Monitoring chalcogenide ions-guided in situ transform active sites of tailored bismuth electrocatalysts for CO reduction to formate.

Although bismuth catalysts enable accelerated electrochemical CO-to-formate conversion, the intrinsic active sites and forming mechanisms under operating conditions remain elusive. Herein, we prepared BiONCN, BiO, and BiOS as precatalysts. Among them, BiONCN-derived catalyst possesses optimum performance of electrochemical CO-to-formate, exhibiting an upsurge of Faradaic efficiency to 98.

Synergistic Anion-Cation Chemistry Enables Highly Stable Zn Metal Anodes.

Engineering aqueous electrolytes with an ionic liquid (IL) for the zinc (Zn) metal anode has been reported to enhance the electrochemical performances of the Zn metal batteries (ZMBs). Despite these advancements, the effects of IL and the mechanisms involving their anions and cations have been scarcely investigated. Here, we introduce a novel electrolyte design strategy that synergizes anion-cation chemistry using a halogen-based IL and elucidates the underlying mechanism.

The Tuning of Strain in Layered Structure Oxide Cathodes for Lithium-Ion Batteries.

Layered structure oxides have emerged as highly promising cathode materials for lithium-ion batteries. In these cathode materials, volume variation related to anisotropic lattice strain during Li insertion/extraction, however, can induce critical structural instability and electrochemical degradation upon cycling. Despite extensive research efforts, solving the issues of lattice strain and mechanical fatigue remains a challenge.

Zinc Dicyanamide: A Potential High-Capacity Negative Electrode for Li-Ion Batteries.

We demonstrate that the β-polymorph of zinc dicyanamide, Zn[N(CN)], can be efficiently used as a negative electrode material for lithium-ion batteries. Zn[N(CN)] exhibits an unconventional increased capacity upon cycling with a maximum capacity of about 650 mAh·g after 250 cycles at 0.5C, an increase of almost 250%, and then maintaining a large reversible capacity of more than 600 mAh·g for 150 cycles.

Synthesis, crystal structures and semiconducting properties of new hexacyanidometallates.

We describe the synthesis, crystal structure and semiconducting properties of a number of hexacyanidometallates with the formula A[MFe(CN)]·HO (A = Na, K; M = Mg, Ca, Sr and Ba). All crystal structures were studied single-crystal or powder X-ray diffraction. The unexpectedly low-symmetric structures in these ferrocyanides are described and contrasted with analogous transition-metal compounds which have been reported to be strictly or nearly cubic.

Synthesis, Crystal Structure, Symmetry Relationships, and Electronic Structure of Bismuth Carbodiimide Bi(NCN) and Its Ammonia Adduct Bi(NCN)·NH.

Bi(NCN), the first binary pnictogen carbodiimide, and its ammonia derivative Bi(NCN)·NH have been prepared via nonaqueous liquid-state low-temperature ammonolysis. The crystal structure of Bi(NCN)·NH in space group solved via single-crystal X-ray diffraction corresponds to a two-dimensional-like motif with layers of NCN alternating with honeycomb-like layers of edge-sharing distorted BiN octahedra, half of which are also coordinated by molecular ammonia occupying the octahedral holes. By contrast, Bi(NCN) adopts a higher-symmetric 2/ structure with a single Bi position and stronger distortion but empty octahedral voids.

Predicting Nitrogen-Based Families of Compounds: Transition-Metal Guanidinates TCN (T=V, Nb, Ta) and Ortho-Nitrido Carbonates T' CN (T'=Ti, Zr, Hf).

Due to its unsurpassed capability to engage in various sp hybridizations or orbital mixings, carbon may contribute in expanding solid-state nitrogen chemistry by allowing for different complex anions, such as the known NCN carbodiimide unit, the so far unknown CN guanidinate anion, and the likewise unknown CN ortho-nitrido carbonate (onc) entity. Because the latter two complex anions have never been observed before, we have chemically designed them using first-principles structural searches, and we here predict the first hydrogen-free guanidinates TCN (T=V, Nb, Ta) and ortho-nitrido carbonates T' CN (T'=Ti, Zr, Hf) being mechanically stable at normal pressure; the latter should coexist as solid solutions with the stoichiometrically identical nitride carbodiimides and nitride guanidinates. We also suggest favorable exothermic reactions as useful signposts for eventual synthesis, and we trust that the decay of the novel compounds is unlikely due to presumably large kinetic activation barriers (C-N bond breaking) and quite substantial Madelung energies stabilizing the highly charged complex anions.

Metathetic synthesis of lead cyanamide as a p-type semiconductor.

Lead cyanamide PbNCN was synthesized by solid-state metathesis between PbCl2 and Na2NCN in a 1 : 1 molar ratio, and its structure was confirmed from Rietveld refinement of X-ray data. Electronic-structure calculations of HSE06 density-functional type reveal PbNCN to be an indirect semiconductor with a band gap of 2.4 eV, in remarkable quantitative agreement with the measured value.