Surface-enhanced Raman spectroscopic investigation on adsorption kinetic of carbon monoxide at the solid-gas...

A molecular-level understanding of CO adsorption behavior would be greatly beneficial to resolving the problem of CO poisoning in fuel cells and medical science. Herein, an efficient borrowing strategy based on surface enhanced Raman scattering (SERS) has been developed to investigate the adsorption behavior of CO at the gas-solid interface. A composite SERS substrate with high uniformity was fabricated by electrochemical deposition of optimal Pt over-layers onto an Au nanoparticle film. The results indicated that the linearly bonded mode follows the Langmuir adsorption curve (type I), while the multiply bonded did not. It took a longer time for the C-O_M vibration to reach the adsorption equilibrium than that of C-O_L. The variation tendency toward the Pt-CO_L frequency was in opposition to that of C-O_L, caused by the chemical and dipole-dipole coupling effects. The increase in dynamic coupling effects of the CO molecules caused a blue shift in ν_CO and a red shift of the Pt-CO band, while its shielding effect on SERS intensity cannot be ignored. Additionally, higher pressure is more conducive for linear adsorption to achieve saturation. Density functional theory calculations were employed to explore the adsorption mechanisms. It should also be noted that the substrate with good recycling performance greatly expands its practical application value. The present study suggested that the SERS-based borrowing strategy shows sufficient even valuable capacity to investigate gas adsorption kinetics behavior.