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Exploring energy storage devices and hydrogen evolution reaction electrode materials with high efficiency electrocatalytic activity, high energy density and low cost has broad prospects, but there are still huge challenges. Compared with traditional energy storage devices, supercapacitors (SCs) are a new type of energy storage device with broad development prospects. However, their practical application is significantly limited by the energy density of electrode materials. The practical application of hydrogen evolution reaction (HER) is limited by the high cost and scarcity of Pt-based precious metal catalysts. It is essential to develop materials with stable structure, low cost and abundant reserves. Here, in this paper, CoS 2 and CoSe 2 composites embedded in carbon nanofibers (CNFs) (expressed as CoS 2 -CoSe 2 /CNFs) were synthesized by electrospinning combined with in-situ growth Zeolite Imidazolate Framework-67 strategy, carbonization and subsequent selenium sulfide process. When employed as the positive material in supercapacitors, a specific capacitance of 292.2 F g−1 is achieved at a current density of 1 A g−1. The specific capacitance of asymmetric supercapacitors (ASCs) assembled with CoS 2 -CoSe 2 /CNFs-5 as positive materials remains stable with no significant change observed in specific capacitance even after undergoing 10,000 cycles. At the same time, when a current density of 10 mA cm−2 is applied in a 0.5 M H 2 SO 4 electrolyte solution, an overpotential reading of 189 mV is observed. The evidence mentioned above showcases the significant capacity of this substance for application in electrochemical energy storage and conversion. • The synergy of different components regulates the electronic structure. • The as-obtained materials exhibited a good energy storage and conversion performance. • The retention of the ZIF-67 skeleton structure can increases the number of active sites. [ABSTRACT FROM AUTHOR]

The demands for highly efficient and low-cost electrochemically active materials are still urgent needs for the fields of electro-catalysis and supercapacitor. Herein, a facile strategy for preparing high-efficient bi-functional electrode material was reported. The electrode material was prepared through embedding Co 2 P nanoparticles in the binary co-doped carbon nanofibers (Co 2 P@N&P-CNFs). This unique structure can effectively prevent the Co 2 P from detaching and provide abundant active sites. Materials prepared in this work showed the superior hydrogen evolution reaction (HER) performance with overpotential of 192 mV at a current density of 10 mA cm−2 and remarkable stability for 20 h. Moreover, the asymmetric supercapacitor (ASC) was fabricated using the Co 2 P@N&P-CNFs as the positive electrode material and carbon nanofibers (CNFs) as the negative electrode material, which shows an outstanding cycle stability (91.5% of the initial capacitance is retained throughout 10,000 charge-discharge tests) and a high E of 22.31 Wh kg−1 at the P of 225.02 W kg−1 at 0.3 A g−1. This work offers an effective route in designing bi-functional active materials for HER and supercapacitor. A novel one-step strategy to synthesize Co 2 P encapsulated N,P dual doped carbon nanofibers (Co 2 P@N,P-CNFs) is developed via electrospinning technology followed by carbonization process. They can be as the bifunctional electrode materials for hydrogen evolution reaction (HER) and supercapacitor. As expected, the as-obtained Co 2 P@N,P-CNFs shows superior HER and supercapacitor performance. Most importantly, a high-performance asymmetric supercapacitor (ASC) is assembled with Co 2 P@N,P-CNFs and CNFs. Image 1 • Co 2 P embedded in N&P co-doped carbon fibers was fabricated by an effective method. • The materials were used as bifunctional materials for electrochemical application. • The as-obtained materials exhibited a good energy storage performance. [ABSTRACT FROM AUTHOR]