morphological and structural changes in the catalyst, sacrificial agent, and their mixtures before and after the photocatalysis were analyzed using Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible (UV–vis) spectroscopy. Based upon single-factor experiments, it was confirmed that mannitol was the primary substance acting as a sacrificial agent in kelp. Orthogonal experiments were conducted to determine the optimum conditions for hydrogen production with a reaction liquid volume of 100 mL. The highest hydrogen production efficiency was achieved for the following conditions: kelp sacrificial agent's concentration of 1.5 g/L; concentration of multistage porous Pd/TiO2 catalyst of 3.5 g/L; Pd loading ratio of 1 wt%. Under these conditions, hydrogen production reached the value of 121.1 μmol in 4 h. Under the same conditions, replacing the kelp sacrificial agent with kelp treated with 4% alkali, resulted in a corresponding hydrogen production of 141.0 μmol in 4 h. Compared to other common biomass sacrificial agents, the use of kelp as a sacrificial agent for photocatalytic water splitting demonstrates superior hydrogen production performance.