Nanocomposites based on opal matrices and iron subgroup metal nanoparticles

Opal-matrix nanocomposites containing metallic nanoparticles

“…The starting chemicals used to prepare the solutions to be infiltrated into opal were the crystalline hydrates Ni(NO 3 ) 2 · 6H 2 O (ana lytical grade), Co(NO 3 ) 2 · 6H 2 O (analytical grade), Fe(NO 3 ) 3 · 9H 2 O (analytical grade), and FeCl 3 · 6H 2 O (analytical grade). Opal/metal nanocomposites had the form of opal matrices consisting of SiO 2 spheres, with opal pores containing 3d transition metal nano particles (Fe, Co, Ni, and their binary and ternary combinations: alloys and solid solutions) synthesized as described previously [32][33][34][35]. Opal crystals con taining nanoparticles of various metals were prepared as described elsewhere [38].…”

“…Refractory metals and oxides can be incorporated into opal pores by reducing appropriate salts in opal with alcohols in a supercritical state [32][33][34][35]. As shown in experimental studies [32][33][34][35], reactions of supercritical alcohols with salts and oxides have a reducing character, ensuring the formation of refrac tory metal or oxide nanoparticles in opal pores.…”

“…As shown in experimental studies [32][33][34][35], reactions of supercritical alcohols with salts and oxides have a reducing character, ensuring the formation of refrac tory metal or oxide nanoparticles in opal pores.…”

“…The objectives of this study were to produce new types of opal matrix (OM) nanocomposites contain ing iron group refractory metal (M = Ni, Co, Fe) nanoparticles prepared by reducing appropriate salts or oxides with supercritical alcohols [32][33][34][35] and to obtain broadband reflection spectra of the (111) sur face of the photonic crystals using a fiber optic tech nique developed previously [5,36,37] for measuring reflection spectra, in order to find characteristics of the band gaps of the nanocomposites.…”

Manufacture of opal-matrix functional nanocomposites by catalytic dehydrogenation of isopropanol under supercritical conditions

“…Inverted opal like metal structures are manufactured by electrolytic deposition of metals on ordered poly styrene templates [10]. For creating 3D composites of OMs and metallic, heterometallic, and semiconductor nanoparticles, the treatment of metal salts or metal oxides, encapsulated in the pore space of mesoporous supports and OMs, with an alcohol (isopropanol or ethanol) under supercritical (SC) conditions appeared fairly efficient [2,5,[11][12][13].…”