Polyoxometalate-based high-nuclear cobalt–vanadium–oxo cluster as efficient catalyst for visible light-driven CO2 reduction

Dual-nodes bridged cobalt-modified Keggin-type polyoxometalate-based chains for highly efficient CO2 photoconversion

The design of efficient catalysts for photocatalytic CO2 conversion is of great importance for the sustainable development of society. Herein, three polyoxometalate (POM)-based crystalline materials were formulated prepared by substituting transition metals and adjusting solvent acidity with 2-(2-pyridyl) benzimidazole (pyim) as the light-trapping ligand, namely {[SiW12O40][Co(pyim)2]2}·2C2H5OH (SiW12Co2), {[SiW12O40][Ni(pyim)2]2}·2C2H5OH (SiW12Ni2), and {[SiW12O40][Mn(pyim)2]2}·2C2H5OH (SiW12Mn2). X-ray crystallography diffraction analysis indicates that the three complexes exhibit isostructural properties, and form a stable one-dimensional chain structure stabilized by two [M(pyim)2]22+ (M = Co, Ni, and Mn) fragments serving as dual-nodes to the adjacent SiW12 units. A comprehensive analysis of the structural characterization and photocatalytic CO2 reduction properties is presented. Under light irradiation, SiW12Co2 exhibited a remarkable CO generation rate of 10 733 μmol g-1 h-1 with a turnover number of 328, outperforming most of the reported heterogeneous POM-based photocatalysts. Besides, cycling tests revealed that SiW12Co2 is an efficient and stable photocatalyst with great recyclability for at least four successive runs. This study proves that the successful incorporation of diverse transition metals into the POM anion could facilitate the development of highly efficient photocatalysts for the CO2RR.

A reduced polyoxometalate-encapsulated organo cobalt modified phosphate framework for improving photocatalytic reduction of CO2

A reduced polyoxometalate-based organo-metallophosphate (MOPO) framework formulated as [Co4(PO4)(C7H8N4)6](PWVI10WV2O40) (Co-PO4-PW12) with an ultra-high CO production rate of 13 676 μmol g-1 h-1 has been presented through photocatalytic CO2 reduction investigations.

Functional Photocatalysts: Material Design, Synthesis and Applications

Rapid industrial and economic growth, experienced on a global scale, has been greatly facilitated by the extensive use and exploitation of traditional energy resources [...].

Metal Clusters Based Multifunctional Materials for Solar Cells

As a multifunctional material, metal clusters have recently received some attention for their application in solar cells.This review delves into the multifaceted role of metal clusters in advancing solar cell technologies, covering diverse aspects from electron transport and interface modification to serving as molecular precursors for inorganic materials and acting as photosensitizers in metal-cluster sensitized solar cells (MCSSCs). The studies conducted by various researchers illustrate the crucial impact of metal clusters, such as gold nanoclusters (Au NCs), on enhancing solar cell efficiency through size-dependent effects, distinct interface behaviors, and tailored interface engineering. From optimizing charge transfer rates to improving light absorption and reducing carrier recombination, metal clusters prove instrumental in shaping the landscape of solar energy conversion.The promising performance of metal-cluster sensitized solar cells, coupled with their scalability and flexibility, positions them as a exciting avenue for future clean energy applications. The article concludes by emphasizing the need for continued interdisciplinary research and technological innovation to unlock the full potential of metal clusters in contributing to sustainable and high-performance solar cells.

Armchair Janus WSSe Nanotube Designed with Selenium Vacancy as a Promising Photocatalyst for CO2 Reduction

Photocatalytic conversion of carbon dioxide into chemical fuels offers a promising way to not only settle growing environmental problems but also provide a renewable energy source. In this study, through first-principles calculation, we found that the Se vacancy introduction can lead to the transition of physical-to-chemical CO₂ adsorption on Janus WSSe nanotube. Se vacancies work at the adsorption site, which significantly improves the amount of transferred electrons at the interface, resulting in the enhanced electron orbital hybridization between adsorbents and substrates, and promising the high activity and selectivity for carbon dioxide reduction reaction (CO₂RR). Under the condition of illumination, due to the adequate driving forces of photoexcited holes and electrons, oxygen generation reaction (OER) and CO₂RR can occur spontaneously on the S and Se sides of the defective WSSe nanotube, respectively. The CO₂ could be reduced into CH₄, meanwhile, the O₂ is produced by the water oxidation, which also provides the hydrogen and electron source for the CO₂RR. Our finding reveals a candidate photocatalyst for obtaining efficient photocatalytic CO₂ conversion.

Novel morphological mono-metallic substituted polyoxometalate immobilized 3-(aminopropyl)-imidazole photocatalysts for visible-light driven degradation: Anti-bacterial activity, membrane bacterial activity applications

A novel keggin-type tetra-metalates substituted polyoxometalate was functionalized by 3-(aminopropyl)-imidazole (3-API) supporting a ligand substitution method. In this paper, polyoxometalate (POMs) (NH₄)₃ [PMo₁₂O₄₀] and transition metal substituted of (NH₄)₃ [{PM^IVMo₁₁O₄₀}.(H₂O)] (M = Mn, V) are used as one of the adsorbents. The 3-API/POMs hybrid have been synthesized and used as adsorbent for the photo-catalysis of azo-dye molecule degradation after visible-light illumination as a simulated organic contaminant in water. The transition metal (M = M^IV, V^IV) substituted keggin-type anions (MPOMs) were synthesized, which reveals the degradation of methyl orange (MO) of about 94.0 % and 88.6 %. Immobilizing high redox ability POMs as an efficient acceptor of photo generated electron, on metal 3-API. In the presence of visible light irradiation result reveals that 3-API/POMs (89.9 %) have incredibly achieved after certain irradiation time and at specific conditions (3)-API/POMs; photo-catalysts dose = 5mg/100 ml, pH = 3 and MO dye concentration = 5 ppm). As the surface of POM catalyst has strong absorption of azo-dye MO molecule engaged as a molecular exploration through photo catalytic reactant. From the SEM images it is clear that the synthesized POMs based materials and POMs conjugated MO have varieties of morphological changes observed such as flakes, rods and spherical like structures. Anti-bacterial study reveals that the process of targeted microorganism occur higher activity against pathogenic bacterium for 180 min of visible-light irradiation is measured in terms of zone of the inhibition. Furthermore, the photo catalytic degradation mechanism of MO using POM, metaled POMs and 3-API/POMs also has been discussed.

Structural Regulation of Two Polyoxometalate-Based Metal-Organic Frameworks for the Heterogeneous Catalysis of Quinazolinones

Two dimeric {ε-Zn₄PMo₁₂}-based metal-organic frameworks (MOFs), [ε-PMo₈^VMo₄^VIO₃₄(OH)₆Zn₄][LO] (SDUT-21, LO = [5-((4'-carboxybenzyl)oxy)isophthalic acid]) and [TBA]₃[ε-PMo₈^VMo₄^VIO₃₇(OH)₃Zn₄][LN] (SDUT-22, TBA⁺ = tetrabutylammonium ion, LN = [5-((4-carboxybenzyl)imino)isophthalic acid]), combining the advantages of polyoxometalates (POMs) and MOFs, were synthesized by the one-pot assembly strategy. The dimeric {ε-Zn₄PMo₁₂} units act as nodes that are linked by the flexible ligands and extended into two- or three-dimensional frameworks. The cyclic voltammetry and proton conductivity measurements of SDUT-21 and SDUT-22 were performed and indicated the high electron and proton transfer abilities. These materials also e xhibited the catalytic performance for the synthesis of quinazolinones in the heterogeneous state, and the different binding capacities toward the substrates caused the catalytic activity of SDUT-21 to be higher than that of SDUT-22 under the same conditions. In addition, the used catalysts could be readily recovered for five successive cycles and maintained high catalytic efficiency.

"Tree"-like Multidentate Ligand-Assisted Synthesis of Polymolybdate-Based Architectures with Multinuclear Metal Clusters: Supercapacitor and Electrochemical Sensing Performances

In this work, aiming for constructing multinuclear metal cluster-modified polymolybdate-based architectures with novel conformation, the "tree"-like multidentate ligand 5-(3-pyridyl)-1H-tetrazole) (3-ptzH) is introduced into the polymolybdate reaction system. Three new polymolybdate-based architectures with various multinuclear metal clusters, H₄[Cu₆(μ₃-OH)₂(3-ptz)₆(γ-Mo₈O₂₈) (H₂O)₂]·2H₂O (BOHU-1), H₂[Ag₄(3-ptz)₂(Mo₈O₂₆)] (BOHU-2), and H₄[Cu₅(3-ptzH)₂(3-ptz)₂(MnMo₉O₃₂)₂(H₂O)₄] (BOHU-3) (BOHU = Bohai University), have been prepared via the hydrothermal method and structurally characterized. In BOHU-1, a kind of pentanuclear copper cluster unit: [Cu₅(μ₃-OH)₂(3-ptz)₆]²⁺ is formed, which connects to construct a one-dimensional (1D) cluster-based chain. The 1D chains are extended to a two-dimensional (2D) layer via the Cu ions, which are further linked by the 4-connected [γ-Mo₈O₂₈]^8- anions to build a three-dimensional (3D) framework. In BOHU-2, when a Ag^I ion was used as the central metal, the 3-ptz adopts different coordination modes to link the Ag ions, forming hexanuclear [Ag₆(3-ptz)₄]²⁺ cluster and finally 1D chains. These 1D cluster-based chains are connected by the 6-connected [γ-Mo₈O₂₆]^4- anions to establish a 2D layer, which is further extended by [Mo₈O₂₆]_n^4n- 1D chains to a 3D framework. For BOHU-3, the chiral [MnMo₉O₃₂]^6- anions are introduced and coordinated with the Cu ions to build left- and right-handed 1D chains, which are connected via the [Cu₃(3-ptz)₄]²⁺ cluster to form a 1D ladder-like chain. The effects of 3-ptz on the formation of multinuclear clusters, as well as the metals and polymolybdates on the multinuclear clusters and final structures of BOHU-1∼3, are discussed. The electrochemical performances of BOHU-1∼3 as electrode materials for supercapacitors and electrochemical sensors are investigated.

Microenvironment Regulation of {Co4IIO4} Cubane for Syngas Photosynthesis

It is a great challenging task for selectivity control of both CO₂ photoreduction and water splitting to produce syngas via precise microenvironment regulation. Herein, a series of UiO-type Eu-MOFs (Eu-bpdc, Eu-bpydc, Ru_x-Eu-bpdc, and Ru_x-Eu-bpydc) with different surrounding confined spaces were designed and synthesized. These photosensitizing Ru_x-Eu-MOFs were used as the molecular platform to encapsulate the [Co^II₄(dpy{OH}O)₄(OAc)₂(H₂O)₂]²⁺ (Co₄) cubane cluster for constructing Co₄@Ru_x-Eu-MOF (x = 0.1, 0.2, and 0.4) heterogeneous photocatalysts for efficient CO₂ photoreduction and water splitting. The H₂ and CO yields can reach 446.6 and 459.8 μmol·g^-1, respectively, in 10 h with Co₄@Ru_0.1-Eu-bpdc as the catalyst, and their total yield can be dramatically improved to 2500 μmol·g^-1 with the ratio of CO/H₂ ranging from 1:1 to 1:2 via changing the photosensitizer content in the confined space. By increasing the N content around the cubane, the photocatalytic performance drops sharply in Co₄@Ru_0.1-Eu-bpydc, but with an enhanced proportion of CO in the final products. In the homogeneous system, the Co₄ cubane was surrounding with Ru photosensitizers via week interactions, which can drive water splitting into H₂ with >99% selectivity. Comprehensive structure-function analysis highlights the important role of microenvironment regulation in the selectivity control via constructing homogeneous and heterogeneous photocatalytic systems. This work provides a new insight for engineering a catalytic microenvironment of the cubane cluster for selectivity control of CO₂ photoreduction and water splitting.

An isolated doughnut-like molybdenum(V) cobalto-phosphate cluster exhibiting excellent photocatalytic performance for carbon dioxide conversion

An isolated doughnut-like molybdenum(V) cobalto-phosphate cluster with the formula (C₁₁NH₁₀)₂{[Co(H₂O)₆]@[H₂₉Co₁₆Mo₁₆(H₂O)₁₆(PO₄)₂₄O₃₆]}(H₂PO₄)·25H₂O has been successfully synthesized by a hydrothermal method. Single crystal X ray diffraction analysis shows that four {Co₄O₆₀} tetramers and eight {Mo₂O₁₀} dimers are linked by oxygen atoms and phosphate groups to construct a doughnut-type structure for [Co@{Co₁₆Mo₁₆}], in which one [Co^II(H₂O)₆]²⁺ octahedron is enclosed. More importantly, [Co@{Co₁₆Mo₁₆}] exhibits promising photocatalytic performance for CO₂ reduction with the CO formation rate of 6764.3 μmol g^-1 h^-1 and the selectivity of 96.89%. In addition, the cycling test indicated that [Co@{Co₁₆Mo₁₆}] can be reused for at least four cycles without significant loss of catalytic activity. The result of this work may provide new insight for the synthesis of highly efficient POM-based photocatalysts for CO₂ reduction.

Filling Polyoxoanions into MIL-101(Fe) for Adsorption of Organic Pollutants with Facile and Complete Visible Light Photocatalytic Decomposition

Transition metal-substituted polyoxometalates (POMs) were filled into a metal–organic framework (MOF) to construct a series of POM@MOF composites (PMo₁₂O₄₀@MIL-101, PMo₁₁VO₄₀@MIL-101, PMo₁₀V₂O₄₀@MIL-101). The composite materials possess ultra-high adsorption ability, especially for PMo₁₀V₂O₄₀@MIL-101, with an adsorption capacity of 912.5 mg·g⁻¹ for cationic antibiotic tetracycline in wastewater, much higher than that of isolated MIL-101(Fe) and the commonly used adsorption materials, such as activated carbon and graphene oxide. In particular, they can be used as efficient photocatalysts for the photodegradation of antibiotics under visible light irradiation. The complete photodegradation of the adsorbed species can induce the facile reusability of these composites for multiple cycles. This work opens an avenue to introduce POMs into an MOF matrix for the simultaneous adsorption and photodegradation of antibiotics.

Construction of Low-Cost Z-Scheme Heterostructure Cu2 O/PCN for Highly Selective CO2 Photoreduction to Methanol with Water Oxidation

Solar-driven CO₂ reaction with water oxidation into alcohols represents a promising approach to achieve real artificial photosynthesis. However, rapid recombination of photogenerated carriers seriously restricts the development of artificial photosynthesis. Herein, a facile method is explored to construct low-cost Z-Scheme heterostructure Cu₂ O/polymeric carbon nitride (PCN) by in situ growth of Cu₂ O hollow nanocrystal on PCN. The protective PCN layer and Z-schematic charge flow can make robust Cu₂ O/PCN photocatalysts, and the spatial separation of electrons and holes with high redox potentials of E_CB (-1.15 eV) and E_VB (1.65 eV) versus NHE can efficiently drive CO₂ photoreduction to methanol in pure water, which is further confirmed by DFT calculation. The Z-scheme heterostructure Cu₂ O/PCN exhibits a high methanol yield of 276 µmol g^-1 in 8 h with ca. 100% selectivity, much superior to that of isolated Cu₂ O and PCN, and all the reported Cu₂ O-based heterostructures. This work provides a unique strategy to efficiently and selectively promote the conversion of CO₂ and H₂ O into high-value chemicals by constructing a low-cost Z-scheme heterostructure.

H-Bond-Mediated Selectivity Control of Formate versus CO during CO2 Photoreduction with Two Cooperative Cu/X Sites

It is highly desirable to achieve solar-driven conversion of CO₂ to valuable fuels with controlled selectivity. The existing catalysts are mainly explored for CO production but rarely for formate generation. Herein, highly selective photoreduction of CO₂ to formate (99.7%) was achieved with a high yield of 3040 μmol g^-1 in 10 h by hierarchical integration of photosensitizers and monometallic [bpy-Cu/ClX] (X = Cl or adenine) catalysts into a stable Eu-bpy metal-organic framework. However, replacing X with pyridine in [bpy-CuCl/X] significantly reduced formate production while increasing the CO yield to 960 μmol g^-1. Systematic investigations revealed that the catalytic process is mediated by the H-bond synergy between Cu-bound X and CO₂-derived species, and the selectivity of HCOO^- can be controlled by simply replacing the coordination ligands. This work provides a molecularly precise structural model to provide mechanistic insights for selectivity control of CO₂ photoreduction.

Novel perylene probe-encapsulated metal-organic framework nanocomposites for ratiometric fluorescence detection of ATP

Adenosine triphosphate (ATP) plays an important role in various biological processes and the ATP level is closely associated with many diseases. Herein, a novel ratiometric fluorescence assay for ATP was developed based on the excimer-monomer transfer of a perylene probe. By encapsulating a perylene probe, N,N'-bis(6-caproic acid)-3,4:9,10-perylenediimide (PDI), into zeolitic imidazolate framework-8 (ZIF-8) nanocrystals, fluorescent nanocomposites (PDI@ZIF-8) with significant excimer emission of the perylene probe were prepared for the first time. The presence of ATP will trigger the decomposition of PDI@ZIF-8 due to much stronger coordination between ATP and Zn2+ than that of 2-methylimidazole and Zn2+. As a result, the encapsulated PDI probes were released, leading to significantly increased monomer emission accompanying the decrease in the excimer emission. The excimer-monomer transition signal was utilized for ratiometric ATP sensing and its potential application for detecting ATP in cell lysates was also successfully demonstrated.

Two new hexa-Ni-substituted polyoxometalates in the form of an isolated cluster and 1-D chain: syntheses, structures, and properties

Two new hexa-Ni-substituted polyoxometalates are made and characterized, exhibiting electrochemical performance and photocatalytic activity for the degradation of organic dyes under UV irradiation.