A comprehensive secondary ion mass spectrometry analysis of ZnO nanowalls: Correlation to photocatalytic responses

Abstract

We report on the visible light induced photocatalytic responses of zinc oxide (ZnO) nanostructures in the form of nanowires and nanowalls grown on aluminum substrates. Morphological and microstructural characteristics of these nanostructures have been analyzed using scanning electron microscopy (SEM) and high resolution electron microscopy (HRTEM). The presence of surface-adsorbed H þ , O 2 À , and OH À species on ZnO nanostructures has been established through secondary ion mass spectrometry (SIMS). The relative change in substrate coverage under varying reaction time has also been evidenced through SIMS and is in agreement with SEM observation. Compared to nanowires, oxygen adsorption on ZnO surfaces and subsequent oxygen in-diffusion are found to be prominent for the nanowall-like structures and are seen to be highest for nanowalls grown in lower reaction time. In contrast to nanowires, nanowalls are found to exhibit higher photocatalytic activity and this can be attributed to higher adsorption of oxygen. The photocatalytic activity of the samples under visible light is originated from the native defect-states and the photocatalytic efficiency is largely influenced by the surface-adsorbants. Control of surface adsorption characteristics of the nanowalls upon tuning wall thicknesses can lead to the development of futuristic efficient photocatalytic devices. V C 2015 AIP Publishing LLC.

Charge Mobility and Strain Engineering in Two-Step MS-Grown MoS2/Seed Layer Heterointerface and Photo-Excitation Mechanism

“…However, the substrate effect on the growth mechanism of MoS 2 is the focus, and the structure effect on the MoS 2 nanosheets is also worthy of attention. Future materials are required to be fabricated into nanowires, nanowalls, and other structures to adapt to a variety of devices, such as sensors, photocatalysts, lithium-ion batteries, etc. − All atoms in the ultrathin materials are located on the surface, and the surface properties and growth behavior of MoS 2 are changed by the regulation of the strain. The strain effect in MoS 2 can be effectively controlled and exploited as long as the appropriate morphology is selected.…”

Synergy of Adsorption and Plasmonic Photocatalysis in the Au–CeO2 Nanosystem: Experimental Validation and Plasmonic Modeling

“…12 On the contrary, photocatalysis breaks down organic contaminants to their nontoxic compo-nents with the aid of a semiconductor harvesting solar light. 14 Table 1 contains some of the available literature wherein semiconductor composites are employed for water treatment through a adsorption−photocatalysis synergistic approach. 15−23 The present study explores the adsorption−photocatalysis pairing in functionalized CeO 2 nanostructures for water treatment application.…”

“…The solid waste serves as a secondary pollutant, which is a significant drawback in adsorption-mediated water treatment . On the contrary, photocatalysis breaks down organic contaminants to their nontoxic components with the aid of a semiconductor harvesting solar light Table contains some of the available literature wherein semiconductor composites are employed for water treatment through a adsorption–photocatalysis synergistic approach. − …”

Oxygen out-diffusion and compositional changes in zinc oxide during ytterbium ions bombardment

“…Secondary ion mass spectrometry (SIMS) is a very precise analytical technique which provides information about the surface and microstructure of a sample [11][12][13][14][15][16][17] and allows to determine the elemental composition of a sample [18][19][20][21][22][23][24][25] and therefore SIMS is a very good candidate to monitor any compositional changes that may occur in ZnO during Yb + ions bombardment. However, regions that undergo these changes are very thin and thus an extreme depth resolution is required to describe them properly.…”