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

Abstract Ammonia (NH3) 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 (AB2O4) structure confirmed by XRD, XRF, and ICP-OES. Electronic structure characterization using UPS and LEIPS revealed a bandgap of 4.722 eV, with EVBM and ECBM 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 H2, N2, and O2 as the main products, with ~64.7% Faradaic efficiency for H2, 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.