Pd-N-C shelled Pd nanoparticle catalysts for high-performance hydrogen peroxide electrosynthesis

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Metal-nitrogen-carbon (M-N-C) catalysts are crucial for electrochemical oxygen reduction reaction (ORR) to produce hydrogen peroxide (H2O2).
• Understanding the structure-performance relationship in M-N-C catalysts is essential for optimizing H2O2 selectivity.
• Current knowledge on how diverse M-N-C structures influence catalytic performance for H2O2 production is limited.

Purpose of the Study:

• To theoretically elucidate the role of specific structural features in Pd-N-C catalysts for selective H2O2 electroproduction.
• To synthesize and experimentally validate a rationally designed Pd-N-C catalyst for enhanced H2O2 selectivity and yield.
• To provide insights for the rational design of high-performance M-N-C electrocatalysts.

Main Methods:

• Systematic theoretical calculations to investigate the electronic structure and catalytic mechanism of Pd-N-C catalysts.
• Synthesis of a single-atom Pd-N-C (PdSA N2-2C) catalyst and a core-shell Pd@PdSA N2-2C catalyst.
• Electrochemical evaluation of catalyst performance, including H2O2 selectivity, yield, and operational stability.

Main Results:

• Theoretical calculations identified a centrosymmetric PdN4 structure (PdSA N2-2C) with a 1:1 pyridinic/pyrrolic nitrogen ratio as optimal.
• The Pd d(z^2) orbital interaction with the OOH intermediate's O 2p orbital was found to strengthen adsorption and facilitate H2O2 formation.
• The synthesized Pd@PdSA N2-2C core-shell catalyst achieved 97% H2O2 selectivity and a high yield (35.88 mol gcat^-1 h^-1) at 200 mA cm^-2, with superior stability.

Conclusions:

• The study successfully correlated specific structural motifs in Pd-N-C catalysts with enhanced H2O2 selectivity via theoretical and experimental approaches.
• The Pd@PdSA N2-2C core-shell catalyst represents a significant advancement in selective electrocatalysis for H2O2 production.
• This work provides a framework for the rational design of advanced M-N-C catalysts for selective electrochemical applications.