Sulfur‐Enriched Porphyrin‐Based Covalent Organic Frameworks as Redox‐Active Electrode for Aqueous Symmetric Supercapacitors

ABSTRACT

In this study, we report the design, synthesis and electrochemical evaluation of three porphyrin‐based covalent organic frameworks (COFs), TTP‐COF, BTP‐COF, and TP‐COF, integrating sulfur‐rich π‐conjugated aldehyde linkers (thieno[3,2‐b]thiophene, bisthiophene and thiophene) with C ₄ ‐symmetric porphyrin knots via imine condensation. These frameworks exhibit enhanced electronic conductivity, efficient ion diffusion, and high structural stability. Among the tested materials, TTP‐COF exhibited superior electrochemical performance in the three‐electrode setup, delivering a high specific capacitance of 193.3 F g ⁻¹ . Furthermore, the symmetric supercapacitor (TTP‐COF // TTP‐COF) demonstrated a remarkable specific capacitance of 129.2 F g ⁻¹ , a high energy density of 35.2 Wh kg ⁻¹ , and outstanding cyclic stability, retaining its performance even after 25,000 charge–discharge cycles. Electrochemical studies revealed a dual charge storage mechanism involving both electric double‐layer capacitance and pseudocapacitance, attributed to redox‐active porphyrin units and sulfur‐containing linkers. Nyquist analysis confirmed the lowest charge transfer resistance ( R _ct = 0.18 Ω) for TTP‐COF, highlighting its efficient charge transport characteristics. A symmetric supercapacitor device based on TTP‐COF successfully powered white and red LEDs, validating its real‐world applicability. This work underscores the potential of rationally engineered porphyrin‐thiophene COFs as advanced materials for next‐generation supercapacitor technologies.