PNNL

Abstract

Perovskite-based oxides are used in electrochemical CO2 and H2O reduction in electrochemical cells due to their compositional versatility, redox properties and stability. However limited knowledge exists on the mechanisms driving these processes. Toward this understanding, herein we probe the core level binding energy shifts of water-derived adspecies (H, O, OH, H2O) as well as the adsorption of CO2 on LaCoO3 and LaNiO3 and we correlate the simulated peaks with experimental Temperature Programmed X-ray Photoelectron Spectroscopy (TPXPS) results. We find the strong adsorption of such chemical species can affect the antiferromagnetic ordering of LaNiO3. The adsorption of such adspecies is further quantified through Bader and differential charge analyses. We find the higher O 1s core level binding energy peak for both LaCoO3 and LaNiO3 corresponds to adsorption of water-related species and CO2, while the lower energy peak is due to lattice oxygen. We further correlate these DFT-based core level O 1s binding energies with the TPXPS measurements to quantify the decrease of the O 1s contribution due to desorption of adsorbates and the apparent increase of the lattice oxygen (both bulk and surface) with temperature. Finally, we quantify the influence of adsorbates on the La 4d, Co 2p and the Ni 3p core level binding energy shifts. This work demonstrates how theoretically generated XPS data can be utilized to predict species-specific binding energy shifts to assist in the deconvolution of the experimental results. The authors thank the primary financial support from the National Science Foundation Ceramics Program (Award Number DMR-1929314/2333166 and DMR-1929306). This work was partially funded by the Joint Center for Deployment and Research in Earth Abundant Materials (JCDREAM) in Washington State. This work used the Extreme Science and Engineering Discovery Environment (XSEDE)50, which is supported by National Science Foundation grant number ACI-1548562. This work also used Bridges-2 at the Pittsburgh Supercomputer Center through allocation CHE170068 from the Advanced Cyberinfrastructure Coordination Ecosystem: Services & Support (ACCESS) program51, which is supported by National Science Foundation grants #2138259, #2138286, #2138307, #2137603, and #2138296. Additional computational resources were provided by the Kamiak HPC under the Center for Institutional Research Computing at Washington State University. The authors also thank the Lumigen Instrument Center at Wayne State University for the use of the X-ray photoelectron spectroscopy facilities (National Science Foundation MRI-1849578). The Pacific Northwest National Laboratory is operated by Battelle for the U.S. DOE.