Copper Single-Atom Catalyst on Nanoconfined Ceramic Membranes for Fenton-Like Removal of Organic Contaminants

Membranes are increasingly used as substrates to host nanoscale catalysts for degrading organic pollutants through Fenton-like advanced oxidation processes (AOPs). However, reducing membrane pore sizes to improve size exclusion poses the challenge of catalysts blocking pores in similar nanoscale spaces. In this proof-of-concept study, we demonstrate successful loading of copper catalysts in isolated single-atom morphology─the theoretical limit of size reduction─onto a ceramic membrane substrate for flow-through AOPs. The novel copper single-atom catalyst-functionalized anodic aluminum oxide membrane demonstrates enhanced catalytic performance by confining surface-catalyzed radical generation within nanometer-sized pores. Using benzoic acid as a model contaminant, the membrane achieved up to 54% degradation at pH 4 through single-pass treatment, with a degradation half-life of approximately 42 s. Minimal copper leaching and stable catalytic activity were observed across a broad pH range (4–8), underscoring the structural robustness and operational durability of the catalytic membrane. Its performance significantly surpasses that of traditional batch systems by reducing residence times and improving mass transfer efficiency. This successful demonstration with copper single-atom catalysts enables catalytic membrane designs with pore sizes much smaller than those possible with conventional nanoparticles.