Morphology-dependent activity of Pd/NiO catalysts for low-concentration methane combustion

Three high-performance Pd/NiO catalysts were successfully synthesized through precise morphological control of support, and evaluated for their catalytic performance in low-concentration methane combustion. The catalyst morphologies and crystalline structures were characterized by Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), and N₂ physical adsorption-desorption(N 2 -BET), while electronic properties were analyzed via Raman spectroscopy (Raman), Fourier Transform Infrared Spectroscopy (FTIR), Hydrogen Temperature Programmed Reduction (H₂-TPR), X-ray photoelectron spectroscopy (XPS), and Electron paramagnetic resonance spectroscopy (EPR) to elucidate the structure-performance relationship and identify key factors enhancing catalytic activity. Three distinct morphologies (cubic-PdY1, flower-like-PdY2, hairball-like-PdY3) were synthesized hydrothermally, with cubic-PdY1 exhibiting superior characteristics: highest surface area (67.76 m 2 g −1 ), optimal pore structure (18.92 nm, 0.321 cm 3 g −1 ), and maximum oxygen vacancy concentration. Catalytic evaluation revealed cubic-PdY1's exceptional activity (T 50 = 298 °C, T 90 = 377 °C), outperforming flower-like-PdY2 (ΔT 50 = 21 °C, ΔT 90 = 48 °C), hairball-like-PdY3 (ΔT 50 = 42 °C, ΔT 90 = 88 °C) and numerous reported methane combustion catalysts. The cubic morphology also showed the lowest activation energy (72 kJ mol −1 ) and remarkable stability (98–100 % conversion over 20 h). These findings establish that support morphology engineering enhances catalytic efficiency through optimized metal-support interactions and oxygen vacancy generation, providing critical insights for developing effective methane abatement technologies. • Modulation of support morphology enhances catalytic activity of methane combustion. • T 50 and T 90 of the cubic Pd/NiO catalysts were 298 °C and 377 °C. • Cubic Pd/NiO has superior stability, with a 2 % decrease in conversion after 20 h. • High catalytic activity due to lower activation energy and higher oxygen vacancies.