Ultrasmall Co₃O₄ Nanoparticles Confined in P, N-Doped Carbon Matrices for High-Performance Supercapacitors

Abstract

Co3O4 nanoparticles with smaller particle size can expose more active sites to react with electrolytes, thereby exhibiting better supercapacitive performance. However, the size of Co3O4 nanoparticles is difficult to be effectively controlled in traditional carbon matrices. Herein, P, N-codoped carbon matrices with ultrahigh surface area and abundant nanocavities are used as a novel host to confine the growth of Co3O4 nanoparticles. The Co3O4/carbon composites with high redox activities of Co3O4 are successfully obtained, in which Co3O4 nanoparticles are strongly anchored in the carbon matrices, resulting in the enhancement of the composites’ capacitive performance (1310 F g–1 at 0.5 A g–1). Meanwhile, the strong anchoring effect of the carbon host on Co3O4 nanoparticles because of the rich doping elements and the confinement effect of the nanocavities ensure long-term stability (92% capacitance retention after 5000 cycles). Furthermore, the assembled asymmetric supercapacitor using this composite as the cathode material and activated carbon as the anode material delivers a high energy density of 47.18 W h kg–1 at 375 W kg–1.

Unlocking the Potential of Oxygen-Deficient Copper-Doped Co3O4 Nanocrystals Confined in Carbon as an Advanced Electrode for Flexible Solid-State Supercapacitors

“…This high rate of performance is also superior to most previously reported values for cobalt-and copper-based electrodes. 24 After 5000 cycles of charging/discharging, the O v -Cu-Co 3 O 4 @C-2 electrode presents a capacity retention of 95.0% at 10 A g −1 , which is higher than those of the pristine Co 3 O 4 @C (84.2%), Cu-Co 3 O 4 @C (91.1%), O v -Cu-Co 3 O 4 @ C-1 (93.8%), and O v -Cu-Co 3 O 4 @C-3 (93.9%) electrodes, respectively (Figure 2h). The exceptional cyclability is revealed by the SEM images of the cycled O v -Cu-Co 3 O 4 @C-2 (Figure S15), where the 1D nanostructure is sufficiently preserved after the cycling test.…”

Recent Developments of Transition Metal Compounds-Carbon Hybrid Electrodes for High Energy/Power Supercapacitors

“…Yang and his co-works successfully obtained Co 3 O 4 /P, N co-doped carbon composites (Co 3 O 4 @PNC) through confining the growth of Co 3 O 4 nanoparticles within the nanopores of P, N co-doped carbon material [ 103 ]. Compared with Co 3 O 4 (about 320 F g −1 ), the Co 3 O 4 @PNC-2 (2 represents mass loadings of Co 3 O 4 ) composite showed a higher specific capacitance of 1310 F g −1 at 0.5 A g −1 , which still remained at 655 F g −1 even at a high current density of 20 A g −1 , indicating an excellent rate capability.…”

Sub‐10‐nm Ag/AgX (X = Br,Cl) Nanoparticles: Superior Visible‐Light‐Driven Plasmonic Photocatalysts

“…[ 14–18 ] In this direction, micro/nanostructured Ag/AgX‐based (X = Br, Cl) plasmonic nanocomposites have been receiving particular attention as promising visible‐light‐driven photocatalysts. [ 17–38 ] This is a consequence of their exceptional catalytic performances, despite the fact that AgX species are frequently employed as the basic source materials in photographic films and are unstable under light irradiations. [ 24 ] By means of bandgap engineering, Z ‐scheme engineering, hybridization, shape control, and synthesis of ultrafine Ag/AgX nanoparticles (NPs) etc., great efforts have been devoted to high‐performance Ag/AgX‐based photocatalysts.…”

“…[ 24 ] By means of bandgap engineering, Z ‐scheme engineering, hybridization, shape control, and synthesis of ultrafine Ag/AgX nanoparticles (NPs) etc., great efforts have been devoted to high‐performance Ag/AgX‐based photocatalysts. [ 17–38 ] Among these sophisticated approaches, the formulation of ultrafine Ag/AgX NPs with a sub‐10‐nm size is recognized to be the most fundamental protocol. [ 26–35 ] This results from the generally exceptional catalytic activity of ultrasmall NPs, wherein it is widely known that when the size of the NPs is less than 10 nm, the number of surface‐exposed atoms starts exceeding that of bulk atoms with an increased surface‐to‐volume ratio and a decreased surface atomic coordination, facilitating an exposure of abundant catalytically active sites and accordingly favoring greatly enhanced catalytic performances.…”

“…have to be involved in most of these scenarios. [ 26–35 ] Considering the great interests in Ag/AgX‐based plasmonic photocatalysts [ 17–38 ] and the general concerns of sub‐10‐nm NPs, [ 42–47 ] a facile, green yet low‐cost synthesis of sub‐10‐nm Ag/AgX with greatly enhanced catalytic performances is a subject of paramount importance deserving investigation.…”