Coordination tuning of nanoporous metal films by secondary electrodeposition to optimize methanol electrooxidation activity

Abstract

In this study, the crystal structure of nanoporous noble metal films has been controlled by the construction of secondary nanostructures assembled by a pulsed electrodeposition method. By employing secondary deposition techniques, the nanoporous structure was preserved, while the crystal structure was adjusted to optimize electrochemical performance. The crystal structure of the nanoporous metal film was precisely regulated to suppress the growth of the Au (220) plane in NPGF, as this orientation exhibits inferior catalytic activity compared to the Au (111) plane. This effect is attributed to the restoration of ion concentrations near the electrode surface during the pulse-off period. The optimized pulsed-NPGF film exhibits reduced development of the Au (220) plane and notable growth of the Au (111) plane. This modification increases the ECSA, thereby improving the catalytic performance in the MOR. The decline in charge transfer resistance achieved through controlling the crystal structure results in a negative shift in the onset potential and an increase in peak current density compared to NPGF and DC-NPGF. Furthermore, the stability of the pulsed-deposited films has been significantly enhanced. The pulsed-NPGF exhibits a higher peak current density compared to NPGF over 100 cycles of the MOR under alkaline conditions and demonstrates superior current density with reduced decay during long-term chronoamperometry (CA) testing during the MOR. This research provides valuable insights into designing nanoporous metal films, demonstrating how controlling the crystal structure can enhance the catalytic performance for electrochemical applications.