Size Tuned Synthesis of FeOOH Nanorods toward Self-Assembled Nanoarchitectonics

Abstract

Various studies were performed to fabricate self-assembling nanoobjects out of noble metals, but a few efforts were made for engineering iron-based nanorods toward sell-assembling blocks. In this regard β-FeOOH nanorods were fabricated in various sizes to achieve iron-based rod nanoblocks with selfassembling potential. Hydrolysis of ferric ions in various concentrations was successfully developed as a novel approach to control the growth of β-FeOOH crystals and tuning the length of rods in the nano range, below 100 nm. It was found that the concentration of ferric ion has no effect on the widths of nanorods, but the length was affected. By increasing the concentration of ferric ions, an increase in the length of nanorods and an increase of aspect ratio occurred. All sizes of the resulting FeOOH nanorods exhibited mesoporous feature, but interestingly the hysteresis loops were different due to different pore patterns. In fact, pores on the larger particles were more uniform in size and shape. Nanorods of small length did not make suitable interactions toward ordered phase formation, but rods with the mean length of about 90 nm or longer, at a certain concentration, were able to form nematic phases. The large (∼+40 mV) zeta-potential of nanorods prevents formation of dense arrays, and just bundle-like structures were observed. These findings highlight the importance of size, surface charge, and concentration of nanoobjects in the formation of 3D structures. The developed technique in the fabrication of β-FeOOH nanorods provides pure structures that are free from any size-controlling agent. These pure structures are suitable for further functionalization or coating. Self-assembling nanoobjects is a developing field in nanotechnology, and therefore studies can help our understanding over the assembling process.

Optimization of Synthesis Conditions of β‐FeOOH Nanorods towards Antimicrobial Benefits

“…As indicated in previous literature, the concentration of ferric salts plays a defining role in the synthesis of β-FeOOH NPs by controlling the growth of nanocrystals. Increasing the concentration of ferric ions leads to an increase in the length of NRs without significant width change and subsequently elevated aspect ratio since a higher concentration of ferric salts provides more ferric precursor along with more acidic pH, facilitating parameters in the hydrolysis process and further growth of NRs [28,33]. In this regard, we also found that increasing the concentration of ferric ions raises the length of NRs without a significant change in aspect ratio (Table 1).…”

“…FeO 6 octahedral units of β-FeOOH NRs are identified by characteristic peaks of two prominent vibration bands, FeO and OH groups. The vibration of FeO groups of octahedral units was observed as Fe−O bending vibrations at about 400 cm -1 and Fe−O stretching vibrations containing symmetrical stretching bands from 435 to 495 cm -1 and asymmetrical stretching bands at 647 to 700 cm -1 [28,38,39]. As shown in Figure 4, the characteristic absorption peaks related to Fe−O bands of octahedral sites are perceptible between 400 and 700 cm -1 in all sample graphs.…”

“…Through the akaganeite synthesis process, as Fe salts dissolve in water, Fe 3+ ions will make a complex with water molecules and from [Fe(H 2 O) 6 ] 3+ . Then, the synthesis process is continued by hydrolysis reaction in two steps, release of protons from water molecules and formed double octahedral units via Fe −OH−Fe bonds, which can interact strongly or weakly with various anions, and form various morphology and size of FeOOH nanorods in the polymerization step [28]. Thus, the type of anions of ferric salt plays a determinative role in the final size and crystallization of the products.…”

Strong metal–support interaction in copper hexacyanoferrate nanocube decorated functionalized multiwall carbon nanotubes for enhanced bi-functional oxygen electrocatalytic activity and stability

“…in the XRD pattern of CuHCF/f-CNT, and are assigned to the tetragonal b-Fe-OOH phase formed due to the reductive environment provided by the PVP in the composite formation. 36 A slightly right shi of peaks can also be observed in the XRD pattern of CuHCF/f-CNT when compared to that of pristine CuHCF, which causes lattice shrinkage due to alkali ion removal from the lattice. 37,38 Besides, an extra peak around 17.7 (marked by #), which indicates a minor phase transformation of the cubic lattice (a…”

Biomimetic and Biological Nanoarchitectonics

“…Functional material systems are supposed to be nanoarchitected from these nanoscale units upon the selection and combination of various unit processes including atomic/molecular manipulation, chemical/material conversion, self-assembly/self-organization, field-assisted arrangement, nano/micro fabrication, and biochemical/biological treatment [ 48 ]. Since the basic concept of nanoarchitectonics is very general, it can be widely applied to fundamental subjects such as material synthesis [ 49 , 50 , 51 ] and structure control [ 52 , 53 , 54 ], as well as to applied fields such as energy [ 55 , 56 , 57 ], the environment [ 58 , 59 , 60 ], catalysts [ 61 , 62 , 63 ], sensors [ 64 , 65 , 66 ], and devices [ 67 , 68 , 69 ].…”