Hydrogen Evolution/Oxidation Electrocatalysts by the Self-Activation of Amorphous Platinum.

Amorphous nanostructures usually exhibit special and intriguing catalytic activities, and the electrochemical performance can be tuned during operation. Herein, a facile approach of the self-activation of amorphous platinum (A-Pt) nanospheres has been applied to develop a durable and efficient hydrogen electrode catalyst toward both the hydrogen evolution reaction (HER) and the hydrogen oxidation reaction (HOR), which was in situ converted to crystalline counterparts and partially oxidized during the electrochemical cycling, leading to the self-activated enhancements of both HER and HOR activities with the decreased overpotential by 5 times and the increased hydrogen oxidation current density by 67%, respectively. Especially, in addition to 12 times higher mass activity compared to benchmark Pt/C, in situ-activated A-Pt also demonstrated a lower HER overpotential even after 20 000 cycles than Pt/C. The significantly improved catalytic performance benefits from the rapid self-reconstruction processes (crystallization and oxidation) of the amorphous Pt during electrochemical cycling. This work shows the intriguing properties of the amorphous nanostructure and provides a new idea for designing an efficient electrocatalyst by phase engineering.