Single‐Atom or Dual‐Atom in TiO 2 Nanosheet: Which is the Better Choice for Electrocatalytic Urea Synthesis?

Abstract As rising star materials, single‐atom and dual‐atom catalysts have been widely reported in the electro‐catalysis area. To answer the key question: single‐atom and dual‐atom catalysts, which is better for electrocatalytic urea synthesis? we design two types of catalysts via a vacancy‐anchorage strategy: single‐atom Pd 1 −TiO 2 and dual‐atom Pd 1 Cu 1 −TiO 2 nanosheets. An ultrahigh urea activity of 166.67 mol urea mol Pd −1 h 1 with the corresponding 22.54 % Faradaic efficiency at −0.5 V vs. reversible hydrogen electrode (RHE) is achieved over Pd 1 Cu 1 −TiO 2 , which is much higher than that of Pd 1 −TiO 2 . Various characterization including an in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and theoretical calculations demonstrate that dual‐atom Pd 1 Cu 1 site in Pd 1 Cu 1 −TiO 2 is more favorable for producing urea, which experiences a C−N coupling pathway with a lower energy barrier compared with Pd 1 in Pd 1 −TiO 2 .