Mechanistic insights into NO-H₂ reaction over Pt/boron-doped graphene catalyst

This work presents a systematical experimental and density functional theory (DFT) studies to reveal the mechanism of NO reduction by H ₂ reaction over platinum nanoparticles (NPs) deposited on boron-doped graphene (denoted as Pt/BG) catalyst. Both characterizations and DFT calculations identified boron (in Pt/BG) as an additional NO adsorption site other than the widely recognized Pt NPs. Moreover, BG led to a decrease of Pt NPs size in Pt/BG, which facilitated hydrogen spillover. The mathematical and physical criteria of the Langmuir-Hinshelwood dual-site kinetic model over the Pt/BG were satisfied, indicating that adsorbed NO on boron (in Pt/BG) was further activated by H-spillover. On the other hand, Pt/graphene (Pt/Gr) demonstrated a typical Langmuir-Hinshelwood single-site mechanism where Pt NPs solely served as active sites for NO adsorption. This work helps understand NO-H ₂ reaction over Pt/BG and Pt/Gr catalysts in a closely mechanistic view and provides new insights into roles of active sites for improving the design of catalysts for NO abatement.