Is There Anything Better than Pt for HER?

The search for cheap and abundant alternatives to Pt for the hydrogen evolution reaction (HER) has led to many efforts to develop new catalysts. Although the discovery of promising catalysts is often reported, none can compete with Pt in intrinsic activity. To enable true progress, a rigorous assessment of intrinsic catalytic activity is needed, in addition to minimizing mass-transport limitations and following best practices for measurements. Herein, we underline the importance of measuring intrinsic catalytic activities, e.g., turnover frequencies (TOFs). Using mass-selected, identical Pt nanoparticles at a range of loadings, we show the pervasive impact of mass-transport limitations on the observed activity of Pt in acid. We present the highest TOF measured for Pt at room temperature. Since our measurements are still limited by mass transport, the true intrinsic HER activity for Pt in acid is still unknown. Using a numerical diffusion model, we suggest that hysteresis in cyclic voltammograms arises from H-2 oversaturation, which is another indicator of mass-transport limitations.

Automated summary

Efforts to find cheap alternatives to platinum for the hydrogen evolution reaction have not yet found a catalyst with intrinsic activity that can compete with platinum. It is important to measure intrinsic catalytic activities and consider the impact of mass-transport limitations on observed activity. Despite achieving the highest turnover frequency for platinum, the true intrinsic HER activity for platinum in acid remains unknown due to mass transport limitations.