Hierarchical TiO₂ Layers Prepared by Plasma Jets.

Area of Science:

• Materials Science
• Environmental Chemistry
• Chemical Engineering

Background:

• Heterogeneous photocatalysis using titanium dioxide (TiO₂) is a key advanced oxidation process for environmental remediation.
• Developing efficient and selective photocatalysts is crucial for tackling air and water pollution.

Purpose of the Study:

• To synthesize and characterize hierarchical TiO₂ layers (Spikelets) using hollow-cathode discharge sputtering.
• To evaluate the photocatalytic performance of these Spikelet TiO₂ layers for the abatement of inorganic (NO, NO₂) and organic (4-chlorophenol) pollutants.

Main Methods:

• Synthesis of hierarchical TiO₂ layers via hollow-cathode discharge sputtering.
• Characterization using XRD, Raman spectroscopy, SEM, FE-SEM, DF-TEM, EDAX, and DC measurements.
• Photocatalytic testing under simulated real-environment conditions for NO, NO₂, and 4-chlorophenol degradation.

Main Results:

• Spikelet TiO₂ layers demonstrated comparable abatement of NO and NO₂ to the industrial benchmark TiO₂ P25.
• Harmful nitrous acid (HONO) formation was suppressed on Spikelet TiO₂ layers.
• Similar mineralization of 4-chlorophenol was achieved with a three-times lower reaction rate constant but a significantly higher external quantum efficiency (EQE).

Conclusions:

• Hierarchical TiO₂ layers exhibit favorable kinetics and reaction selectivity for environmental remediation.
• The suppressed HONO formation and high EQE make these materials promising for air and water purification.
• Feasible scale-up potential suggests broad applicability in environmental applications.