High-Entropy Boride HfZrTiTaMoB: Promising Materials for Solar Selective Absorption Coatings in Photothermal...

Area of Science:

• Materials Science
• Nanotechnology
• Renewable Energy

Background:

• High-entropy borides (HEBs) offer thermal stability and tunable electronic properties.
• Applications of HEBs in photothermal materials are underexplored.
• Solar selective absorption coatings (SSACs) are crucial for efficient solar energy collection.

Purpose of the Study:

• To develop novel SSACs for photothermal applications using high-entropy borides.
• To investigate the performance and stability of HEB-based SSACs.
• To evaluate the photothermal conversion efficiency of the developed coatings.

Main Methods:

• Fabrication of bilayer SSACs using a HEB target with multiple transition-metal elements.
• Incorporation of different antireflective layers (Al2O3 and Si3N4) on stainless steel (SS) substrates.
• Characterization of optical properties (absorptivity and emittance) and thermal stability.

Main Results:

• The SS/HEB/Al2O3 and SS/HEB/Si3N4 coatings achieved high absorptivity (90.0%-91.6%) and low emittance (8.6%).
• The coatings exhibited excellent thermal stability, withstanding 500 °C for 5 hours and maintaining spectral selectivity after 400 °C for 100 hours.
• Photothermal conversion efficiencies reached 88.3%-89.9% under 100 sun, and achieved 85 °C under 1 sun, outperforming commercial coatings.

Conclusions:

• HEB-based SSACs show promising optical properties and efficient photothermal conversion.
• These coatings offer significant potential for advancements in solar energy collection.
• The simple, scalable bilayer structure and robust performance make HEBs attractive for photothermal applications.