Reactions of (-)-sparteine with alkali metal HMDS complexes : conventional meets the unconventional

Conventional (-)-sparteine adducts of lithium and sodium 1,1,1,3,3,3-hexamethyldisilazide (HMDS) were prepared and characterised, along with an unexpected and unconventional hydroxyl-incorporated sodium sodiate, [(-)-sparteine·Na(-HMDS)Na·(-)-sparteine]+[Na4(-HMDS)4(OH)]--the complex anion of which is the first inverse crown ether anion

From a Molecular Single-Source Precursor to a Selective High- Performance RhMnOx Catalyst for the Conversion of Syngas to Ethanol

The first carbonyl RhMn cluster Na2[Rh3Mn3(CO)18] 2 has been synthesized and structurally characterized, resulting from the salt metathesis reaction of RhCl3 with Na[Mn(CO)5] 1 in 49% isolated yield. The dianionic Rh3Mn3 cluster core of 2 can serve as a molecular single‐source precursor (SSP) for the low temperature preparation of selective high‐performance RhMn catalysts for the conversion of syngas to ethanol (StE). Impregnation of 2 on silica (davisil) led to three different silica‐supported RhMnOx catalysts with dispersed Rh nanoparticles tightly surrounded by a MnOx matrix. With ethanol selectivities of up to 24.1%, the Rh3Mn3 cluster precursor‐derived catalysts show the highest reported selectivity and performance in the conversion of StE for silica‐supported RhMnOx catalysts

Oxygen Evolution Activity of Amorphous Cobalt Oxyhydroxides Interconnecting Precatalyst Reconstruction, Long Range Order, Buffer Binding, Morphology, Mass Transport, and Operation Temperature

Nanocrystalline or amorphous cobalt oxyhydroxides CoCat are promising electrocatalysts for the oxygen evolution reaction OER . While having the same short range order, CoCat phases possess different electrocatalytic properties. This phenomenon is not conclusively understood, as multiple interdependent parameters affect the OER activity simultaneously. Herein, a layered cobalt borophosphate precatalyst, Co H2O 2[B2P2O8 OH 2] H2O, is fully reconstructed into two different CoCat phases. In contrast to previous reports, this reconstruction is not initiated at the surface but at the electrode substrate to catalyst interface. Ex situ and in situ investigations of the two borophosphate derived CoCats, as well as the prominent CoPi and CoBi identify differences in the Tafel slope range, buffer binding and content, long range order, number of accessible edge sites, redox activity, and morphology. Considering and interconnecting these aspects together with proton mass transport limitations, a comprehensive picture is provided explaining the different OER activities. The most decisive factors are the buffers used for reconstruction, the number of edge sites that are not inhibited by irreversibly bonded buffers, and the morphology. With this acquired knowledge, an optimized OER system is realized operating in near neutral potassium borate medium at 1.62 0.03 VRHE yielding 250 mA cm amp; 8722;2 at 65 C for 1 month without degrading performanc

The Pivotal Role of s , p , and f Block Metals in Water Electrolysis Status Quo and Perspectives

Transition metals, in particular noble metals, are the most common species in metal mediated water electrolysis because they serve as highly active catalytic sites. In many cases, the presence of nontransition metals, that is, s , p , and f block metals with high natural abundance in the earth crust in the catalytic material is indispensable to boost efficiency and durability in water electrolysis. This is why alkali metals, alkaline earth metals, rare earth metals, lean metals, and metalloids receive growing interest in this research area. In spite of the pivotal role of these nontransition metals in tuning efficiency of water electrolysis, there is far more room for developments toward a knowledge based catalyst design. In this review, five classes of nontransition metals species which are successfully utilized in water electrolysis, with special emphasis on electronic structure catalytic activity relationships and phase stability, are discussed. Moreover, specific fundamental aspects on electrocatalysts for water electrolysis as well as a perspective on this research field are also addressed in this account. It is anticipated that this review can trigger a broader interest in using s , p , and f block metals species toward the discovery of advanced polymetal containing electrocatalysts for practical water splittin

In Situ Formed Sn1 xInx In1 ySnyOz Core Shell Nanoparticles as Electrocatalysts for CO2 Reduction to Formate

Electrochemical reduction of CO2 CO2RR driven by renewable energy has gained increasing attention for sustainable production of chemicals and fuels. Catalyst design to overcome large overpotentials and poor product selectivity remains however challenging. Sn SnOx and In InOx composites have been reported active for CO2RR with high selectivity toward formate formation. In this work, the CO2RR activity and selectivity of metal metal oxide composite nanoparticles formed by in situ reduction of bimetallic amorphous SnInOx thin films are investigated. It is shown that during CO2RR the amorphous SnInOx pre catalyst thin films are reduced in situ into Sn1 XInX In1 YSnYOz core shell nanoparticles composed of Sn rich SnIn alloy nanocores with x lt; 0.2 surrounded by InOx rich bimetallic InSnOx shells with 0.3 lt; y lt; 0.4 and z amp; 8776; 1 . The in situ formed particles catalyze the CO2RR to formate with high faradaic efficiency 80 and outstanding formate mass activity 437 A gIn Sn amp; 8722;1 amp; 8722;1.0 V vs RHE in 0.1 m KHCO3 . While extensive structural investigation during CO2RR reveals pronounced dynamics in terms of particle size, the core shell structure is observed for the different electrolysis conditions essayed, with high surface oxide contents favoring formate over hydrogen selectivit

Intermetallic Cobalt Indium Nanoparticles as Oxygen Evolution Reaction Precatalyst A Non Leaching p Block Element

Merely all transition metal based materials reconstruct into similar oxyhydroxides during the electrocatalytic oxygen evolution reaction OER , severely limiting the options for a tailored OER catalyst design. In such reconstructions, initial constituent p block elements take a sacrificial role and leach into the electrolyte as oxyanions, thereby losing the ability to tune the catalyst s properties systematically. From a thermodynamic point of view, indium is expected to behave differently and should remain in the solid phase under alkaline OER conditions. However, the structural behavior of transition metal indium phases during the OER remains unexplored. Herein, are synthesized intermetallic cobalt indium CoIn3 nanoparticles and revealed by in situ X ray absorption spectroscopy and scanning transmission microscopy that they undergo phase segregation to cobalt oxyhydroxide and indium hydroxide. The obtained cobalt oxyhydroxide outperforms a metallic cobalt derived one due to more accessible active sites. The observed phase segregation shows that indium behaves distinctively differently from most p block elements and remains at the electrode surface, where it can form lasting interfaces with the active metal oxo phase

An Intermetallic CaFe6Ge6 Approach to Unprecedented Ca Fe O Electrocatalyst for Efficient Alkaline Oxygen Evolution Reaction

Based on the low cost and relatively high catalytic activity, considerable efforts have been devoted towards developing redox active transition metal TM oxygen electrocatalysts for the alkaline oxygen evolution reaction OER while the role of redox inactive alkaline earth metals has often been neglected in OER. Herein, for the first time, we developed a novel ternary intermetallic CaFe6Ge6 precatalyst, whose surface rapidly transforms into a porous ultrathin Ca amp; 8722;Fe amp; 8722;O heteroshell structure during alkaline OER through the oxidative leaching of surficial Ge. Benefiting from synergistic effects, this highly efficient OER active material with distinct Ca amp; 8722;Fe amp; 8722;O layers has a large electrochemical surface area and more exposed active Fe sites than a Ca free FeOx phase. Also, the presence of Ca in Ca amp; 8722;Fe amp; 8722;O is responsible for the enhanced transport and activation of hydroxyls and related OER reaction intermediate as unequivocally illustrated by a combination of quasi in situ Raman spectroscopy and various ex situ method

Ba Ni Ge Clathrate Transformation Maximizes Active Site Utilization of Nickel for Enhanced Oxygen Evolution Performance

Discovering novel oxygen evolution reaction OER pre catalysts with exceptional catalytic activity and long term stability is pivotal for advancing decarbonization technologies. In this study, we present the ternary Ba8Ni6Ge40 phase with an open clathrate structure exhibiting remarkable performance in alkaline OER. When integrated into an alkaline water electrolyzer, this clathrate precatalyst achieves high stability under a sustained current density of amp; 8764;550 mA cm amp; 8722;2 for 10 days. By combining in situ Raman spectroscopy, quasi in situ X ray absorption spectroscopy, and micro structural characterizations, we elucidate the complete electrochemical transformation of Ba8Ni6Ge40 90 weight leaching forming ultrathin nanosheets composed of a porous and defective NiOOH nanostructure with maximized accessible active site exposure. Notably, a reversible phase transition mainly between Ni OH 2 and NiOOH has also been established in the electrochemical redox process. Meanwhile, the successful application of the model Ba8Ni6Ge40 precatalyst represents a promising new class of functional inorganic materials for water electrolysi