Both global warming and limited fossil resources make the transition from fossil to solar fuels an urgent matter. In this regard, the splitting of water activated by sunlight is a sustainable and carbon‐free new energy conversion scheme able to produce efficient technological devices. The availability of appropriate catalysts is essential for the proper kinetics of the two key processes involved, namely, the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER). During the last decade, ruthenium nanoparticle derivatives have emerged as true potential substitutes for the state‐of‐the‐art platinum and iridium oxide species for the HER and OER, respectively. Thus, after a summary of the most common methods for catalyst benchmarking, this review covers the most significant developments of ruthenium‐based nanoparticles used as catalysts for the water‐splitting process. Furthermore, the key factors that govern the catalytic performance of these nanocatalysts are discussed in view of future research directions.

This article describes the generalization of an overlooked mechanism for CH bond activation at early transition metal centers, namely 1,3-CH bond addition at an η 2 -alkene intermediate. The X-ray-characterized [Cp 2 Zr(c-C 3 H 5 ) 2 ] eliminates cyclopropane by a β-H abstraction reaction to generate the transientA rapidly cleaves the CH bond of furan and thiophene to give the furyl and thienyl complexes [Cp 2 Zr(c-C 3 H 5 )(2-C 4 H 3 X)] (X = O, S), respectively. Benzene is less cleanly activated. Mechanistic investigations including kinetic studies, isotope labeling, and DFT computation of the reaction profile all confirm that rapid stereospecific 1,3-CH bond addition across the Zr(η 2 -alkene) bond of A follows the rate-determining β-H abstraction reaction. DFT computations also suggest that an α-CC agostic rotamer of [Cp 2 Zr(c-C 3 H 5 ) 2 ] assists the β-H abstraction of cyclopropane. The nature of the α-CC agostic interaction is discussed in the light of an NBO analysis.

Electrocatalytic Nitrobenzene Hydrogenation and competitive Hydrogen Evolution Reaction (HER) have been studied, using two catalytic systems: oxidized carbon fibers (organic) and Ruthenium nanoparticles supported on unaltered carbon fibers (inorganic).