Few-Atomic Zero-Valent Palladium Ensembles for Efficient Reductive Dehydrogenation and Dehalogenation Catalysis

Area of Science:

• Heterogeneous catalysis
• Materials science
• Environmental chemistry

Background:

• Single-atom catalysts (SACs) have high atom utilization but low reactivity in reductive reactions.
• The high-valent state of SACs limits their efficiency in certain catalytic processes.

Purpose of the Study:

• To investigate the catalytic performance of supported palladium ensembles (Pd_1+c-red/CN) in formic acid dehydrogenation and 4-chlorophenol dechlorination.
• To compare the reactivity of Pd ensembles with supported Pd SACs (Pd_1-ox/CN).

Main Methods:

• Experimental catalytic tests for formic acid dehydrogenation and 4-chlorophenol dechlorination.
• Density functional theory (DFT) calculations to understand reaction mechanisms.
• Characterization of catalyst structure and valence states.

Main Results:

• Pd_1+c-red/CN exhibited 42-104 times higher FA dehydrogenation rates and 16-210 times higher 4-CP dechlorination rates compared to Pd_1-ox/CN.
• Optimal adsorption sites on Pd_1+c-red/CN facilitate H* formation crucial for dechlorination.
• High electron density on Pd_1+c-red/CN promotes direct electron transfer, enhancing dechlorination.

Conclusions:

• Zero-valent palladium ensembles (Pd_1+c-red/CN) demonstrate superior reactivity in reductive catalysis compared to SACs.
• Catalyst structure and valence state critically influence performance in dehydrogenation and dehalogenation.
• Pd_1+c-red/CN shows significant potential for environmental remediation of organohalides.