Two-dimensional nanomaterials hold great promise as electrode materials for the construction of excellent electrochemical energy storage and transformation apparatuses. In the study, metallic layered cobalt sulfide was, firstly, applied to the area of energy storage as a supercapacitor electrode. By a facile and scalable method for cathodic electrochemical exfoliation, metallic layered cobalt sulfide bulk can be exfoliated into high-quality and few-layered nanosheets with size distributions in the micrometer scale range and thickness in the order of several nanometers. With a two-dimensional thin sheet structure of metallic cobalt sulfide nanosheets, not only was a larger active surface area created, but also, the insertion/extraction of ions in the procedure of charge and discharge were enhanced. The exfoliated cobalt sulfide was applied as a supercapacitor electrode with obvious improvement compared with the original sample, and the specific capacitance increased from 307 F∙g⁻¹ to 450 F∙g⁻¹ at the current density of 1 A∙g⁻¹. The capacitance retention rate of exfoliated cobalt sulfide enlarged to 84.7% from the original 81.9% of unexfoliated samples while the current density multiplied by 5 times. Moreover, a button-type asymmetric supercapacitor assembled using exfoliated cobalt sulfide as the positive electrode exhibits a maximum specific energy of 9.4 Wh∙kg⁻¹ at the specific power of 1520 W∙kg⁻¹.

Elbaite is a natural silicate mineral with a spontaneous electric field. In the current study, it was selected as a pyroelectric catalyst to promote hydrogen peroxide (H₂O₂) for dye decomposition due to its pyro-electro-chemical coupling. The behaviors and efficiency of the elbaite/H₂O₂ system in rhodamine B (RhB) degradation were systematically investigated. The results indicate that the optimal effective degradability of RhB reaches 100.0% at 4.0 g/L elbaite, 7.0 mL/L H₂O₂, and pH = 2.0 in the elbaite/H₂O₂ system. The elbaite/H₂O₂ system exhibits high recyclability and stability after recycling three times, reaching 94.5% of the degradation rate. The mechanisms of RhB degradation clarified that the hydroxyl radical (·OH) is the main active specie involved in catalytic degradation in the elbaite/H₂O₂ system. Moreover, not only does elbaite act as a pyroelectric catalyst to activate H₂O₂ in order to generate the primary ·OH for subsequent advanced oxidation reactions, but it also has the role of a dye sorbent. The elbaite/H₂O₂ system shows excellent application potential for the degradation of RhB.