Ammonia decomposition and hydrogen production via novel FeCoNiCuMnO high-entropy ceramic catalysts

Ammonia (NH 3 ) decomposition offers a pathway for water purification and green hydrogen production, yet conventional catalysts often suffer from poor stability due to agglomeration. This study presents a novel (FeCoNiCuMn)O high-entropy ceramic (HEC) catalyst synthesized via fast-moving bed pyrolysis (FMBP), which prevents aggregation and enhances catalytic performance. The HEC catalyst, applied as an anode in electrochemical oxidation (EO), demonstrated a uniform spinel (AB 2 O 4 ) structure confirmed by XRD, XRF, and ICP-OES. Electronic structure characterization using UPS and LEIPS revealed a bandgap of 4.722 eV, with E VBM and E CBM values facilitating redox reactions. Under 9 V and 50 mA/cm² current density, the HEC electrode achieved 99% ammonia decomposition within 90 min and retained over 90% efficiency after four cycles. Surface analysis by XPS and HAXPES indicated oxidation state variations, confirming catalyst activity and stability. Gas chromatography identified H 2 , N 2 , and O 2 as the main products, with ~64.7% Faradaic efficiency for H 2 , classifying it as green hydrogen. This dual-function approach highlights the (FeCoNiCuMn)O HEC anode as a promising and sustainable solution for wastewater treatment and hydrogen production.