Angstrom-scale distance-dependent synergy in clusters via atom-by-atom regulation for enhanced photocatalytic CO2 reduction

Abstract

Constructing multi-active-site catalysts with a suitable atomic distance to bring the synergistic enhancement catalytic effect into full play is still challenging. Multi-atom clusters with well-defined, uniform, and controllable atomic configurations and distances provide an unprecedented opportunity. Herein, we designed and synthesized a series of atomically precise Pd_x supported on TiO₂ (Pd_x-TiO₂, x = 1, 2, 3, and 5) to elucidate the concept of angstrom-scale, distance-dependent synergistic catalysis via atom-by-atom regulation. Benefiting from enhanced light utilization, CO₂ adsorption, and photoinduced charge transfer and separation capability, Pd₃-TiO₂ exhibited the most optimal activity in the pure H₂O-mediated photocatalytic CO₂ reduction reaction (CO₂RR), with a CO/CH₄ yield of 86.09/42.94 μmol g⁻¹ h⁻¹, respectively. The combination of precise structural characterization, ex/in situ photoelectrochemical tests, and theoretical calculations provided in-depth insights into the superior CO₂RR activity of Pd₃-TiO₂. The appropriate atomic distance maximized the interaction between Pd atoms and enhanced the synergistic effect, thereby reducing the rate-determining step energy barrier for CO₂-to-CO, as well as promoting the formation of the key intermediate *CO for CH₄ generation. This work illuminates a novel avenue to fully utilize the synergistic effect between multiple active sites through atomic spacing adjustment for advanced catalyst design.