Bilateral growth of monoclinic WO3 and 2D Ti3C2Tx on 3D free-standing hollow graphene foam for all-solid-state supercapacitor

Abstract

• Hollow graphene foam was successfully prepared by TA-CVD method. • m -WO 3 /Ti 3 C 2 T X /HGF-7 electrode was fabricated by UPED and drop-casting methods. • The electrode exhibited a specific capacitance of 573F g −1 with 93.3% cycling stability. • An ASC device showed 27.2 Wh kg −1 energy density at power density of 752 W kg −1 . • The ASC device endured superior cycling stability of 93% over 10,000 GCD cycles. The free-standing three dimensional (3D) hollow graphene foam (HGF) decorated nanostructured pseudocapacitive materials could offer a large active surface area and a extreme conductive porous 3D network for fast reversible charge transfer reactions in the supercapacitor. Herein, the 3D HGF was prepared by a template assisted-chemical vapor deposition (TA-CVD) method and the monoclinic WO 3 ( m- WO 3 ) interconnected nanoparticles as well as 2D Ti 3 C 2 T x sheets were bilaterally loaded on the inner and outer sides of HGF by a simple unipolar electrodeposition (UPED) method and a drop casting method, respectively. The obtained 3D free-standing m- WO 3 /Ti 3 C 2 T X /HGF electrode exhibited an excellent specific capacitance of 573F g −1 at 5 mV s −1 with outstanding rate performance and 93.3% cycling stability over 5000 cycles, which can be attributed to the metal-like conductivity and reversible redox reactions of hydrophilic 2D Ti 3 C 2 T x . The asymmetric solid-state supercapacitor (ASC) illustrated a 2-fold wider potential of 1.4 V in an acidic electrolyte when compared with the MXene-based symmetric supercapacitor. It displayed an excellent specific capacitance of 145.2F g −1 (111.3 mF cm −2 ) at 5 mV s −1 , an ultra-high energy density of 27.2 Wh kg −1 (20.83 μWh cm −2 ) at a power density of 752 W kg −1 along with 93% cycling stability over 10,000 cycles. Therefore, such a m- WO 3 /Ti 3 C 2 T x /HGF electrode should be promising for the fabrication of advanced supercapacitors.