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In response to energy challenges, rechargeable zinc–air batteries (RZABs) serve as an ideal platform for energy storage with a high energy density and safety. Nevertheless, addressing the sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in RZAB requires highly active and robust electrocatalysts. High-entropy Prussian blue analogues (HEPBAs), formed by mixing diverse metals within a single lattice, exhibit enhanced stability due to their increased mixing entropy, which lowers the Gibbs free energy. HEPBAs innately enable sacrificial templating, an effective way to synthesize complex structures. Impressively, in this study, we successfully transform HEPBAs into exquisite multiphase (multimetallic alloy, metal carbide, and metal oxide) heterostructure nanoparticles through a controlled synthesis process. The elusive multiphase heterostructure nanoparticles manifested two active sites for selective ORR and OER. By integrating CNT into HEPBA-derived nanoparticles (HEPBA/CNT-800), the HEPBA/CNT-800 demonstrates superior activity toward both ORR (E1/2= 0.77 V) in a 0.1 M KOH solution and the OER (η = 330 mV at 50 mA cm–2) in a 1 M KOH solution. The RZAB with a HEPBA/CNT-based air electrode demonstrated an open-circuit voltage of 1.39 V and provided a significant energy density of 71 mW cm–2. Moreover, the charge and discharge cycles lasting up to 40 h at a current density of 5 mA cm–2demonstrate its excellent stability. This work provides an alternative avenue for the rational design of HEPBA’s derivative for a sustainable rechargeable metal–air battery platform.

In this study, a trimetallic selenide material with a hollow spherical structure (Co9Se8–CuSe2–WSe2) was synthesized through two consecutive solvothermal reactions. The synergistic effect between the quaternary elements, the benefits of the selenization of metals, and the unique morphology led to the prominent electrocatalytic ability of Co9Se8–CuSe2–WSe2hollow spheres. Co9Se8–CuSe2–WSe2hollow spheres were then mixed with oxygen plasma-treated multiwalled carbon nanotubes (MWCNT) as counter electrode (CE) material for dye-sensitized solar cells (DSSCs), achieving a photoelectric conversion efficiency (η) of 9.23% under one sun condition (AM 1.5G, 100 mW cm–2), surpassing the 8.08% of devices with platinum counter electrodes (PtCEs). For indoor conditions, a T5 light source was applied to the DSSCs with Co9Se8–CuSe2–WSe2+ MWCNT CE, and the efficiency increased to 14.14% under 3600 lx irradiance. Finally, Co9Se8–CuSe2–WSe2+ MWCNT CE demonstrated good stability with 92.23% retention after 1000 cycles of cyclic voltammetry, exceeding the 82.49% of PtCE. Therefore, Co9Se8–CuSe2–WSe2+ MWCNT shows potential as a substitute for platinum as CE material for DSSCs.