A Strategy for Breaking Polyoxometalate‐based MOFs To Obtain High Loading Amounts of Nanosized Polyoxometalate Clusters to Improve the Performance of Dye‐sensitized Solar Cells

Abstract

Polyoxometalates (POM) have already been confirmed to act as effective electron-transfer mediators for improving the power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs) based on previous studies. However, the improvement may be limited by the agglomeration of the polyoxoanions. In this paper, the previous synthesis strategy is improved upon by breaking the metal-organic frameworks (MOFs) with POMs as the secondary building units ([Ni(bpp)(H O) ] [P W O ]⋅24 H O (1) (bpp=1,3-bis(4-pyridyl)propane) and H [Cu (H O) (P W O ) (3-dpye) ]⋅28 H O (2) (3-dpye=N,N'-bis(3-pyridinecarboxamide)-1,2-ethane)) to design and synthesize small sized and highly disperse POM nanoparticles by means of compositing with TiO , through calcination to remove the organic ligand. TEM and element mapping confirm that P W O (denoted as P W ) nanoparticles with the diameter of ≈1 nm are uniformly distributed in TiO composites. The loading amount (wt. %) of POM in MOFs reaches 75.67 %. The small sized and highly disperse P W nanoparticles may provide more active sites and specific surface areas for improving the PCE of DSSCs. Finally, the investigations indicate that the PCE of composite P W ⋅NiO@TiO photoanodes is up to 7.56 %, which was 26 % higher than the pristine TiO based photoanodes.

Electrochemistry of Polyoxometalates: From Fundamental Aspects to Applications

“…The [α‐SiCo 3 W 9 O 37 (H 2 O) 3 ] 10− /reduced graphene oxide nanocomposite exhibits J sc of 17.5 mA cm −2 , V oc of 0.705 V and FF of 0.558 for the photoanode in the pure inorganic donor‐acceptor type dye‐sensitized solar cells . Many of POMs, [PW 12 O 40 ] 3− , [PMo 12 O 40 ] 3− , [SiW 12 O 40 ] 4− and [P 2 W 18 O 40 ] 3− immobilized on the surface of ITO, FTO and TiO 2 with photosensitizer organic materials improved their photovoltaic performances ,…”

Two Polyoxometalate‐Based Hybrid Compounds Modified by Iron Schiff Base Complexes: Syntheses, Crystal structures, Cyclic Voltametric Studies and Nonlinear Optical Properties

“…[35,36] The (Table S6). Similarly, for the oxidation states of all V and Mo centers, the apical V1 atom and semi-occupied V2(Mo6) are assigned as the V IV center, and the Mo (3,5) and Mo(1,2,4,6) are assigned as the Mo V and Mo VI respectively. [37] BVS calculations also support this conclusion and the calculated value of average oxidation state of Mo is in conform with the theoretical value in compound 2 (Table S9).…”

“…Polyoxometalates (POMs), as a unique category of high‐valent early transition‐metal oxide clusters, possess aesthetic structures and versatile sizes [1,2] . They have been used as secondary building units widely to synthesize polyoxoanion‐supported complexes as a result of prolific coordination abilities and high thermal stability [3–5] . The advancement in POM chemistry is always extremely related to functionalized POMs during the last few decades [6,7] .…”

“…[1,2] They have been used as secondary building units widely to synthesize polyoxoanion-supported complexes as a result of prolific coordination abilities and high thermal stability. [3][4][5] The advancement in POM chemistry is always extremely related to functionalized POMs during the last few decades. [6,7] Generally, introducing organic groups can confer many unmatched properties to the final POM-based hybrid species in many emerging areas, including catalysis, [8] nonlinear optics, [9,10] electrochemistry, [11,12] magnetism [13,14] and so on.…”

Polyoxometalates: Tailoring metal oxides in molecular dimension toward energy applications

“…A donor‐acceptor arrangement polyoxotungstate K 6 H 4 [α‐SiW 9 O 37 Co 3 (H 2 O) 3 ]·17H 2 O is cosensitized with CdSe to cover a larger portion of the visible spectrum, while TiO 2 nanotubes are modified with polyoxometalate in a dye‐sensitized solar cell with zinc phthalocyanine (Figure 6c). Improved amount of loading of P 2 W 8 O 6 26− polyoxometalate‐based metal‐organic framework on TiO 2 is achieved, leading to a 26% improvement in the TiO 2 ‐based solar cell . Larger loading amount of polyoxotungstates on TiO 2 is not always desirable, since the agglomeration can unfortunately lead to reduced optoelectronic performance; thus, a homodispersed polyoxometalate nanoparticle arrangement on metal oxide substrate impeding the charge trap formation is a prerequisite .…”