Investigation and development of photocathodes using polyaniline Encapsulated Ti3C2Tx MXene nanosheets for dye-sensitized solar cells†

Abstract

In the current study, polyaniline (PANI) modified two-dimensional Ti₃C₂T_x MXene composites (PANI-Ti₃C₂T_x) are exploited as photocathodes in dye-sensitized solar cells (DSSCs). The study revealed that incorporating PANI into Ti₃C₂T_x improved the material's electrochemical properties, owing to the presence of amino groups in PANI that enhanced the material's electrical conductivity and thereby facilitated more rapid ion transport. In addition, PANI enhanced the surface wettability of Ti₃C₂T_x, resulting in an increase in the number of electroactive sites. The presence of PANI molecules in the interlayer and on the surface of Ti₃C₂T_x was confirmed through X-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX), and X-ray photoelectron spectroscopy (XPS). Subsequently, electrochemical analysis of the PANI-Ti₃C₂T_x photocathode or counter electrode (CE) revealed a commendable electrocatalytic activity with the iodide/triiodide electrolyte, a favourable charge transfer kinetics, and a charge transfer resistance as low as platinum. Additionally, at AM 1.5G, the performance of the DSSC constructed using the thermally decomposed Pt-CE was 8.3% when subjected to simulated 1 sun light, whereas the efficiency of the DSSC constructed using the as-prepared composite material was 6.9% under corresponding conditions. PANI-Ti₃C₂T_x as the photocathode (CE) in a DSSC showed a higher power conversion efficiency (PCE) improvement than PANI CE and Ti₃C₂T_x CE DSSCs, emphasizing its potent catalytic activity and quick mass transport of electron capability. By capitalizing on the conductivity and electrocatalytic property of the two components, the as-fabricated PANI-Ti₃C₂T_x photocathode significantly increased the overall PCE of DSSCs. Furthermore, the DSSC utilizing the PANI-Ti₃C₂T_x CE demonstrated exceptional reproducibility and stability. This underscores its consistently high performance and significant resistance to corrosion in the iodide/triiodide redox electrolyte environment. Overall, these findings show that the PANI-Ti₃C₂T_x composite has the potential to be a competitive alternative to platinum-based CE materials for the development of DSSCs with exceptional performance.