Electrochemical capacitors (best known as supercapacitors) are high‐performance energy storage devices featuring higher capacity than conventional capacitors and higher power densities than batteries, and are among the key enabling technologies of the clean energy future. This review focuses on performance enhancement of carbon‐based supercapacitors by doping other elements (heteroatoms) into the nanostructured carbon electrodes. The nanocarbon materials currently exist in all dimensionalities (from 0D quantum dots to 3D bulk materials) and show good stability and other properties in diverse electrode architectures. However, relatively low energy density and high manufacturing cost impede widespread commercial applications of nanocarbon‐based supercapacitors. Heteroatom doping into the carbon matrix is one of the most promising and versatile ways to enhance the device performance, yet the mechanisms of the doping effects still remain poorly understood. Here the effects of heteroatom doping by boron, nitrogen, sulfur, phosphorus, fluorine, chlorine, silicon, and functionalizing with oxygen on the elemental composition, structure, property, and performance relationships of nanocarbon electrodes are critically examined. The limitations of doping approaches are further discussed and guidelines for reporting the performance of heteroatom doped nanocarbon electrode‐based electrochemical capacitors are proposed. The current challenges and promising future directions for clean energy applications are discussed as well.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/aenm.202001239

Heteroatom-Doped and Oxygen-Functionalized Nanocarbons for High-Performance Supercapacitors

Adsorption and sensing of CO and C2H2 by S-defected SnS2 monolayer for DGA in transformer oil: A DFT study

C7N6 monolayer as high capacity and reversible hydrogen storage media: A DFT study

In this paper, we designed a three-band narrowband perfect absorber based on bulk Dirac semi-metallic (BDS) metamaterials. The absorber consists of a hollow Dirac semi-metallic layer above, a gold layer below and a photonic crystal slab (PCS) in the middle. The study found that the terahertz wave absorber achieved three perfect absorption rates of more than 95% in the range of 1 to 2.4 THz. The minimum bandwidth (FWHM) is 0.02 THz, and the maximum quality factor (Q) is 106. A reasonable explanation of high absorption can be obtained by impedance matching, electric dipole and other principles. The absorption spectra of the two polarizations show different responses at different incident angles. In addition, we also obtained the influence of the structural parameters of the upper layer of the metamaterial on the absorption performance. We defined the refractive index sensitivity (S) with a maximum sensitivity of 0.1525 THz RIU-1 and a highest quality factor (FOM) of 4.26 in the refractive index range of 1 to 1.8. The maximum adjustable range is 0.06 THz in the Fermi energy range of 60 to 140 meV. Because of its excellent characteristics, our absorber will have good development prospects in the fields of optical switching, biochemical imaging, and space detection.

Three-band perfect absorber with high refractive index sensing based on an active tunable Dirac semimetal

Highly enhanced NH3-sensing performance of BC6N monolayer with single vacancy and Stone-Wales defects: A DFT study

Influence of defects and dopants on the sensitivity of arsenene towards HCN

Effect of the N/P/S and transition-metal co-doping on the quantum capacitance of supercapacitor electrodes based on mono- and multilayer graphene

Hot compression tests of Mg-Gd-Y-Zr alloy at different deformation temperatures and strains were carried out with Gleeble-1500 simulator at strain rate of 0.002 s−1. The microstructure evolution of 400 °C/0.002 s−1 sample under different strain was analyzed emphatically by transmission electron microscopy and electron backscatter diffraction technology. Dynamic precipitation characteristics and nucleation-expansion mechanism of dynamic recrystallization (DRX) were discussed in detail. The results indicated that the dynamic precipitation takes place prior to DRX, and the morphology, size and distribution of precipitates change with increasing strain. At the later stage of deformation, the large-size hard phase β-Mg5(Gd,Y) can induce the particle-stimulated nucleation (PSN) mechanism under large strain and act as an effective nucleation site for DRX. In addition, we constructed a schematic diagram of the DRX nucleation-expansion mechanism of Mg-Gd-Y-Zr alloy under high temperature deformation. The first layer of DRX grains is formed by discontinuous dynamic recrystallization (DDRX) mechanism characterized by grain boundary bulge out, and the precipitates distributed at the original grain boundary promote DDRX nucleation; The expansion of necklace structure depends on continuous dynamic recrystallization (CDRX) mechanism; Subgrain division can further refine DRX grains.

Dynamic precipitation and recrystallization mechanism during hot compression of Mg-Gd-Y-Zr alloy

We systemically investigate the effect of dopants on the geometrics, electronic and magnetic properties of asymmetric washboard structure of antimonene (aW-Sb) by using density functional theory (DFT) calculations. The large binding energies and short bond lengths indicate the doped systems still maintain high stability. Pristine aW-Sb is a nonmagnetic semiconductor with a narrow band gap, while the doped aW-Sb exhibit metallic by doping. Furthermore, the Ti, V, Cr, Mn and Fe doping induced magnetic states, and the result of spin density indicates that the magnetic moments are mainly localized at dopant and the adjacent Sb atoms.

/pdf/the-influence-of-dopants-on-aw-phase-antimonene-theoretical-46puaa0fao.pdf

The influence of dopants on aW-phase antimonene: theoretical investigations

We have studied the microstructure evolution and deformation behavior of Mg-5Gd-3Y-(1Sn)-0.5Zr alloys during hot compression (T = 350 °C, 400 °C, 450 °C and 500 °C, e ˙  = 0.002 s−1, 0.01 s−1, 0.1 s−1 and 1 s−1) by transmission electron microscopy and electron backscattering technology. Sn can promote dynamic precipitation to activate the particle-stimulated nucleation (PSN) mechanism induced by the cluster precipitates and promote and dynamic recrystallization (DRX); in addition, Sn can inhibit the formation of high-angle grain boundaries (HAGBs) by reducing the activation of pyramidal and slip and delaying DRX. The two processes are in a competitive relationship with each other in the hot deformation of Mg-Gd-Y-Sn-Zr alloys. At low temperatures (350 °C–400 °C) and high strain rates, the former dominates: DRX is promoted, accompanied by a decrease in flow stress. At high temperatures (450 °C–500 °C) and low strain rates, the latter is dominant due to the absence of dynamic precipitation: DRX is delayed, and flow stress is increased accordingly. Flow stress between the two extreme deformation conditions is determined by the competitive relationship between them. We also found that the addition of Sn could increase the thermal deformation activation energy of Mg-Gd-Y-Zr alloys, weaken the texture and inhibit twin growth. Finally, we constructed a schematic diagram of the DRX mechanism during the thermal deformation process to illustrate the effects of PSN, CDRX, and DDRX on the evolution of the microstructure in detail.

Qian Zhang

Papers

Influence of defects and dopants on the sensitivity of arsenene towards HCN

Effect of the N/P/S and transition-metal co-doping on the quantum capacitance of supercapacitor electrodes based on mono- and multilayer graphene

Dynamic precipitation and recrystallization mechanism during hot compression of Mg-Gd-Y-Zr alloy

The influence of dopants on aW-phase antimonene: theoretical investigations

Effect of Sn addition on the deformation behavior and microstructural evolution of Mg-Gd-Y-Zr alloy during hot compression