Selective and controlled H₂ generation upon additive-free HCOOH dehydrogenation over a Pd/NCS nanocatalyst

Area of Science:

• Materials Science
• Catalysis
• Green Chemistry

Background:

• Sodium formate addition is a conventional method to enhance hydrogen evolution from formic acid dehydrogenation, but it increases costs and wastes resources.
• Developing additive-free catalytic systems is crucial for sustainable and cost-effective hydrogen production.

Purpose of the Study:

• To design and synthesize N-doped carbon nanosphere-stabilized palladium nanoparticles (Pd/NCSs) for efficient, additive-free hydrogen generation from formic acid dehydrogenation.
• To investigate the catalytic performance and mechanism of Pd/NCSs, focusing on the role of N-doping in enhancing palladium's activity.
• To demonstrate the controlled H2 evolution by adjusting pH.

Main Methods:

• Synthesis of N-doped carbon nanospheres (NCSs).
• Immobilization of palladium nanoparticles onto NCSs to form Pd/NCSs catalysts.
• Evaluation of catalytic activity for additive-free formic acid dehydrogenation using techniques like turnover frequency (TOF) measurements.
• Analysis of catalyst structure and electronic properties, particularly the interaction between palladium and graphitic C/N.

Main Results:

• Pd/NCS-800 catalyst exhibited a significantly higher turnover frequency (TOF) of 1640 h⁻¹ compared to commercial Pd/C (134 h⁻¹), a 12-fold improvement.
• The enhanced catalytic activity is attributed to the electron cloud density enrichment of Pd atoms by graphitic nitrogen/carbon in NCSs, facilitating C-H bond cleavage.
• Selective hydrogen evolution from additive-free formic acid dehydrogenation was successfully controlled by adjusting the solution pH.

Conclusions:

• N-doped carbon nanosphere-stabilized palladium nanoparticles (Pd/NCSs) are highly efficient nano-catalysts for additive-free formic acid dehydrogenation.
• The unique electronic structure of Pd/NCSs, facilitated by N-doping, significantly enhances catalytic performance.
• This study presents a promising strategy for sustainable and controlled hydrogen production from formic acid without relying on additives.