Performance of Hemp‐Derived Interconnected Carbon Nanosheets on Counter Electrode in Dye‐Sensitized Solar Cells

Biomass‐derived carbon nanomaterials have emerged as sustainable alternatives to platinum‐based counter electrodes for dye‐sensitized solar cells (DSSCs). In the present study, interconnected carbon nanosheets (ICNS) were synthesized from hemp bast fibers through hydrothermal carbonization followed by KOH activation and investigated as counter‐electrode materials for DSSCs. Morphological and structural characterization revealed a highly porous interconnected nanosheet architecture containing partially graphitized carbon domains and abundant defect sites. Raman and X‐ray diffraction analyses confirmed the coexistence of graphitic and disordered carbon structures, providing a favorable combination of electrical conductivity and electrocatalytic activity. Electrochemical studies demonstrated that the ICNS electrodes were catalytically active toward the I 3 − /I − redox couple, although their charge‐transfer resistance remained high. To improve interfacial charge‐transfer kinetics, Pt–ICNS hybrid electrodes containing different platinum loadings were fabricated. Electrochemical impedance spectroscopy revealed a progressive decrease in charge‐transfer resistance from 7.704 Ω cm 2 for pure ICNS to 2.75 Ω cm 2 for the 18 wt.% Pt–ICNS electrode. Consequently, the power conversion efficiency increased from 4.01% to 6.56%, approaching the performance of the reference Pt/FTO electrode (7.18%). The enhanced performance is attributed to the synergistic interaction between the conductive porous carbon framework and catalytically active platinum sites.