Strong Electron Interaction at the Amorphous/Crystalline Interface Enables Advanced Oxygen Evolution Reaction
Xingheng Zhang, Xiaojing Lin, Shoufu Cao, Xiaodong Chen, Qi Hou, Shuxian Wei, Siyuan Liu, Zhaojie Wang, Fangna Dai, Xiaoqing Lü
Abstract
Incorporating amorphous and crystalline components is undoubtedly a strategy to learn from each other’s strengths and complement each other’s weaknesses for advanced electrocatalysts. Here, an efficient and stable oxygen evolution reaction (OER) catalyst with an amorphous/crystalline interface is reported. Specifically, a rapid coprecipitation approach is proposed to load amorphous FePO 4 nanoparticles onto crystalline NH 4 CoPO 4 ·H 2 O nanosheets, resulting in a fascinating amorphous/crystalline interface. The prominent coupled effect between FePO 4 and NH 4 CoPO 4 ·H 2 O is afforded by the interfacial phosphates, which build efficient channels to transfer electrons from Co to Fe. Besides the unique electronic structure, the coupled amorphous/crystalline hybrid facilitates the formation of highly active Co intermediates and accelerates the reaction kinetics and charge transport. Detailed electrochemical characterization reveals that this advantageous interface structure results in a notable decrease in the overpotential of the OER compared to materials with an amorphous phase or crystalline phase alone. The FePO 4 /NH 4 CoPO 4 ·H 2 O hybrid exhibits a small overpotential of only 230 mV to achieve a current density of 10 mA cm –2 in 1 M KOH and 220 mV at 1 mA cm –2 in 0.1 M phosphate-buffered solution (PBS), which are much lower than the corresponding values of the pristine ones. It is envisioned that the highly operable amorphous–crystalline interface may open up new opportunities in rational design for advanced electrocatalysts.