Improved Photoelectrochemical Cell Performance of Tin Oxide with Functionalized Multiwalled Carbon Nanotubes–Cadmium Selenide Sensitizer

Here we report functionalized multiwalled carbon nanotubes (<i>f</i>-MWCNTs)–CdSe nanocrystals (NCs) as photosensitizer in photoelectrochemical cells, where <i>f</i>-MWCNTs were uniformly coated with CdSe NCs onto SnO₂ upright standing nanosheets by using a simple electrodeposition method. The resultant blended photoanodes demonstrate extraordinary electrochemical properties including higher Stern–Volmer constant, higher absorbance, and positive quenching, etc., caused by more accessibility of CdSe NCs compared with pristine SnO₂–CdSe photoanode. Atomic and weight percent changes of carbon with <i>f</i>-MWCNTs blending concentrations were confirmed from the energy dispersive X-ray analysis. The morphology images show a uniform coverage of CdSe NCs over <i>f</i>-MWCNTs forming a core–shell type structure as a blend. Compared to pristine CdSe, photoanode with <i>f</i>-MWCNTs demonstrated a 257% increase in overall power conversion efficiency. Obtained results were corroborated by the electrochemical impedance analysis. Higher scattering, more accessibility, and hierarchical structure of SnO₂-<i>f</i>-MWCNTs-blend–CdSe NCs photoanode is responsible for higher (a) electron mobility (6.89 × 10^–4 to 10.89 × 10^–4 cm² V^–1 S^1–), (b) diffusion length (27 × 10^–6), (c) average electron lifetime (32.2 ms), and transit time (1.15 ms)