Zirconium and Hafnium Twin Monomers for Mixed Oxides

Abstract

Carboxyl‐functionalized multiwalled carbon nanotubes (MWNT‐COOH) decorated with palladium (Pd) nanoparticles (NPs, Pd–MWNT‐COOH) are prepared by using a one‐pot thermal decomposition method without addition of reductant or surfactant. An increased ratio of the D band to G band in Raman spectra and a decreased ratio of oxygen‐containing groups measured using X‐ray photoelectron spectroscopy suggest the interaction between Pd NPs and carboxyl groups in Pd–MWNT‐COOH. TEM studies reveal improved dispersion of Pd NPs after introducing MWNT‐COOH or MWNTs; the carboxyl groups act as anchors to perfectly disperse Pd NPs in Pd–MWNT‐COOH, which is responsible for the highest peak current of Pd–MWNT‐COOH for the methanol oxidation reaction. The best catalytic performance is observed in conditions that afford a balanced adsorption between hydroxide and methanol through varying the concentrations of methanol and KOH. Increasing temperature can also improve the catalyst performance due to enhanced reaction kinetics.

Twin Polymerization—a New Principle for Hybrid Material Synthesis

“…Thus, if two TM with different metal atoms are polymerized together, a variety of nanostructured mixed metal oxides or metal oxide mixtures are available. This has been shown for SiO 2 /SnO 2 , SiO 2 /B 2 O 3 ,[23a] SiO 2 /TiO 2 , SiO 2 /HfO 2 , and SiO 2 /ZrO 2 oxidic systems so far.…”

Chiral Spirocyclic Germanium Thiolates - An Evaluation of Their Suitability for Twin Polymerization based on A Combined Experimental and Theoretical Study

“…The Ge-S benzylic bond lengths (2.1836 (5) and 2.1969(5) for 1; 2.157(2) and 2.164(2) for R a -3 [14] ; 2.167(2) and 2.1707 (19) for S a -3 [14] ) and the Ge-S benzenethiolate distances (2.2292(5) and 2.2270(5) for 1; 2.1910(7) and 2.1956 (7) for 2) are in agreement with values reported for the structurally related 2,2'-spirobi[benzo[d][1,3,2]dithiagermole] (GeÀS 2.195(2) -2.199(2) ) [15] and other germanium thiolates exhibiting tetrahedral coordination of the germanium atom such as tetrakis(phenylthio)germane (GeÀS 2.2149(6) -2.2191 (5) ) [16] and tetrakis(p-tolylthio)germane (GeÀS 2.211(1) -2.221 (1) ). [17] The Ge-O benzylic bond lengths of thiolate 2 (1.744(2) and 1.7657 (19) ) and the Ge-O phenolate distances of R a -3 (1.767 (5) and 1.775 (5) ) and S a -3 (1.783(4) and 1.784(4) ) are slightly shorter than the values reported for 6-bromo-2,2-ditert-butyl-4H-1,3,2-benzo[d]dioxagermine (Ge-O benzylic 1.7846 (18) and Ge-O phenolate 1.8168 (17) ). [18] However, the germanium oxygen bond lengths are within the typical range (1.749(3) -1.849(2) ) as reported for germanium(IV) alkoxides such as LGe(O i Pr)·(HO i Pr) (L = 6,6',6''-(nitrilotris(methylene))tris(2,4-dimethylphenolate)), [19] GeL 2 (L = [1,1'-bi(cyclohexane)]-1,1'-bis(olate)) [20] and [2,2'-Se(4,6-di-tert-butyl-C 6 H 2 O) 2 ] 2 Ge.…”

“…In recent years diverse organic‐inorganic hybrid materials, which are composed of a metal oxide and an organic phase e. g., polyfurfuryl alcohol (M = Si, Sn, Ti, W, Zr and Hf), poly(thiophene‐2‐methanol) (M = Sn and Ti) and phenolic resin (M = Si, Sn, W, Zr and Hf), have been synthesized using the concept of twin polymerization (TP), which is defined as “the formation of two macromolecular structures starting from one monomer in just one process step” . Such hybrid materials can be converted into porous materials e. g., microporous carbon, and Sn@C/SiO 2 , and mesoporous SiO 2 and SiO 2 /SnO 2 , if TP of appropriate precursors e. g., twin monomers consisting of salicyl alcoholate moieties, results in two polymeric networks that interpenetrate each other on the nanoscale.…”

From molecular germanates to microporous Ge@C via twin polymerization

“…The concept of twin polymerization (TP), which is defined as a concerted formation of two polymers in one synthetic step starting from a single monomer, 1 provides a convenient approach for the synthesis of organic-inorganic hybrid materials (HM) such as polyfurfuryl alcohol/MO x (MO 2 = Si, 2,3 Sn, 4 Ti, 5,6 Zr and Hf, 7 MO 3 = WO 3 8 ), poly(thiophene-2-methanol)/MO 2 (M = Sn, 4 and Ti 5 ), phenolic resin/MO x (MO 2 = Si, 9,10 Sn, 4 Zr and Hf, 7 MO 3 = WO 3 , 8 MO x = MO 2 /SiO 2 with M = Sn, 11 Zr and Hf 7 ), since it was reported in 2007 for the first time. 2 With regard to homo-geneity of the materials, salicylic alcoholates of silicon were shown to be ideal precursors to provide nanostructured interpenetrating networks of the organic and inorganic components.…”