Bidentate phosphonate monoesters are analogues of popular dicarboxylate linkers in MOFs, but with an alkoxy tether close to the coordinating site. Herein, we report 3-D MOF materials based upon phosphonate monoester linkers. Cu(1,4-benzenediphosphonate bis(monoalkyl ester), CuBDPR, with an ethyl tether is nonporous; however, the methyl tether generates an isomorphous framework that is porous and captures CO(2) with a high isosteric heat of adsorption of 45 kJ mol(-1). Computational modeling reveals that the CO(2) uptake is extremely sensitive both to the flexing of the structure and to the orientation of the alkyl tether.
While typically structures from linear diphosphonate ligands form dense phases, we report that with the functionalized ligand 1,4-dihydroxy-2,5-benzenediphosphonate (DHBP) and Zn2+ a microporous network is formed. {[Zn(DHBP)](DMF)2} (1; DMF = dimethylformamide) possesses three-dimensional microporosity as shown by X-ray diffraction and confirmed by CO2 and N2 sorption studies. Compound 1 is composed of one-dimensional columns of tetrahedral Zn ions with homoleptic phosphonate coordination. This infinite building unit enables a robust and porous yet still crystalline material.
A bis(phosphonatemonoester) is employed as a linker in a Zn(II) metal organic framework. The complex is a layered structure pillared only by vdW interactions between alkyl groups. Nonetheless, permanent pores are formed as confirmed by PXRD and gas sorption analysis.
Transition metal phosphides (TMPs), especially the dual‐metal TMPs, are highly active non‐precious metal oxygen evolution reaction (OER) electrocatalysts. Herein, an interesting atom migration phenomenon induced by Kirkendall effect is reported for the preparation of cobalt–iron (Co–Fe) phosphides by the direct phosphorization of Co–Fe alloys. The compositions and distributions of the Co and Fe phosphides phases on the surfaces of the electrocatalysts can be readily controlled by CoxFey alloys precursors and the phosphorization process with interesting atom migration phenomenon. The optimized Co7Fe3 phosphides exhibit a low overpotential of 225 mV at 10 mA cm−2 in 1 m KOH alkaline media, with a small Tafel slope of 37.88 mV dec−1 and excellent durability. It only requires a voltage of 1.56 V to drive the current density of 10 mA cm−2 when used as both anode and cathode for overall water splitting. This work opens a new strategy to controllable preparation of dual‐metal TMPs with designed phosphides active sites for enhanced OER and overall water splitting.
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