Sol-Gel Photocatalytic Coating Transparency Stability
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Solution Overview
Problem
Existing technologies fail to provide transparent photocatalytic coatings suitable for industrial and architectural applications, as cement-based compositions result in opaque solutions, and organic-based formulations degrade over time.
Innovation Solution
A sol-gel transparent photocatalytic coating is developed, comprising a water solvent, photocatalyst precursor, nonionic surfactant, epoxy silane, chelating agent, inorganic acid, and optionally an inorganic salt, which can be applied using conventional methods and exhibits stability and effectiveness even with low photocatalyst quantities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cement-based compositions are used for photocatalytic coatings, then stability and photocatalytic effect are improved, but transparency is worsened (opaque solution)
Solution Approach 1:
The patent changes the chemical composition parameters from cement-based to sol-gel based system, transitioning from an opaque matrix to a transparent matrix while preserving photocatalytic functionality. This involves changing the base material composition from hydraulic binder to sol-gel precursors (metal alkoxides) that form transparent inorganic networks upon hydrolysis and condensation.
Solution Approach 2:
The patent creates a composite sol-gel system combining metal alkoxides (for transparency and stability), photocatalyst precursors (for photocatalytic activity), and organic modifiers (for processability). This composite approach integrates multiple functions: the sol-gel matrix provides transparency and stability, while embedded photocatalyst particles maintain catalytic activity without compromising optical properties.
2Shape
If organic-based formulations are used for photocatalytic coatings, then transparency is improved, but stability is worsened (degradation over time)
Solution Approach 1:
The patent changes the chemical nature of the matrix from purely organic to inorganic-sol-gel based, which fundamentally alters the stability parameters. The sol-gel derived inorganic network (SiO2, TiO2, or hybrid) provides resistance to UV degradation, hydrolysis resistance, and thermal stability that organic polymers lack, while maintaining optical transparency.
Solution Approach 2:
The sol-gel matrix acts as an intermediary between organic transparency requirements and inorganic stability requirements. It provides a stable inorganic framework that can host organic photocatalyst molecules or inorganic nanoparticles, protecting them from degradation while allowing light transmission for photocatalytic activation.
3Reliability
If high quantities of photocatalyst are used, then photocatalytic effect is improved, but transparency is worsened and cost increases
Solution Approach 1:
The patent applies local quality by concentrating photocatalyst activity at specific sites (nanoparticle surfaces or molecular centers) rather than requiring bulk concentration. The sol-gel matrix distributes photocatalyst particles uniformly at low concentrations (0.1-10 wt%), and the nanoscale dispersion maintains transparency while providing sufficient catalytic sites through high surface area to volume ratio.
Solution Approach 2:
The sol-gel matrix forms a porous or nanostructured network that provides high surface area for photocatalyst dispersion. This porous structure allows low quantities of photocatalyst to be effectively distributed throughout the coating, maximizing their exposure to light and substrates while maintaining optical transparency due to the nanoscale pore sizes being below the wavelength of visible light.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The sol-gel coating achieves a highly transparent and stable photocatalytic effect, reducing pollutants and exhibiting anti-fouling, anti-bacterial, and anti-viral properties, while maintaining a low VOC content and being free of toxic heavy metals.
Implementation Method 1
Photocatalysis is a natural phenomenon that regards some substances, known as photocatalysts, which - when irradiated with light of suitable wavelength - are capable of catalysing some chemical reactions
Implementation Method 2
the presence of air and light, oxidative processes are activated on a surface containing a photocatalytic substance
Implementation Method 3
The coating as described guarantee also a high hydrophilia and self-cleaning of the surface
Data Source
Figure 1
AI summary
Sol-gel photocatalytic transparent coating composition, which comprises: (a) at least one water solvent; (b) at least one photocatalyst precursor (TTIP); (c) at least one non-ionic surfactant (d) at least one epoxy silane; (e) at least one chelating agent (f) at least one inorganic acid; (g) at least one an inorganic salt; Such composition can be used with conventional means, such as spray coating and ensures a highly trasparent photocatalytic coating with very low thickness that can be applied on several substrates which is stable over time with good resistance also to weathering agents and with relative low quantities of photocatalyst, generally lower than 10% by weight.