Thermally Optimized Chemical Vapor Deposition of Iron and Cobalt on Pd-Decorated Reduced Graphene Oxide for Atomic-Scale Catalytic Interface Engineering

This study investigates the catalytic mechanisms underlying the chemical vapor deposition (CVD) of iron (Fe) and cobalt (Co) on palladium-decorated reduced graphene oxide (Pd/rGO) compared to bare rGO. Pd nanoparticles (~9.37 nm) on rGO significantly enhance precursor decomposition and catalyst formation. Temperature-resolved gas-phase Fourier-transform infrared (FTIR) spectroscopy tracked ferrocene and cobaltocene decomposition, revealing distinct optimal temperature windows—termed Frontier Thermal Bulwarks (FTBs)—for Fe (100–270 °C) and Co (40–140 °C) deposition. Pd/rGO exhibited earlier onset of gas-phase precursor decomposition (~100 °C for Fe and ~40 °C for Co) and higher C–H stretching band intensities than rGO, highlighting Pd’s role in efficient H₂ dissociation and ligand activation. Unique spectral features, including 1037/1094 cm⁻¹ peaks for cobaltocene, correspond to specific intermediate species arising from its 19-electron instability. The selective CVD on Pd/rGO promotes intimate Fe/Co-Pd interactions, which may enhance catalytic performance while minimizing precious metal usage. These findings provide key insights for optimizing CVD conditions in the development of advanced nanostructured catalysts for energy and environmental applications.