Sulfidization of Au(111) from Thioacetic Acid: an Experimental and Theoretical Study

FISCHER JEISON ; ZOLDAN VINÍCIUS ; BENITEZ, GUILLERMO. A.; RUBERT A.A.; RAMIREZ ALEJANDRO; PILAR CARRO; SALVAREZZA, R.C; PASA ANDRÉ; VELA, MARIA E.

LANGMUIR

AMER CHEMICAL SOC

Lugar: Washington; Año: 2012 vol. 28 p. 15278 - 15285

0743-7463

We have studied the adsorption of thioacetic acid (TAAH) on Au(111) from solution deposition. The close proximity between the SH and the CO groups turns this molecule very attractive to explore the effect of the functional group on the stability of the S-C and S-Au bonds. While thioacetic acid was supposed to decompose slowly in water by hydrolysis supplying hydrogen sulfide, this behavior is not expected in non polar solvents such as toluene or hexane. Therefore, we have used these solvents for the TAAH self-assembly on the Au(111) surface. The characterization of the adsorbates has been done by electrochemical techniques, X-ray photoelectron spectroscopy (XPS), and scanning tunneling microscopy (STM). We have found that even in non polar solvents thioacetic acid decomposes into S. The results have been discussed on the basis that the adsorbed species suffer a cleavage on the Au surface leaving the S attached to it. The dissociation is a spontaneous process that reaches the final state very fast, once it is energetically avorable, as can be interpreted from DFT calculations. The thioacetic adsorption reveals the strong effect that produces a functional group and the key role of the S-H bond cleavage in the selfassembly process