[en] The new compound Ag_2Mn_3(VO4)_3 was synthesized by hydrothermal and solid state reaction routes, and its crystal structure was determined from single-crystal X-ray diffraction data. Ag_2Mn_3(VO4)_3 crystallizes with a monoclinic symmetry, space group C2/c, with a=11.8968(11) Aa, b=13.2057(13) Aa, c=6.8132(7) Aa, β=111.3166(15) ( ) and V=997.16(17) Aa"3 (Z=4). Its crystal refinement yielded the residual factors R(F)=0.0249 and wR(F"2)=0.0704 for 95 parameters and 1029 independent reflections at a 3σ(I) level. Ag_2Mn_3(VO4)_3 can be considered as a new member of the AA"'MM"'_2(XO4)_3 alluaudite family. The specific arrangement of M and M"' octahedral sites and of X tetrahedral sites gives rise to two different channels aligned along the crystallographic c-axis and containing the A and A"' sites. The A, A"', M, and X sites are fully occupied by Ag"+, Mn"2"+, and V"5"+, respectively; whereas a Mn"2"+/Mn"3"+ mixture is observed in the M"' site.

[en] Lithium-ion batteries are overreliant on cobalt containing cathodes. Current projections estimate that hundreds of millions of electric vehicles (EVs) will be on the road by 2050, and this ever-growing demand threatens to deplete global cobalt reserves at an alarming rate. Moreover, cobalt supply chain issues have significantly increased cobalt prices throughout the last decade. As such, energy storage research and development need to reduce the reliance on cobalt to meet ever-growing demand for lithium-ion batteries. The present review summarizes the science and technology gaps and potential of numerous cobalt-free Li-ion cathodes including layered, spinel, olivine, and disordered rock-salt systems. Despite the promising performance of these Co-free cathodes, scale-up and manufacturing bottlenecks associated with these materials must also be addressed to enable widespread adoption in commercial batteries. Overall, this review broadly highlights the enormous promise of "zero-cobalt" Li-ion batteries to enable sustainable production of EVs in the coming decades. (© 2022 Wiley‐VCH GmbH)

[en] Hybrid organic photovoltaic (OPV) cells based on conjugated polymer photoactive materials are promising candidates for flexible, high-performance and low-cost energy sources owing to their inexpensive materials, cost-effective processing and ease of fabrication by simple solution processes. However, the modest PV performance obtained to date—in particular the low power conversion efficiency (PCE)—has impeded the large scale deployment of OPV cells. The low PCE in OPV solar cells is mainly attributed to the low carrier mobility, which is closely correlated to the transport diffusion length of the charge carriers within the photoactive layers. The 2D graphene material could be an excellent candidate for assisting charge transport improvement in the active layer of OPV cells, due to its huge carrier mobility, thermal and chemical stability, and its compatibility with the solution process. In this work, we report on the improvement of the optoelectronic properties and photovoltaic performance of graphene nanoplatelet (GNP)-doped P3HT:PCBM photoactive blended layers, integrated into a bulk heterojunction (BHJ) organic-photovoltaic-based device, using PEDOT:PSS on an ITO/glass substrate. First, the light absorption capacity was observed to increase with respect to the GNP content, while the photoluminescence showed clear quenching, indicating electron transfer between the graphene sheets and the polymeric matrix. Then, the incorporation of GNP into the BHJ active layer resulted in enhanced PV performance with respect to the reference cell, and the best PV performance was obtained with 3 wt.% of GNP loading, with an open-circuit voltage of 1.24 V, a short-circuit current density value of 6.18 mA cm⁻², a fill factor of 47.12%, and a power conversion efficiency of about 3.61%. We believe that the obtained results contribute to the development of organic photovoltaic devices and to the understanding of the impact of sp²-bonded carbon therein. (paper)

[en] The family of titanium Nasicon-phosphates of generic formula M_0.5^IITi₂(PO₄)₃ has been revisited using hydrothermal techniques. Two phases have been synthesized: Mn_0.5^IITi₂(PO₄)₃ (MnTiP) and Co_0.5^IITi₂(PO₄)₃ (CoTiP). Single crystal diffraction studies show that they exhibit two different structural types. Mn_0.5^IITi₂(PO₄)₃ phosphate crystallizes in the R-3 space group, with the cell parameters a = 8.51300(10) A and c = 21.0083(3) A (V = 1318.52(3) A³ and Z = 6). The Co_0.5^IITi₂(PO₄)₃ phosphate crystallizes in the R-3c space group, with a = 8.4608(9) A and c = 21.174(2) A (V = 1312.7(2) A³ and Z = 6). These two compounds are clearly related to the parent Nasicon-type rhombohedral structure, which can be described using [Ti₂(PO₄)₃] framework composed of two [TiO₆] octahedral interlinked via three [PO₄] tetrahedra. ³¹P magic-angle spinning nuclear magnetic resonance (MAS-NMR) data are presented as supporting data. Curie-Weiss-type behavior is observed in the magnetic susceptibility. The phases are also characterized by IR spectroscopy and UV-visible.

[en] Two new complex diphosphates Rb₂M(H₂P₂O₇)₂.2H₂O [M = Zn (I), Mg (II)], have been synthesized using wet chemistry. Their crystals have been isolated and characterized by X-ray diffraction, FTIR and micro-Raman techniques. Both compounds crystallize in the triclinic system, S.G. P-1, Z = 1 and following parameters (A,^o), [6.9573(1), 7.3615(1), 7.7938(1), 81.851(1), 70.622(1), 86.263(1), R₁/wR₂=0.0315/0.1083 for (I) and 6.9546(1), 7.3752(1), 7.8117(1), 81.986(1), 70.275(1), 85.988(1), R₁/wR₂=0.0275/0.0865 for (II)]. The crystal packing in (I) and (II) consists in a three-dimensional network made by layers, parallel to ac-plane. H₂P₂O₇^2- shows bent eclipsed conformation and the M²⁺ ion lies on inversion centre. IR and Raman spectra confirm the bent geometry of the POP bridge angle.

[en] The new compounds CuMgVO_4 and AgMgVO_4 have been synthesized by a solid state reaction route. Their crystal structures were determined from single-crystal X-ray diffraction data. CuMgVO_4 crystallizes with Na_2CrO_4-type structure with space group Cmcm, a = 5.6932 (10), b = 8.7055 (15), c = 6.2789 (10) Å, V = 311.20 (9) Å"3, and Z = 4, whereas AgMgVO_4 crystallizes in the maricite-type structure with space group Pnma, a = 9.4286 (14), b = 6.7465 (10), c = 5.3360 (8) Å, V = 339.42 (9) Å"3, and Z = 4. Both structures of CuMgVO_4, and AgMgVO_4 contain MgO_4 chains made up of edge-sharing MgO_6 octahedra. In CuMgVO_4 the MgO_4 chains are interconnected through CuVO_4 double chains made up of VO_4 and CuO_4 tetrahedra sharing corners and edges, however in AgMgVO_4 the chains are interlinked by the VO_4 and AgO_4 tetrahedra sharing only corners. - Highlights: • We have been able to grow CuMgVO_4 and AgMgVO_4 single crystals. • We solved their crystal structures using single crystal data. • We compared the crystal structures of CuMgVO_4 and AgMgVO_4.

[en] The new mixed-anion phosphate Na₄Mg₃(PO₄)₂(P₂O₇) has been prepared and its structure has been determined by single crystal X-ray diffraction. The crystal structure was refined to R = 0.0290 (wR = 0.0836) for 1527 independent reflexions. This compound crystallizes in the orthorhombic non-centrosymmetric space group Pn2₁a with a = 17.985(2) A, b = 6.525(9) A, c = 10.511(1) A, and Z = 4. The framework is built up from [PO₄] tetrahedra, [P₂O₇] groups and [MgO₆] octahedra. The three dimensional structure consists of [Mg₃P₂O₁₃]_∞ infinite layers parallel to the bc plane. The layers are built up from [MgO₆] octahedra and [PO₄] tetrahedral, they are connected along the a axis by O-P-O-P-O bridges of the diphosphate groups. Large tunnels extending along the three main crystallographic directions host four crystallographically distinct sodium cations. The infrared spectrum of Na₄Mg₃(PO₄)₂(P₂O₇) is interpreted on the basis of P₂O₇^4- and PO₄^3- vibrations. The appearance of ν_sP-O-P in the spectrum suggests a bent P-O-P bridge for the P₂O₇^4- ions in the compound, which is in agreement with the X-ray data.

[en] This paper is devoted to the iron corrosion phenomena induced by the α (⁴He²⁺) water radiolysis species studied in conjunction with the production/consumption of H₂ at the solid/solution interface. On one hand, the solid surface is characterized during the ⁴He²⁺ ions irradiation by in situ Raman spectroscopy; on another hand, the H₂ gas produced by the water radiolysis is monitored by ex situ gas measurements. The ⁴He²⁺ ions irradiation experiments are provided either by the CEMHTI (E = 5.0 MeV) either by the ARRONAX (E = 64.7 MeV) cyclotron facilities. The iron corrosion occurs only under irradiation and can be slowed down by H₂ reductive atmosphere. Pure iron and carbon steel solids are studied in order to show two distinct behaviors of these surfaces vs. the ⁴He²⁺ ions water irradiation: the corrosion products identified are the magnetite phase (Fe(II)Fe(III)₂O₄) correlated to an H₂ consumption for pure iron and the lepidocrocite phase (γ-Fe(III)OOH) correlated to an H₂ production for carbon steel sample. This paper underlined the correlation between the iron corrosion products formation onto the solid surface and the H₂ production/consumption mechanisms. H₂O₂ species is considered as the single water radiolytic species involved into the corrosion reaction at the solid surface with an essential role in the oxidation reaction of the iron surface. We propose to bring some light to these mechanisms, in particular the H₂ and H₂O₂ roles, by the in situ Raman spectroscopy during and after the ⁴He²⁺ ions beam irradiation. This in situ experiment avoids the evolution of the solid surface, in particular phases which are reactive to the oxidation processing

[en] The new titanium oxyphosphate Co_0.5TiPO₅ has been prepared by solid state reaction. Its structure has been determined by single crystal X-ray diffraction and was further investigated by FT-IR spectroscopy and magnetic measurements. The compound crystallizes in the monoclinic system, S.G: P2₁/c [a = 7.358(1) A, b = 7.378(2) A, c = 7.383(3) A, β = 119.66(3) deg., Z = 4, R₁ = 0.0142, wR₂ = 0.0429]. The structure can be described as a network of very distorted TiO₆ octahedra, in which the Ti⁴⁺ ions are displaced from the centres of the octahedra, and slightly distorted PO₄ tetrahedra. Half of the octahedral cavities are occupied by Co atoms. The other half of octahedral sites is vacant and favourable for the electrochemical insertion of lithium. The insertion of lithium was studied by galvanostatic charging and discharging between different voltage limits

[en] Na₄MnV(PO₄)₃ is a sodium ion conducting material with a NASICON type crystal structure. This phase is not much known as an electrode material. The present work focuses on the sodium ion intercalation/de-intercalation mechanism and charge/discharge behavior of the material. The Na₄MnV(PO₄)₃ is synthesized through a sol-gel process and characterized by XRD, SEM, and XPS. The structural analysis confirms the formation of a phase pure crystalline material with nanometric particle size which adopts a trigonal crystal structure. Galvanostatic intermittent titration technique (GITT) measurements indicate that Na₄MnV(PO₄)₃ is electrochemically active having slanting voltage plateaus. Ex-situ and In-situ XRD analysis, as a function of sodium concentration, indicate that the intercalation/de-intercalation of sodium is associated with a single-phase reaction rather than a biphasic reaction when cycled between 1.5 and 4.5 V. The electrochemical measurements on composite electrodes, Na₄MnV(PO₄)₃/CNTS (1 & 3 wt.%), show promising charge/discharge capacity (∼140 mAh/g), good cyclability (100% capacity retention after 40 cycles) and reasonable rate capability. The cyclic voltammetry (CV) and X-ray Photoelectron Spectroscopy (XPS) analyses indicate that the main contributions towards the activity of Na₄MnV(PO₄)₃ can be attributed to the active of Mn²⁺/Mn³⁺ and V³⁺/V⁴⁺ redox couple with partial activity of V⁴⁺/V⁵⁺. The obtained results suggest that Na₄MnV(PO₄)₃ is a promising electrode material which can be achieved better rate performance with long cycling stability and battery performance through engineering of the particle morphology and microstructure.