LAUSR

To understand the processes of voltage cycling induced catalysts degradation, influence of cycle profiles on Pt degradation is investigated using mathematical method. Results show that the electrochemical surface area (ECSA) loss rate increases significantly with longer dwell time at the upper potential limit (UPL), which is mainly attributed to the enhanced Pt mass loss. Scan rate is also found to have little impact on the ECSA loss in the range of 1~37.5 mV/s, as lower scan rate will increase the Pt mass loss but mitigate the Ostwald ripening. However, too long dwell time at the UPL or too slow scan rate would promote the formation of a more steady-state of Pt oxide coverage, which is speculated to mitigate the Pt dissolution. Decreasing cycle number has also been demonstrated to be the main contributor to the lower ECSA loss due to Ostwald ripening. Additionally, Ostwald ripening and Pt mass loss have comparable contributions to catalysts degradation at the UPL ≤ 0.9 V, while Pt mass loss contributes more at higher UPL, which suggests that different load cycling strategies should be proposed for mitigating catalyst degradation at different UPL.