Mechanism-Guided Selectivity and Bifunctionality in Glycerol Electrooxidation on Ag-Based Transition-Metal Single-Atom Alloys
Mingyue Lv, Hui Wang, Jing‐yao Liu
Abstract
Electrocatalytic glycerol oxidation reaction (GOR) offers a promising route for upgrading biomass-derived molecules to value-added chemicals and fuels. However, achieving high catalytic activity and product selectivity remains a significant challenge, requiring a comprehensive understanding of the underlying reaction mechanism. In this study, we systematically investigate a series of transition-metal single-atom-doped Ag(111) catalysts (TM 1 Ag, TM = Pd, Pt, Au, Cu, Ru, Rh, and Ir), selected based on electrochemical stability criteria including like Pourbaix diagrams. Two glycerol (GLY) adsorption configurations (GLY up * and GLY dn *) are selectively converted to glyceraldehyde and dihydroxyacetone via four pathways (Paths a–d), with reactions initiated by O–H activation (Paths a and c) favored over C–H activation (Paths b and d), followed by subsequent oxidation steps (Paths I–X). The calculated activity trend follows the order: Ru 1 Ag > Rh 1 Ag > Pt 1 Ag ≈ Ir 1 Ag > Pd 1 Ag > Au 1 Ag > Ag(111) > Cu 1 Ag. To rationalize the performance differences, we propose two intrinsic descriptors─the ratio of valence electron count to electronegativity ( Z VAL / X ) and the atomic radius ( r TM ) that effectively correlate with the overall GOR activity. Notably, TM 1 Ag catalysts with TM = Ru, Rh, Pt, Ir, or Pd exhibit enhanced selectivity toward glycolic acid (GCA). Importantly, all selected catalysts effectively suppress the competing oxygen evolution reaction. Furthermore, Pd 1 Ag and Pt 1 Ag demonstrate good bifunctional performance, concurrently facilitating anodic GOR toward GCA and the cathodic hydrogen evolution reaction to generate H 2 . This work provides mechanistic insights design principles for developing high-performance electrocatalysts for biomass valorization.