Active parts for CH₄ decomposition and electrochemical oxidation at metal/oxide interfaces by isotope labeling-secondary ion mass spectrometry

Active parts for CH₄ decomposition and electrochemical oxidation of reformed gases were investigated at the well defined Ni-mesh/oxide interfaces in μm level. The effective reaction areas were determined by isotope labeling technique under the mixture of CH₄, D₂O, and ¹⁸O₂ at 1073 K. A deposition of carbon preferentially occurred on the Ni-mesh surface on Y₂O₃-stabilized ZrO₂ (YSZ) and Sm₂O₃-doped CeO₂ (SDC) electrolyte oxides. A slight reduction of carbon deposition was observed on SDC substrate under non-polarized condition. The electronic and structural properties changes of Ni were observed by XANES/EXAFS analysis. By anodic polarization, a significant reduction of deposited carbon was observed on Ni-mesh surface in Ni-mesh/YSZ and Ni-mesh/SDC samples. Oxygen spill over can be effective for eliminating the deposited carbon on the Ni-mesh. Hydrogen and isotope oxygen concentration (¹⁸O₂) on the Ni-mesh was changed by the oxide substrates under anodic polarization.