Abstract
In this work, nanocomposites made of nanosized zirconia crystallized in situ in an amorphous silicon oxycarbo(nitride) (SiOC(N)) matrix have been designed through a precursor route for visible light photocatalytic applications. The relative volume fraction of the starting precursors and the pyrolysis temperatures not only influences the phase fraction of zirconia crystallites but also stabilizes the tetragonal crystal structure of zirconia (t-ZrO2) at room temperature. The presence of carbon in interstitial sites of zirconia and oxygen vacancy defects led to drastic reduction in the band gap (2.2 eV) of the nanocomposite. Apart from being a perfect host avoiding sintering of the active phase and providing mechanical stability, the amorphous matrix also reduces the recombination rate by forming heterojunctions with t-ZrO2. The reduction in band gap as well as the formation of heterojunctions aids in harnessing the visible light for photocatalytic activity.
Highlights
Large scale industrialization and urbanization has led to extensive pollution and contamination of rivers and water bodies, posing a threat to future generations and sustainable development[1]
It is well established that nanostructured materials with large surface area greatly enhance the absorption of the irradiated light during photocatalysis[29] and it appears advantageous to synthesize zirconia with crystallite size restricted to nanoscale dimensions for photocatalytic applications
In this work we report the photocatalytic behavior of t-ZrO2/SiOCN nanocomposites with in-situ formation of crystallized zirconia stabilized with a tetragonal crystal structure in a structurally stable SiOCN matrix via the concept of “Nanocomposites Through Chemistry of Single-Source Precursors”[37,38,39]
Summary
Large scale industrialization and urbanization has led to extensive pollution and contamination of rivers and water bodies, posing a threat to future generations and sustainable development[1]. It is important to note that the band gap value depends on the crystal structure (3.84 eV for cubic, 4.11 eV for tetragonal and 4.51 eV for monoclinic)[24], defects and processing route of the ceramics[25]. It is clear that the photocatalytic response of ZrO2 is governed to a large extent by the crystal structure, crystallite size, specific surface area, surface adsorbed species, surface defects and chemical composition of zirconia. This necessitates the need for developing a simplified processing approach wherein control of a large number of factors which contribute to the photocatalytic effect in the visible region is possible. The photocatalytic behavior of nanocomposites was not investigated
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