The microstructure of electrospun MXene-engineered membranes was observed via the SEM and TEM. The cross-section morphology of the WGID membrane is shown in
Fig. 3a, revealing that the proposed WGID membrane was consisted of a typical tri-layered structure on an electrospun membrane including PVDF&PU, PU@MXene(10%) and PU@MXene(20%). The uniform nanofibers of the WGID membrane could be observed with the inset of optical photographs in
Fig. 3b-d, as well as the fiber diameter and pore size distribution as exhibited in Fig. S7. The electrospun membrane possessed a polymer-MXene skeleton, as shown by TEM images (
Figs. 3e and S8). Also, the elements of demonstrated by EDS elemental mapping revealed that C, O, and Ti were uniformly distributed on the surface of the WGID sample (
Fig. 3f), indicating that MXene is successfully incorporated into the polymeric matrix. The TGA curve numerically demonstrated the calcined samples of the PU@MXene electrospun membranes with MXene nanosheets loadings of 10 and 20 wt%, respectively, and PVDF&PU electrospun membranes with the result of 20 wt%, as exhibited in
Figs. 3g and S9. Moreover, the XRD pattern of the as-electrospun membranes is displayed in
Fig. 3h, which illustrates the structure of PVDF&PU, PU@MXene(20%), and the WGID membrane. The distinct peaks at 6.9° indicated a MXene lattice structure (002) packed inside the polymer-MXene skeleton. Also, the characteristic peak of PVDF&PU was located at 19.8° with lattice structure of (110) [
37,
41]. To investigate the binding status of the elements, the chemical compositions of all as-electrospun membranes were characterized by XPS. As shown in
Figs. 3i and S10, the Ti 2
p peak was appeared in PU@MXene and the WGID electrospun membranes, assigned to Ti 2
p 1/2, Ti 2
p 3/2 with the corresponding binding energies of 463.73 and 458.28 eV, respectively, Ti − C with a value of 454.61 eV was also detected [
43,
53]. Also, in contrast to the FTIR spectrum of PVDF&PU (
Fig. 3j), the emerging absorption peaks at 3327 and 1724 cm
−1 belong to the characteristic N-H stretching vibration and urethane bond of MXene-engineered electrospun membranes, respectively [
37,
54]. As a result, we successfully fabricated a MXene-engineered WGID membrane for PCE which, as subsequently shown, rendered a tri-layered electrospun membrane.