Controlled Synthesis of ZnO Nanorods Using Different Seed Layers

Abstract

Single-crystal, low-cost, low-temperature, hydrothermal synthesis ZnO nanorods were grown on ZnO fine grained random nanocrystalline seed layers prepared by atomic layer deposition (ALD) and benchmarked against spin coating techniques for seed layers. As the growth temperature increased to 90 °C, more nanorods were observed on the samples. Increasing the growth time from 16 h to 24 h resulted in higher nanorod density for the ALD seeded samples, but less nanorods for the spin-coated seeded samples. Our work demonstrates that the final density of ZnO nanorods and their shape and size are primarily influenced by the characteristics of the ZnO seed layer, such as composition, morphology, grain size, impurity content and thickness, as well as the time spent heated. At ∼10 nm the ALD generated random polycrystalline seed layer grains were one order of magnitude smaller compared to the spin coating generated seed layer grains which appear structurally different as ∼100 nm columnar grains. This morphological seed layer difference caused the ZnO nanorods grown on spin coated seed layers to reach only ∼34% of the average nanorod length achieved on ALD seeds with comparable rod diameter and can also account for the diminished nanorod density. The exact mechanism of how the seed layer affects nucleation and subsequent nanorod growth is unknown, but results suggest that there is a significant impact. Future research can be directed to investigating the ability of metal nanoparticles to self-assemble on these nanorods and to further nanoscale catalysis.

Broadband Dielectric Spectroscopic Detection of Ethanol: A Side-by-Side Comparison of ZnO and HKUST-1 MOFs as Sensing Media

“…It has been demonstrated experimentally that the sensitivity and response speed of VOC detection with ZnO appears to depend on numerous factors, including but not limited to the nanoscale morphology, quality, and chemistry of the ZnO surface. For example, while ZnO microrods on SiO2/Si substrate synthesized at low temperature (95° C) via wet chemical process showed maximum sensitivity and response time for ethanol and methanol vapor detection at 150 °C [45], we have shown elsewhere that hydrothermally synthesized ZnO nanorods grown on fine-grained random nanocrystalline-seed ZnO layers [39] prepared by atomic layer deposition (ALD) exhibit maximum sensitivity at around 320 °C [38].…”

“…For the ZnO-sensing study, the gas sensor device consisted of hydrothermally synthesized ZnO nanorods grown on a random polycrystalline fine-grain ZnO seed layer, which was fabricated by atomic layer deposition (ALD) on a native-oxide-covered p-type boron-doped silicon substrate with resistivity of about 4 Ωcm to about 6 Ωcm and a thickness of about 500 μm to about 550 μm, as we described previously [39]. The surface-anchored ZnO nanorods used in the ethanol detection are described elsewhere [38].…”

The influence of sodium alginate on the structural and adsorption properties of resorcinol‐formaldehyde resins and their porous carbon derivatives

“…[3][4][5][6][7] Such materials are promising and have proven to be very effective in the synthesis of carbon adsorbents, electrode materials for energy sources and supercapacitors, and mesoporous carbon membranes for hydrogen storage. [8][9][10][11] The possibility of obtaining RFR aerogels and low-density porous carbon on this basis has generated particular interest. [1,12] It is known that the structural adsorption properties and texture of porous materials based on these polymers are determined by the ratio of resorcinol, formaldehyde and water, the pH of the reaction medium and the presence of catalytic additives, the temperature and time of the radiopharmaceutical gel, the drying conditions and the carbonation conditions.…”

“…The porous RFRs are widely used as ion exchange resins and as a source for the preparation of carbon materials with controlled porosity [3–7] . Such materials are promising and have proven to be very effective in the synthesis of carbon adsorbents, electrode materials for energy sources and supercapacitors, and mesoporous carbon membranes for hydrogen storage [8–11] . The possibility of obtaining RFR aerogels and low‐density porous carbon on this basis has generated particular interest [1,12] …”

Synthesis of Palladium Nanoparticles Supported over Fused Graphene-like Material for Hydrogen Evolution Reaction

“…The aggregation of nanoparticles leads to the loss of catalytic property [21]. It is necessary to utilize a support template to not only avoid the aggregation, but also improve the performance of nanoparticles [20][21][22][23][24]. Various templates were effectively applied in supporting nanoparticles such as graphene oxide, mesoporous silica, and carbon nanotubes; however, these materials are either expensive or require toxic chemicals or hazardous synthesis methods [25][26][27].…”