CoSe₂ Nanoparticles Dispersed in WSe₂ Nanosheets for Efficient Electrocatalysis and Supercapacitance Applications

CoSe2 nanoparticles dispersed in WSe2 nanosheets forming heterostructured nanohybrids have been synthesized by a hot-injection colloidal synthesis process for refining their electronic functionalities intensively. Transmission electron microscopy (TEM) images reveal that the WSe2/CoSe2 nanohybrids present as granular nanoparticles of CoSe2 dispersed in WSe2 nanosheets in a scattered way, thus constructing a heteronanostructured system. X-ray diffraction (XRD) patterns, X-ray photoelectron spectroscopy (XPS), and Raman spectroscopic studies besides the microscopic investigations confirmed the formation of the heterostructured nanohybrids along with the electronic interaction between CoSe2 and WSe2 in the heterostructured nanohybrids. The electrochemical investigations demonstrated that the WSe2/CoSe2 heterostructured nanohybrids exhibit improved acidic HER and basic OER electrocatalytic behavior as well as supercapacitor performance than both of the isolated CoSe2 and WSe2 components. The heterostructured nanohybrids are characterized for electrocatalytic performance with a lower overpotential (η10) and Tafel slope values of 157 mV and 79 mV dec–1 for HER and 330 mV and 76 mV dec–1 for OER, respectively. Meanwhile, the heterostructured nanohybrids illustrated very high capacitance (2720 F g–1 at 1 A g–1 and 1200 F g–1 for 20 A g–1) and an enhanced cyclic stability with 93.75% capacitance retention at 20 A g–1, which is superior to that of both of isolated CoSe2 and WSe2 as well as most reported counterparts. The superior electrochemical performance is resulted from an improved electronic conductivity related to the nanoscale heterostructured hybrids through transfer of electrons between CoSe2 and WSe2 that could facilitate the charge-transfer reactions on the surface/interface in an electrochemical process as well as improved ion adsorption due to an increased surface area. Hybridization of CoSe2 and WSe2 to the nanoscale heterostructures with modulated electronic structures and increased active sites could promote the electrocatalysis and charge capacitance performances subsequently.