ABSTRACT
Nonphotocatalytic water splitting through oxygen-deficient, mesoporous metal oxide design-based hydroelectric cells (HECs) is a well-known phenomenon. To exploit more power from HECs, a metal oxide with more oxygen deficiency is desirable. In this study, oxygen-deficient mesoporous SnO2 via a sol-gel method and its composites with reduced graphene oxide (rGO) have been presented. Raman spectra of SnO2-rGO nanocomposites revealed an increase in the oxygen vacancies, while the X-ray diffraction (XRD) pattern confirmed the strain formation in the nanocomposite lattice owing to defect formation. The X-ray photoemission spectroscopy (XPS) results also indicated the presence of oxygen vacancies on the surface of SnO2, whereas Brunauer-Emmett-Teller (BET) measurements revealed that adding rGO into SnO2 increased the surface area from 44.54 to 84.00 m2 g-1. The water molecules are chemidissociated on the oxygen-deficient mesoporous surface of the pellet followed by physiodissociation at the mesopores. The redox reaction of the dissociated ions at the Zn anode and the Ag inert cathode produces current in the outer circuit. Interestingly, adding few drops of water into a SnO2-rGO-based HEC resulted in a short-circuit current of 148 mA with an open-cell voltage of 1.0 V. The maximum power delivered by the SnO2-rGO-based HEC is 148 mW. The addition of rGO into SnO2 boosts the peak current remarkably from 68 to 148 mA, which is the highest reported current generated by a hydroelectric cell.
ABSTRACT
As globally, the main focus of the researchers is to develop novel electrode materials that exhibit high energy and power density for efficient performance energy storage devices. This review covers the up-to-date progress achieved in transition metal dichalcogenides (TMDs) (e.g. MoS2, WS2, MoSe2,and WSe2) as electrode material for supercapacitors (SCs). The TMDs have remarkable properties like large surface area, high electrical conductivity with variable oxidation states. These properties enable the TMDs as the most promising candidates to store electrical energy via hybrid charge storage mechanisms. Consequently, this review article provides a detailed study of TMDs structure, properties, and evolution. The characteristics technique and electrochemical performances of all the efficient TMDs are highlighted meticulously. In brief, the present review article shines a light on the structural and electrochemical properties of TMD electrodes. Furthermore, the latest fabricated TMDs based symmetric/asymmetric SCs have also been reported.
ABSTRACT
Two unprecedented organic amine templated silver organophosphonate hybrid solids have been synthesized hydrothermally by varying the molar ratio of the reactants. Both of the compounds consist of novel tetra- and penta-nuclear silver phosphonate basic building units. The dielectric constants are extremely large due to the charge separation of anionic metal phosphonate frameworks and cationic templated piperazine moieties in the compounds, as found for the first time in a hybrid organophosphate family. The conductivity and UV-visible absorption studies provide strong evidence about the semiconducting nature of the present compounds.
ABSTRACT
The generation of electricity by dissociating water into H3O+ and OH- ions through a hydroelectric cell (HEC) without liberating any toxic waste has achieved a groundbreaking feat. Nanoporous magnesium-doped SnO2 and cobalt-doped SnO2 materials have been prepared via a novel sol-gel method. The X-ray diffraction patterns of Mg-doped SnO2 and Co-doped SnO2 completely match with those of pure SnO2, which confirms the interstitial substitution of Mg and Co in the pristine SnO2. The results shown by Brunauer-Emmett-Teller theory curves illustrate the surface area of Mg-doped SnO2 and Co-doped SnO2 to be 46.22 and 46.81 m2/g, respectively, with their pore radii being â¼3 nm. The synthesized nanoparticles were pressed into square pellets of area 4.08 cm2. A zinc electrode was pasted on one side of each pellet and silver was painted on the other side to develop the HECs. The fabricated HECs of Mg-doped SnO2 and Co-doped SnO2 with 4.08 cm2 area deliver short-circuit current, open-circuit voltage, and off-load output power of 41.69 mA, 0.787 V, and 32.81 mW and 77.52 mA, 0.454 V, and 35.19 mW, respectively. Cyclic voltammetry of both materials exhibited cathodic and anodic peaks in relation to the redox reactions taking place at Zn and silver electrodes. Nyquist curves of both HECs in the wet state confirm the ionic diffusion of split H3O+ and OH- ions as compared to the dry state. An off-load output power of 35.19 mW delivered by the HEC of Co-doped SnO2 with 4.08 cm2 area is quite promising and has great potential to replace other green energy sources.
ABSTRACT
This study reports a unique graphitic-C3N4 supported ZnCo2O4 composite, synthesized through a facile hydrothermal method to enhance the electrochemical performance of the electrode. The g-C3N4@ZnCo2O4 hybrid composite based electrode exhibits a significant increase in specific surface area and maximum specific capacity of 157 mAhg-1 at 4 Ag-1. Moreover, g-C3N4@ZnCo2O4 electrode maintained significant capacity retention of 90% up to 2500 cycles. Utilizing this composite in the development of the symmetric device, g-C3N4@ZnCo2O4//g-C3N4@ZnCo2O4 displays a specific capacity of 121 mAhg-1. The device exhibits an energy density of 39 Whkg-1 with an equivalent power density of 1478 Wkg-1. A good cycling stability performance with an energy efficiency of 75% and capacity retention of 71% was observed up to 10,000 cycles. The superior performance of g-C3N4@ZnCo2O4 is attributed to the support of the g-C3N4 which increases the surface area, electroactive sites and provides chemical stability for electrochemical performance. The outstanding performance of this exclusive device symbolizes remarkable progress in the direction of high-performance energy storage applications.