Activated Carbon-MnO2 Composite on Nickel Foam as Supercapacitors Electrode in Organic Electrolyte

Since energy storage is an essential component of global energy development, starting with batteries, fuel cells, and supercapacitors, it is an important topic of particular concern. Supercapacitors continue to be developed due to their high power density when compared to batteries, despite all of the benefits and drawbacks of the three. Activated carbon (AC) is materials that frequently utilized as a supercapacitor electrode due to the high surface area. Metal oxides such as manganese dioxide (MnO2) with high teoritical specific capacitance which loaded in activated carbon will caused an improvement on supercapacitors electrochemical performance. The composite was fabricated using blending method with a mass difference of MnO2, then deposited on a porous Ni-foam substrate. Ni-foam pores play as main role on the process of transferring electrolyte ions in the system so that the AC/MnO2 has, resulting a supercapacitor based AC-MnO2 15% nanocomposite with a gravimetric capacitance, energy density and power density of 79 F/g at 1 A/g, W/kg and Wh/kg respectively. The cell could maintain up to 93% after 100 cycles

The dynamics of ultraviolet-induced oxygen vacancy at the surface of insulating SrTiO3(001)

The effect of ultra-violet (UV) irradiation on the electronic structure and the surface resistance of an insulating SrTiO3(001) crystal is studied in this work. Upon UV irradiation, we shows that the two-dimensional electron gas (2DEG) emerges at the insulating SrTiO3 surface and there is a pronounced change in the surface resistance. By combining the observations of the change in valance band and the resistance change under different environments of gas pressure and gas species, we find that UV-induced oxygen vacancies at the surface plays a major role in the resistance change. The dynamic of the resistance change at different oxygen pressures also suggests an alternative method of low-pressure sensing.PostprintPeer reviewe

Negative electronic compressibility and tunable spin splitting in WSe2

This work was supported by the Engineering and Physical Sciences Research Council, UK (Grant Nos. EP/I031014/1, EP/M023427/1, EP/L505079/1, and EP/G03673X/1), TRF-SUT Grant RSA5680052 and NANOTEC, Thailand through the CoE Network. PDCK acknowledges support from the Royal Society through a University Research Fellowship. MSB was supported by the Grant-in-Aid for Scientific Research (S) (No. 24224009) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan.Tunable bandgaps1, extraordinarily large exciton-binding energies2, 3, strong light–matter coupling4 and a locking of the electron spin with layer and valley pseudospins5, 6, 7, 8 have established transition-metal dichalcogenides (TMDs) as a unique class of two-dimensional (2D) semiconductors with wide-ranging practical applications9, 10. Using angle-resolved photoemission (ARPES), we show here that doping electrons at the surface of the prototypical strong spin–orbit TMD WSe2, akin to applying a gate voltage in a transistor-type device, induces a counterintuitive lowering of the surface chemical potential concomitant with the formation of a multivalley 2D electron gas (2DEG). These measurements provide a direct spectroscopic signature of negative electronic compressibility (NEC), a result of electron–electron interactions, which we find persists to carrier densities approximately three orders of magnitude higher than in typical semiconductor 2DEGs that exhibit this effect11, 12. An accompanying tunable spin splitting of the valence bands further reveals a complex interplay between single-particle band-structure evolution and many-body interactions in electrostatically doped TMDs. Understanding and exploiting this will open up new opportunities for advanced electronic and quantum-logic devices.PostprintPeer reviewe

Particle-Hole Symmetry Breaking in the Pseudogap State of Bi2201

In conventional superconductors, a gap exists in the energy absorption spectrum only below the transition temperature (Tc), corresponding to the energy price to pay for breaking a Cooper pair of electrons. In high-Tc cuprate superconductors above Tc, an energy gap called the pseudogap exists, and is controversially attributed either to pre-formed superconducting pairs, which would exhibit particle-hole symmetry, or to competing phases which would typically break it. Scanning tunnelling microscopy (STM) studies suggest that the pseudogap stems from lattice translational symmetry breaking and is associated with a different characteristic spectrum for adding or removing electrons (particle-hole asymmetry). However, no signature of either spatial or energy symmetry breaking of the pseudogap has previously been observed by angle-resolved photoemission spectroscopy (ARPES). Here we report ARPES data from Bi2201 which reveals both particle-hole symmetry breaking and dramatic spectral broadening indicative of spatial symmetry breaking without long range order, upon crossing through T* into the pseudogap state. This symmetry breaking is found in the dominant region of the momentum space for the pseudogap, around the so-called anti-node near the Brillouin zone boundary. Our finding supports the STM conclusion that the pseudogap state is a broken-symmetry state that is distinct from homogeneous superconductivity.Comment: Nature Physics advance online publication, 04/04/2010 (doi:10.1038/nphys1632) Author's version of the paper

Activated Carbon-MnO

Since energy storage is an essential component of global energy development, starting with batteries, fuel cells, and supercapacitors, it is an important topic of particular concern. Supercapacitors continue to be developed due to their high power density when compared to batteries, despite all of the benefits and drawbacks of the three. Activated carbon (AC) is materials that frequently utilized as a supercapacitor electrode due to the high surface area. Metal oxides such as manganese dioxide (MnO2) with high teoritical specific capacitance which loaded in activated carbon will caused an improvement on supercapacitors electrochemical performance. The composite was fabricated using blending method with a mass difference of MnO2, then deposited on a porous Ni-foam substrate. Ni-foam pores play as main role on the process of transferring electrolyte ions in the system so that the AC/MnO2 has, resulting a supercapacitor based AC-MnO2 15% nanocomposite with a gravimetric capacitance, energy density and power density of 79 F/g at 1 A/g, W/kg and Wh/kg respectively. The cell could maintain up to 93% after 100 cycles

Hierarchical Activated Carbon–MnO₂ Composite for Wide Potential Window Asymmetric Supercapacitor Devices in Organic Electrolyte

The consumption of electrical energy grows alongside the development of global industry. Generating energy storage has become the primary focus of current research, examining supercapacitors with high power density. The primary raw material used in supercapacitor electrodes is activated carbon (AC). To improve the performance of activated carbon, we used manganese dioxide (MnO2), which has a theoretical capacitance of up to 1370 Fg−1. The composite-based activated carbon with a different mass of 0–20% MnO2 was successfully introduced as the positive electrode. The asymmetric cell supercapacitors based on activated carbon as the anode delivered an excellent gravimetric capacitance, energy density, and power density of 84.28 Fg−1, 14.88 Wh.kg−1, and 96.68 W.kg−1, respectively, at 1 M Et4NBF4, maintaining 88.88% after 1000 test cycles