Mixed-Phase TiO₂ Nanotube–Nanorod Hybrid Arrays for Memory-Based Resistive Switching Devices

Abstract

Metal oxide nanostructure hybrid materials have garnered focused attention for next-generation memory-based devices. TiO 2 nanostructure hybrids dwell in that league of materials. In reference to that, the present work reports the growth of mixed-phase TiO 2 nanostructures (MxPh-TNs) and their hybrids by grafting metal nanoparticles (MNPs). MxPh-TNs are a concoction of rutile nanorods and anatase nanotubes, imaged using field-emission scanning electron microscope and further confirmed by micro-Raman spectroscopy. During the growth of MxPh-TNs, a rutile and anatase mixed-phase interface is formed, as confirmed by high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. Furthermore, by grafting MNPs of platinum (Pt) and palladium−platinum (Pd−Pt) over MxPh-TNs, a top interface is investigated in order to have modifications in their structure and electronic interaction. Thus, dual interfaces corresponding to a mixed phase (rutile and anatase) and MNPs/TNs result in the modification of formed nanostructures and their hybrids (MX-TNHs), as confirmed by X-ray photoelectron spectroscopy and Kelvin probe force microscopy (KPFM) studies. Modification at the interface results in improved crystallinity and symmetric barriers for charge transport in hybrid structures. MxPh-TNs and MX-TNHs are further explored for device applications in the form of memristive resistive switching devices. It is observed that the device performances of Pt/MX-TNHs and Pd−Pt/MX-TNHs are better than that of MxPh-TNs in terms of the memory window (I ON /I OFF ratio). The improved device performance in the hybrid structures are due to the enhanced charge separation and defects at the interface of MNPs (Pt and Pd−Pt) and MxPh-TNs.

Enhanced Photocatalytic Activity in 2D‐1D WS2/TiO2 and 2D‐2D MoS2/WS2 Heterosystems

“…The curve of 2D‐2D MoS 2 /WS 2 heterostructures exhibits linear behaviour of the I–V curve, indicating the formation of Ohmic contact between 2D MoS 2 and 2D WS 2 . Similarly, the curve of 2D‐1D WS 2 /TiO 2 heterostructures exhibits non‐linear behaviour of the I–V curve, indicating the formation of Schottky contact between the 2D WS 2 and 1D TiO 2 [30] . Furthermore, IV curves confirm the conducting nature of WS 2 , 2D‐1D WS 2 /TiO 2, and 2D‐2D MoS 2 /WS 2 heterostructures.…”

“…Similarly, the curve of 2D-1D WS 2 /TiO 2 heterostructures exhibits non-linear behaviour of the I-V curve, indicating the formation of Schottky contact between the 2D WS 2 and 1D TiO 2 . [30] Furthermore, IV curves confirm the conducting nature of WS 2 , 2D-1D WS 2 /TiO 2, and 2D-2D MoS 2 /WS 2 heterostructures. A bias voltage was applied, with the Al layer serving as the upper electrode and the FTO layer serving as the lower electrode, which was grounded.…”

“…The WS 2 nanosheets show low adsorption capacity and comparatively low photocatalytic activity (Figure 7a). In contrast, despite the unsatisfactory photocatalytic activity of WS 2 , its absorption capacity is higher than that of TiO 2 [30] and MoS 2 [36–38] . The absorption capacity was enhanced of WS 2 due to the formation of 2D‐2D MoS 2 /WS 2 followed by 2D‐1D WS 2 /TiO 2 heterojunction.…”

Implementation of Stable Nonvolatile Resistive Switching Behaviors in TiO2 Nanoparticle‐Incorporated 2D Layered Halide Perovskite‐Based Devices

“…The presence of planes indicates that the obtained films belong to the 2D layered PEA 2 PbBr 4 , while the (002) plane represented by the star symbol corresponds to the TiO 2 . [ 35,36 ] It demonstrates the coexistence of 2D layered PEA 2 PbBr 4 and titanium oxide in the prepared switching films. Furthermore, all of PEA 2 PbBr 4 peaks belong to (00 n), indicating the layer‐by‐layer structure.…”

A Review on the Progress of Optoelectronic Devices Based on TiO2 Thin Films and Nanomaterials

“…Among various one-dimensional nanostructures, different morphologies of titanium dioxide nanostructures have attracted much attention. To investigate the synergistic effect between TiO 2 anatase and rutile mixed-phase interfaces, Bamola et al reported mixed-phase TiO 2 nanostructures (MxPh-TNs) and their growth through mixtures of grafted metal nanoparticles (MNPs) [ 77 ]. Figure 11 a shows a schematic representation of the formation of this nanostructure.…”