Iron Oxide-Based Nanotube Arrays Derived from Sacrificial Template-Accelerated Hydrolysis: Large-Area Design and Reversible Lithium Storage

Abstract

We report a novel “sacrificial template-accelerated hydrolysis” (STAH) approach to the synthesis of iron oxide-based nanotube arrays including hematite α-Fe2O3 and magnetite Fe3O4 on centimeter-scale conducting alloy substrates. ZnO nanowire arrays are chosen as the inexpensive and sacrificial templates that do not contribute to the component of final iron oxide nanotubes but can be in situ dissolved by the acid produced from the Fe3+ precursor hydrolysis. Interestingly, the ZnO template dissolution in turn accelerates the Fe3+ hydrolysis, which is essential to initiating the nanotube formation. Such a STAH approach provides a morphology-reservation transformation, when various shaped ZnO templates are adopted. Moreover, by introducing glucose into the precursor solution, we also successfully obtain carbon/hematite(C/α-Fe2O3) composite nanotube arrays on large-area flexible alloy substrate, with a large number of pores and uniform carbon distribution at a nanoscale in the nanotube walls. These arrays have been demonstrated as excellent additive-free anode materials for lithium ion batteries in terms of good cycling performance up to 150 times (659 mA h g−1) and outstanding rate capability. Our result presents not only a new route for inorganic nanotube formation but also an insight for rational design of advanced electrode materials for electrochemical batteries and sensors.

Evaluating the performance of nanostructured materials as lithium-ion battery electrodes

“…An initial intercalation mechanism was suggested which accounted for initial capacity gains and was associated with a transformation from cubic Fe2O3 to hexagonal Li2Fe2O3 before conversion at 0.8 V (identifiable by a long plateau region in the discharge profile), resulting in the formation of Fe 0 and Li2O species. The addition of carbon was suggested to offer structural support by means of a buffering effect while the improved electrical conductivity of the C/Fe2O3 nanotubes enabled the enhanced rate performance (up to 12C) that was reported [170]. Similar performance has been demonstrated with porous α-Fe2O3 nanodiscs prepared by oxalic acid etching of single crystal Fe2O3 nanocrystals [168].…”

“…More recently, advanced Fe2O3 structures such as nanoflakes [166], nanocapsules [167], nanodiscs [168], hollow nanoparticles [169], nanotubes [170], and reduced-graphene/Fe2O3 nanocomposites [171] have emerged with enhanced Li-ion performance. Liu et al [170], prepared 1D α-Fe2O3 and C-Fe2O3 nanotubes grown directly on conducting substrates by a so-called "sacrificial template-accelerated hydrolysis" (STAH) method, using arrays of ZnO nanowires as hard templates. The H + generated due to hydrolysis of the Fe 3+ precursor, resulted in dissolution of the ZnO nanowire template which in turn, facilitated the hydrolysis of the Fe 3+ precursor (Fig.…”

Tailoring Iron Oxide Nanostructures for High-Capacity Lithium Storage

“…[44] Nanotubes with efficient Li + diffusion channels and sufficient free space for volume expansion have also been demonstrated to be a promising electrode structure. [34][35][36][37] In 2005, Chen's group studied the lithium storage performances of α-Fe2O3 nanotubes prepared by hard templating. [34] The α-Fe2O3 nanotubes delivered an initial discharge capacity of 1415 mAh·g -1 ; the capacity decreased to 510 mAh·g -1 after 100 cycles.…”

Multiscale patterning of a metallic glass using sacrificial imprint lithography

“…Our strategy also widens the possible selection of mold materials to include those that are usually impractical for 3D nanopatterning (e.g., machined metal molds). Considered generally, the sacrificial template can be freely selected from any nanomaterial; however, hydrothermally grown ZnO nanomaterials present a range of desirable properties for the process: (i) it is widely established that such structures can be grown with tunable morphologies on a wide variety of substrates in an inexpensive manner [25][26][27] ; (ii) hydrothermal growth is performed through an immersion-based deposition that is batch-scalable; (iii) ZnO can be rapidly etched in a mild acid or base (Supplementary Figure S1), which has led to past applications in templating 28,29 ; (iv) the growth process utilizes mild, aqueous conditions and inexpensive reagents; and (v) ZnO itself Figure 1 Formation of a 3D nano/microstructured architecture by sacrificial templating. Top: process shown schematically.…”