Compressive Strain Reduces the Hydrogen Evolution and Oxidation Reaction Activity of Platinum in Alkaline Solution

It is unclear why the hydrogen evolution and oxidation reactions (HER/HOR) of platinum (Pt) are much slower in base than in acid. Neither is it clear why the sluggish HER/HOR of Pt in a base can be improved by mixing Pt with some transition metals. Herein, we constructed dealloyed carbon-supported Pt-Cu nanoclusters (DPtCu3/C) with a core-shell Cu@Pt structure wherein the Pt-Cu alloying core is surrounded by Pt shells as a model HER/HOR catalyst to interpret these puzzles. Combined microscopy and in situ X-ray absorption spectroscopy verified the Cu@Pt structure in association with the compressive strain in D-PtCu3/C during the HER/HOR. The superior oxygen reduction reaction activity of the D-PtCu3/C to that of Pt/C in both acid and alkaline solution confirmed that the compressive strain weakens the Pt-O binding energy (E-pt(-O)) of the D-PtCu3/C. The D-PtCu3/C with compressed Pt shells exhibited inferior HER/HOR activity and a positive shift of the sharp hydrogen adsorption/desorption peaks toward higher potential in comparison with Pt/C in alkaline solution. These results verified that the compressive strain reduces the HER/HOR activity of Pt by weakening Ept-O. This conclusion indicates that the HER/HOR kinetics of Pt in a base is mainly limited by the overly weak Ept-O rather than overly strong Pt-H binding energy.

Automated summary

The study found that applying compressive strain can reduce the Pt-O binding energy of DPtCu3/C, thereby enhancing its oxygen reduction reaction activity and weakening the HER/HOR activity of Pt in alkaline solution. This suggests that the HER/HOR kinetics of Pt in a base is mainly limited by the overly weak Pt-O binding energy.