The synthesis of Co 3 O 4 /C composite with aloe juice as the carbon aerogel substrate for asymmetric supercapacitors

Abstract(#br)Transition metal oxide (TMO)-based 3D hollow nanocomposites with a high loading capacity, large specific surface area, and good dispersity have gained considerable attention for energy-related applications. The controllable fabrication of TMO-based hollow nanostructures with adequate mass transfer channels through a simple and eco-friendly method is highly desirable. Herein, 3D net-like Co 3 O 4 /C composites were solvothermally fabricated and calcined using aloe juice as a novel carbon substrate. The as-prepared material showed a specific capacitance of 1345.2 F g −1 at 1 A g −1 and excellent charge–discharge stability with capacitance retention of 92.7% after 10000 cycles. Moreover, an asymmetric supercapacitor composed of an ALC-700 positive electrode and an active-carbon negative electrode exhibited a high energy density of 68.17 Wh⋅kg −1 at 549 W kg −1 and excellent cycling performance. We report the first use of carbonized aloe juice as a carbon matrix to obtain a 3D hierarchical porous structure for energy devices. The proposed method of aerogel can be generalized to utilize the juices of other fruits, sugarcane, and various plants

Structure and Electrochemical Properties of Mn3O4 Nanocrystal-Coated Porous Carbon Microfiber Derived from Cotton

Biomorphic Mn3O4 nanocrystal/porous carbon microfiber composites were hydrothermally fabricated and subsequently calcined using cotton as a biotemplate. The as-prepared material exhibited a specific capacitance of 140.8 F·g−1 at 0.25 A·g−1 and an excellent cycle stability with a capacitance retention of 90.34% after 5000 cycles at 1 A·g−1. These characteristics were attributed to the introduction of carbon fiber, the high specific surface area, and the optimized microstructure inherited from the biomaterial

Fabrication of In_xGa_1−xN Nanowires on Tantalum Substrates by Vapor-Liquid-Solid Chemical Vapor Deposition

InxGa1−xN nanowires (NWs) have drawn great attentions for their applications in optoelectronic and energy conversion devices. Compared to conventional substrates, metal substrates can offer InxGa1−xN NW devices with better thermal conductivity, electric conductivity, and mechanic flexibility. In this article, InxGa1−xN NWs were successfully grown on the surface of a tantalum (Ta) substrate via vapor-liquid-solid chemical vapor deposition (VLS-CVD), as characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), scanning and transmission electron microscope (STEM), and photoluminescence spectroscopy (PL). It was found that the surface pretreatment of Ta and the composition of metallic catalysts played important roles in the formation of NWs. A dimpled nitrided Ta surface combined with a catalyst of nickle is suitable for VLS-CVD growth of the NWs. The obtained InxGa1−xN NWs grew along the [1100] direction with the presence of basal stacking faults and an enriched indium composition of ~3 at.%. The successful VLS-CVD preparation of InxGa1−xN nanowires on Ta substrates could pave the way for the large-scale manufacture of optoelectronic devices in a more cost-effective way

ZnGaNO Photocatalyst Particles Prepared from Methane-Based Nitridation Using Zn/Ga/CO₃ LDH as Precursor

Methane-based nitridation was employed to produce wurtzite zinc-gallium oxynitride (ZnGaNO) photocatalyst particles using Zn/Ga/CO₃ layered double hydroxides (LDHs) as precursor. Introduction of methane to nitridation would promote the formation of Zn–O bonding and suppress shallow acceptor complexes such as V_(Zn)-Ga_(Zn) and Ga-O_i in ZnGaNO particles. On the other hand, high flow rate of methane would induce breaking of Ga–N bonding and enhance surface deposition of metallic Ga atoms. After loading with Rh and RuO₂, ZnGaNO particles had free electron density in an order of S50 > S20 > S90 > S0, which correlated well with their photocatalytic performance upon visible-light irradiation. The best performance of the loaded S50 was ascribed to the relatively flat surface band bending of the particle. Methane-based nitridation of Zn/Ga/CO₃ LDHs would provide a new route to tune the surface chemistry of ZnGaNO and enhance the photocatalytic performance to its full potential