Dual-electron-enhanced effect in K-doped MoS2 few layers for high electrocatalytic activity as the counter electrode in dye-sensitized solar cells

Designing counter electrodes (CEs) with high efficiency and understanding the mechanism of dye-sensitized solar cells (DSSCs) are still challenges. In this paper, we synthesized K-doped molybdenum disulfide (K-MoS2) with few layers and it has a great enhancement effect on the electrocatalytic activity compared to pure MoS2 CE and reference Pt CE. A dual electron-path model is proposed to explain the mechanism, which is supported by first-principles calculations. When an electron in MoS2 is transferred to the triiodide, the K atoms can act as an electron reservoir to provide another electron in a short time to improve the catalytic activity. So the proposed dual-electron effect in this paper is helpful to understand the charge transfer mechanism on the interfaces of these CEs and may be crucial for obtaining high photoelectric efficiencies in DSSCs.