Engineering catalytic sites at the atomic level provides an opportunity to understand the catalyst’s active sites, which is vital to the development of improved catalysts. Here we show a reliable and tunable polyoxometalate template-based synthetic strategy to atomically engineer metal doping sites onto metallic 1T-MoS2, using Anderson-type polyoxometalates as precursors. Benefiting from engineering nickel and oxygen atoms, the optimized electrocatalyst shows great enhancement in the hydrogen evolution reaction with a positive onset potential of ~ 0 V and a low overpotential of −46 mV in alkaline electrolyte, comparable to platinum-based catalysts. First-principles calculations reveal co-doping nickel and oxygen into 1T-MoS2 assists the process of water dissociation and hydrogen generation from their intermediate states. This research will expand on the ability to improve the activities of various catalysts by precisely engineering atomic activation sites to achieve significant electronic modulations and improve atomic utilization efficiencies. While heterogeneous catalysts can act as tangible, efficient materials for energy conversion, understanding the active catalytic sites is challenging. Here, authors engineer specific catalytic sites into molybdenum sulfide to improve and elucidate hydrogen evolution electrocatalysis.

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Atomically engineering activation sites onto metallic 1T-MoS 2 catalysts for enhanced electrochemical hydrogen evolution.

The Anderson–Evans polyoxometalate: From inorganic building blocks via hybrid organic–inorganic structures to tomorrows “Bio-POM”

Selective oxidations of ethane to ethene and acetic acid and of propane to acrylic acid were carried out over hydrothermally synthesized Mo-V-M-O (M=Al, Ga, Bi, Sb, and Te) complex metal oxide catalysts. All the synthesized solids were rod-shaped crystallites and gave a common XRD peak corresponding to 4.0 A d -spacing. From the different XRD patterns at low angle region below 10° and from the different shape of the cross-section of the rod crystal obtained by SEM, the solids were classified into two groups: Mo-V-M-O (M=Al, possibly Ga and Bi) and Mo-V-M-O (M=Sb, and Te). The former catalyst was moderately active for the ethane oxidation to ethene and to acetic acid. On the other hand the latter was found to be extremely active for the oxidative dehydrogenation. The Mo-V-M-O (M=Sb, and Te) catalysts were also active for the propane oxidation to acrylic acid. It was found that the grinding of the catalysts after heat-treatment at 600°C in N 2 increased the conversions of propane and enhanced the selectivity to acrylic acid. Structural arrangement of the catalytic functional components on the surface of the cross-section of the rod-shaped catalysts seems to be important for the oxidation activity and selectivity.

Selective oxidation of light alkanes over hydrothermally synthesized Mo-V-M-O (M=Al, Ga, Bi, Sb, and Te) oxide catalysts

Anderson-type molybdopolyanions containing tris(alkoxo) ligands [MMo6O18{(OCH2)3CR}2]3− (M = MnIII, FeIII) and [H2MMo6O18{(OCH2)3CR}2]2− (M = NiII, ZnII), (R = CH3, NO2, CH2OH), were prepared by treatment of [N(C4H9)4]4[α-Mo8O26] with tris(hydroxymethyl)methane derivatives in the presence of manganese(III) acetylacetonate, iron(III) acetylacetonate, nickel(II) acetate, or zinc(II) acetate. The complexes were structurally characterized in solution, and also by single-crystal X-ray diffraction in the cases of [N(C4H9)4]3[MnMo6O18{(OCH2)3CNO2}2], [N(C4H9)4]2[H2NiMo6O18{(OCH2)3CCH2OH}2], and [N(C4H9)4]2[H2ZnMo6O18{(OCH2)3CCH3}2]. Two tris(alkoxo) ligands replace the six hydroxo groups usually found in Anderson polyanions of formula [H6MMo6O24]n−. The complex structures may be divided into two groups: In the first one the tris(alkoxo) ligands are bound entirely to the central heteroatom, while in the second one they cap a tetrahedral cavity. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Anderson‐Type Heteropolymolybdates Containing Tris(alkoxo) Ligands: Synthesis and Structural Characterization

Anderson-type polyoxomolybdates [MMo6O18{(OCH2)3CNH2}2]3− (M = MnIII, FeIII) were prepared and structurally characterized. The tris(alkoxo) ligands are bound to the central heteroatom via their oxygen atoms. The corresponding compounds with M = NiII or ZnII are not accessible since these cations have a preference for the amino functionality. The pendant amino groups of the manganese-containing derivative react with pyridinecarbaldehydes to give the corresponding imines. This provides new mono- and bidentate binding sites for metal cations. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

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Developing Remote Metal Binding Sites in Heteropolymolybdates

Anderson-type heteropolyanions of molybdenum(VI) and tungsten(VI)

The previously reported preparation of some Anderson-type molybdopolyanions containing divalent metal ions (Zn, Cu, Co or Mn) as a heteroatom has been reinvestigated. The molybdopolyanions of Zn(II) and Cu(II) were confirmed, although the Cu(II) polyanion was not stable and could not be recrystallized. On the other hand, the polyanions of Co(II) and Mn(II) could not be reproduced. Another type of heteropoly compound, [X(H2O)6-x(Mo7O24)]4− [X = Cu(II), Co(II) or Mn(II)], was isolated as solids, which are not stable thermally. The mixed-type Anderson polyanions, [Ni(II)Mo6-xWx,O24H6]4−, which have been questioned as mixtures of species with different x values, were also reinvestigated using IR, UV absorption and MCD spectra. They are single species, but not mixtures, although some positional isomers may be present for the compounds where x = 2-4. The possibility of oxidation of the heteroatom with the Anderson structure maintained was examined. The oxidation of [Ni(II)Mo6O24H6]4− by the S2O2−8 ion in aqueous solution gave the Waugh-type [Ni(IV)Mo9O32]6− polyanion, whereas the oxidation of [Ni(II)W6O24H6]4− gave no heteropoly compound.

Takahiro Shirai

Papers

Anderson-type heteropolyanions of molybdenum(VI) and tungsten(VI)

Anderson-Type Heteropolyanions of Molybdenum(VI) and Tungsten(VI).