Effects of p-type (Ag, Cu) dopant on the electronic, optical and photocatalytic properties of MoS₂, and impact on Au/Mo_100-x-yAg_xCu_yS₂ performance

MoS₂ is an alternative of graphene due to its intriguing properties and it is necessary to modify the properties for achieving p-MoS₂ and complementary device applications. Doping is one of the most prevalent techniques for modification of materials properties and fabricating p-MoS₂. Herein, we report on Ag and Ag-Cu doped MoS₂ investigated by theoretical and experimental studies. Detailed study of DFT highlights the confirmation of p-type MoS₂. The band gap can be tuned from 1.21 to 0.51 eV (theoretically) and 1.92–1.30 eV (experimentally). The enhancement of absorption in the visible region attributed to Ag and Ag-Cu doping. The conduction band (CB) edge potential is smaller in negative than H⁺/H₂ (0.0 eV) for undoped, Ag = 2.5% and Ag-Cu (Ag = 2.5, Cu = 10%) doped MoS₂, hence the photogenerated electrons can weakly reduce H⁺ to produce H₂. While the deeper valence band (VB) edge potential than O₂/H₂O (1.23 eV) confirms that the holes created upon photon absorption strongly shows the ability for water oxidation. However for other doping both potential edges are more positive which insights strong oxidative material. Interestingly, the theoretical calculation suggests that the CB edge potential should be upward shifting for enhancing the photocatalytic activity of MoS₂. EDX and XPS measurements disclose the presence of Mo, S, Ag and Cu elements in the thin films. Furthermore, decreasing forward current and shifting threshold voltage (V_T) toward higher voltage in (Ag, Cu) doped Au/Mo_100-x-yAg_xCu_yS₂ insights p-type MoS_2. Therefore, these demonstrations could be extended its applications to be enable high-performance electronic and optoelectronic devices.