ADSORPTION AND DECOMPOSITION OF HYDRAZINE ON CARBON MONOXIDE-MODIFIEDPT(111) SURFACES

The decomposition of hydrazine has been studied on a GO-modified Pt(ll l) surface. Hydrazine decomposition on the clean Pt(lll) surface proce eds with a maximum rate at 310 K and an apparent first-order activatio n energy of approximately 18.7 kcal/mol. Decomposition results in the formation of nitrogen, hydrogen, and ammonia. Coadsorbed carbon monoxi de inhibits hydrazine decomposition by increasing the decomposition te mperature. No new reaction products are observed. At a carbon monoxide coverage of 0.43 ML, the maximum hydrazine decomposition rate occurs at 340 K with an apparent activation energy of 20.6 kcal/mol. The hydr azine decomposition product distribution on the GO-modified surface is shifted to favor ammonia production, relative to the 2:1 ammonia/nitr ogen ratio observed for decomposition on the clean surface. The order of coadsorption does not affect the desorption spectra for partial CO coverages. The observed shift in product distribution and lack of depe ndence on order of exposure indicate that hydrazine decomposition is n ot mediated by a multihydrazine surface complex. A simple reaction mec hanism consistent with the data and previous studies is proposed. Hydr azine dehydrogenation is postulated as the rate-limiting step common t o nitrogen and ammonia formation. Since hydrazine decompostion product s desorb below the CO desorption temperature, no perturbation in the C O desorption spectra is observed.