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Although transition metal materials are extensively studied for hydrogen evolution reaction (HER) because of their intrinsic electrochemical properties, their practical applications have been hindered by low conductivity, unsatisfactory activity, and poor stability. To develop an approach for practical applications, it is imperative to improve their electrocatalytic performance. Herein, we report the fabrication of hollow NiMoP nanopetals embedded with Ndoped carbon dots (CDs) by a simple hydrothermal method. The addition of CDs can effectively modulate the morphology, reduce aggregation, and maintain long-term stability. Impressively, the optimal Ni 5 Mo 3 P@CDs 3 exhibits excellent HER performance, in terms of a low overpotential of 183 mV at 10 mA cm −2 , small Tafel slope of 41.04 mV dec −1 , high conductivity, and remarkable long-term stability in acidic media for HER. This work opens an effective avenue to construct excellent property and accessible electrocatalysts for HER with the assistance of CDs.

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A series of cyano-functionalized polyimides (CN-PIs) were prepared and derived from a novel diamine monomer having cyano and biphenyl groups. Meanwhile, another series of PIs without cyano groups (H-PIs) were prepared as counterparts for comparison purposes. Both series of PIs exhibited good solvent resistance, good thermal stability, remarkable film-forming ability, and excellent tensile properties. The Tg values of CN-PIs were 260–330°C, which were 10–17°C higher than the corresponding –CN free H-PIs. The CN-PIs exhibited no obvious decomposition below 470°C, and their 5% weight loss temperatures were above 568°C under nitrogen atmosphere. All the CN-PI films had high tensile strength and Young’s moduli, which were related to their rigid backbones and strong interactions between molecular chains. Due to their higher molar polarization, CN-PIs expressed the higher dielectric constants (3.29–3.69 at 1 MHz) in comparison with the corresponding H-PIs. CN-PIs exhibited the improved transparency, and both CN-PIs and H-PIs had better transparency than commercial Kapton® film. Introducing –CN groups could have an effect on the coefficient of thermal expansion and peel strength of the PIs. The peel strength of the PI, which was derived from cyano-functionalized diamine monomer and 4,4′-oxydiphthalic anhydride, could even reach 1.10 N mm-1, suggesting its strong interaction to copper matrix and potential use in flexible circuit board.