Although rhenium may not be the most common choice of active species in catalysis, it has been reported as a highly active and selective catalyst over a wide range of reactions. Its applications include hydrogenation reactions of great relevance in the field of renewable materials and bio‐derived platform molecules, such as valorization of lignin, CO₂, and carboxylic acids. Different from several transition metals, rhenium presents oxidation numbers varying from −3 to +7. Such diversity in the coordination chemistry of rhenium is reflected in the variety of known rhenium compounds, since this metal can form stable structures such as ligand‐bridged multinuclear and organometallic compounds as well as inorganic oxides, metal‐organic frameworks, and clusters. The exceptional flexibility in rhenium speciation yields numerous selective catalysts; however, it also makes the characterization of rhenium catalysts challenging, and its influence on the catalytic activity is not trivial. This review will outline the most established rhenium‐based materials used in hydrogenation catalysis and shed some light on the relation of rhenium species to catalyst selectivity based on advanced characterization techniques. Finally, our perspectives on the use of rhenium catalysts to produce value‐added products will be given.

Hydrogen (H₂) has emerged as a sustainable energy carrier capable of replacing/complementing the global carbon-based energy matrix. Although studies in this area have often focused on the fundamental understanding of catalytic processes and the demonstration of their activities towards different strategies, much effort is still needed to develop high-performance technologies and advanced materials to accomplish widespread utilization. The main goal of this review is to discuss the recent contributions in the H₂ production field by employing nanomaterials with well-defined and controllable physicochemical features. Nanoengineering approaches at the sub-nano or atomic scale are especially interesting, as they allow us to unravel how activity varies as a function of these parameters (shape, size, composition, structure, electronic, and support interaction) and obtain insights into structure–performance relationships in the field of H₂ production, allowing not only the optimization of performances but also enabling the rational design of nanocatalysts with desired activities and selectivity for H₂ production. Herein, we start with a brief description of preparing such materials, emphasizing the importance of accomplishing the physicochemical control of nanostructures. The review finally culminates in the leading technologies for H₂ production, identifying the promising applications of controlled nanomaterials.

Methane has a rather relevant role in the “Power-to-Gas” concept, which is central in the current paradigm of climate change and renewable energies. Methane, the main component of natural gas, can be produced by catalytic hydrogenation reactions, particularly of CO₂. A very effective catalyst in this reaction, hydrotalcite-derived nickel nanoparticles supported on alumina, Ni/Al₂O₃-HTC, can be employed in a high-pressure flow reactor to convert CO₂ and H₂ into CH₄ at 100% selectivity and 84% conversion, whereas at atmospheric pressure, methane can be obtained with up to 90% selectivity. The high-pressure aspect also allows fast-paced production—over 5 m³·h⁻¹·kg_cat⁻¹ of CH₄ can be generated.