Precursor-controlled copper oxide speciation and H2S adsorption performance in 3D-printed activated carbon microstructures

Copper precursor chemistry is fundamental in determining copper speciation and reactive adsorption performance in activated carbon systems; however, its influence in structured adsorbents has not been systematically explored. This study reports the successful fabrication of CuO-functionalized activated carbon microstructures via additive manufacturing, alongside a systematic investigation into the influence of copper precursor chemistry on Cu speciation, dispersion, and dynamic H2S adsorption performance. Three copper precursors: copper nitrate, acetate, and chloride, were introduced into 3D-printed activated carbon microstructures and converted to reactive copper phases through controlled thermal treatment. Comprehensive structural and surface characterization (BET-2D-NLDFT, SEM-EDX, PXRD, and XPS) reveals that precursor chemistry strongly influences copper oxidation state distribution, crystallinity, pore-scale deposition, and final retained Cu loading. Breakthrough testing using dry 500 ppm H2S demonstrates that nitrate-derived microstructures exhibit the most favorable combination of retained Cu loading, reactive CuO/Cu2O abundance (98 wt% collectively), and crystallite development, delivering up to 33% longer breakthrough times and 34% higher equilibrium capacities relative to acetate- and chloride-derived materials. Acetate-derived samples achieve the shortest mass-transfer zone consistent with more efficient pore utilization, while chloride-derived materials show inferior performance, likely associated with lower retained Cu loading, defective and poorly crystalline copper domains. These results highlight the interplay between precursor chemistry and sorbent structure in determining chemisorptive performance. The trends reported here are established under dry conditions and provide insight into precursor-dependent behavior in Cu-functionalized activated carbon microstructures, offering a basis for their rational design under controlled H2S conditions.