Alteration of the structure and surface composition of crystalline-amorphous porous clay heterostructures upon iron doping from metal-organic source M. Zimowska, a * L. Lityńska-Dobrzyńska, b Z. Olejniczak, c R.P. Socha, a J. Gurgul a and K. Łątka d Porous clay heterostructures (PCH) have been prepared through the surfactant directed assembly of organosilica in the galleries of synthetic layered clay mineral Laponite. Fe-containing PCH nanostructures with nominal (Si + Mg)/Fe = 10 were prepared by post-synthesis impregnation of porous clay hybrid composites with metal-organic C 6 H 5 FeO. After impregnation, the as- synthesized Fe–PCH samples were either directly calcined at 550 °C or, prior to calcination, hydrothermally treated in the high pressure reactor. The impact of the PCH composite doping by the trivalent (Fe 3+ ) cations on the physicochemical properties was investigated with the use of spectroscopic methods. Detailed information on the character and lattice positions occupied by iron, the extent of its incorporation, its local structure and symmetry within samples were provided by comparing the FTIR analysis with the 57 Fe Mössbauer spectroscopy and 29 Si MAS NMR data. The nature of different Fe species formed after post-synthesis treatments was determined by Mössbauer spectroscopy and HRTEM. High pressure treatment resulted in the alteration of sample morphology and better, more homogenous dispersion of the Fe species in the composite lattice. FTIR indicated slight impairment of the clay structure in the PCH network followed by surface enrichment with Mg species because of Mg cations leaching from the octahedral sheets as confirmed by XPS study. Copyright © 2016 John Wiley & Sons, Ltd. Keywords: porous clay heterostructures; iron incorporation; crystalline-amorphous composite; FT-IR spectroscopy; Mössbauer spectroscopy; HRTEM Introduction Porous clay hybrid composites known as porous clay heterostructures (PCH) obtained after the fusion of the mesoporous silica with layered silicates are materials of increasing interest in applied environmental catalysis [1–6] . Clay structure consists of tetra- hedral and octahedral sheets joined into single layer unit, in Laponite (2:1 synthetic layered silicate from smectite group) one oc- tahedral sheet with Mg as a central atom is sandwiched between two tetrahedral sheets occupied by Si atoms [7,8] . Substitution of Li + for Mg 2+ generates negative charge of the layers, which is bal- anced by the hydrated metal cations. The amorphous silica formed between the galleries of clay mineral with the use of surfactant tem- plated method, basing on the ion-exchange ability of the clay, expands the interlayer distance of clay and develops the specific surface area. As a result merging properties of clay mineral and amorphous silica provides the support with high thermal stability, highly developed specific surface area and the unique opportunity for the design, synthesis and study of the nanoscale structures formed in the confined space of the resulted composite. The strategy for functionalization of PCH is particularly applicable to heterogeneous catalysis. Mostly aluminium, titanium or copper were used for this purpose [1,5,9] . Very few reports refer to PCH mod- ified with Fe species, and they considered the ion exchange properties of PCH to deposit Fe from FeCl 3 [4–6] . The catalytic perfor- mance of these catalysts in the selective reduction of NO with ammonia is improved by the presence of the coexisting Ti and Cu ions. Controlled surface modification of porous heterostructures derived from clay minerals is crucial for their use in catalytic appli- cations, particularly when applied to the cleaning of industrial flue gases from volatile pollutants. The way for neutralization of harmful VOC components and their conversion into relatively harmless compounds is the development of a new generation supported catalysts active in the processes of VOC decomposition not as ex- pensive as the noble metals containing ones. Iron supported PCH * Correspondence to: M. Zimowska, Jerzy Haber Institute of Catalysis and Surface Chemistry PAS, Niezapominajek 8, Kraków, Poland. E-mail: nczimows@cyf-kr.edu.pl a Jerzy Haber Institute of Catalysis and Surface Chemistry PAS, Niezapominajek 8, Kraków, Poland b Institute of Metallurgy and Materials Science, PAS, Reymonta 25, Kraków, Poland c Institute of Nuclear Physics PAS, Radzikowskiego 152, 31-342, Kraków, Poland d Marian Smoluchowski Institute of Physics, Jagiellonian University, Lojasiewicza 11, Kraków, Poland Surf. Interface Anal. (2016) Copyright © 2016 John Wiley & Sons, Ltd. ECASIA special issue paper Received: 1 September 2015 Revised: 29 February 2016 Accepted: 3 March 2016 Published online in Wiley Online Library (wileyonlinelibrary.com) DOI 10.1002/sia.6011