A Highly efficient Pd-Ni Bimetallic Single-Atom Catalyst for Selective Hydrogenation of Cinnamaldehyde

Abstract

Selective hydrogenation of cinnamaldehyde (CAL) is an important model reaction for evaluating the activity and selectivity of heterogeneous catalysts. Herein, a Pd–Ni bimetallic single-atom catalyst (Pd₁–Ni₁/Al₂O₃) was fabricated through a facile impregnation–pyrolysis strategy using metalloporphyrins as metal precursors. Aberration-corrected HAADF-STEM, XPS, and synchrotron XAFS analyses confirm the atomic dispersion of Pd and Ni species and their stabilization through strong metal–support interactions. Under optimized conditions (70 °C, 80 min, and 1 MPa H₂), Pd₁–Ni₁/Al₂O₃ achieves 99.9% cinnamaldehyde conversion and 95.4% hydrocinnamaldehyde selectivity, outperforming the corresponding monometallic catalysts. Density functional theory calculations reveal that the incorporation of isolated Ni sites modulates the electronic structure of neighboring Pd centers, strengthens metal–support interactions, and promotes a more favorable hydrogenation pathway. This work demonstrates the effectiveness of atomic-scale electronic coupling in regulating catalytic performance and provides insights into the rational design of bimetallic single-atom catalysts.