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Oxygen reduction reaction (ORR) catalysts with hierarchical pore structures, high specific surface area and multiple heteroatoms doping is very attractive due to the rapid mass transport and abundant active sites. In this work, we reported a facile confined strategy to prepare N, P co‐doped hierarchical porous carbon (NPHC) and investigated their catalytic performance for ORR. The strategy greatly simplifies the synthesis procedure of 3D hierarchical carbon templated by SiO2, which can utilize small organic molecules as carbon sources and avoids the pre‐polymerization and post‐washing process. Moreover, this strategy can be readily extended to synthesis other carbons by simply changing the carbon sources and heteroatom sources, or to synthesize metal compounds/carbon composites by adding metal sources during the synthesis process for energy conversion and storage. [ABSTRACT FROM AUTHOR]

Designing a highly efficient non-precious based oxygen reduction reaction (ORR) electrocatalyst is critical for the commercialization of various sustainable energy storage and conversion devices such as metal-air batteries and fuel cells. Herein, we report a convenient strategy to synthesis Fe3O4 embedded in N doped hollow carbon sphere (NHCS) for ORR. What's interesting is that the carbon microsphere is composed of two-dimensional (2D) nanoplate that could provide more exposed active sites. The usage of solid ZnO nanowires as zinc source is crucial to obtain this structure. The Fe3O4@NHCS-2 exhibits better catalytic activity and durability than the commercial Pt/C catalyst. Moreover, it further displays high-performance of Zn-air batteries as a cathode electrocatalyst with a high-power density of 133 mW·cm−2 and high specific capacity of 701 mA·h·g−1. The special hollow structure composed 2D nanoplate, high surface area, as well as synergistic effect between the high active Fe3O4 nanoparticles and N-doped matrix endows this outstanding catalytic activity. The work presented here can be easily extended to prepare metal compounds decorated carbon nanomaterials with special structure for a broad range of energy storage and conversion devices. [ABSTRACT FROM AUTHOR]

• Co-Co 6 Mo 6 C 2 @NC nano polyhedron was synthesized using ZIF-67 as a precursor. • The Co 6 Mo 6 C 2 can significantly improve the OER catalytic activity of the catalyst. • The Co-Co 6 Mo 6 C 2 @NC-5 exhibits a low OER overpotential of 270 mV at 10 mA cm−2. • The Co-Co 6 Mo 6 C 2 @NC-5 exhibits a high ORR half-wave potential of 0.80 V. • The Co-Co 6 Mo 6 C 2 @NC can be used as a bifunctional electrocatalyst for Zn-air battery. A high effective bifunctional electrocatalyst was developed for rechargeable Zn-air batteries by rational integrating high active Co sites for ORR and Co 6 Mo 6 C 2 specie for OER. [Display omitted] To facilitate the development of rechargeable metal-air batteries, the exploration of high effective bifunctional electrocatalysts is essential. In this work, we report a facile strategy to synthesize N doped carbon (NC) encapsulated Co-Co 6 Mo 6 C 2 (Co-Co 6 Mo 6 C 2 @NC) nano polyhedron using ZIF-67 as a precursor and investigated its catalytic performance for both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). The introduction of Co 6 Mo 6 C 2 into Co@NC can significantly improve the OER catalytic activity of the catalyst, while the high ORR catalytic activity of the catalyst is maintained. Specifically, Co-Co 6 Mo 6 C 2 @NC-5 shows a decent half-wave potential of 0.80 V for ORR, and a very low overpotential of 270 mV at 10 mA cm−2 for OER, demonstrating its bifunctional activity. The rechargeable Zn-air battery assembled using Co-Co 6 Mo 6 C 2 @NC-5 exhibits a maximum power density of 90.75 mW cm−2 and a high specific capacity of 768 mA h g−1, as well as good durability of 50 h without attenuation in performance, highlighting its practical application. [ABSTRACT FROM AUTHOR]

Abstract The oxygen reduction reaction (ORR) is one of the core reactions that occur in fuel cells and metal air batteries. Metal-free catalysts such as porous carbons are promising candidates for ORR and the performance of porous carbons strongly depends on their nanostructure. Herein, we reported the synthesis of high surface area N doped carbon nanotube (CNT-900) by using ZnO@zeolite imidazolate framework (ZnO@ZIF-8) nanowire as a precursor. When used for an ORR catalyst, the CNT-900 show obvious superior performance compared with the carbon derived from ZIF-8. In addition, it exhibits comparable activity with 20 wt% Pt/C and superior stability. Combined with green and facile synthesis strategy, the method in this work can be easily extended to synthesis other nanomaterials for energy storage and conversion application. Graphical abstract N doped carbon nanotube with high surface area and ORR performance was synthesized by using ZnO@ZIF-8 nanowire as precursor. Unlabelled Image Highlights • ZnO@ZIF-8 was facilely synthesized at room temperature and converted to N doped carbon nanotube at 900 °C. • The CNT-900 shows very high surface area, which greatly improves its ORR performance. • The CNT-900 exhibits comparable activity with 20 wt% Pt/C and superior stability. [ABSTRACT FROM AUTHOR]

• ZnS decorated N, S co-doped porous carbon polyhedron are synthesized. • A small fraction of ZnS can greatly improve the ORR activity of the catalyst. • The ZnS@NC-3 shows comparable ORR activity with 20 wt% Pt/C catalyst. • The Zn-air battery using ZnS@NC-3 shows an open circuit voltage of 1.524 V. • The Zn-air battery exhibit a power density of 176 mW cm−2 and a specific capacity of 736 mA h g−1. Developing low cost, environmentally friendly and high efficiency oxygen reduction reaction (ORR) electrocatalysts is critical for clean energy conversion and storage devices including fuel cells and metal-air batteries. Herein, we developed a facile method to doping N, S and ZnS into carbon framework simultaneously. The N, S co-doping and extra ZnS active sites could prominently enhance the ORR performance of the carbon. The optimized sample ZnS@NC-3 exhibit an onset potential of 0.94 V and a half-wave potential of 0.84 V, which is comparable to 20 wt% Pt/C. In addition, the methanol tolerance and cycle ability are obvious superior than that of Pt/C. Moreover, when used as electrocatalysts for Zn-air battery, the battery exhibits an open circuit voltage of 1.524 V, a high specific capacity of 736 mA h g−1 and a max power density of 176 mW cm−2, demonstrating its great potential for clean energy conversion. [ABSTRACT FROM AUTHOR]