MoS2-CdS composite for photocatalytic reduction of hexavalent chromium and thin film optoelectronic device applications

We introduce an enhanced light-harvesting MoS₂-based nanocomposite exhibiting improved solar light induced photocurrent generation, both in solution and solid phases. The MoS₂-CdS composite was synthesized via easy to achieve, cost effective, two-step solution process for the photocatalytic potassium dichromate [Cr(VI)] reduction and photocurrent generation in thin-film optoelectronic devices. Incorporating 10 wt% MoS₂ into the composite increased the degradation efficiency of CdS from 43.9 to 91.9%. Furthermore, the MoS₂-CdS composite demonstrated a 2.88-fold increase in the degradation rate constant and a 2.15% enhancement in the apparent quantum yield compared to controlled CdS. Additionally, the electrical power consumption per order decrease in Cr(VI) reduced from 25.74 kWh m^-3 for controlled CdS to 9 kWh m^-3 aimed at 10 wt% MoS₂-CdS composite, indicating optimal synergy between the counterparts of MoS₂-CdS in its composite. The resulting thin-film device with 10 wt% MoS₂-CdS exhibited robust photocurrent generation and nonlinear I-V characteristics under solar illumination, attributed to the unique electronic properties of the MoS₂-CdS heterojunction, influencing carrier transport via band alignment and interface carrier trapping effects. Moreover, photocurrent generation increased linearly with illumination intensity, and dynamic photo response studies revealed rapid photocurrent generation under illumination. Furthermore, the optoelectronic key parameters of CdS, including photosensitivity, photoresponsivity, and detectivity, were enhanced by factors of 5.09, 3.33, and 12.3, respectively, upon composite formation with MoS₂. This study offers novel insights into developing high-performance and cost-effective bimetallic sulfide photocatalysts for efficient solar light-induced photocurrent generation in both solution and solid phases.