Formation of paratacamite nanomaterials via the conversion of aged and oxidized copper nanoparticles in hydrochloric acidic media.

Nanoparticles and nanostructured aggregates of paratacamite are prepd. in acidic solns. through the conversion of copper-based nanoparticles. Aged and oxidized copper nanoparticles with an av. primary particle size of ∼15 nm, when combined with hydrochloric acid solns. in the range of 0.025 to 0.1 M, show interesting behavior yielding both a change in nanoparticle primary size, as measured by an electrospray scanning mobility particle sizer, and in chem. compn. to produce a copper chloride hydroxide mineral identified as paratacamite (γ-Cu2(OH)3Cl) by powder X-ray diffraction of the dehydrated solid sample. Taken together, these data suggest that paratacamite nanoparticles in soln. can aggregate to yield microporous paratacamite materials. Microporous paratacamite was characterized by several techniques including X-ray diffraction, transmission electron microscopy, energy dispersive X-ray anal., electron energy loss spectroscopy, XPS and surface area measurements. Oxidn. of these copper-based nanoparticles with mol. oxygen and the role of the oxidized layer in the formation of paratacamite have been investigated. Comparison to microscale copper particles showed there is unique oxidn. behavior of nanoscale copper particles that results in unique reaction chem. of oxidized nanoscale copper particles with hydrochloric acid solns. to form paratacamite. This study provides a new route for the formation of paratacamite nanomaterials that can be used in a wide range of chem. interesting applications including hydrogen storage materials and as a heterogeneous catalyst for the synthesis of green solvents such as di-Me and di-Et carbonates. Addnl., this study suggests a potentially new pathway for the degrdn. of art objects and ancient artifacts as well as other cultural heritage materials contg. small copper particles that has not been previously considered. [on SciFinder(R)]