Mechanistic Insight into Enhanced Hydrogen Evolution Reaction Activity of Ultrathin Hexagonal Boron Nitride-Modified Pt Electrodes

Enhancing the intrinsic activity of a benchmarked electrocatalyst such as platinum (Pt) is highly intriguing from fundamental as well as applied perspectives. In this work, hydrogen evolution reaction (HER) activity of Pt electrodes, benchmarked HER catalysts, modified with ultrathin sheets of hexagonal boron nitride (h-BN) is studied in acidic medium (Pt/h-BN), and augmented HER performance, in terms of the overpotential at a 10 mA cm^-2 current density (10 mV lower than that of Pt nanoparticles) and a lower Tafel slope (29 ± 1 mV/decade), of the Pt/h-BN system is demonstrated. The effects of h-BN surface modification of bulk Pt as well as Pt nanoparticles are studied, and the origin of such an enhanced HER activity is probed using density functional theory-based calculations. The HER charge transfer resistance of h-BN-modified Pt is found to be drastically reduced, and this enhances the charge transfer kinetics of the Pt/h-BN system because of the synergistic interaction between h-BN and Pt. An enormous reduction in the hydrogen adsorption energy on h-BN monolayers is also found when they are placed over the Pt electrode [-2.51 eV (h-BN) to -0.25 eV (h-BN over Pt)]. Corrosion preventive atomic layers such as h-BN-protected Pt electrodes that perform better than Pt electrodes do open possibilities of benchmarked catalysts by simple modification of a surface via atomic layers.