A highly porous MgO entrenched MWCNT composite as a low-cost Pt-free counter electrode for dye-sensitized solar cells and visible light photocatalytic performance towards Congo-red.

Nanostructured composite photocatalysts, consist of multi-walled carbon nanotubes (MWCNT), and cubic face magnesium oxide (MgO) were prepared by sol–gel methodology. Powder X-ray powder diffraction (PXRD) results reveals that the sample was composed of CNT and cubic MgO. Field emission scanning electron microscope (FESEM) studies showed that multi-walled CNTs with the outer diameters of 20–25 nm and length up to several micrometers, which were uniformly coated with the disc like nanoparticles whose diameter was in the range of 20–30 nm. The optical absorption edge was shifted to longer wavelength for MgO/MWCNTs composite, which is confirmed through UV-vis diffuse reflectance (DRS) analysis. The prepared MgO-MWCNTs composite proficiently catalyzed the photodegradation of phenol and congo-red under visible light irradiation. After seven trials, just 3.5 % of the photocatalytic efficiency of the MgO/MWCNTs composite was lost to congo-red, which is an excellent result. We go into great detail about the potential photocatalytic pathway as well. When used in a photovoltaic device, the MgO/MWCNT CE showed high PCE of 5.15% with long term stability. The EIS results also prove that lower resistance and high electron life time. The DSSC based on MC3 CE enhanced the photocurrent conversion efficiency to 5.12% compared to 3.71% with MgO CE. The DSSC based on MC3 composite CE exhibited highest IPCE performance (79%), whereas the MgO, MC1 and MC2 based CEs showed lower IPCE value of nearly 48%, 52% and 42%, respectively [ABSTRACT FROM AUTHOR]