Amorphous/crystalline CoP/Ni2P@FeP heterostructure nanofibers as lattice oxygen involved electrocatalyst for efficient oxygen evolution reaction

The rational design and construction of amorphous/crystalline heterostructures with multiphasic interfaces represents an effective approach to enhance the oxygen evolution reaction (OER) activity of transition metal phosphides (TMP)-based electrocatalysts. Herein, we report a CoP/Ni 2 P@FeP heterostructured nanofibers electrocatalyst (CoP/Ni 2 P@FeP NFs) via electrospinning, oxidation, in situ growth of CoNiFe-PBA nanocubes and subsequent phosphorization, in which amorphous Co and Ni co-doped FeP nanosheets are anchored on crystalline nanofibers composed of CoP and Ni 2 P. Electrochemical tests combined with theoretical calculations demonstrates that the construction of the amorphous/crystalline heterostructure with triphasic interfaces induces electronic rearrangement of CoP/Ni 2 P@FeP NFs, which leads to the upshift of the O 2p band center of the CoNiFeOOH species formed after surface reconstruction, thereby facilitating the OER through the LOM pathway and ultimately enhancing the intrinsic catalytic activity. As a result, the CoP/Ni 2 P@FeP NFs exhibits low overpotentials of 256, 297 and 311 mV to achieve high current densities of 100, 500 and 1000 mA cm −2 , respectively. Moreover, the electrolytic cell assembled with CoP/Ni 2 P@FeP NFs and Pt/C only requires voltages of 1.508, 1.607 and 1.690 V to deliver current densities of 100, 500 and 1000 mA cm −2 , respectively, and exhibits outstanding long-term stability at 200 mA cm −2 for 200 h.