Enhancing effects of edge-N in Pt-based carbon support on hydrogen evolution reaction

Abstract

N-doped carbons have been widely employed as support materials for metal-based catalysts. However, the specific impact of edge-N in Pt-based carbon supports for hydrogen evolution reaction (HER) has rarely been systematically studied. In this study, activated carbon (AC) from coconut shells was used as a model support. Edge-N-dominated carbon supports (NAC) were obtained by calcining a mixture of melamine and AC. Furthermore, the NAC was annealed at 1200 °C to generate N-deficient NAC-1200. Structural analyses revealed that the incorporation of edge-N not only reduces the Pt particle size but also enhances Pt dispersion and anchoring. Consequently, the optimized Pt/NAC catalyst demonstrated a smaller overpotential of 44 mV in contrast to Pt/AC (81 mV) and Pt/NAC-1200 (69 mV). Moreover, the Pt/NAC catalyst exhibited a lower activation energy of 27.11 kJ mol^-1 compared to Pt/AC (30.43 kJ mol^-1) during the HER process, along with significantly enhanced HER stability. Theoretical calculations further confirmed the critical role of edge-N species, particularly pyridinic-N, in tuning the electronic structure and reducing the reaction barrier of the Pt/C catalyst, thus greatly enhancing HER performance. This study provides valuable insights for the development of advanced edge-N-dominated carbon supports.