Highly active platinum single-atom catalyst grafted onto 3D carbon cloth support for the electrocatalytic hydrogen evolution reaction

Platinum single-atom catalysts (PtSACs) on 3D support are emerging as the new frontier in catalysis due to their atom-economy, outstanding performance, and the advantage to bridge the gap between homogeneous and heterogeneous catalysis. Here we report on a simple, single-step electrochemical grafting attachment of a metal-selective ligand, 2,6:2′,2″-terpyridine, and the synthesis of platinum single-atom electrocatalyst via metal uptake from aqueous salt solution. At an ultra-low loading of 0.26 ± 0.02 μg•cm⁻² of platinum, the single-atom catalysts supported on porous 3D carbon cloth electrode via chemical bonding revealed higher mass activity ratios, up to 83.0 at η = 50 mV/RHE, compared to the commercial catalyst 20 % Pt/C. Using hydrogen binding energy as the descriptor for efficiency, density functional theory calculations show that promoting hydrogen evolution using terpyridine-Pt proceeds when the catalyst is in a 2+ charge state and with a single hydroxy co-ligand attached to Pt catalytic center. Calculations predict an HER overpotential of about 0.28 V. The electro-grafted terpyridine ligand proved to act as effective scavenger for leached platinum from the counter electrode during extended operational hours. The method to make the PtSAC is facile, non-hazardous and versatile without involving any elaborate pre- and/or post-treatment steps and, the cost of the added platinum to the ligand is only 0.1 US$ m⁻².