Screening of Catalytic Sites in Pt$_{13-n}$N$_n$ Nanoparticles (N = Pd and Ni; n = 0, 3, 6, 9, 13) for the Water–Gas Shift Reaction

Context Understanding the structure–activity relationships of bimetallic nanoparticles is crucial for to designing efficient catalysts for the water–gas shift reaction (WGSR). In this study, we systematically examine the structural stability, electronic properties, and catalytic performance of Pt\((_{13-n})\)N\((_n)\) (N = Pd and Ni; n = 0,3,6,9,13) nanoclusters. Our findings show that Pt\((_7)\)Ni\((_6)\) and Pt\((_{10})\)Pd\((_3)\) are thermodynamically favored under reaction conditions. Electronic analysis indicates that intermediate d-band center positions correlate with improved catalytic potential. Mechanistic analysis via the carboxylate pathway suggests that Pt\((_7)\)Ni\((_6)\) provides a balanced combination of adsorption strength and activation barriers, making it a promising candidate for WGSR catalysis. These results emphasize the role of composition-dependent electronic effects in tuning the catalytic activity. Methods Nanoclusters were optimized using density functional theory (DFT) as implemented in the CP2K software, employing the PBE exchange-correlation functional and the Gaussian and Plane Waves (GPW) scheme. Structural stability was assessed through binding energies and the harmonic superposition approximation (HSA). Electronic properties were analyzed using the projected density of states (PDOS) and d-band center descriptors, with spin polarization effects explicitly included. The potential energy surface and transition states for the carboxylate mechanism were mapped using the semi-empirical GFN2-xTB method, and transition states were subsequently confirmed by vibrational analysis.