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

Abstract

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 (kapp), and lower charge transfer resistance (Rct) values. Lower values of Rct 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.