The need for high efficiency energy production, conversion, storage and transport is serving as a robust guide for the development of new materials. Materials with physical-chemical properties matching specific functions in devices are produced by suitably tuning the crystallographic- defect- and micro-structure of the involved phases. In this review, we discuss the case of Rare Earth doped Ceria. Due to their high oxygen diffusion coefficient at temperatures higher than ~500°C, they are very promising materials for several applications such as electrolytes for Solid Oxide Fuel and Electrolytic Cells (SOFC and SOEC, respectively). Defects are integral part of the conduction process, hence of the final application. As the fluorite structure of ceria is capable of accommodating a high concentration of lattice defects, the characterization and comprehension of such complex and highly defective materials involve expertise spanning from computational chemistry, physical chemistry, catalysis, electrochemistry, microscopy, spectroscopy, and crystallography. Results coming from different experimental and computational techniques will be reviewed, showing that structure determination (at different scale length) plays a pivotal role bridging theoretical calculation and physical properties of these complex materials.

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Carbon dioxide concentration level is reaching a non-returning point. Carbon capture technologies are immature and short-term actions are necessary. The conversion of CO 2 into methanol is a technical challenge. Commercial copper-zinc-alumina catalysts convert maximum 7 % carbon dioxide in syngas at high pressures (5 MPa to 10 MPa) and moderate temperatures (473 K to 573 K) into methanol. However, there are not records on the synthesis of methanol at low pressure (P < 2.5 MPa) and without a large excess of hydrogen in the feed. Here, we tested three new catalysts prepared by co-precipitation of copper, zinc and aluminum nitrates (CZA), with strontium, magnesium or calcium as basic promoters to enhance CO 2 conversion to methanol. We discussed the microstructure of the catalysts according to the supersaturation of the relative carbonates formed during the co-precipitation synthesis. Compared to the benchmark, the sample doped with Ca showed higher carbon conversion with all the feed compositions tested (syngas, synthetic biosyngas and CO 2 with H 2 ). CZA doped with Sr is inactive in this reaction.

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Dear Editor, we are submitting the thoroughly revised version of our manuscript, enriched with further data and several new experiments, particularly of electrochemical character. Please find here below the detailed answers to the Referees' queries. We thank them for their revision and you for the opportunity to submit an improved version. We do hope that the manuscript can now be acceptable for publication.

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