Integration of Lanthanide–Transition‐Metal Clusters onto CdS Surfaces for Photocatalytic Hydrogen Evolution

Organizing Photosensitive and Photothermal Single-Sites Uniformly in a Trimetallic Metal-Organic Framework for Efficient Photocatalytic Hydrogen Evolution

Effective combination of the photosensitivity and photothermal property in photocatalyst is vital to achieve the maximum light utilization for superior photocatalytic efficiency. Herein, this work successfully organizes photosensitive Cd-NS single-sites and photothermal Ni-NS single-sites uniformly at a molecular level within a tailored trimetallic metal-organic framework. The optimized Ho6-Cd0.76Ni0.24-NS exhibits a superior photocatalytic hydrogen evolution rate of 40.06 mmol g-1 h-1 under visible-light irradiation and an apparent quantum efficiency of 29.37% at 420 nm without using cocatalysts or photosensitizers. A systematical mechanism study reveals that the uniformly organized photosensitive and photothermal single-sites have synergistic effect, which form ultrashort pathways for efficient transport of photoinduced electrons, suppress the recombination of photogenerated charge carriers, hence promote the hydrogen evolution activity. This work provides a promising approach for organizing dual-functional single-sites uniformly in photocatalyst for high-performance photocatalytic activity.

Phase-Stabilized Nickel-Molybdenum Electrocatalyst by Samarium Doping for Hydrogen Evolution in Alkaline Water Electrolysis

Although the nickel-molybdenum electrocatalyst exhibits excellent activity in the alkaline hydrogen evolution reaction (HER), its stability is poor mainly due to molybdenum leaching. This work reports that doping samarium into nickel-molybdenum electrocatalyst effectively suppresses molybdenum leaching by forming a stable phase consisting of Sm, Mo, and O elements. The resulting electrode displays no noticeable activity degradation during the long-term testing (> 850 h) under a current density of 500 mA cm-2 in 1 м KOH. This enhanced stability is ascribed to the formation of a robust phase within the HER potential windows in alkaline electrolytes, as evidenced by the Pourbaix diagram. Furthermore, the samarium-modified electrocatalyst exhibits increased activity, with the overpotential decreasing by ≈59 mV from 159 to 100 mV at 500 mA cm-2 compared to the unmodified counterpart. These remarkable properties stem from samarium doping, which not only facilitates the formation of a stable phase to inhibit molybdenum leaching but also adjusts the electronic properties of molybdenum to enhance water dissociation.

Tuning Electrocatalytic Water Oxidation Activity: Insights from the Active-Site Distance in LnCu6 Clusters

Atomically precise metal clusters serve as a unique model for unraveling the intricate mechanism of the catalytic reaction and exploring the complex relationship between structure and activity. Herein, three series of water-soluble heterometallic clusters LnCu6, abbreviated as LnCu6-AC (Ln = La, Nd, Gd, Er, Yb; HAC = acetic acid), LnCu6-IM (Ln = La and Nd; IM = Imidazole), and LnCu6-IDA (Ln = Nd; H2IDA = Iminodiacetic acid) are presented, each featuring a uniform metallic core stabilized by distinct protected ligands. Crystal structure analysis reveals a triangular prism topology formed by six Cu2+ ions around one Ln3+ ion in LnCu6, with variations in Cu···Cu distances attributed to different ligands. Electrocatalytic oxygen evolution reaction (OER) shows that these different LnCu6 clusters exhibit different OER activities with remarkable turnover frequency of 135 s-1 for NdCu6-AC, 79 s-1 for NdCu6-IM and 32 s-1 for NdCu6-IDA. Structural analysis and Density Functional Theory (DFT) calculations underscore the correlation between shorter Cu···Cu distances and improves OER catalytic activity, emphasizing the pivotal role of active-site distance in regulating electrocatalytic OER activities. These results provide valuable insights into the OER mechanism and contribute to the design of efficient homogeneous OER electrocatalysts.

Exploration and Insights on Topology Adjustment of Giant Heterometallic Cages Featuring Inorganic Skeletons Assisted by Machine Learning

Inorganic molecular cages are emerging multifunctional molecular-based platforms with the unique merits of rigid skeletons and inherited properties from constituent metal ions. However, the sensitive coordination bonds and vast synthetic space have limited their systematic exploration. Herein, two giant cage-like clusters featuring the organic ligand-directed inorganic skeletons of Ni4[La74Ni104(IDA)96(OH)184(C2O4)12(H2O)76]·(NO3)38·(H2O)120 (La74Ni104, 5 × 5 × 3 - C2O4) and [La84Ni132(IDA)108(OH)168(C2O4)24(NO3)12(H2O)116]·(NO3)72·(H2O)296 (La84Ni132, 5 × 5 × 5 - C2O4) were discovered by a high-throughput synthetic search. With the assistance of machine learning analysis of the experimental data, phase diagrams of the two clusters in a four-parameter synthetic space were depicted. The effect of alkali, oxalate, and other parameters on the formation of clusters and the mechanism regulating the size of two n × m × l clusters were elucidated. This work uses high-throughput synthesis and machine learning methods to improve the efficiency of 3d-4f cluster discovery and finds the highest-nuclearity 3d-4f cluster to date by regulating the size of the n × m × l inorganic cages through oxalate ions, which pushes the synthetic methodology study on elusive inorganic giant cages in a significantly systematic way.

Ultrathin Carbon Nitride Nanosheets Exfoliated and In Situ Modified with a Nickel Bis(Chelate) Complex for Boosting Photocatalytic Performances

Exfoliation and interfacial modification of two-dimensional (2D) polymeric carbon nitride (CN) are considerably vital for applications in photo/electrocatalysis fields. Here, a grinding-ultrasonic route was designed to construct nickel bis(chelate) complex (Ni(abt)₂, abt = 2-aminobenzenethiolate)-modified CN ultrathin nanosheets. Under the assistance of the shear force derived from the grinding process, Ni(abt)₂ was implanted into the interlamination of bulk CN, resulting in the formation of ultrathin CN (UCN) nanosheets. Simultaneously, Ni(abt)₂ molecules were anchored on the surfaces of as-formed UCN nanosheets due to the π-π stacking interaction. Interestingly, compared with single Ni(abt)₂ and UCN, the as-obtained Ni(abt)₂/UCN nanosheets exhibited excellent photocatalytic hydrogen evolution capability. A molecule-semiconductor internal electron transmission mechanism was suggested for explaining the separation and transfer of electron-hole pairs. Density functional theory (DFT) calculations demonstrated that the interface-induced electron redistribution tuned the electron density and hydrogen adsorption of the active centers, thus enhancing the photocatalytic performance of the hybrid catalyst. In addition, the as-obtained Ni(abt)₂/UCN nanosheets could also catalyze the reduction of nitroaromatics in the presence of NaBH₄. It was found that under the simulated sunlight irradiation, the conversion efficiency of nitroaromatic compounds to amino aromatic ones was up to 97.3%, far higher than that under the condition without light irradiation (51.7%), suggesting that the photocatalytic-produced hydrogen took part in the reduction of nitroaromatic compounds.

High-stability spherical lanthanide nanoclusters for magnetic resonance imaging

High-nuclear lanthanide clusters have shown great potential for the administration of high-dose mononuclear gadolinium chelates in magnetic resonance imaging (MRI). The development of high-nuclear lanthanide clusters with excellent solubility and high stability in water or solution has been challenging and is very important for expanding the performance of MRI. We used N-methylbenzimidazole-2-methanol (HL) and LnCl3·6H2O to synthesize two spherical lanthanide clusters, Ln32 (Ln = Ho, Ho32; and Ln = Gd, Gd32), which are highly stable in solution. The 24 ligands L- are all distributed on the periphery of Ln32 and tightly wrap the cluster core, ensuring that the cluster is stable. Notably, Ho32 can remain highly stable when bombarded with different ion source energies in HRESI-MS or immersed in an aqueous solution of different pH values for 24 h. The possible formation mechanism of Ho32 was proposed to be Ho(III), (L)- and H2O → Ho3(L)3/Ho3(L)4 → Ho4(L)4/Ho4(L)5 → Ho6(L)6/Ho6(L)7 → Ho16(L)19 → Ho28(L)15 → Ho32(L)24/Ho32(L)21/Ho32(L)23. To the best of our knowledge, this is the first study of the assembly mechanism of spherical high-nuclear lanthanide clusters. Spherical cluster Gd32, a form of highly aggregated Gd(III), exhibits a high longitudinal relaxation rate (1 T, r1 = 265.87 mM-1·s-1). More notably, compared with the clinically used commercial material Gd-DTPA, Gd32 has a clearer and higher-contrast T1-weighted MRI effect in mice bearing 4T1 tumors. This is the first time that high-nuclear lanthanide clusters with high water stability have been utilized for MRI. High-nuclear Gd clusters containing highly aggregated Gd(III) at the molecular level have higher imaging contrast than traditional Gd chelates; thus, using large doses of traditional gadolinium contrast agents can be avoided.

Heterometallic 3d-4f Alkoxide Precursors for the Synthesis of Binary Oxide Nanomaterials

In this study, a new method for the synthesis of heterometallic 3d-4f alkoxides by the direct reaction of metallic lanthanides (La, Pr, Nd, Gd) with MCl₂ (M = Mn, Ni, Co) in 2-methoxyethanol was developed. The method was applied to the synthesis of the heterometallic oxo-alkoxide clusters [Ln₄Mn₂(μ₆-O)(μ₃-OR)₈(HOR)_xCl₆] (Ln = La (1), Nd (2), Gd (3); x = 0, 2, 4); [Pr₄M₂(μ₆-O)(μ₃-OR)₈(HOR)_xCl₆] (M = Co (4), Ni (5); x = 2, 4); and [Ln₄Mn₂(μ₃-OH)₂(μ₃-OR)₄(μ-OR)₄(μ-Cl)₂(HOR)₄Cl₆] (Ln = La (11) and Pr (12)). Mechanistic investigation led to the isolation of the homo- and heterometallic intermediates [Pr(μ-OR)(μ-Cl)(HOR)Cl]_n (6), [Co₄(μ₃-OR)₄(HOR)₄Cl₄] (7), [Ni₄(μ₃-OR)₄(HOEt)₄Cl₄] (8), [Mn₄(μ₃-OR)₄(HOR)₂(HOEt)₂Cl₄] (9), and [Nd(HOR)₄Cl][CoCl₄] (10). In the presence of an external M(II) source at 1100 °C, 1-4 and 12 were selectively converted into binary metal oxide nanomaterials with trigonal or orthorhombic perovskite structures, i.e., LaMnO₃, GdMnO₃, NdMnO₃, Pr_0.9MnO₃, and PrCoO₃. Compound 5 decomposed into a mixture of homo- and heterometallic oxides. The method presented provides a valuable platform for the preparation of advanced heterometallic oxide materials with promising magnetic, luminescence, and/or catalytic applications.

Platonic and Archimedean solids in discrete metal-containing clusters

Metal-containing clusters have attracted increasing attention over the past 2-3 decades. This intense interest can be attributed to the fact that these discrete metal aggregates, whose atomically precise structures are resolved by single-crystal X-ray diffraction (SCXRD), often possess intriguing geometrical features (high symmetry, aesthetically pleasing shapes and architectures) and fascinating physical properties, providing invaluable opportunities for the intersection of different disciplines including chemistry, physics, mathematical geometry and materials science. In this review, we attempt to reinterpret and connect these fascinating clusters from the perspective of Platonic and Archimedean solid characteristics, focusing on highly symmetrical and complex metal-containing (metal = Al, Ti, V, Mo, W, U, Mn, Fe, Co, Ni, Pd, Pt, Cu, Ag, Au, lanthanoids (Ln), and actinoids) high-nuclearity clusters, including metal-oxo/hydroxide/chalcogenide clusters and metal clusters (with metal-metal binding) protected by surface organic ligands, such as thiolate, phosphine, alkynyl, carbonyl and nitrogen/oxygen donor ligands. Furthermore, we present the symmetrical beauty of metal cluster structures and the geometrical similarity of different types of clusters and provide a large number of examples to show how to accurately describe the metal clusters from the perspective of highly symmetrical polyhedra. Finally, knowledge and further insights into the design and synthesis of unknown metal clusters are put forward by summarizing these "star" molecules.

Engineering 3d-2p-4f Gradient Orbital Coupling to Enhance Electrocatalytic Oxygen Reduction

The development of highly efficient and economical materials for the oxygen reduction reaction (ORR) plays a key role in practical energy conversion technologies. However, the intrinsic scaling relations exert thermodynamic inhibition on realizing highly active ORR electrocatalysts. Herein, a novel and feasible gradient orbital coupling strategy for tuning the ORR performance through the construction of Co 3d-O 2p-Eu 4f unit sites on the Eu₂ O₃ -Co model is proposed. Through the gradient orbital coupling, the pristine ionic property between Eu and O atoms is assigned with increased covalency, which optimizes the e_g occupancy of Co sites, and weakens the OO bond, thus ultimately breaking the scaling relation between *OOH and *OH at Co-O-Eu unit sites. The optimized model catalyst displays onset and half-wave potential of 1.007 and 0.887 V versus reversible hydrogen electrode, respectively, which are higher than those of commercial Pt/C and most Co-based catalysts ever reported. In addition, the catalyst is found to possess superior selectivity and durability. It also reveals better cell performance than commercial noble-metal catalysts in Zn-air batteries in terms of high power/energy densities and long cycle life. This study provides a new perspective for electronic modulation strategy by the construction of gradient 3d-2p-4f orbital coupling.

Self-Assembled Zeolitic Imidazolate Framework/CdS Hollow Microspheres with Efficient Charge Separation for Enhanced Photocatalytic Hydrogen Evolution

Enhanced interfacial charge separation is of great importance to high-efficiency photocatalytic hydrogen production. Herein, we successfully fabricated novel ZIF-67/CdS hollow sphere (HS) and ZIF-8/CdS HS heterostructures through an in situ self-assembly process, in which ZIF-67 and ZIF-8 are closely coated on CdS HSs to form "double-shell"-like structures. This hierarchical heterostructure with porous outer layers on the surface of CdS HSs can expose accessible active sites and possess close contact. Upon visible-light illumination, the optimal proportion of ZIF-67/CdS HS displays a hydrogen generation rate of 1721 μmol g^-1 h^-1, which is 11.9 and 3.1 times higher than that of a pure CdS HS (145 μmol g^-1 h^-1) and ZIF-8/CdS HS (555 μmol g^-1 h^-1), respectively. The proposed photocatalytic mechanism is explored: ZIF-8/CdS HS follows the type-II mechanism, and ZIF-67/CdS HS follows the Z-scheme mechanism. The reason for the higher photocatalytic activity of ZIF-67/CdS HS is that ZIF-67 not merely with a porous structure facilitates the diffusion of H₂ gas, but with a well-matched band structure promotes charge transfer and separation.

Family of Nanoclusters, Ln33 (Ln = Sm/Eu) and Gd32, Exhibiting Magnetocaloric Effects and Fluorescence Sensing for MnO4. Inorg Chem 2022;61:8861-8869. [PMID: 35653200 DOI: 10.1021/acs.inorgchem.2c00898]

A family of nanoclusters, [Ln₃₃(EDTA)₁₂(OAc)₂(CO₃)₄(μ₃-OH)₃₆(μ₅-OH)₄(H₂O)₃₈]·OAc·xH₂O (x ≈ 50, Ln = Sm for 1; x ≈ 70, Ln = Eu for 2) and [Gd₃₂(EDTA)₁₂(OAc)₂(C₂O₄)(CO₃)₂(μ₃-OH)₃₆(μ₅-OH)₄(H₂O)₃₆]·x(H₂O) (x ≈ 70 for 3; H₄EDTA = ethylene diamine tetraacetic acid), was prepared through the assembly of repeating subunits under the action of an anion template. The analysis of the structures showed that compounds 1 and 2 containing 33 Ln³⁺ ions were isostructural, which were constructed by three kinds of subunits in the presence of CO₃^2- as an anion template, while compound 3 had a slightly different structure. Compound 3 containing 32 Gd³⁺ ions was formed by three types of subunits in the presence of CO₃^2- and C₂O₄^2- as a mixed anion template. The CO₃^2- anions came from the slow fixation of CO₂ in the air. Meanwhile, one kind of high-nuclearity lanthanide clusters showed high chemical stability. The quantum Monte Carlo (QMC) calculation suggested that weak antiferromagnetic interactions were dominant between Gd³⁺ ions in 3. Magnetocaloric studies showed that compound 3 had a large entropy change of 43.0 J kg^-1 K^-1 at 2 K and 7 T. Surprisingly, compound 2 showed excellent recognition and detection effects for permanganate in aqueous solvents based on the fluorescence quenching phenomenon.

Hierarchical Assembly of Coordination Macromolecules with Atypical Geometries: Gd44 Co28 Crown and Gd95 Co60 Cage

The discovered giant clusters are always highly symmetric owing to the spontaneous assembly of one or two basic units. Herein we report the Gd₄₄ Co₂₈ crown and Gd₉₅ Co₆₀ cage, formulated as [Gd₄₄ Co₂₈ (IDA)₂₀ (OH)₇₂ (CO₃ )₁₂ (OAc)₂₈ (H₂ O)₆₄ ]⋅(ClO₄ )₂₄ and [Na₄ Gd₉₅ Co₆₀ (IDA)₄₀ (OH)₁₅₀ (CO₃ )₄₀ (OAc)₅₈ (H₂ O)₁₆₄ ] ⋅ (ClO₄ )₄₁ (H₂ IDA=iminodiacetic acid), respectively, by providing a library containing multiple low-nuclearity units. The heart-like units and crown-like tetramer found in both compounds indicate unprecedented assembly levels, leading to an atypical geometry characteristic compared to the giant clusters directly assembled by regular units. These two clusters not only significantly increase the size of Ln-Co clusters but also exhibit the enhanced magnetic entropy change at ultra-low temperatures. This work provided an effective way to fabricate cluster compounds with giant size and geometry complexity simultaneously.

Triethanolamine stabilized non-alkyl Sn4Cd4 and alkyl Sn2Cd12 oxo clusters with distinct electrocatalytic activities

Two unprecedented Sn/Cd-oxo clusters, including non-alkyltin Sn^II₂Sn^IV₂Cd₄ and alkyltin Sn^IV₂Cd₁₂, have been constructed using triethanolamine and inorganic or organic tin precursors, respectively. Comparative electrocatalytic CO₂ reduction experiments show that the presence of non-alkyl and variable-valent tin centres could greatly improve the catalytic activities.

Asymmetric Cyanosilylation of Aldehydes by a Lewis Acid/Base Synergistic Catalyst of Chiral Metal Clusters

Metal clusters with well-defined crystal structures are extremely useful for studying the synergistic catalytic effects and associated catalytic mechanisms. In this study, two pairs of chiral lanthanide-transition metal clusters (R)/(S)-Co₃Ln₂ (Ln = Tb or Dy) were synthesized using Schiff-base ligands [(R)- or (S)-H₃L] with multiple Lewis base sites (O sites). The as-prepared (R)/(S)-Co₃Ln₂ chiral metal clusters exhibited good catalytic functionality in the asymmetric synthesis of chiral cyanohydrins, with high conversions of up to 99% and medium-to-high enantiomeric excess values of up to 78%. The catalysis process followed a mechanism in which the bifunctional metal clusters of (R)/(S)-Co₃Ln₂, containing Lewis acid sites and Lewis base sites, simultaneously activated the aldehydes and trimethylsilyl cyanide, respectively. Consequently, synergistic catalysis was realized. The enantioselectivity of the different aldehydes and stereochemical configuration of the resulting products are attributed to the formation of a steric chiral pocket via the external chiral ligands on the clusters. In addition, heterogeneous asymmetric cyanosilylation using (R)/(S)-Co₃Ln₂ chiral metal clusters achieved high chemoselectivity and regioselectivity under mild conditions.

Assembling Lanthanide–Transition Metal Clusters on TiO2 for Photocatalytic Nitrogen Fixation

Ammonia synthesis using light with low energy consumption offers an effective solution for energy saving and environmental protection. Herein, an abundant oxygen vacancy photocatalyst was synthesized via the integration of...

Recent Advances in the Catalytic Applications of Lanthanide-Oxo Clusters

Lanthanide-oxo/hydroxo clusters (LOCs) in this mini-review refer to polynuclear complexes featuring a polyhedral metal-oxo/hydroxo cluster core of lanthanide ions exclusively or with coexisting 3d metal ions. We summarize herein the recent works using this unique family of cluster complexes for catalysis; this aspect of research stands in stark contrast to their extensively studied synthetic and structural chemistry as well as the much-researched magnetic properties. Following a brief introduction of the synthetic strategies for these clusters, pertinent results from available literature reports are surveyed and discussed according to the types of catalyzed reactions. Particular attention was paid to the selection of a cluster catalyst for a specific type of reactions as well as the corresponding reaction mechanism. To the end, the advantages and challenges in utilizing LOCs as multifunctional catalysts are summarized, and possible future research directions are proposed.

Photocatalytic H2O Overall Splitting into H2 Bubbles by Single Atomic Sulfur Vacancy CdS with Spin Polarization Electric Field

Low efficient transfer of photogenerated charge carriers to redox sites along with high surface reaction barrier is a bottleneck problem of photocatalytic H₂O overall splitting. Here, in the absence of cocatalysts, H₂O overall splitting has been achieved by single-atomic S vacancy hexagonal CdS with a spin polarization electric field (PEF). Theoretical and experimental results confirm that single-atomic S vacancy-induced spin PEF with opposite direction to the Coulomb field accelerates charge carrier transport dynamics from the bulk phase to surface-redox sites. By systematically tuning the spin PEF intensity with single-atomic S vacancy content, common pristine CdS is converted to a photocatalyst that can efficiently complete H₂O overall splitting by releasing a great number of H₂ bubbles under natural solar light. This work solves the bottleneck of solar energy conversion in essence by single atom vacancy engineering, which will promote significant photocatalytic performance enhancement for commercialization.

Ordered Macroporous Carbonous Frameworks Implanted with CdS Quantum Dots for Efficient Photocatalytic CO2 Reduction

Solar-driven photocatalytic CO₂ reduction is regarded as a promising way to simultaneously mitigate the energy crisis and CO₂ pollution. However, achieving high efficiency of photocatalytic CO₂ reduction, especially without the assistance of sacrifice reagents or extra alkaline additives, remains a critical issue. Herein, a photocatalyst of 3D ordered macroporous N-doped carbon (NC) supported CdS quantum dots (3DOM CdSQD/NC) is successfully fabricated toward photocatalytic CO₂ reduction via an in situ transformation strategy. Additionally, an amines oxidation reaction is introduced to replace the H₂ O oxidation process to further boost the photocatalytic CO₂ reduction efficiency. Impressively, 3DOM CdSQD/NC exhibits superior activity and selectivity in photocatalytic CO₂ reduction coupled with amines oxidation, affording a CO production rate as high as 5210 µmol g^-1 h^-1 in the absence of any sacrificial agents and alkaline additives. Moreover, 3DOM CdSQD/NC achieves an apparent quantum efficiency of 2.9% at 450 nm. Mechanism studies indicate that the 3D ordered macropores in the NC matrix are beneficial to the transfer of photogenerated carriers. Furthermore, the highly dispersed CdS QDs on the NC skeleton are able to significantly promote the adsorption of both CO₂ and amine molecules and depress the CO₂ activation energy barriers by stabilizing the *COOH intermediate, directly contributing to the high activity.

Multiphoton Upconversion Materials for Photocatalysis and Environmental Remediation

Solar-driven photocatalysis holds great potential for energy conversion, environmental remediation, and sustainable chemistry. However, practical applications of conventional photocatalytic systems have been constrained by their insufficient ability to harvest solar radiation in the infrared spectrum. Lanthanide-doped upconversion materials possess high photostability, tunable absorption, and the ability to convert low-energy infrared radiation into high-energy emission, making them attractive for infrared-driven photocatalysis. This review highlights essential principles for rational design of efficient photocatalysts. Particular emphasis is placed on current state-of-the-arts that offer enhanced upconversion luminescence efficiency. We also summarize recent advances in lanthanide-doped upconversion materials for photocatalysis. We conclude with new challenges and prospects for future developments of infrared-driven photocatalysts.

Co(OH)2 water oxidation cocatalyst-decorated CdS nanowires for enhanced photocatalytic CO2 reduction performance

Photocatalytic CO2 reduction is a promising technology to resolve the greenhouse effect and energy crisis. In this work, a Co(OH)2 nanoparticle decorated CdS nanowire (Co(OH)2/CdS) based heterostructured photocatalyst was prepared via a solvothermal and subsequent co-precipitation method, and it was used for photocatalytic CO2 reduction. The optimal Co(OH)2/CdS photocatalyst achieves a CO production rate of 8.11 μmol g-1 h-1 under visible light irradiation (λ > 420 nm), which is about 2 times higher than that of bare CdS. The experimental results show that a Co(OH)2 cocatalyst possesses a great capability of consuming holes, which promotes the oxygen-producing half-reaction and accelerates charge separation, thus enhancing the CO2 photoreduction performance of CdS. Notably, without using complex synthesis processes, hazardous substances or expensive ingredients, Co(OH)2/CdS shows high light absorption, efficient charge separation and complete CO product selectivity. This work offers a new pathway for the construction of cost-effective photocatalytic materials to achieve highly efficient CO2 reduction activity by the integration of a Co(OH)2 cocatalyst.

Snapshots of Ce70 Toroid Assembly from Solids and Solution

Crystallization at the solid-liquid interface is difficult to spectroscopically observe and therefore challenging to understand and ultimately control at the molecular level. The Ce₇₀-torroid formulated [Ce^IV₇₀(OH)₃₆(O)₆₄(SO₄)₆₀(H₂O)₁₀]^4-, part of a larger emerging family of M^IV₇₀-materials (M = Zr, U, Ce), presents such an opportunity. We elucidated assembly mechanisms by the X-ray scattering (small-angle scattering and total scattering) of solutions and solids as well as crystallizing and identifying fragments of Ce₇₀ by single-crystal X-ray diffraction. Fragments show evidence for templated growth (Ce₅, [Ce₅(O)₃(SO₄)₁₂]^10-) and modular assembly from hexamer (Ce₆) building units (Ce₁₃, [Ce₁₃(OH)₆(O)₁₂(SO₄)₁₄(H₂O)₁₄]^6- and Ce₆₂, [Ce₆₂(OH)₃₀(O)₅₈(SO₄)₅₈]^14-). Ce₆₂, an almost complete ring, precipitates instantaneously in the presence of ammonium cations as two torqued arcs that interlock by hydrogen boding through NH₄⁺, a structural motif not observed before in inorganic systems. The room temperature rapid assemblies of both Ce₇₀ and Ce₆₂, respectively, by the addition of Li⁺ and NH₄⁺, along with ion-exchange and redox behavior, invite exploitation of this emerging material family in environmental and energy applications.

A new family of decanuclear Ln7Cr3 clusters exhibiting a magnetocaloric effect

Two dimeric Ln–Cr clusters with formula {Ln(H₂O)₈[Ln₆Cr₃(L)₆(CH₃COO)₆(μ₃-OH)₁₂(H₂O)₁₂]}·(ClO₄)₆·xH₂O (Ln = Gd, x = 35 for 1 and Ln = Dy, x = 45 for 2, HL = 2-pyrazinecarboxylic acid) were obtained by a ligand-controlled hydrolytic method with a mixed ligand system (2-pyrazinecarboxylic acid and acetate). Single crystal structure analysis showed that two trigonal bipyramids of [Gd₃Cr₂(μ₃-OH)₆]⁹⁺ worked as building blocks in constructing the metal-oxo cluster core of [Gd₆Cr₃(μ₃-OH)₁₂]¹⁵⁺ by sharing a common top – a Cr³⁺ ion. Additionally, compound 1 forms a three-dimensional framework with a one-dimensional nanopore channel along the a-axis through a hydrogen-bond interaction between the cationic cluster core and the free mononuclear cation [Gd(H₂O)₈]³⁺ and the π-bond interactions of the pyrazine groups on the two cationic cluster cores. Magnetic calculations indicated a weak ferromagnetic coupling interaction for Gd⋯Gd and Gd⋯Cr in compound 1, with its magnetic entropy change (−ΔS_m) reaching 21.1 J kg⁻¹ K⁻¹ at 5 K, 7 T, while compound 2 displayed an obvious frequency-dependency at H_dc = 2000 Oe.

Two decanuclear Ln–Cr clusters Ln₇Cr₃ were obtained, which formed a three-dimensional framework with one-dimensional nanopore channel through hydrogen-bond and π-bond interactions. Gd₇Cr₃ had a magnetic entropy change of 21.1 J kg⁻¹ K⁻¹ at 5 K, 7 T.

Two Decanuclear DyIIIxCoII10-x (x = 2, 4) Nanoclusters: Structure, Assembly Mechanism, and Magnetic Properties

The aggregation and formation of heterometallic nanoclusters usually involves a variety of complex self-assembly processes; thus, the exploration of their assembly mechanisms through process tracking is more challenging than that for homometallic nanoclusters. We explored here the effect of solvent on the formation of heterometallic clusters, which gave two heterometallic nanoclusters, [Dy₂Co₈(μ₃-OCH₃)₂(L)₄(HL)₂(OAc)₂(NO₃)₂(CH₃CN)₂]·CH₃CN·H₂O (1) and [Dy₄Co₆(L)₄(HL)₂(OAc)₆(OCH₂CH₂OH)₂(HOCH₂CH₂OH)(H₂O)]·9CH₃CN (2), with the H₃L ligand formed from the in situ condensation reaction of 3-amino-1,2-propanediol with 2-hydroxy-1-naphthaldehyde in the presence of Co(OAc)₂·4H₂O and Dy(NO)₃·6H₂O. It is worth noting that the skeleton of cluster 1 has a high stability under high-resolution electrospray ionization mass spectrometry (HRESI-MS) conditions with a gradually increasing energy of the ion source. Cluster 2 underwent a multistep fragmentation even under a zero ion-source voltage for the measurement of HRESI-MS. Further analysis showed that cluster 2 underwent a possible fragmentation mechanism of Dy₄Co₆L₆ → Dy₂Co₆L₅/DyL → DyCo₂L₃/DyCo₂L → DyL/Co₂L₂. Most notably, the species emerging in the formation process of cluster 1 were tracked using time-dependent HRESI-MS, from which we proposed its possible formation mechanism of H₂L → Co₂L₂ → Co₂DyL₂/Co₃L₂ → Co₃DyL₂ → Co₄DyL₂ → Co₅Dy₂L₄ → Co₈Dy₂L₆. As far as we know, it is the first time to track the formation process of Dy-Co heterometallic clusters through HRESI-MS with the proposed assembly mechanism. The magnetic properties of the two titled Dy^III_xCo^II_10-x (x = 2, 4) clusters were studied. Both of them exhibit slow magnetic relaxation, and 1 is a single-molecule magnet at zero direct-current field.

A Giant 3d-4f Polyoxometalate Super-Tetrahedron with High Proton Conductivity

The assembly of gigantic heterometallic metal clusters remains a great challenge for synthetic chemistry. Herein, based on the slow release strategy of lanthanide ions and in situ formation of lacunary polyoxometalates, two giant 3d-4f polyoxometalate inorganic clusters [LaNi₁₂ W₃₅ Sb₃ P₃ O₁₃₉ (OH)₆ ]^23- (LaNi₁₂ ) and [La₁₀ Ni₄₈ W₁₄₀ Sb₁₆ P₁₂ O₅₆₈ (OH)₂₄ (H₂ O)₂₀ ]^86- (La₁₀ Ni₄₈ ) are obtained. The nanoscopic inorganic cluster La₁₀ Ni₄₈ possesses a super tetrahedron structure, which can be viewed as assembly from four LaNi₁₂ molecules encapsulating a central [La₆ (SbO₃ )₄ (H₂ O)₂₀ ]⁶⁺ octahedron core. This giant aesthetic La₁₀ Ni₄₈ tetrahedron containing 214 metal ions is the largest 3d-4f cluster reported thus far in polyoxometalate system. More interestingly, the LaNi₁₂ and La₁₀ Ni₄₈ display high stability in solution and La₁₀ Ni₄₈ displays excellent proton conductivity.

Efficient Charge Migration in Chemically-Bonded Prussian Blue Analogue/CdS with Beaded Structure for Photocatalytic H2 Evolution

The design of a powerful heterojunction structure and the study of the interfacial charge migration pathway at the atomic level are essential to mitigate the photocorrosion and recombination of electron-hole pairs of CdS in photocatalytic hydrogen evolution (PHE). A temperature-induced self-assembly strategy has been proposed for the syntheses of Prussian blue analogue (PBA)/CdS nanocomposites with beaded structure. The specially designed structure had evenly exposed CdS which can efficiently harvest visible light and inhibit photocorrosion; meanwhile, PBA with a large cavity provided channels for mass transfer and photocatalytic reaction centers. Remarkably, PB-Co/CdS-LT-3 exhibits a PHE rate of 57 228 μmol h^-1 g^-1, far exceeding that of CdS or PB-Co and comparable to those of most reported crystalline porous material-based photocatalysts. The high performances are associated with efficient charge migration from CdS to PB-Co through CN-Cd electron bridges, as revealed by the DFT calculations. This work sheds light on the exploration of heterostructure materials in efficient PHE.

Ag2 S-CdS p-n Nanojunction-Enhanced Photocatalytic Oxidation of Alcohols to Aldehydes

Selective oxidation of alcohols to aldehydes under mild conditions is important for the synthesis of high-value-added organic intermediates but still very challenging. For most of the thermal and photocatalytic systems, noble metal catalysts or harsh reaction conditions are required. Herein, the synthesis and use of Ag₂ S-CdS p-n nanojunctions as an efficient photocatalyst for selective oxidation of a series of aromatic alcohols to their corresponding aldehydes is reported. High quantum efficiencies (59.6% and 36.9% under 380 and 420 nm, respectively) are achieved in air atmosphere at room temperature. Photoluminescence and photo-electrochemical tests show that the excellent performance is mainly due to the p-n junction-enhanced charge separation and transfer for the activation of both O₂ (in air) and substrates. This study demonstrates the potential of p-n junction in photocatalytic synthesis under mild conditions.

Hollow Octahedral Cu2-xS/CdS/Bi2S3 p-n-p Type Tandem Heterojunctions for Efficient Photothermal Effect and Robust Visible-Light-Driven Photocatalytic Performance

Reasonable design of the nanostructure of heterogeneous photocatalysts is of great significance for improving their performance and stability. We report the design and fabrication of hollow sandwich-layered octahedral Cu_2-xS/CdS/Bi₂S₃ p-n-p type tandem heterojunctions constructed via the continuous growth deposition method on the surface of hollow octahedral Cu_2-xS with well-defined structures and interfaces. The unique hollow sandwich nanostructure has a large specific surface area and abundant reaction sites and enhances the separation and transfer of photogenerated carriers. In addition, the formation of a p-n-p heterojunction coupled with the surface plasmon resonance effect of Cu_2-xS could also aid in photocatalytic H₂ evolution performance and photocatalytic degradation efficiency. Under vis-NIR light irradiation, the optimized Cu_2-xS/CdS/Bi₂S₃ photocatalyst displays a notable H₂ production rate of 8012 μmol h^-1 g^-1, and 2,4-dichlorophenol is almost completely photocatalytically degraded in 150 min. This strategy and rational design offer a new path toward the design of specific nanocatalysts with enhanced activity and stability and challenging reactions.

Substitution Effects Regulate the Formation of Butterfly-Shaped Tetranuclear Dy(III) Cluster and Dy-Based Hydrogen-Bonded Helix Frameworks: Structure and Magnetic Properties

The generation of two types of complexes with different topological connections and completely different structural types merely via the substitution effect is extremely rare, especially for -CH₃ and -C₂H₅ substituents with similar physical and chemical properties. Herein, we used 3-methoxysalicylaldehyde, 1,2-cyclohexanediamine, and Dy(NO₃)₃·6H₂O to react under solvothermal conditions (CH₃OH:CH₃CN = 1:1) at 80 °C to obtain the butterfly-shaped tetranuclear Dy^III cluster [Dy₄(L¹)₄(μ₃-O)₂(NO₃)₂] (Dy₄, H₂L¹ = 6,6'-((1E,1'E)-(cyclohexane-1,3-diylbis(azanylylidene))bis(methanylylidene))bis(2-methoxyphenol)). The ligand H₂L¹ was obtained by the Schiff base in situ reaction of 3-methoxysalicylaldehyde and 1,2-cyclohexanediamine. In the Dy₄ structure, (L¹)^2- has two different coordination modes: μ₂-η¹:η²:η¹:η¹ and μ₄-η¹:η²:η¹:η¹:η²:η¹. The four Dy^III ions are in two coordination environments: N₂O₆ (Dy1) and O₉ (Dy2). The magnetic testing of cluster Dy₄ without the addition of an external field revealed that it exhibited a clear frequency-dependent behavior. We changed 3-methoxysalicylaldehyde to 3-ethoxysalicylaldehyde and obtained one case of a hydrogen-bonded helix framework, [DyL²(NO₃)₃]_n·2CH₃CN (Dy-HHFs, H₂L² = 6,6'-((1E,1'E)-(cyclohexane-1,3-diylbis(azanylylidene))bis(methanylylidene))bis(2-ethoxyphenol)), under the same reaction conditions. The ligand H₂L² was formed by the Schiff base in situ reaction of 3-ethoxysalicylaldehyde and 1,2-cyclohexanediamine. All Dy^III ions in the Dy-HHFs structure are in the same coordination environment (O₉). The twisted S-shaped (L²)^2- ligand is linked by a Dy(III) ion to form a spiral chain. The spiral chain is one of the independent units that is interconnected to form Dy-HHFs through three strong hydrogen-bonding interactions. Magnetic studies show that Dy-HHFs exhibits single-ion-magnet behavior (U_eff = 68.59 K and τ₀ = 1.10 × 10^-7 s, 0 Oe DC field; U_eff = 131.5 K and τ₀ = 1.22 × 10^-7 s, 800 Oe DC field). Ab initio calculations were performed to interpret the dynamic magnetic performance of Dy-HHFs, and a satisfactory consistency between theory and experiment exists.

Covalent organic framework photocatalysts: structures and applications

In the light of increasing energy demand and environmental pollution, it is urgently required to find a clean and renewable energy source. In these years, photocatalysis that uses solar energy for either fuel production, such as hydrogen evolution and hydrocarbon production, or environmental pollutant degradation, has shown great potential to achieve this goal. Among the various photocatalysts, covalent organic frameworks (COFs) are very attractive due to their excellent structural regularity, robust framework, inherent porosity and good activity. Thus, many studies have been carried out to investigate the photocatalytic performance of COFs and COF-based photocatalysts. In this critical review, the recent progress and advances of COF photocatalysts are thoroughly presented. Furthermore, diverse linkers between COF building blocks such as boron-containing connections and nitrogen-containing connections are summarised and compared. The morphologies of COFs and several commonly used strategies pertaining to photocatalytic activity are also discussed. Following this, the applications of COF-based photocatalysts are detailed including photocatalytic hydrogen evolution, CO₂ conversion and degradation of environmental contaminants. Finally, a summary and perspective on the opportunities and challenges for the future development of COF and COF-based photocatalysts are given.

Construction of ZnTiO3/Bi4NbO8Cl heterojunction with enhanced photocatalytic performance

Constructing heterojunction is an effective strategy to enhance photocatalytic performance of photocatalysts. Herein, we fabricated ZnTiO₃/Bi₄NbO₈Cl heterojunction with improved performance via a typical mechanical mixing method. The rhodamine (RhB) degradation rate over heterojunction is higher than that of individual ZnTiO₃ or Bi₄NbO₈Cl under Xenon-arc lamp irradiation. Combining ZnTiO₃ with Bi₄NbO₈Cl can inhibit the recombination of photo-excited carriers. The improved quantum efficiency was demonstrated by transient-photocurrent responses (PC), electrochemical impedance spectroscopy (EIS), photoluminescence (PL) spectra, and time-resolved PL (TRPL) spectra. This research may be valuable for photocatalysts in the industrial application.

Anion-Dependent Assembly of 3d-4f Heterometallic Clusters Ln5Cr2 and Ln8Cr4

A series of heterometallic Ln-Cr clusters with the formulas [Ln₅Cr₂(H₂L)₂(OAc)₆(μ₃-OH)₆(H₂O)₁₅](ClO₄)₇·xH₂O (Ln = Gd and x = 33 for 1 and Ln = Dy and x = 21 for 2) and [Ln₈Cr₄(H₂L)₄(OAc)₈(μ₃-OH)₁₆(μ₄-O)₁(H₂O)₈](Cl)(ClO₄)₅·10H₂O (Ln = Gd for 3 and Ln = Dy for 4) was obtained through the reaction of the acetate ligands 2,2-dimethylolpropionic acid (H₃L) and Ln(ClO₄)₃ in the presence of chromium salts with different anions under the same high pH conditions. X-ray analysis revealed that compound 1 contained a metal unit [Gd₃Cr₂] displaying the pentagonal bipyramid configuration and that compound 3 was templated by Cl^- and ClO₄^- as a mixed anion template featuring a quadrangular structure. In compound 3, the 12 metal atoms were arranged in a wheel-shaped metal skeleton [Gd₈Cr₄], which was produced by 4 tetrahedral metal units [Gd₃Cr] sharing vertices. The introduction of the mixed anion template increased the number of metal atoms in the Ln-Cr clusters. Magnetic calculations indicated that there was weak antiferromagnetic Gd···Cr coupling and weak ferromagnetic Gd···Gd coupling in 1, whereas both Gd···Cr and Gd···Gd in 3 exhibited weak antiferromagnetic interactions. Magnetothermal studies showed that compounds 1 and 3 displayed magnetic entropy changes of 25.2 J kg^-1 K^-1 at 5 K and 7 T and 33.8 J kg^-1 K^-1 at 2 K and 7 T, respectively.

New Versatile Synthetic Route for the Preparation of Metal Phosphate Decorated Hydrogen Evolution Photocatalysts

Photocatalytic hydrogen generation will benefit from the realization of more active but less expensive cocatalysts compared with noble metal counterparts. Herein we developed a universal vapor deposition method that selectively uses the thermal decomposition products of sodium hypophosphite as a phosphorus source for the fabrication of inexpensive and highly efficient metal phosphate (MPi) modified CdS nanorods. We find that the modification with a bimetal phosphate (i.e., 5 wt % NiCoPi) leads to an activity enhancement by a factor of approximately 52 in boosting visible-light-driven hydrogen evolution relative to the pristine CdS nanorods. The photocatalyst exhibits a high hydrogen generation rate of 13.44 mmol·g^-1·h^-1, which is much higher than that of its single metal counterparts (NiPi, 8.70 mmol·g^-1·h^-1; CoPi, 5.79 mmol·g^-1·h^-1) and 1 wt % Pt modified CdS (1.33 mmol·g^-1·h^-1). Its apparent quantum efficiency reaches 23.5% at 420 nm. Furthermore, it also shows remarkable photostability for eight consecutive cycles of photocatalytic activity tests with total reaction time of 24 h. The excellent photocatalytic performance of the photocatalyst is believed to be associated with the in situ formed Ni^ICoP and NiCo^IIIPi cocatalysts, which not only play an important role in photogenerated charge separation but also provide highly active catalytic reaction sites for the corresponding hydrogen evolution reaction and the sacrificial agent oxidation reaction.

A single-ligand-protected Eu60−nGd(Tb)n cluster: a reasonable new approach to expand lanthanide aggregations

Two fascinating configurations were obtained based on mixed-lanthanide conditions, abbreviated as mixed-Ln₆₀. The synthesis provides a way to obtain similar metal-core Ln high-nuclearity clusters, breaking the ionic radius limitation.