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Oxygen electrocatalytic activities in transition-metal atoms and/or heteroatom-doped carbon nanostructures are strongly dependent on their conductivity and electron configurations. Herein, this study reports Mn3O4/self-growth carbon nanotubes induced by a transition metal cobalt hybrid as the efficient bifunctional oxygen electrocatalyst for rechargeable zinc–air batteries. The positive effect posed by the hierarchical structure and heteroatom doping provides an extra electronic state, eventually enhancing the oxygen adsorption and charge transfer during oxygen electrochemical reactions. The assembled rechargeable zinc–air battery achieves a high power density of 128 mW cm−2 and an excellent cycle stability of over 160 h at 5 mA cm−2. This study provides a feasible approach for designing efficient bifunctional oxygen electrocatalysts for broad applications in the field of energy conversion technology.

Achieving a profound understanding of the reaction kinetics of a catalyst by modulating its electronic structure is significant. Herein, we present a scalable approach to achieving a spatially partial substitution of S into NiMoO4. The increase in active components in a true Ni3+ oxidation state as a result of optimizing the coordination environment greatly improved urea oxidation activity.

Achieving a profound understanding of the reaction kinetics of a catalyst by modulating its electronic structure is significant. Herein, we present a scalable approach to achieving a spatially partial substitution of S into NiMoO

The slow kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) remain the primary problem impeding the commercialization of zinc-air batteries (ZABs). Herein, we demonstrate a hybrid composite consisting of multivalent CoSx nanoparticles and nitrogen-doped carbon nanotubes catalytically active-nickel (NCNTs/Ni) as an advanced ORR/OER electrocatalyst with excellent electrocatalytic activity. The Co-N bonds in the hybrid catalyst effectively enhance interfacial charge transfer, resulting in synergetic effects for enhanced oxygen electrochemistry. The optimized hybrid, CoSx/NCNTs/Ni-2, affords excellent performance in an alkaline ZAB, achieving a high-power density of 131 mW cm−2, and the voltage gap remained at only 0.87 V after 200 h of continuous charge–discharge at 5 mA cm−2. This study provides a facile strategy for the construction of bifunctional hybrids with non-precious metals for potential application in ZABs and other sustainable energy conversion devices.

The active sites on oxygen electrocatalyst and the number of inherent active species are important factors affecting the performance of Zn-air battery. Constructing multiphase interfaces is an effective strategy to increase the number of active species for oxygen electrocatalysts. In this work, the number of intrinsic active species of spinel oxygen electrocatalyst was increased and its catalytic activity was enhanced by the synergistic action of bimetallic center three interfaces and heteroatom-doped carbon nanostructures. The resulting NiCo2O4/NCNTs/NiCo as catalyst exhibits superior activity toward ORR (E1/2 = 0.83 V, JL = −5.38 mA cm−2) and OER (Ej10 = 1.58 V). Further, the obtained catalyst work as a cathode assembles as Zn-air battery with a high open-circuit potential of 1.51 V and excellent cycle stability (586 h). Theoretical results indicate that the desorption of *OH species is the rate-determining step for ORR, the multiphase interfaces in the NiCo2O4/NCNTs/NiCo will provide additional electrons due to the upward shift of antibonding orbitals relative to the Fermi level. Consequently, it boosts the oxygen adsorption and charge transfer and accelerate the reaction kinetics. This work emphasizes the synergistic effect between multiphase interfaces in transition metal composite catalysts and opens up a promising way for the preparation of efficient and stable transition metal electrocatalysts.

The optimal preparation condition of V2O5/TiO2 catalyst was investigated by the orthogonal experimental method. Five factors were chosen including A(molar ratio of NH4VO3 to oxalic acid),B(aging time of solution),C(active component content),D(impregnation temperature) and E(impregnation time). Every factor had four levels. The levels of A were1:2, 1:1, 3:2 and 2:1. The levels of B were 12h, 14h, 16h and 18h. The levels of C were 2%, 4%, 6% and 8%. The levels of D were 45°C, 55°C, 65°C, 75°C. The levels of E were 2h, 3h, 4h and 5h.The orthogonal experiment table was L16(45). Then the de-NOx rate of V2O5/TiO2 catalysts was tested in SCR catalytic reactor. The results showed that the influence of chosen factors decreased in the following order: C> B> E> D> A. The optimal plan of preparation experiments, obtained from the orthogonal experiment, is C3B1E3D3A4. So the optimal condition of preparation experiments are that active component content is 6%，aging time of solution is 12h，impregnation time is 4h，impregnation temperature is 65°C，molar ratio of ammonium metavanadate and oxalic acid is 2:1.