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Transition metal single atoms anchored on nitrogen‐doped carbon (M‐N‐C) matrix with M‐N‐C active sites have shown to be promising catalysts for both hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR). Herein, a hybrid catalyst with low‐level loading of atomic Pt and Co species encapsulated in nitrogen‐doped graphene (Pt@CoN4‐G) is developed. The Pt@CoN4‐G shows low overpotential for HER in wide‐pH electrolyte and manifests improved mass activity with almost eight times greater than that of Pt/C at an overpotential of 50 mV. The Pt@CoN4‐G also exhibits a top‐level ORR activity (half‐wave potential, E1/2 = 0.893 V) and robust stability (>200 h) in alkaline medium. Using theoretical calculations and comprehensive characterizations , the strong metal–support interactions between Pt species and CoN4‐G support and synergistical cooperation of multiple active sites are clarified. A flow alkali‐Al/acid hybrid fuel cell using Pt@CoN4‐G as cathode catalyst delivers a large power density of 222 mW cm−2 with excellent stability to achieve simultaneously hydrogen evolution and electricity generation. In addition, Pt@CoN4‐G endows a flow Zn‐air battery with high power density (316 mW cm−2), good stability under large current density (>100 h at 100 mA cm−2), and long cycle life (over 600 h at 5 mA cm−2). [ABSTRACT FROM AUTHOR]

Hydrogen (H2) has been utilized as a versatile feedstock or promising energy carrier in a variety of fields, yet the implementation of high‐rate H2 production presents a grand challenge for its readily accessible application. Herein, a newly alkali‐Al/acid hybrid fuel cell (3AHFC) that shows the capability of rapidly producing H2 upon delivering a considerably high energy density is reported, which is set up by paring Al anode in alkaline anolyte with acidic catholyte and a relatively cheap nanohybrid of Ru nanoparticle decorating crumpled reduced graphene oxide (Ru/c‐rGO) as cathode catalysts. It is demonstrated that the 3AHFC can release a power density of up to 240.6 mW cm−2 with a Faradic efficiency of approaching 99% for fast H2 generation (300 mA cm−2). Such hybrid electrolyte H2‐generation fuel cell can also be extended for either seawater anolyte or metallic Mg anode, presenting great promise for the practice feasibility of on‐site H2 production for applications in tough or even extreme environments. [ABSTRACT FROM AUTHOR]

Abstract: An alkaline–acid Zn–H2O fuel cell is proposed for the simultaneous generation of electricity with an open circuit voltage of about 1.25 V and production of H2 with almost 100 % Faradic efficiency. We demonstrate that, as a result of harvesting energy from both electrochemical neutralization and electrochemical Zn oxidation, the as‐developed hybrid cell can deliver a power density of up to 80 mW cm−2 and an energy density of 934 Wh kg−1 and maintain long‐term stability for H2 production with an output voltage of 1.16 V at a current density of 10 mA cm−2. [ABSTRACT FROM AUTHOR]