Mesoporous Metal Catalysts Templated on Clay Nanotubes

Abstract

Halloysite is a natural tubular aluminosilicate clay of ca. 50 nm diameter and 0.5–1.5 micrometers in length. The nanoarchitectural modification of halloysite inner/outer surfaces can be achieved through supramolecular and covalent interactions exploiting its different inside/outside chemistry (Al2O3/SiO2). The tubular morphology makes halloysite a prospective nanotemplate for core-shell structured mesoporous catalysts. Catalytic metals can be incorporated on the nanotubes’ outer surface or in the inner lumens with selective metal binding. 2–5 nm diameter Au, Ag, Pt, Pd, Co, Ru, Cu-Ni, Fe2O3, CoxBy, CdS, and CdxZn1−xS particles were templated on halloysite. In this work, CdS and Ru-containing halloysite based nanocatalysts were synthesized via modification with organic ligands and microwave-assisted wetness ion impregnation. The catalytic hydrogenation of benzene and its homologues as well as phenol was performed. The impacts of the core-shell architecture, the metal particle size and seeding density were optimized for high reaction efficiency. An efficient Co-halloysite catalyst was formed using azines as ligands, and it contained 16 wt. % of cobalt with hydrogen evolution rate of 3.0 L/min × g(cat). The mesocatalysts produced are based on a safe and cheap natural clay nanomaterial and may be scaled-up for industrial applications.

Differential antimicrobial and cellular response of electrolytically metalized halloysite nanotubes having different amounts of surface metallization

“…19 It has been incorporated in corrosion-resistant coatings 20,21 and fireretardant materials. 22,23 Due to its charged hollow lumen it is used as a container for various chemicals including drugs, 16,[24][25][26] dyes, 27,28 and metals, 30 in recent years it has generated interest as an adsorbent surface for various antimicrobial, 29 catalytic, 31,32 and heavy metal remediation, 33 as a filler for structural modification in bone cements, [34][35][36] dental fillings, 37 and polymer additive. [38][39][40] The deposition of metal NPs on HNTs is a straightforward process because of their inherent adsorbent ability, which can be further enhanced using chemical modifications.…”

Interfacial nanoarchitectonics for responsive cellular biosystems

“…The design and fabrication of functional materials and systems for these conversions with high efficiency and desired specificity are crucial matters for various social demands such as energy [ [18] , [19] , [20] ], environmental [ [21] , [22] , [23] , [24] ], and biomedical [ [25] , [26] , [27] ] issues. The synthetic efforts by organic chemistry [ [28] , [29] , [30] ], polymer chemistry [ [31] , [32] , [33] ], supramolecular chemistry [ [34] , [35] , [36] ], and materials sciences [ [37] , [38] , [39] , [40] , [41] ] used to be limited tools to create desired functional materials. However, rapid developments of biotechnology [ [42] , [43] , [44] ] and nanotechnology [ 45 , 46 ] open novel ways to understand and control precise nanolevel phenomena.…”

Liquid Phase Hydrogenation of Pharmaceutical Interest Nitroarenes over Gold-Supported Alumina Nanowires Catalysts

“…Some strategies consider the preparation of nanometric catalysts, obtained from core-shell (0D) structures that include in their design the insertion of the active phase in the core [20][21][22] or the Shell [23]. Other reported strategies include the preparation of supported catalysts by the deposition of Au in support via 1D arrangements (nanotubes, nanowires) [18,[24][25][26], 2D (graphene sheets, clays) [27][28][29], or in 3D structures such as mesostructured silicas [16,30,31], carbonaceous supports [32][33][34] and others.…”