Local structure and crystallinity have been confirmed to be critical in the catalytic activity of catalysts, and the formation of amorphous phase can approach significantly enhanced catalytic performance. The controlled...

Organic molecules have been considered promising energy‐storage materials in aqueous zinc‐ion batteries (ZIBs), but are plagued by poor conductivity and structural instability because of the short‐range conjugated structure and low molecular weight. Herein, an imine‐based tris(aza)pentacene (TAP) with extended conjugated effects along the CN backbones is proposed, which is in situ injected into layered MXene to form a TAP/Ti3C2Tx cathode. Theoretical and electrochemical analyses reveal a selective H+/Zn2+ co‐insertion/extraction mechanism in TAP, which is ascribed to the steric effect on the availability of active CN sites. Moreover, Ti3C2Tx, as a conductive scaffold, favors fast Zn2+ diffusion to boost the electrode kinetics of TAP. Close electronic interactions between TAP and Ti3C2Tx preserve the structural integrity of TAP/Ti3C2Tx during the repeated charge/discharge. Accordingly, the TAP/Ti3C2Tx cathode delivers a high reversible capacity of 303 mAh g−1 at 0.04 A g−1 in aqueous ZIBs, which also realizes an ultralong lifetime over 10 000 cycles with a capacity retention of 81.6%. Furthermore, flexible Zn||TAP/Ti3C2Tx batteries with a quasi‐solid‐state electrolyte demonstrate potential application in wearable electronic devices. This work offers pivotal guidance to create highly stable organic electrodes for advanced ZIBs.

The proton exchange membrane fuel cells (PEMFCs) have been considered as promising future energy conversion devices, and have attracted immense scientific attention due to their high efficiency and environmental friendliness. Nevertheless, the practical application of PEMFCs has been seriously restricted by high cost, low earth abundance and the poor poisoning tolerance of the precious Pt-based oxygen reduction reaction (ORR) catalysts. Noble-metal-free transition metal/nitrogen-doped carbon (M–NxC) catalysts have been proven as one of the most promising substitutes for precious metal catalysts, due to their low costs and high catalytic performance. In this review, we summarize the development of M–NxC catalysts, including the previous non-pyrolyzed and pyrolyzed transition metal macrocyclic compounds, and recent developed M–NxC catalysts, among which the Fe–NxC and Co–NxC catalysts have gained our special attention. The possible catalytic active sites of M–NxC catalysts towards the ORR are also analyzed here. This review aims to provide some guidelines towards the design and structural regulation of non-precious M–NxC catalysts via identifying real active sites, and thus, enhancing their ORR electrocatalytic performance.

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