Trimetallic nanocatalysts to enhanced hydrogen production from hydrous hydrazine: The role of metal centers

Abstract

A simple low-cost cetyltrimethylammonium bromide (CTAB) assisted step-wise metal displacement plating method was used to prepare noble-and noble-metal free Ni/Fe/Pd, Ni/Fe/Ag and Ni/Fe/Cu nickel based nanocatalysts for the hydrogen production from complete hydrazine decomposition in basic solution at mild temperature. Pd/Ag/Ni was prepared by seedless method. Compared to the mono-metallic (Ag0, Pd0, Fe0, Ni0 and Cu0) and bi-metallic (Pd/Ag, Ag/Ni and Ni/Fe), the tri-metallic catalyst exhibits higher catalytic performance towards hydrazine decomposition. The nessler's reagent was used to detect the formation of ammonia during hydrazine dehydrogenation. The effect of [catalyst], [hydrazine], [NaOH] and temperature were determined on hydrogen generation by using Ni/Fe/Pd. The generation of hydrogen follows excellent first-order kinetics with [hydrazine]. The activation energies were determined to be 32.1, 42.3, 44.6 and 75.9 kJ/mol for Ni/Fe/Pd, Ni/Fe/Ag, Ni/Fe/Cu and Pd/Ag/Ni, respectively. Noble-metal nickel based Ni/Fe/Pd nanocatalyst shows better catalytic efficiency and hydrogen selectivity. The durability of Ni/Fe/Pd provides evidence to excellent catalytic degree for five kinetic runs. The morphology of Ni/Fe/Pd was determined by using FESEM, EDX, TEM, XRD and UV–visible spectroscope. Hydrazine dehydrogenation mechanism proposed, which follows the following rate-law:−d[hydrazine]dt=k1KadOH−]Ni@Fe@Pd][NH2−NH2]T1+Kb[OH−]+Kad[NH2−NH2]T