Band bending induced charge redistribution on the amorphous MIL-53(Al)/Co-LDH conjunction to boost the supercapacitive and oxygen evolution performance

Abstract

The modulation of electron configuration is an efficient alternative to inspire electrochemical property. In this work, a gentle ligand-competition amorphization is used to shape the amorphous aMIL-53(Al) nanosheets enriched oxygen vacancies. The Co-LDH nanoplate is pregnant from Co-ZIF. Thus, the layered 2D/2D aMIL-53(Al)/Co-LDH p-n junction (aMC-x) has been optionally designed. The charge redistribution across the p-n junction has made Co-LDH positive and aMIL-53(Al) negative in the space-charge region. Benefiting from compositional heterogeneity with band bending and oxygen vacancies, the aMC-1 has yielded excellent electrochemical merits for oxygen evolution and capacitive performance. A high specific capacitance of 773.2 F g−1 at 1 A g−1 is achieved, about 2.23 and 44.8 folds higher than those of original Co-LDH and aMIL-53(Al), respectively. The asymmetric supercapacitor (ASC) could provide a maximum power density of 7978.8 W kg−1 at a current density of 9.8 Wh kg−1 and good durability. Moreover, the aMIL-53(Al)/Co-LDH heterojunction achieves a lower overpotential of 278 mV and smaller Tafel slope of 51.1 mV dec−1 in OER. As expected, the synergistic effect in the p-n junction based on amorphous MOF is a potential strategy to regulate the electronic structure and promote the electrochemical activities.