Preparation and characterization of bimetallic Ni–Ir/C catalysts for HI decomposition in the thermochemical water-splitting iodine–sulfur process for hydrogen production

Abstract A series of bimetallic 10%Ni-xIr/C (x = 0.5, 1.0, 1.5, 2.0 wt%) and monometallic 10%Ni/C and 2%Ir/C catalysts were prepared through the impregnation–reduction method modified by adding the ionic surfactant hexadecyltrimethylammonium bromide (CTAB) as the stabilizing agent during the impregnation. Their catalytic performance was tested by HI decomposition under atmospheric pressure at 400 °C and 500 °C. X-ray diffraction, Brunauer–Emmett–Teller surface area, transmission electron microscopy, and X-ray photoelectron spectroscopy were adopted to characterize the structure, specific surface area, morphology, and surface chemical state, respectively. Results showed that the addition of Ir metal and the use of CTAB played important roles in enhancing the activity and stability of the Ni-based bimetallic catalysts. Among all the catalysts tested, the bimetallic 10%Ni-1.5%Ir/C catalyst presented excellent activity and stability for HI decomposition.