Time-dependent Surface Polarization Breaks Static Scaling Relationship for Selective Acetylene Hydrogenation

Static scaling correlations between adsorption energies of chemically related surface species post limits on selectivity in chemical processes, as exemplified by constraints in heterogeneous catalysis. Here, we demonstrate that dynamic surface polarization under oscillating electric potentials can overcome this limitation in Pd-catalyzed acetylene semi-hydrogenation. Unlike static polarization, which improves ethylene selectivity by only 12% with a 9% activity loss, dynamic polarization enhances selectivity by >45% without further sacrificing conversion, yielding an ethylene productivity of 7.52 mol gPd-1 h-1 —among the highest reported. Mechanistic insights from hydrogenation kinetics, in-situ DRIFTS, XAS, and DFT reveal that time-dependent polarization dynamically modulates the Pd’s electronic structure and adsorption energetics. Alternating between strong-binding states (positive polarization) during acetylene hydrogenation and weak-binding states (negative polarization) during ethylene formation effectively suppresses over-hydrogenation while maintaining semi-hydrogenation activity. This work establishes dynamic electric surface modulation as a powerful strategy for decoupling adsorption-energy correlations to improve heterogeneous catalysis and other adsorption-mediated processes.