Lattice Distortion Suppressed in MoO₃ by Incorporating Minor Impurities of rGO: Strategy for Enhanced Electrocatalytic Hydrogen Evolution

Structural stability is critical for improving the electronic properties and charge-transfer efficiency of the catalyst, directly contributing to its enhanced electrocatalytic hydrogen evolution reaction (HER) activity. In this study, orthorhombic MoO 3 and rGO-MoO 3 catalysts were synthesized by using a straightforward hydrothermal method, and they demonstrated excellent activity for electrochemical water splitting for hydrogen generation. In this study, conventional laboratory techniques, except for Raman spectroscopy, were unable to clearly detect or differentiate the presence and impact of a very small amount (0.5%) of rGO in MoO 3 . However, X-ray absorption fine structure analysis performed at the synchrotron facility provided definitive confirmation of the influence of minor rGO incorporation in this study. The analysis revealed that the incorporation of rGO suppresses lattice distortions and enhances the stability of local atomic coordination within the MoO 3 framework. The Tafel slopes for MoO 3 and rGO-MoO 3 composite nanorods are 205 and 173 mV/dec, indicating improved reaction kinetics with rGO incorporation. The estimated specific capacitance values from the linear fit of CV at different scan rates are 2.0 mF/cm 2 for MoO 3 and 6.7 mF/cm 2 for the rGO-MoO 3 composite nanorods. Therefore, this study provides valuable insights into tuning the structural properties of materials and enhancing the HER performance through the incorporation of trace amounts of carbon-based materials, effectively suppressing lattice distortions.