The wide bandgap energy of TiO2 limited its photocatalytic
activity to UV light. To meet this challenge, TiO2 nanorods
were doped with Si atoms and decorated by CdTe QDs to enhance the
electronic structure, broaden the absorption domain, and improve photoelectrochemical
(PEC) water splitting. Incorporation of Si atoms in the TiO2 structure effectively enhanced the transfer of charge carriers and
the wettability of the surface in the Si:TiO2 electrode
and made it an effective platform for solar-assisted water splitting.
Moreover, the IPCE results prove that CdTe QDs with high absorption
coefficient and photon upconversion spread the photoresponse of CdTe/Si:TiO2 to visible light with an improved photocurrent density of
4.3 mA cm–2 at the potential of 1.23 V vs RHE. The
excellent increase of 12.5 times in PEC activity of CdTe/Si:TiO2 electrode as compared to unmodified TiO2 nanoarrays
and its low overpotential are due to the faster electron transfer
kinetics, enhanced charge carriers density (N
d), and reduced charge recombination rate. The photocurrent
stability of CdTe/Si:TiO2 in numerous on/off cycles and
its long-term durability with a photocurrent decay of about 5% over
10 h show its high photocorrosion resistance. The current study signifies
that CdTe/Si:TiO2 is a suitable and highly efficient photoelectrocatalyst
for water splitting.