Impact of nitrogen configuration on the anchoring mechanism of platinum nanoparticles on carbon substrates: synergistic modification for hydrogen evolution in acidic and alkaline media

Abstract

The regulation and stabilization of the chemical microenvironment of Pt nanoparticles represent a major challenge in enhancing the electrocatalytic hydrogen evolution reaction (HER). Incorporating Pt nanoparticles into nitrogen-doped carbon (NC) substrates offers a promising strategy, yet, it is still ambiguous to fully understand the electronic interaction between Pt and NC substrates and the impacts of N configurations (pyridinic-N, pyrrolic-N, and graphitic-N) on the anchoring mechanism of Pt nanoparticles on carbon substrates. Herein, this study proposes a strategy to regulate the relative contents of nitrogen species in NC substrates by manipulating the pyrolysis temperature of ZIF-8 to fabricate supported electrocatalysts denoted as Pt/NC-x, where Pt nanoparticles are immobilized within the NC substrates. X-ray photoelectron spectroscopy (XPS) spectra refine the distribution of different nitrogen species, while density functional theory (DFT) calculations validate that each N configuration fully exploits respective functions and amplifies collective influence, thereby maximizing the synergy between Pt nanoparticles and NC substrates. The resultant Pt/NC-900 electrocatalysts with befitting ratios of pyridinic-N, pyrrolic-N and graphitic-N exhibit the lowest overpotentials (33 and 22 mV at 10 mA cm⁻² and 96 and 160 mV at 100 mA cm⁻²) and the highest mass activities (2.02 and 1.08 A mg_Pt⁻¹ at −100 mV) under both acidic and alkaline conditions, outperforming commercial Pt/C. This research demonstrates the roles of pyridinic-N, pyrrolic-N and graphitic-N in the HER and provides novel insights into the design and synthesis of supported metallic and non-metallic HER electrocatalysts across a wide pH range.