Photogenerated Carrier Separation and Localized Surface Plasmon Resonance in MoS₂/Metal Nanocomposites: Implications for Photoelectric Devices

Integrating noble metals with semiconductors is a viable approach to enhancing the photoelectric conversion efficiency of samples. The combination of metals with semiconductors has found widespread application in the field of optoelectronics and devices. Herein, metal (M = Ag/Cu) and MoS2 (MoS2/M) nanocomposites were successfully synthesized using magnetron sputtering and hydrothermal two-step methods. The sizes and morphologies of the metals can be adjusted by controlling the sputtering time. Metals Ag and Cu were anchored onto defective MoS2 nanomaterials, serving as photoanodes and light absorbers, respectively. The vacancy-induced defect structure, along with the synergistic effect of the interface and size, can simultaneously regulate the charge-carrier dynamics and the band structure of MoS2/M nanocomposites. The transient photocurrent responses and the electrochemical impedance spectroscopy results demonstrate the excellent photoelectrochemical (PEC) properties of the MoS2/M nanocomposites. A finite-difference time-domain simulation reveals that the strong plasmonic electromagnetic field generated by metal can significantly enhance the energy-band transition rate of neighboring materials and improve photogenerated carrier separation. Compared with pure MoS2, MoS2/M nanocomposites exhibit enhanced nonlinear-optical (NLO) behavior. This improvement stems from an effective charge separation, which is facilitated by a synergistic interaction between the electric field and the plasmonic magnetic field. Density functional theory calculations indicate a decrease in the energy of the Mo d orbital, which contributes to the acceptance of d electrons from Ag/Cu. The exceptional performance of MoS2/M nanocomposites is primarily attributed to the occupancy of Mo d orbitals, driven by the intense interaction among MoS2 and Ag/Cu optimal combination. This work offers valuable insights into the design of heterojunctions with abundant surface/interface contact and defect features to enhance tunable electron-transfer kinetics. Such advancements pave the way for achieving a high NLO conversion efficiency and the development of efficient PEC anode materials.