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Key Words:Transition metal selenidesMXeneD -band centerElectrochemical activitySupercapacitor
Abstract:Heteroatom substitution stands as a promising strategy to boost the redox activity of transition metal selenides in supercapacitors; nonetheless, the underlying mechanisms that govern this enhanced activity have yet to be fully elucidated. It is presented that d-band center can be utilized as a descriptor to elucidate the redox activity. Within this context, we employ CoNi2Se4/MXene heterostructure as a paradigm, wherein CoNi2Se4 nanoplates are meticulously dispersed on MXene, thereby fostering a more efficient ion diffusion pathway to the redox reaction sites. Subsequently, phosphorus (P) heteroatoms, characterized by lower electronegativity and elevated ionization energy, are incorporated into CoNi2Se4/MXene architecture, which upshifts the d-band center of Ni/Co active sites in CoNi2Se4 close to the Fermi level, resulting in a depletion in the occupancy of antibonding orbitals upon interaction with the O 2p orbital from electrolyte ion OH- . This enhances the interfacial charge transfer and ensures robust OH- adsorption, thereby boosting redox activity. Meanwhile, P doping also introduces Se vacancies, facilitating the ion adsorption and diffusion. Leveraging these advancements, the prepared cathode delivers a higher specific capacitance and retains a better cycling stability. This investigation not only delineates criteria for heteroatom selection but also sheds light on the intricate mechanisms of heteroatom substitution, offering a fresh perspective on the orbital-scale manipulation to augment the redox activity of supercapacitor electrodes.
Volume:513
Issue:-
Translation or Not:no