Is There Anything Better than Pt for HER?

Area of Science:

• Electrochemistry
• Catalysis
• Materials Science

Background:

• The search for efficient, low-cost alternatives to platinum (Pt) for the hydrogen evolution reaction (HER) is ongoing.
• Current HER catalysts often lack the intrinsic activity of Pt, hindering progress.
• Accurate assessment of intrinsic catalytic activity is crucial for advancing HER research.

Purpose of the Study:

• To highlight the importance of measuring intrinsic catalytic activity, such as turnover frequencies (TOFs).
• To investigate the impact of mass-transport limitations on observed Pt activity in acidic media.
• To present the highest measured TOF for Pt at room temperature and discuss limitations.

Main Methods:

• Utilizing mass-selected, identical Pt nanoparticles at varying loadings.
• Employing rigorous electrochemical measurements to assess catalytic activity.
• Applying a numerical diffusion model to analyze experimental data and identify limitations.

Main Results:

• Demonstrated the significant influence of mass-transport limitations on the observed activity of Pt catalysts.
• Reported the highest turnover frequency (TOF) for Pt in acid at room temperature to date.
• Identified H2 oversaturation, indicated by hysteresis in cyclic voltammograms, as a consequence of mass-transport limitations.

Conclusions:

• Accurate measurement of intrinsic catalytic activity, like TOFs, is essential for evaluating HER catalysts.
• Mass-transport limitations significantly affect observed catalytic performance, even for highly active Pt.
• The true intrinsic HER activity of Pt in acid remains undetermined due to persistent mass-transport limitations.