CO Reduction Catalysts on Gold Electrode Surfaces Influenced by Large Electric Fields.
Melissa L Clark, Aimin Ge, Pablo E Videla, Benjamin Rudshteyn, Christopher J Miller, Jia Song, Victor S Batista, Tianquan Lian, Clifford P Kubiak
Author Information
Melissa L Clark: Department of Chemistry and Biochemistry , University of California, San Diego , 9500 Gilman Drive, MC 0358 , La Jolla , California 92093 , United States.
Aimin Ge: Department of Chemistry , Emory University , 1515 Dickey Drive, Northeast , Atlanta , Georgia 30322 , United States. ORCID
Pablo E Videla: Department of Chemistry and Energy Sciences Institute , Yale University , 225 Prospect Street , New Haven , Connecticut 06520 , United States. ORCID
Benjamin Rudshteyn: Department of Chemistry and Energy Sciences Institute , Yale University , 225 Prospect Street , New Haven , Connecticut 06520 , United States. ORCID
Christopher J Miller: Department of Chemistry and Biochemistry , University of California, San Diego , 9500 Gilman Drive, MC 0358 , La Jolla , California 92093 , United States.
Jia Song: Department of Chemistry , Emory University , 1515 Dickey Drive, Northeast , Atlanta , Georgia 30322 , United States.
Victor S Batista: Department of Chemistry and Energy Sciences Institute , Yale University , 225 Prospect Street , New Haven , Connecticut 06520 , United States. ORCID
Tianquan Lian: Department of Chemistry , Emory University , 1515 Dickey Drive, Northeast , Atlanta , Georgia 30322 , United States. ORCID
Clifford P Kubiak: Department of Chemistry and Biochemistry , University of California, San Diego , 9500 Gilman Drive, MC 0358 , La Jolla , California 92093 , United States. ORCID
Attaching molecular catalysts to metal and semiconductor electrodes is a promising approach to developing new catalytic electrodes with combined advantages of molecular and heterogeneous catalysts. However, the effect of the interfacial electric field on the stability, activity, and selectivity of the catalysts is often poorly understood due to the complexity of interfaces. In this work, we examine the strength of the interfacial field at the binding site of CO reduction catalysts including Re(S-2,2'-bipyridine)(CO)Cl and Mn(S-2,2'-bipyridine)(CO)Br immobilized on Au electrodes. The vibrational spectra are probed by sum frequency generation spectroscopy (SFG), showing pronounced potential-dependent frequency shifts of the carbonyl stretching modes. Calculations of SFG spectra and Stark tuning rates based on density functional theory allow for direct interpretation of the configurations of the catalysts bound to the surfaces and the influence of the interfacial electric field. We find that electrocatalysts supported on Au electrodes have tilt angles of about 65-75° relative to the surface normal with one of the carbonyl ligands in direct contact with the surface. Large interfacial electric fields of 10-10 V/m are determined through the analysis of experimental frequency shifts and theoretical Stark tuning rates of the symmetric CO stretching mode. These large electric fields thus significantly influence the CO binding site.
