Unlocking the redox chemistry of graphene oxide-based nanocomposites with 12-tungstophosphoric acid and perylene-tetracarboxylic dianhydride for electrochemical energy storage

This study addresses the existing knowledge gap regarding the relationship between hydrothermal treatment duration, the evolution of oxygen functional groups, and pseudocapacitive properties of graphene oxide (GO)-based nanocomposites by uniquely combining temperature-programmed desorption (TPD) and laser desorption ionization (LDI) analyses with traditional characterization methods. The structural evolution and electrochemical behavior of GO-based nanocomposites with 12-tungstophosphoric acid (WPA, 15 wt%) and 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA, 15 wt%) were systematically investigated following hydrothermal treatment (HTT) at 180 °C for 1–12 h. For detailed characterization an 8 h-long hydrothermal treatment was selected because of the first appearance of macroscopic hierarchical ordering. Complementary spectroscopic techniques (FTIR, Raman, XPS) and X-ray diffraction analyses revealed progressive reduction of oxygen functionalities and partial restoration of graphitic domains, accompanied by reduced inter-layer spacing and enhanced structural ordering. TPD confirmed the selective removal of carboxyl and lactone groups and transformation of hydroxyl and epoxy groups into carbonyl/quinone-type functionalities, with PTCDA- and WPA-containing samples exhibiting distinct desorption profiles, indicating differences in oxygen group stability and component interactions. Electron microscopy demonstrated hierarchically porous morphologies, where PTCDA was embedded within GO on macro- and nano-scale, while WPA was dispersed in the form of molecular clusters. Among the investigated materials, GO/PTCDA delivered the highest specific capacitance (308 F g −1 at 10 mV s −1 ), whereas the ternary GO/WPA/PTCDA composite exhibited superior rate capability, reaching 320 F g −1 at 400 mV s −1 . These enhancements are attributed to favorable surface modifications, improved ion diffusion pathways, and synergistic redox contributions. The findings establish a direct structure-property relationship between the evolution of oxygen functional groups and pseudocapacitive response, providing also a molecular insight into component integration, which is important for the rational design of next-generation GO-based supercapacitors. • Controlled hydrothermal synthesis enables advanced GO-based nanocomposites. • Synthesis of ternary GO/WPA/PTCDA composite reported for the first time • GO/PTCDA shows highest capacitance of ∼308 F g −1 at low scan rates. • Three-component GO/WPA/PTCDA system delivers 320 F g −1 at 400 mV s −1 . • Synergy of WPA and PTCDA enhances redox activity and ion transport.