Activating a Metallization Switch for Record Hydrogen Evolution in Single-Atom Modified Polar MOF Piezocatalysts

Area of Science:

• Materials Science
• Catalysis
• Energy Conversion

Background:

• Piezocatalytic hydrogen evolution converts mechanical energy to chemical fuels.
• Efficiency is limited by the trade-off between piezoelectric polarization and conductivity.
• Poor conductivity hinders charge transport in highly polar materials.

Purpose of the Study:

• To decouple piezoelectricity and conductivity for enhanced piezocatalysis.
• To develop a novel catalyst for efficient hydrogen evolution.
• To overcome the bottleneck in piezocatalysis.

Main Methods:

• Atomically dispersed nickel single atoms on amino-functionalized UiO-66 (Ni SAs@UiO-66-NH2).
• Enhancement of piezoelectric response through polar amino groups and Ni-N coordination.
• Inducing a semiconductor-to-metal transition under mechanical stress.

Main Results:

• Piezoelectric coefficient (d33) increased from 48 to 242 pm V-1.
• Transient metallic conduction pathways facilitated efficient electron extraction.
• Achieved near-optimal hydrogen adsorption energetics (ΔGH* ≈ 0.12 eV at 100 MPa).
• Exceptional hydrogen evolution rates: 1871 µmol g-1 h-1 (water) and 17,613 µmol g-1 h-1 (methanol).

Conclusions:

• Ni SAs@UiO-66-NH2 successfully decouples piezoelectricity and conductivity.
• The catalyst demonstrates superior performance compared to existing MOF-based piezocatalysts.
• This approach offers a promising pathway for efficient mechanical-to-chemical energy conversion.