Facile Synthesis of RGO–PANI–Nd₂O₃ composite as an Efficient Platinum-Free Counter Electrode for Dye-Sensitized Solar Cells

Dye-sensitized solar cells (DSSCs) have been extensively studied for their enormous promises as an affordable alternative to conventional p-n junction solar cells. Their broad applicability is limited by the high cost of platinum (Pt) counter electrodes (CE). In this paper, ternary composites (RGO-PANI-Nd₂O₃composites) consists of reduced graphene oxide (RGO), polyaniline (PANI), and neodymium oxide (Nd₂O₃) were synthesized and explored for the first time as a Pt-free counter electrode for DSSCs. The composite was synthesized via the Hummers method followed by in-situ emulsion polymerization of aniline on the RGO sheet and subsequently added rare earth metal nitrate through a hydrothermal method. The introduction of Nd₂O₃ into the RGO-PANI matrix is expected to improve electrocatalytic properties by means of additional catalytic centers. Structural, morphological, and optical analyses confirmed successful composite formation. When used as a CE in DSSCs, the RGO-PANI-Nd₂O₃ electrode achieved a power conversion efficiency of 1.08%, an improvement of 77.8% over that of the RGO-PANI CE (0.24%) and close to that of platinum (1.92%). Although the efficiency remains lower as compared to Pt CE under identical device conditions, the composite exhibits a notable improvement in catalytic performance compared to Pt-free electrodes. Analysis of the cyclic voltammetry showed that the RGO-PANI-Nd₂O₃ composite enhanced electrochemical reversibility, redox current, and electron transfer rates of the electrode-electrolyte interface. The work clearly demonstrates that the modification of the carbon/polymer matrix with rare-earth metal oxides can enhance the electrochemical properties of the CE. The RGO-PANI-Nd₂O₃ composite material is, therefore, an effective, low-cost, and eco-friendly substitute for platinum CE in efficient DSSCs.