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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]

The composite materials, carbon nanofibers-based cobalt oxide and Ag (CoxO-Ag/CNFs) were fabricated through a facile electrospinning method followed by calcination. They were Co2+-Ag/CNFs, Co2+@Co3+-Ag/CNFs. And the Co2+@Co3+-Ag/CNFs sample was obtained through transform Co2+-Co3+ partially by the catalytic oxidation performance of silver, instead of the traditional high-temperature calcination process. Meanwhile, the high conductive of Ag can promote the transportation of electrons and ions between the electrode and electrolyte. The flexible composite materials as free-standing and additive-free film electrodes for supercapacitors. In virtue of the presence of Ag, the composite materials have better conductivity and supercapacitor performance than Co/CNFs-based electrode. Interestingly, the sample of Co2+-Ag/CNFs has a higher capacitors than Co2+@Co3+-Ag/CNFs sample, that indicates the supercapacitor performance has an important relationship with the valence state of cobalt. [ABSTRACT FROM AUTHOR]

Flexible and portable supercapacitors as a variety of energy storage devices are used in wearable electronic devices. However, the practical application of flexible supercapacitors is still restricted by comparatively poor performance. Herein, we have successfully prepared porous carbon nanofibers supported Sn and Zn bimetallic composites as flexible and freestanding electrode material in supercapacitors. Sn element encapsulated in nano-fiber films were prepared by electrospinning technique, the SnO x -ZnO/MCNFs composites were formed by immersion of different proportions of Zn2+, and further high temperature carbonization process. In addition, on the basis of comparative experiments, a possible mechanism for effective synergy between the two metals were raised. The specific capacitance of SnO x -ZnO/MCNFs-10 mmol/L at 0.5 A g−1 is 783 F g−1 with the retention rate of 87% after 5000 cycles, which is higher than their respective counterparts SnO x /MCNFs (599 F g−1) and ZnO/MCNFs (429 F g−1). Moreover, a flexible all-solid-state asymmetric supercapacitor (ASC) was further assembled with the energy density of 37.7 Wh kg−1 at the power density of 374.9 W kg−1, and long-term cyclic stability (76.2% after 5000 cycles). The reason for the remarkable electrochemical performance could be the reasonable combination of the two electrode materials, which provides a new idea for the application of composite materials in supercapacitors. • Porous carbon nanofibers supported Sn and Zn have been successfully prepared. • The specific capacitance of SnO x -ZnO/MCNFs-10 at 0.5 A g−1 is 783 F g−1 with the retention rate of 87% after 5000 cycles. • The SnO x and ZnO in the sample showed strong synergistic effect. [ABSTRACT FROM AUTHOR]

Multichannel carbon nanofibers-based amorphous vanadium (VMCNFs) was fabricated via electrospinning technology and calcination process. The amorphous V 2 O 5 were homogeneous dispersed in the carbon nanofibers with inner hollow channels. One-dimensional structure nanomaterials with a compound inner fistulous pore construction promote the electrochemical property due to the synergistic effect between the hollow inner channels and carbon nanofibers with amorphous vanadium. With changing the addition amount of PS acting as a porogen, the optimized VMCNFs-0.5, in which the molar ratio of VO(acac) 2 /styrene monomer (SM) was 0.5, exhibited a high specific capacitance of 739 F g −1 at 0.5 A g −1 and good cycling performance with 80.3% capacitance retention after 1500 cycles. Thus this novel method can provide an acceptable idea for practical applications in energy storage. [ABSTRACT FROM AUTHOR]