High-entropy type Fe-Ni-P-O-C amorphous Nanospheres: Remarkable Fe-ion migration induced efficient surface reconstruction for oxygen evolution reaction

Amorphous transition metal compounds ( a -TMC) become one of the most promising pre-catalysts toward oxygen evolution reaction (OER) due to their high-entropy nature and flexible self-reconstruction to highly active derivatives. However, the loosen bonds inside the amorphous structure make it an electronic insulator with unstable structure. Here, monodispersed Ni 2+ -phytate nanospheres implanted by Fe 3+ ions (NS FeNiPA ) were firstly prepared and subsequently transferred into homogeneous high-entropy type Fe-Ni-P-O-C amorphous nanospheres (CNS FeNiPO ). It is shown that the CNS FeNiPO presents robust structure and remarkable Fe ions migration during potential-driven activation process, which benefits efficient surface reconstruction and spherical morphology preservation. The CNS FeNiPO with low mass loading of 0.1 mg cm -2 could deliver small overpotential of 270 mV at 10 mA cm -2 and almost 100% retention of the initial current density after 10 h test. The improved electrocatalytic activity is attributed to the boosted electron transfer from Ni sites to O-containing intermediates by introduction of Fe and P atoms. Moreover, rechargeable Zn-air battery with CNS FeNiPO +Pt/C could achieve lower charge potential platform and better cycling performance than that with commercial RuO 2 +Pt/C. This work provides new insights into the design and understanding of high-entropy amorphous pre-catalysts toward OER. High-entropy type amorphous Fe-Ni-P-O-C nanospheres (CNS FeNiPO ) present rigid Ni-P-O-C skeleton and observable Fe-ion migration during the potential-driven activation, which leads to high electrocatalytic activity toward oxygen evolution reaction.