Effect of synthesis temperature on the morphology and stability of copper(i) hydride nanoparticles

Abstract

The effect of synthesis temperature on the morphology and stability of copper(I) hydride nanoparticles is studied. Monovalent copper hydride is obtained by reduction of Cu²⁺ sulfate with hypophosphorous acid at temperatures ranging from 45 °C to 75 °C. The CuH nanoparticles that formed have the shape of desert roses and are found to be very porous. The lattice parameter, size, and morphology of these nanoparticles depend on the synthesis temperature. CuH is a metastable compound. In air under ambient conditions, it first decomposes into copper metal and hydrogen gas and then the copper oxidizes. The copper particles that are left after the decomposition of copper(I) hydride in air have the same desert-rose morphology as the CuH nanoparticles. The copper particles with desert-rose shapes are observed for the first time. Copper(I) hydride decomposes slower in an aqueous environment than in air to form copper(I) oxide as the final product through formation of hydrated copper(I) hydroxide as an intermediate phase. The retarded decomposition of CuH in water may be explained by the formation of a protective CuOH·H₂O layer on the surface of copper(I) hydride.