Opportunity
Carbon nitride (CNₓ) materials are widely recognized for their potential as metal-free photocatalysts in applications such as water splitting, energy storage, and water filtration membranes. However, existing methods for synthesizing carbon nitrides face significant challenges. Conventional techniques often produce hydrophobic surfaces due to inert carbon-based structures, requiring additional chemical treatments or plasma functionalization to achieve hydrophilicity. These post-synthesis modifications not only introduce complexity and cost but also degrade the material's structural integrity and durability. Furthermore, existing synthesis methods lack control over surface wettability, leading to inconsistent performance in water-based applications. The need for a direct, efficient, and scalable synthesis method that yields superhydrophilic carbon nitride materials with tailored properties remains unmet. This patent addresses these limitations by offering a novel approach to directly synthesize superhydrophilic carbon nitride thin films and powders without hazardous post-processing steps.
Technology
This invention introduces a method for the direct synthesis of two co-products:
- Superhydrophilic carbon nitride thin film (CNₓ, x = 0.86–1.04) with a water contact angle of 0–5°.
- Superhydrophilic carbon nitride powder (g-C₃N₄) with enhanced wettability.
The key innovation lies in the use of guanidine carbonate salt as a precursor material in a chemical vapor deposition (CVD) process. The method involves controlled thermal decomposition and polycondensation under a constant dry air flow (comprising N₂, O₂, Ar, and CO₂), which spontaneously embeds oxygen-based functional groups (e.g., –OH, –NO₂, =O) on the surface. This eliminates the need for harmful chemical treatments while ensuring superior hydrophilicity and structural stability.
The process optimizes substrate positioning, temperature (450–600°C), and gas flow rates to achieve:
- Needle-shaped nanostructures on thin films, enhancing surface roughness and wettability.
- High oxygen-carbon ratios (0.01–0.63), crucial for superhydrophilicity.
- Simultaneous production of films and powders, improving manufacturing efficiency.
Advantages
- Direct synthesis eliminates toxic post-processing, reducing production time and costs.
- Superhydrophilicity (0–5° contact angle) enhances performance in water-involved applications.
- Dual co-product yield (thin film + powder) increases versatility for different applications.
- Scalable CVD process allows large-scale production with precise control over material properties.
- Enhanced photocatalytic activity due to improved electron transfer and gas bubble detachment.
Applications
- Photocatalysis: Metal-free photocatalysts for hydrogen evolution reaction (HER) and water splitting.
- Self-cleaning coatings: Superhydrophilic surfaces for smart windows and solar panels.
- Water filtration: Hydrophilic membranes for efficient desalination and pollutant removal.
- Energy storage: Electrode materials for batteries and supercapacitors.
- Biomedical devices: Anti-fouling surfaces for medical implants and sensors.
