Plasmon Modifies Formic Acid Dehydrogenation Kinetics

Understanding the illumination-modified kinetics is a fundamentally important issue for exploring the plasmon-enhanced catalytic mechanism. Here, we prepare Pd-based plasmonic particles with tunable plasmon features including local field enhancement and hot carrier density for photocatalytic formic acid dehydrogenation. We demonstrate that the plasmon plays a vital role for a kinetics switch from a competitive Langmuir–Hinshelwood mechanism to a noncompetitive L–H mode. An intense local electric field enhancement could induce a spatial–temporal separation of different dehydrogenation-favorable adsorption configurations, and different electric field directions facilitate C–H and O–H bond activations, respectively. Concurrently, the plasmonic hot holes and hot electrons show selective adsorption toward different reactants. Both local field and hot carriers work together to effectively avoid competitive adsorption of reactant molecules at the particle surface and well guarantee catalytic activity in particular at high reactant concentrations. Interestingly, a low plasmonic energy utilization efficiency or a high temperature leads to a coexistence of noncompetitive and competitive modes, and the “cooperation” between plasmon nonthermal and thermal effect determines the ensemble kinetics behavior. This work indicates that unique noncompetitive adsorption kinetics may serve as a typical descriptor of plasmon-involved catalysis that remarkably differs from traditional thermocatalysis under appropriate plasmonic excitation.