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Rechargeable aqueous Zn-ion batteries (ZIBs) have obtained extensive attention owing to their high safety, low-cost, environmental friendliness and high energy density. Nevertheless, developing suitable cathode materials remains challenging due to requirements for appropriate microstructure. We present a porous N-doped carbon nanosheet/MnO2 (NCS/MnO2) derived from bacterial cellulose (BC) by a simple route. BC chunks were soaked in urea solution and then carbonized under Ar flow at 900 °C. N-doped carbon nanosheets were obtained and MnO2 was added by reaction with NaMnO4. Benefiting from both the conductivity and porosity of the NCS support, the NCS/MnO2 composite delivers a high capacity and long cycling stability (114 mA h g−1 at 2 A g−1 after 1800 cycles). The electrode reaction mechanism was further investigated and the MnO2 dissolution/deposition mechanism was confirmed, with a critical role of zinc sulfate hydroxide (ZSH) to assist the deposition of MnO2

The generation of methane fuel using surplus renewable energy with CO as the carbon source enables both the decarbonization and substitution of fossil fuel feedstocks. However, high temperatures are usually required for the efficient activation of CO. Here we present a solid catalyst synthesized using a mild, green hydrothermal synthesis that involves interstitial carbon doped into ruthenium oxide, which enables the stabilization of Ru cations in a low oxidation state and a ruthenium oxycarbonate phase to form. The catalyst shows an activity and selectivity for the conversion of CO into methane at lower temperatures than those of conventional catalysts, with an excellent long-term stability. Furthermore, this catalyst is able to operate under intermittent power supply conditions, which couples very well with electricity production systems based on renewable energies. The structure of the catalyst and the nature of the ruthenium species were acutely characterized by combining advanced imaging and spectroscopic tools at the macro and atomic scales, which highlighted the low-oxidation-state Ru sites (Ru, 0 < n < 4) as responsible for the high catalytic activity. This catalyst suggests alternative perspectives for materials design using interstitial dopants.

Proton exchange membrane water electrolysis (PEMWE) technology is especially advantageous for green H2 production as a clean energy vector. During the water electrolysis process, the oxygen evolution reaction (OER) requires a large amount of iridium (2-3 mgIr cm−2) as catalyst. This material is scarce and expensive, representing a major bottleneck for large-scale deployment of electrolyzers. This work develops an anode with 10-fold reduction of Ir loading (0.2 mgIr cm−2) compared to what it is used in commercial PEMWE for more than 1000 h. An advanced catalyst based on an Ir mixed oxide (Sr2CaIrO6) is used for this purpose. Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS) analyses show that the unconventional structure of the reconstructed catalyst can contribute to the reduction of Ir in the catalyst layer. The reconfiguration of the ionomer in the catalyst layer is also observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM), results in almost the full coverage of the catalytic layer with ionomer. The results presented herein demonstrate that it is possible to achieve high performance and stability in PEMWE with low Ir loading in the anode without showing significant degradation.

Dodecacarbonyltriruthenium Ru(CO) has been immobilized onto a biopolymer (chitosan) supported on SiO (Ch@SiO) to give Ru−Ch@SiO. Ch@SiO behaves as a soft, recoverable and bulky ligand allowing the stabilization of released Ru active species and preventing its irreversible reduction to Ru. Under these conditions very high activity (TOF= 1086 h; TON=2749) and regioselectivity (n:iso=92 : 8) are obtained, surpassing that of the homogeneous Ru(CO) counterpart. Spectroscopic studies have shown that Ru(CO) transforms into a mononuclear Ru (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@SiO 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.

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.

Two imidazolate-based Co-MOFs, IFP-5 and IFP-8 (imidazolate framework Potsdam), with a different peripheral group -R (-Me and -OMe, respectively) have been synthesized by a solvothermal method and tested toward the oxygen evolution reaction (OER). Remarkably, IFP-8 presents much lower overpotentials (319 mV at 10 mA/cm2 and 490 mV at 500 mA/cm2) than IFP-5 toward OER, as confirmed by online gas chromatography measurements (Faradaic yield of O2 > 99%). Moreover, the system is extraordinarily stable during 120 h, even when used as a catalyst toward the overall water splitting reaction without any sign of fatigue. An integrated ex situ spectroscopic study, based on powder X-ray diffraction, extended X-ray absorption fine structure, and attenuated total reflection, allows the identification of the active species and the factors that determine the catalytic activity. Indeed, it was found that the performances are highly affected by the nature of the -R group, because this small change strongly influences the conversion of the initial metal organic framework to the active species. As a consequence, the remarkable activity of IFP-8 can be ascribed to the formation of Co(O)OH phase with a particle size of a few nanometers (3-10 nm) during the electrocatalytic oxygen evolution. Copyright © 2019 American Chemical Society.