MoO 2 @Cu@C Composites Prepared by Using Polyoxometalates@Metal-Organic Frameworks as Template for All-Solid-State Flexible Supercapacitor

Abstract We have synthesized a composite of MoO 2 @Cu@CusingathermolysistemplateofPOM@MOFcrystal(POM = polyoxometalates, MOF = Metal⿿organic frameworks), in which the Keggin-type Mo-based POMs with negative charges exist as secondary building units of Cu-based MOF. In addition, the material is confirmed to exhibit an excellent capacity of 28.33 mAh g ⿿1 at a current density of 1 A g ⿿1 , which is much higher than MoO 2 -based supercapacitors reported before. Moreover, we have fabricated a symmetrical flexible all-solid-state device with the MoO 2 @Cu@C electrode using PVA-KOH gel polymer as electrolyte and separator, and it shows outstanding sTable performance retaining 91% of its highest charge capacity maintained after 5000 cycles. The present study displayed a novel thermolysis template in the term of POM@MOF and provided an accessible foundation for investigations of MoO 2 -based supercapacitors.