Novel activated carbon derived from tomato waste and its composite with MoS2 for quantum dot sensitized solar cells

In this study, a novel multifunctional nanocomposite was developed by integrating molybdenum disulfide (MoS2) with activated carbon (AC) derived from tomato waste, utilizing both sustainable pyrolysis (ACF) and hydrothermal (ACH) synthesis methods. The surface areas of ACF and ACH were determined to be 480.044 and 385.883 m2/g, respectively. ACF exhibited superior structural characteristics, including higher porosity and a wider interlayer spacing (21.88°, d = 0.41 nm), compared to ACH (24.65°, d = 0.36 nm). Upon compositing ACH with MoS2, enhanced graphitization and improved electrical conductivity were observed, as indicated by a distinct XRD peak at 26.27° (d = 0.33 nm) and significant photoluminescence quenching. SEM analysis revealed a porous, sheet-like morphology for ACH, while BET confirmed its mesoporous structure and an increased active surface area of 460.93 m2/g. These attributes facilitate rapid ion diffusion and efficient electron transport, making the MoS2/ACH composite an excellent candidate for quantum dot-sensitized solar cells (QDSSCs). In addition, the nanocomposite was employed as a counter electrode in QDSSCs, exhibiting notable enhancements in power conversion efficiency. Electrochemical impedance spectroscopy demonstrated improved charge transfer kinetics, with reductions in series resistance (Rs) from 11.41 for ACF to 4.38 Ω for ACF/1T-MoS2 and charge transfer resistance (Rct), which dropped from 1202 to 178 Ω for ACF and AC/1T-MoS2, respectively. Cyclic voltammetry indicated excellent electrochemical stability, as evidenced by consistent curve shapes across multiple cycles. The synergistic interaction between the porous carbon matrix and MoS2 nanosheets underpins the material’s superior performance in renewable energy applications.