In recent years, photocatalytic moisture cracking has emerged as a promising approach to convert solar energy into conservable hydrogen fuels, indicating the important potential of applications in environmental restoration and energy conversion.
However, current research on photocatalytic technology focuses primarily on material design and overlooks optimisation of photocatalytic reaction systems.
In response, researchers have developed a new integrated, immobilized photothermal catalyst system.
“Specifically, traditional photocatalytic moisture cracks usually cause photocatalysts to be uniformly dispersed in the liquid phase to form a triphaas reaction system for solid gas,” explained Professor Maochang Liu, who led the study.
“This triphath system suffers from inherently low solar energy utilization efficiency and slow mass transfer processes.”
What is Photocatalytic Water Broken? How does it work?
Photocatalytic water cracking is the process of splitting water (H₂O) into hydrogen (H₂) and oxygen (O₂) using light energy, providing a clean method for producing hydrogen.
This reaction relies on photocatalysts, usually photocatalysts, which are semiconducting materials such as titanium dioxide (Tio₂). This usually absorbs sunlight and produces excited electrons and holes.
When the photocatalyst absorbs photons with energy above the bandgap, the electrons are promoted from the valence band to the conduction band, leaving a positive hole. These charge carriers promote the redox reaction. Excitation electrons reduce protons (H⁺) to form hydrogen gas, while holes oxidize water molecules to release oxygen.
Efficient water separation requires careful design of the photocatalyst to ensure light absorption, charge separation, and surface reaction activity.
Although promising, challenges such as low efficiency, catalyst stability and limited light absorption still need to be addressed in large-scale applications.
Improved photocatalytic efficiency with full spectrum responsiveness
Conventional photocatalytic reactions generally rely primarily on ultraviolet and visible light spectra, and cannot effectively use near-infrared light, which constitutes more than 50% of the solar spectrum.
“The development of new reaction systems with full spectral responsiveness has emerged as an important breakthrough to increase photocatalytic efficiency,” Liu said.
Currently, researchers have successfully developed a fixed, photo-heated catalytic water splitting system.
This innovative system combines photothermal substrates with high performance photocatalysts, allowing for the synergistic process of liquid water evaporation and vapor phase water cracking for hydrogen production under light illumination without the need for additional energy inputs.
Demonstrate outstanding hydrogen production rates
CDS/COFE2O4 (CCF) PN heterojunction photocatalysts are manufactured by calcification methods to promote consistent spatial transmission and efficient separation of photogenerating carriers.
The system structure utilized annealed melamine sponge (AMS) as a photothermal substrate to convert the solid GAS TRI-PHASE system into a more efficient gas-soluble bi-phase configuration.
The optimized CCF/AMS photocatalytic water splitting system exhibits a pronounced hydrogen evolution rate of 254.1 µmol H–1, representing a significantly forward leap compared to traditional triphaus systems.
Practical applications of water splitting systems
The system provides important insights and practical guidance to increase the efficiency of photocatalytic water splitting through innovative material design and construction of reaction systems.
Liu concluded: “This gas-curable dual system can increase solar energy utilization efficiency, increase overall reaction temperature, reduce gas transport resistance at the catalyst interface, thereby significantly improving the efficiency of photocatalytic water splitting.”
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