of the PO 2 -Nb 4 C 3 electrode was exemplified by assembling the PO 2 -Nb 4 C 3 //NHPC device with both high energy density (55 Wh L −1 ) and large power density (9765 W L −1 ). We hope that our results will encourage increasing efforts devoted to regulating the surface chemistry of MXenes and other 2D materials via terminal group engineering at the molecular level, which would contribute to the development of energy−power-balanced energy-storage devices.Research data are not shared.

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Considerable efforts have been made to realize nanoscale diodes based on single molecules or molecular ensembles for implementing the concept of molecular electronics. However, so far, functional molecular diodes have only been demonstrated in the very low alternating current frequency regime, which is partially due to their extremely low conductance and the poor degree of device integration. Here, we report about fully integrated rectifiers with microtubular soft-contacts, which are based on a molecularly thin organic heterojunction and are able to convert alternating current with a frequency of up to 10 MHz. The unidirectional current behavior of our devices originates mainly from the intrinsically different surfaces of the bottom planar and top microtubular Au electrodes while the excellent high frequency response benefits from the charge accumulation in the phthalocyanine molecular heterojunction, which not only improves the charge injection but also increases the carrier density.

Developing resource‐abundant and sustainable metal‐free bifunctional oxygen electrocatalysts is essential for the practical application of zinc–air batteries (ZABs). 2D black phosphorus (BP) with fully exposed atoms and active lone pair electrons can be promising for oxygen electrocatalysts, which, however, suffers from low catalytic activity and poor electrochemical stability. Herein, guided by density functional theory (DFT) calculations, an efficient metal‐free electrocatalyst is demonstrated via covalently bonding BP nanosheets with graphitic carbon nitride (denoted BP‐CN‐c). The polarized PN covalent bonds in BP‐CN‐c can efficiently regulate the electron transfer from BP to graphitic carbon nitride and significantly promote the OOH* adsorption on phosphorus atoms. Impressively, the oxygen evolution reaction performance of BP‐CN‐c (overpotential of 350 mV at 10 mA cm−2, 90% retention after 10 h operation) represents the state‐of‐the‐art among the reported BP‐based metal‐free catalysts. Additionally, BP‐CN‐c exhibits a small half‐wave overpotential of 390 mV for oxygen reduction reaction, representing the first bifunctional BP‐based metal‐free oxygen catalyst. Moreover, ZABs are assembled incorporating BP‐CN‐c cathodes, delivering a substantially higher peak power density (168.3 mW cm−2) than the Pt/C+RuO2‐based ZABs (101.3 mW cm−2). The acquired insights into interfacial covalent bonds pave the way for the rational design of new and affordable metal‐free catalysts.

Sodium metal is the ultimate anode for next generation high-energy-density sodium metal batteries due to its superior theoretical specific capacity, low redox potential, and natural abundance. However, sodium metal suffers...