Electronegativity-driven electron modulation of Pt active sites in bimetallic heterostructured catalysts for enhanced liquid organic hydrogen carriers dehydrogenation

The Pt/TiO₂ catalyst system stands as a representative model in heterogeneous catalysis, yet precise modulation of its surface electronic structure remains challenging. Support-mediated modulation suffers from intrinsic limitations, either blocking active sites through TiO₂ overlayer encapsulation or restricting its effectiveness to ultra-small Pt nanoparticles. Meanwhile, conventional alloying strategies inevitably induce uncontrollable structural reconstruction of Pt active sites. Here, we report an electronegativity-guided design strategy in which Mulliken electronegativity differences are used to select secondary metals (Zn, Cu, Pd, and Au) and predict the thermodynamic driving force for interfacial electron transfer toward Pt. By employing a mild solvothermal reduction approach, the two metals remain as distinct nanoparticles in close interfacial contact without forming alloy phases, preserving the full geometric integrity of Pt active sites while enabling effective electronic modulation. The degree of electron enrichment on Pt scales with the electronegativity difference between the secondary metal and Pt, and the donated electrons preferentially occupy vacant Pt D-orbitals, progressively shifting the D-band center downward. Catalytic evaluation confirms that dehydrogenation activity correlates directly with the degree of Pt electron enrichment, which is in turn governed by the electronegativity difference between the secondary metal and Pt. DFT calculations further establish a mechanistic connection between Pt electron density and dehydrogenation kinetics through a dual promotion effect on the dehydrogenation of perhydro-N-ethylcarbazole. Thermodynamically, the enhanced Pauli repulsion weakens d-π interactions, thereby facilitating the desorption of conjugated products. Kinetically, the increased Pt 5d orbital filling strengthens the Pt 5d - H 1 s hybridization, which weakens the C-H bond and reduces the intrinsic activation barrier of the rate-limiting step by 35.71%. Consequently, compared with Pt/TiO₂, the optimal PtZn/TiO₂ delivers a 23.21% reduction in the apparent activation energy and an 83.89% boost in the turnover frequency. Furthermore, PtZn/TiO₂ demonstrates broad applicability toward other carbazole-based liquid organic hydrogen carriers. These findings offer a rational design strategy for Pt-based catalysts in reactions sensitive to Pt electronic structure.