Size tuning of Pt nanoparticles on ZrO2: Optimizing catalytic performance for hydrogen evolution and water-splitting reactions - A DFT study.

In heterogeneous catalysis, determining the optimal metal particle size is challenging due to the intricate relationship between particle size, electronic structure, and activity. Here, we investigate the size-dependent activity of Pt nanoparticle (PtNP)-based ZrO 2 catalyst for hydrogen evolution reaction (HER) and water-splitting reaction (WSR) using density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations. By analyzing different Pt nanoparticle sizes (Pt 4 , Pt 7 , Pt 11 , P 15 , Pt 19, and Pt 25) supported on ZrO 2 , we determined their optimized geometries, and electronic structures, and calculated the hydrogen adsorption energies (Δ G H) for HER and activation energies barrier (Δ ‡ G) for WSR. The calculated results demonstrate that Pt 11 is the optimal size for HER, exhibiting the lowest Δ G H (−0.066 eV), while Pt 15 shows the lowest Δ ‡ G (0.24 eV) for WSR. The density of states (DOS) shows that the occupied Pt states fill the gap of ZrO 2 (3.72 eV), significantly reducing the band gap (E g) of the PtNP/ZrO 2 composites. The most favorable configuration of the PtNP on ZrO 2 for HER and WSR is determined to be a three-Pt-layer structure with rooflike edges which corresponds to a nanoparticle size of ∼0.70–1.55 nm for experiments. These findings can be regarded as an effort toward the design and optimization of metal-based oxide catalysts for renewable energy applications. [Display omitted] • Investigations of effect of Pt nanoparticle size on the catalytic activity of ZrO 2 -based catalyst. • The occupied Pt states reduce the band gap of the PtNP/ZrO 2 composites, enabling visible light photocatalytic activity. • Identified Pt 11 and Pt 15 clusters to be optimal size for hydrogen evolution reaction (Pt 11) and water-splitting reactions. • The calculated optimal size corresponds to an approximate nanoparticle size range of 0.70–1.55 nm in experiments. • Three-Pt-layer structure with rooflike edges identified as the most favorable configuration for catalytic performance. [ABSTRACT FROM AUTHOR]