Synergistic ternary polypyrrole/WO3/MWCNT nanocomposites for environmental remediation and electrochemical water splitting

Abstract

The development of cost-effective and multifunctional nanocatalysts is essential to address pressing environmental and energy challenges, particularly organic pollutant removal and sustainable hydrogen production. Herein, we report a ternary nanocomposite comprising polypyrrole (PPy), tungsten trioxide (WO₃), and multiwalled carbon nanotubes (MWCNTs), synthesized and evaluated for dual catalytic applications. The PPy/WO₃/MWCNT composite exhibited remarkable photocatalytic activity toward the degradation of Ponceau BS (PBS) dye under visible light, achieving 98.2% degradation within 40 min following first order kinetics. Adsorption kinetics and isotherm analyses indicated monolayer adsorption behavior with a maximum capacity of 124.6 mg g⁻¹, well described by the Langmuir model (R² = 0.99). The heterojunction between PPy and WO₃ facilitated efficient charge separation, active sites and extended light absorption, while MWCNTs provided conductive pathways and electron reservoirs. Beyond photocatalysis, the composite demonstrated outstanding electrocatalytic activity for overall water splitting in alkaline media, requiring an overpotential of only 146 mV for the hydrogen evolution reaction (HER) and 328 mV for the oxygen evolution reaction (OER) to achieve 10 mA cm⁻². The superior performance is attributed to the synergistic combination of high surface area, enhanced charge transfer kinetics, and multiple redox-active sites. Furthermore, the nanocomposite exhibited excellent long-term stability under both HER and OER conditions, highlighting its promise as a sustainable multifunctional catalyst for environmental remediation and clean energy conversion.