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In this work, a one-pot solid phase reaction was used to synthesize PtIn/3D-GNs composites with different alloying degrees. The as-synthesized composites were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), and X-ray photoelectron spectroscopy (XPS). The results indicate that PtIn alloy was formed in the PtIn/3D-GNs composites. However, In(0) content in the composites (denoted as PtIn/3D-GNs (O)) when In2O3 was used as a precursor of In is almost twice as much as that in the composites (denoted as PtIn/3D-GNs (S)) using In(NO3)3 as a precursor of In, which indicates the higher Pt–In alloying degree in PtIn/3D-GNs (O). Electrochemical tests show that PtIn/3D-GNs composites exhibit superior electrocatalytic activity, better stability and enhanced antipoisoning ability toward methanol oxidation reaction (MOR) in comparison with Pt/3D-GNs and the commercial Pt/C. Interestingly, the synergistic effect between the charge separation of In2O3 and the SPR excitation of In(0) under light irradiation contributes to their good electro-photocatalytic performance under simulated sunlight irradiation. Especially, the higher Pt–In alloying degree in PtIn/3D-GNs (O) contributes to its better conductivity, which is responsible for its more efficient electro-photocatalytic properties. [ABSTRACT FROM AUTHOR]

A potential non-noble metal oxide catalyst with its low-cost and efficient catalytic ability attract increasing attention. In this paper, a highly efficient bifunctional electrocatalyst Co||MnCo 2 O 4.5 /NC with heterostructure and oxygen vacancies is prepared utilizing solid reaction in-situ. The optimal catalyst is obtained at 650 °C with the mass ratio (1:8) of MnCo 2 O 4.5 and Dicyandiamide (DCD). It shows excellent electrocatalytic activity for oxygen reduction reaction (ORR) with high half-wave potential (0.81 V) and limit current density (6.22 mA cm−2), which is better than that of the commercial 20% Pt/C(0.81 V, 5.52 mA cm−2). At the same time, it also exhibits superior electrocatalytic activity for oxygen evolution reaction (OER) with low overpotential (330 mV) and a faster dynamics process. The superior electrocatalytic properties may be resulted from the presence of heterostructure and increasing ratio of oxygen vacancies, which helps to the rapid transfer of electrons and creates more active sites. Moreover, the self-generated N-doped carbon provides high conductivity of the as-prepared Co||MnCo 2 O 4.5 /NC composite. It can be seen that the application of interface engineering technologies is useful for improving the performance of the catalyst, providing an effective and facile synthesis strategy for non-noble metal catalyst. • The Co||MnCo 2 O 4.5 /NC was prepared based on spinel MnCo 2 O 4.5 using solid phase reaction in situ. • The Co||MnCo 2 O 4.5 /NC has the dual characteristic of the heterostructure and more oxygen vacancies. • The Co||MnCo 2 O 4.5 /NC presents excellent difunctional electrocatalytic properties toward ORR and OER. • The zinc-air battery using Co||MnCo 2 O 4.5 /NC as a catalyst shows outstanding energy density and extraordinary stability. [ABSTRACT FROM AUTHOR]