A heterogeneous ruthenium catalyst consisting of isolated single atoms and disordered clusters stabilized in a N-doped carbon matrix has been synthesized with very good activity and remarkable regioselectivity in the hydroformylation of 1-hexene. The role of the nitrogen heteroatoms has been probed essential to increase the catalyst stability and activity, enabling the stabilization of Ru­(II)–N sites according to X-ray photoelectron spectroscopy (XPS) and XANES. Intrinsic size-dependent activity of Ru species of different atomicity has been extracted, correlating the observed reaction rate and the particle size distribution determined by means of aberration-corrected high-angle annular dark-field scanning transmission electron microscopy, permitting the identification of single-atom sites as the most active ones. This catalyst appears as a promising alternative with respect to its heterogeneous counterparts, paving the way for designing improved Ru heterogeneous catalysts.

Atomically dispersed catalysts (ADCs) have recently drawn considerable interest for use in water electrolysis to produce hydrogen, because they allow for maximal utilization of metal species, particularly the expensive and...

Dodecacarbonyltriruthenium Ru3(CO)12 has been immobilized onto a biopolymer (chitosan) supported on SiO2 (Ch@SiO2) to give Ru−Ch@SiO2. Ch@SiO2 behaves as a soft, recoverable and bulky ligand allowing the stabilization of released Ru active species and preventing its irreversible reduction to Ru0. Under these conditions very high activity (TOF= 1086 h−1; TON=2749) and regioselectivity (n:iso=92 : 8) are obtained, surpassing that of the homogeneous Ru3(CO)12 counterpart. Spectroscopic studies have shown that Ru3(CO)12 transforms into a mononuclear Run+ (n=2,3) di o try carbonyl species by interacting with the amido/amino groups of the biopolymer, being released into the reaction media whilst stabilized by the chitosan functional groups. The herein 0.5 Ru‐Ch@SiO2 catalyst can operate be operated under a semi‐continuous mode for at least 14 h without deactivation, representing providing a starting point in the search for a green catalyst with definitive industrial application in hydroformylations. In particular in the search for a heterogeneous catalyst away from the use of phosphines and their known drawbacks (i. e. tedious synthesis, facile oxidation of phosphor center, ..) as well as expensive Rh as active site.

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Electrocatalysts play a crucial role in hydrogen production via water electrolysis. In this presentation, we report the synthesis of atomically dispersed ruthenium (Ru) supported on nitrogen-doped carbon (Ru-NC) with ultra-low Ru loading (0.2 wt%) through a two-step deposition-pyrolysis method. Briefly, controlled amounts of ammonium alginate (AG), 20% wt., were dispersed on a carbonaceous support (Norit CN-1) followed by subsequent introduction of the ruthenium precursor (RuCl3·3H2O) under alcoholic solution (1-butanol). Finally, the Ru-containing solids were pyrolized at 800 ºC for 2 h under N2 flow to yield the Ru-NC catalyst. Extensive transmission electron microscopy investigations reveal that Ru is dispersed on the NC support in the form of both single atoms and small clusters (Figure 1a). The as-prepared Ru-NC exhibits superior electrocatalytic activity and good stability for both HER and OER, showing bifunctionality. It only requires a low overpotential of 47.1 and 72.8 mV to deliver a current density of 10 mA cm-2 for HER in 0.5 M H2SO4 and 1.0 M KOH, respectively, and 300 mV for OER in 1.0 M KOH. The overall water electrolysis performance has been investigated in alkaline solution using Ru-NC as both HER and OER catalysts in the presence of an anion exchange membrane water electrolysis (AEM-WE), where a cell voltage of 1.67 V is needed to achieve 10 mA cm-2. Furthermore, with a bipolar membrane (BPM), we demonstrate water electrolysis in acid-alkaline dual electrolytes (BPM-WE), where HER is accomplished in a kinetically favorable acidic solution and OER in a kinetically favorable basic solution. Such asymmetric acid-alkaline BPM-WE operates under a low cell voltage of only 0.89 V to deliver a current density of 10 mA cm-2 and can sustain over 100 hours without significant performance decay due to the assistance of electrochemical neutralization resulting from the crossover of the electrolytes, which shows a great potential for energy-saving hydrogen production. Figure 1