Control of Local Electronic Structure of Pd Single Atom Catalyst by Adsorbate Induction

Area of Science:

• Heterogeneous catalysis
• Materials science
• Nanotechnology

Background:

• Controlling electronic states of single-atom catalysts is crucial for activity.
• Metal-organic frameworks (MOFs) offer tunable supports for single-atom catalysts.
• Maintaining isolated metal atoms is challenging during catalyst activation.

Purpose of the Study:

• To develop an in situ adsorbate induced strategy for activating single Pd atoms on Zr-based MOFs.
• To investigate the structural and electronic changes in MOFs during catalyst activation.
• To evaluate the catalytic performance of the activated single-atom catalyst in acetylene semihydrogenation.

Main Methods:

• In situ X-ray diffraction (XRD)
• Spherical aberration-corrected electron microscopy
• X-ray adsorption fine structure (XAFS)
• Density functional theory (DFT) calculations

Main Results:

• In situ treatment induced changes in MOF lattice parameters due to reaction heat.
• Electron-deficient single Pd atoms were successfully generated and stabilized.
• The catalyst exhibited high intrinsic activity (0.132 s⁻¹) and selectivity (93%) in acetylene semihydrogenation.
• Long-term stability comparable to state-of-the-art Pd catalysts was achieved.

Conclusions:

• The in situ adsorbate induced strategy effectively activates single Pd atoms on Zr-based MOFs.
• The electron deficiency of Pd single atoms is key to superior catalytic performance.
• Reduced C2H4 desorption energy and hydrogenation activation barriers contribute to enhanced activity and selectivity.