Continuous-Flow Solution Plasma for the Atom-Economic Synthesis of Single/Dual-Atom Catalysts

Single-atom catalysts (SACs) manifest unique advantages in various aspects of catalysis but face challenges in atom-economic synthesis. Solution reduction holds the promise of fast, continuous, and low-cost synthesis of SACs, however, almost no chemical, electrochemical, or photochemical reduction can avoid the aggregation of metal atoms in solution. The issue becomes even tougher to composite dual-atom metals together. Herein, a continuous-flow solution plasma (CSP) method is developed, which utilizes high-flux hydrated electrons, hydrogen radicals, and enhanced metal–support interaction, to achieve over 97% capture efficiency of metal precursors to fabricate CeO₂-based single-atom Au, Rh, Pd, Ru, and Pt in only 0.03-s residence time. Further, a programmed CSP synthesis of Au₁Rh₁/CeO₂ and Au₁Pd₁/CeO₂ dual-atom catalysts is demonstrated. Under Xe lamp irradiation, Au₁Rh₁/CeO₂ breaks room temperature constraints in CO conversion for the water–gas shift reaction with a T₅₀ (the temperature at which 50% CO conversion occurs) of 298 K. The innovative CSP technology provides an atom-economic approach to the continuous production of SACs using clean electricity without any additional reducing agent, paving the way for the programmed and green synthesis of SACs for industrial catalysis, energy conversion, and environment remedy applications.