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Li–O2 batteries with outstanding energy density are considered to be promising next-generation power sources for various future electric devices. However, the battery performance is limited by the inferior electrocatalytic activity of catalysts in the cathode. In this work, MoSe2 catalysts with hybrid 1T and 2H phases were prepared through an efficient two-step hydrothermal strategy. The combination of the 1T phase with the 2H phase could synergically enhance the catalytic activities towards both oxygen reduction reaction and oxygen evolution reaction, and the built-in heterojunction between them also dramatically facilitated the interfacial charge transfer kinetics. Additionally, the hierarchical flower-like architecture with multidimensional channels would promote the rapid electron and mass diffusion, as well as provide enough space for storing discharge products. Thanks to the above merits, MoSe2 cathodes delivered improved electrocatalytic properties for Li–O2 batteries. This present work may pave a new avenue for highly efficient bifunctional electrocatalyst construction for Li–O2 batteries. [ABSTRACT FROM AUTHOR]

To efficiently convert CO2 into high-value added products via the electrocatalytic reduction, the rational regulation of surface defects (e.g., oxygen vacancies) and the interfacial structure of electrocatalysts are crucial but still challenging. Herein, a feasible strategy is presented to manipulate oxygen vacancies and interfacial boundaries on hierarchical tin oxide aggregates via a thermal reduction process. The optimized Sn/SnO2-2h electrocatalyst exhibited the maximum faradaic efficiencies (FEs) of 92.5 and 96.4% for C1 products (FEC1) in the H-type cell and the flow cell, respectively. Online differential electrochemical mass spectrometry confirmed the lower onset potential for the electrocatalytic CO2 reduction reaction (ECRR) in comparison with the pristine SnO2. With the defect evolution from oxygen vacancies (Ovacs), the formation of Sn/SnO2 with favorable interfacial features is crucial to achieve an enhanced performance. More importantly, the in situ characterization studies and density functional theory (DFT) calculations revealed that the synergistic effect of both residual Ovacs and the interfacial structure is responsible for the energy favorable reduction of carbon dioxide via proton-coupled electron transfer, thus improving the selectivity for formate generation. This facile strategy for modulating surface defects provides an ideal approach to guide the future designs of ECRR catalysts. [ABSTRACT FROM AUTHOR]