Ruthenium and palladium oxide promoted zinc oxide nanoparticles: Efficient electrocatalysts for hydrazine oxidation reaction

• Published in: Journal of electroanalytical chemistry (Lausanne, Switzerland) Vol. 917; p. 116422
• Main Authors: Khan, Safia, Shah, Syed Sakhawat, Ahmad, Awais, Yurtcan, Ayse Bayrakçeken, Jabeen, Erum, Alshgari, Razan A., Janjua, Naveed Kausar
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.07.2022; Elsevier Science Ltd
• Subjects: Aluminum oxide; Catalysts; Co-impregnation; Cyclic voltammetry; Diffusion coefficient; Electrocatalysts; Electrochemical impedance spectroscopy; Electrode materials; Electrodes; Electrooxidation; Fourier transforms; Fuel cells; Gamma alumina; Hydrazine; Hydrazines; Hydrogen production; HzOR; Infrared spectroscopy; Metal oxide electrocatalyst; Metal oxides; Microparticles; Nanoparticles; Oxidation; Palladium; Ruthenium; Ruthenium oxide; Spectrum analysis; Transitional aluminas; Zinc oxide; Zinc oxides; Electrooxidation; Cyclic voltammetry; Co-impregnation; Ruthenium; HzOR; Zinc oxide; Palladium; Gamma alumina; Hydrazine; Metal oxide electrocatalyst
• ISSN: 1572-6657; 1873-2569
• DOI: 10.1016/j.jelechem.2022.116422

[Display omitted] •RuO2 and PdO are co-impregnated with ZnO on γ-Al2O3 support to develop mixed metal oxide electrocatalysts for HzOR.•Ternary metal oxide catalysts displayed superior current output than binary catalysts i.e. 1% RuO2-ZnO/Al2O3 and 1% PdO-ZnO/Al2O3 displayed 1.3 and 23.3 folds’ increase in current density comparative to binary catalyst i.e. ZnO/Al2O3.•PdO-ZnO/Al2O3 displayed the best catalytic response towards N2H4 electrooxidation among all catalysts in series owing to its high surface area of 0.23 cm2, highest current density of 5.2 mA cm−2 and largest diffusion coefficient i.e. 50 × 10−6 cm2 s−1.•Incorporation of trace amounts of noble metal oxides (i.e. 0.1 to 1.0%) in binary catalysts promoted their electrocatalytic properties. Development of highly catalyzing electrode materials for hydrazine electrooxidation reaction (HzOR) demands a judicious assortment of intrinsically active candidates, precise engineering of electrodes for enhancement of active sites and building of electronically conductive structures. Herein, we report the novel, innovative and robust heterogeneous electrocatalysts for HzOR for ultimate hydrogen generation and their applicability in direct hydrazine fuel cell (DHFC). The presented catalysts comprised of ZnO microparticles supported on γ-Al2O3 with different weight percentages (10, 20, 30, 40 wt/wt%). Binary catalyst i.e. 20% ZnO/Al2O3 displayed the maximum catalytic output towards HzOR, so it is chosen to further combine with RuO2 and PdO to investigate a promoted and enhanced oxidation output. Ternary metal oxide catalysts i.e. RuO2-ZnO/Al2O3 and PdO-ZnO/Al2O3 with varied contents of RuO2 and PdO (0.1, 0.5 and 1 wt/wt%) are prepared via co-impregnation method. X-Ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy coupled energy dispersive spectroscopy (SEM-EDS), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are the techniques employed for physio-chemical characterization of samples. Among all the investigated catalysts, 1% PdO-ZnO/Al2O3 produced the most catalyzing behavior toward HzOR owing to its largest diffusion coefficient (50.0 × 10−6 cm2 s−1), highest current density (5.2 mA cm−2) and high ECSA (0.23 cm2). The catalysts showed sufficient reproducibility and stability by scanning multiple cycles and testing similar electrodes after different time intervals. This is the first study of hydrazine electrooxidation protocol employing RuO2 and PdO promoted γ-alumina supported ZnO structured electrocatalysts.