context: In summary, we have reported a facile strategy for preparing Pt3Ni1/NixFe LDHs as a binder-free catalytic electrode for HSABs. The HSAB with the Pt3Ni1/NixFe LDHs cathode delivered a higher open circle potential of 2.98 V and a lower ΔV of 0.50 V, together with remarkable cycling stability and excellent rechargeability with an average high round-trip efficiency of 79.9% during 350 cycles, which outperforms the HSABs assembled with the commercial catalyst composed of 20% Pt/C and RuO2. The remarkable charge–discharge performance and long-term cycling stability are mainly ascribed to the following: (1) the abundant Ni2+ vacancies alter the surface electronic structure of NiFe LDHs, which promotes electron/ion transfer kinetics and induces the strong interactions with PtNi nanoalloys. (2) The uniformly dispersed ultrafine PtNi nanoparticles on Pt3Ni1/NixFe LDHs enhance the electronic conductivity and provide abundant catalytic active sites, thus greatly boosting the ORR and OER in an alkaline medium. (3) The 3D hierarchically porous architectures of Pt3Ni1/NixFe LDHs offer high integrity and durability, high accessibility for electroactive sites, and enhance the interfacial kinetics that facilitates media transfer, as well as prevent catalytic by-product aggregation. (4) The binder-free design is conducive to exposing more active sites, leading to good catalytic performance. Thus, we believe that the discovery of the bifunctional Pt3Ni1/NixFe LDHs electrocatalyst sheds new light on the rational design of high-performance binder-free catalytic electrodes for large-scale application in energy conversion and storage.
answer: Pt3Ni1/NixFe LDHs