Agglomeration behavior of carbon-supported platinum nanoparticles in catalyst ink: modeling and experimental investigation

Abstract

Within catalyst inks, the agglomeration of carbon-supported Pt nanoparticles (Pt/C NPs) stands out as a primary destabilizing factor. This study simulates the agglomeration process of particles under varying ionic strengths (ISs), employing the Brownian motion of Pt/C NPs and inter-particle forces. The energy barriers (EBs) within particles govern particle interactions, subsequently translating into the adhesive efficiency of particle collisions (α). By modulating the ISs in Ink-P (IS = 0.00182), Ink-01 (IS = 0.01), and Ink-001 (IS = 0.001), the Zeta potential and EBs are diminished, thereby increasing α. Structural parameters of agglomerates during the agglomeration process, such as fractal dimension (df) and porosity, are computationally assessed using Matlab. The simulated df for Ink-P, Ink-001, and Ink-01 are 1.82, 1.62, and 1.54, respectively, while the experimentally measured df are 1.92–1.95, 1.67–1.7, and 1.56–1.59, confirming the effectiveness of the simulation method. High α led to isotropic growth of agglomerates, resulting in higher df. Increased IS causes compression of the electric double layer and higher α, ultimately leading to rapid destabilization of the ink. This method not only enhances comprehension of nanoscale particle agglomeration, explaining variations in ink stability and agglomerate structures, but also broadens its applicability to diverse nanoparticle dispersion systems.