Pt Single Atom Electrocatalysts at Graphene Edges for Efficient Alkaline Hydrogen Evolution

Abstract

Graphene edges exhibit a highly localized density of states that result in increased reactivity compared to its basal plane. However, exploiting this increased reactivity to anchor and tune the electronic states of single atom catalysts (SACs) remains elusive. To investigate this, a method to anchor Pt SACs with ultra-low mass loadings at the edges of edge-rich vertically aligned graphene (as low as 0.71 µg Pt cm–2) is developed. Angle-dependent X-ray absorption spectroscopy and density-functional theory calculations reveal that edge-anchored Pt SACs has a robust coupling with the π-electrons of graphene. This interaction results in a higher occupancy of the Pt 5d orbital, shifting the d-band center toward the Fermi level, improving the adsorption of *H for the hydrogen evolution reaction (HER). Pt primarily coordinated to the graphene edge shows improved alkaline HER performance compared to Pt coordinated in mixed environments (turnover frequencies of 22.6 and 10.9 s–1 at an overpotential of 150 mV, respectively). This work demonstrates an effective route to engineering the coordination environment of Pt SACs by using the graphene edge for enhanced energy conversion reactions.