Electronic structures of metal and semiconductor composites
play
a crucial role in photoelectric conversion. To obtain a fast-response
photoelectrochemical (PEC) anode, its orbital regulation is a challenge.
Herein, the occupancy state of the d orbitals of Mo is adjusted to
achieve high-efficiency photoelectric conversion by adjusting the
quantity of Cu by magnetron sputtering deposited in Cu/MoS2 composites. Characterization results indicate that the SEM morphology
of MoS2 changes distinctly. Meanwhile, the (111) and (200)
diffraction peaks and 0 and 2+ valence states of Cu appeared
in XRD and XPS, respectively, confirming the successful synthesis
of Cu/MoS2. The prior band shift at the heterojunction
causes efficient separation of photogenerated charge carriers and
the shift of the position of Mo 3d to higher binding energies, which
results in weaker intrinsic luminescence at 810 nm in the PL spectrum
and smaller charge transfer resistance in the electrochemical impedance
spectroscopy spectra, confirming the high PEC performance of the Cu/MoS2 composites. Meanwhile, the density functional theory calculations
reveal that the energy of the d orbital of Mo in MoS2 decreases,
which is helpful to accept electrons in Cu 3d. The Mo d track-occupancy
introduced through the strong interplay between the most desirable
combination of MoS2 and Cu will be accountable for such
record-high performance. Therefore, this study makes a strong case
for fine-tuning the electronic structures of PEC anode materials.