Ag-boosted hydroxyl adspecies generation and carbonyl intermediates release for Pt-Ag-catalyzed ethylene glycol electro-oxidation.

Abstract

Electro-reforming of organics such as alcohols into commodity chemicals and H₂ powered by renewables is intriguing and prevailing with the remarkable renaissance of electrochemical technology. Integrating Pt/Pd with an auxiliary metal, metal oxide, and metal hydroxide are feasible strategies to design the desirable catalysts toward alcohols electro-oxidation reactions. These catalysts however have high affinity toward carbonyl intermediates that occupy and poison the active sites. Thus, the target products suffer from poor selectivity. To address these issues, a facile binary Pt-Ag alloy nanowires (NWs) catalytic system was reported for efficient electro-oxidative reforming of ethylene glycol (EG), yielding glycolate with a selectivity of 91.5 %, an EG conversion of 96.4 %, and Faradaic efficiency (FE) of 87.4 %. Experimental and theoretical investigations revealed that Ag-induced electronic structure perturbations in Pt_0.66Ag catalyst boosted the kinetics and robustness as a conventional promoter toward EG electro-oxidation reaction (EGOR). Moreover, the one-electron oxidation of water/hydroxide ion to generate abundant hydroxyl adspecies (OH_ad) on Ag served as another crucial promoter for efficient dehydrogenation, glycolate formation, and carbonyl intermediates release via a highly efficient, noncompetitive Langmuir-Hinshelwood (L-H) mechanism, but not the competitive L-H mechanism or the Eley-Rideal (E-R) mechanism. These findings provide new insights into the selective alcohol electro-oxidation reaction, and facilitate the generation of commodity chemicals via partial electro-oxidation reactions.