γ-Alumina Supported Copper Oxide Nanostructures Promoted with Ruthenium Oxide (RuO₂-CuO/Al₂O₃) and Palladium Oxide (PdO-CuO/Al₂O₃): Efficient Electrodes for Heterogeneous Catalysis of Ammonia Electrooxidation

RuO₂ and PdO promoted CuO/Al₂O₃ mixed metal oxide nanostructures synthesized via co-impregnation technique demonstrated a robust electrocatalytic activity towards ammonia electro-oxidation (AEO). Physio-chemically characterized RuO₂-CuO/Al₂O₃ and PdO-CuO/Al₂O₃ catalyst powders exhibited high electrochemical active surface area (ECSA), highest being shown by 1% RuO₂-CuO/Al₂O₃. All fabricated electrodes displayed pleasing electroactive response towards AEO but ternary metal oxides showed superior and promoted catalytic output owing to their larger ECSA, higher current densities (j), larger diffusion coefficients (D°), greater apparent rate constants (k_app), and lower charge transfer resistance (R_ct) values. Lower values of R_ct obtained from EIS indicated the facilitation of electro-oxidation process over modified electrodes. The finest catalysis performance is expressed by 1% RuO₂-CuO/Al₂O₃ producing the maximum oxidation current. All the promoted CuO/Al₂O₃ mixed metal oxide exhibited excellent stability and reproducibility in analyte solution. Consequently, γ-Al₂O₃ supported metal oxide electrocatalysts can be of great socio-economic significance by enhancing the energy production kinetics thereby achieving a higher energy output.