Designing efficient bifunctional catalysts with multi-component composites is essential for the application of zinc-air batteries (ZABs). Herein, a bimetallic phosphides-oxides heterostructures coupled heteroatom-doped carbon (FeCoP-FeCo₂O₄@PNPC) was designed by in-situ growth of phosphor-oxide heterostructures on heteroatom-doped carbon materials and employed as bifunctional electrocatalyst for ZABs. The heteroatom-doped carbon substrate with ORR active sites can effectively improve the conductivity and the double transition metal atoms can enhance the catalytic activity. The heterostructure adjusts the d-band center, making the material gain and loss of electrons are at a medium level, which is conducive to the material’s capture of raw materials and the release of products. is beneficial to electron transfer. The dense FeCo₂O₄ nanorods act as a protection layer to improve stability, and the oxide-phosphide heterostructure and synergistic coupling with the heteroatom-doped carbon substrate also contribute to the catalytic activity. The small ΔE of 0.765 V for catalyzing both OER and ORR, high power density of 121.6 mW·cm^–2 and the extraordinary long-term stability of more than 240 h for liquid state rechargeable ZAB can be realized. The flexible solid-state rechargeable ZAB with FeCoP-FeCo₂O₄@PNPC also exhibits superior mechanical flexibility and cycling stability.

Aqueous zinc-ion batteries encounter impediments on their trajectory towards commercialization, primarily due to challenges such as dendritic growth, hydrogen evolution reaction. Throughout recent decades of investigation, electrolyte modulation by using function additives is widely considered as a facile and efficient way to prolong the Zn anode lifespan. Herein, N-(2-hydroxypropyl)ethylenediamine is employed as an additive to attach onto the Zn surface with a substantial adsorption energy with (002) facet. The as-formed in-situ solid-electrolyte interphase layer effectively mitigates hydrogen evolution reaction by constructing a lean-water internal Helmholtz layer. Additionally, N-(2-hydroxypropyl)ethylenediamine establishes a coordination complex with Zn²⁺, thereby modulating the solvation structure and enhancing the mobility of Zn²⁺. As expected, the Zn-symmetrical cell with N-(2-hydroxypropyl)ethylenediamine additive demonstrated successful cycling exceeding 1500 h under 1 mA cm⁻² for 0.5 mAh cm⁻². Furthermore, the Zn//δ-MnO₂ battery maintains a capacity of approximately 130 mAh g⁻¹ after 800 cycles at 1 A g⁻¹, with a Coulombic efficiency surpassing 98%. This work presents a streamlined approach for realizing aqueous zinc-ion batteries with extended service life.

The sluggish reaction kinetics at the oxygen cathode is one of the important issues hindering the commercialization of the metal-air batteries. Although the noble metal can be used as the high-efficiency electrocatalyst to solve the problems to some extent, the high cost and scarcity of these noble-metal catalysts have limited their application in electrocatalysis. In this review, we discussed the mechanisms of the ORR and OER, and proposed the principles for the bifunctional electrocatalysts firstly, and then the state-of-the-art bifunctional catalysts, including carbon-based materials and transition-metal-based materials. On the basis of that, the self-supporting 3D noble-metal-free bifunctional ORR/OER catalysts were also discussed. Finally, the perspectives for the bifunctional electrocatalysts were discussed.