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. [ABSTRACT FROM AUTHOR]