Ultrasmall Clusters Research Articles

Valence-engineering modulation of MoS2 clusters for enhancing biocatalytic activity

We develop ultra-small and water-soluble MoS2 clusters with superior antioxidant activity and enzyme-like activity via valence-engineering modulation with Ce doping.

Elucidating Confinement and Microenvironment of Ru Clusters Stably Confined in MFI Zeolite for Efficient Propane Oxidation.

Achieving active and stable heterogeneous catalysts by encapsulating noble metal species within zeolites is highly promising for high utilization and cost efficiency in thermal and environmental catalytic reactions. Ru, considered an economical noble metal alternative with comparable performance, faces great challenges within MFI-type microporous zeolites due to its high cohesive energy and mobility. Herein, an innovative strategy was explored that couples hydrothermal in situ ligand protection with stepwise calcination in a flowing atmosphere to embed ultrasmall Ru clusters anchored at K+-healed silanol sites (≡Si-Ruδ+-O-K complexes) within 10-membered ring sinusoidal channels of MFI. Comprehensive experiments and theoretical calculations unveiled that the interplay between confined Ru clusters and MFI induces local strain in MFI, creating a unique catalytic microenvironment around the Ru clusters. This synergy interaction enhances alkane deep oxidation as the confined Ru clusters and the MFI microenvironment collectively pre-activate C3H8 and O2, facilitate the cleavage of C-H and C-C bonds at low temperatures. Notably, the stable geometric and electronic properties of the confined Ru show exceptional thermal stability up to 1000 °C, rivaling fresh catalysts. These findings shed vital methodological and mechanistic insights for developing efficacious heterogeneous catalysts for thermal catalysis.

Elucidating Confinement and Microenvironment of Ru Clusters Stably Confined in MFI Zeolite for Efficient Propane Oxidation

Achieving active and stable heterogeneous catalysts by encapsulating noble metal species within zeolites is highly promising for high utilization and cost efficiency in thermal and environmental catalytic reactions. Ru considered an economical noble metal alternative with comparable performance, faces great challenges within MFI‐type microporous zeolites due to its high cohesive energy and mobility. Herein, an innovative strategy was explored coupling hydrothermal in situ ligand protection with stepwise calcination in a flowing atmosphere to embed ultrasmall Ru clusters anchored at K+‐healed silanol sites (≡Si–Ruδ+‐O‐K complexes) within 10‐membered ring sinusoidal channels of MFI. Comprehensive experiments and theoretical calculations unveiled that the interplay between confined Ru clusters and MFI induces local strain in MFI, creating a unique catalytic microenvironment around the Ru clusters. This synergy exhibits superior alkane deep oxidation, performance owing to the confined Ru clusters and the MFI microenvironment collectively pre‐activate C3H8 and O2, facilitate the cleavage of C‐H and C‐C bonds at low temperatures. Notably, the stable geometric and electronic properties of confined Ru show exceptional thermal stability up to 1000 °C, rivaling fresh catalysts. These findings shed vital methodological and mechanistic insights for developing efficacious heterogeneous catalysts for thermal catalysis.

(Invited) Understanding on the Fundamental Processes of Electrocatalytic Conversion of CO2 to Multi-Carbon Chemicals

The electrochemical CO2 reduction reaction (CO2RR) for chemical production using renewable electricity offers attractive “carbon-neutral” and “carbon-negative” mitigation strategies for greenhouse emission. CO2RR to C2+ chemicals, the compounds containing two or more carbons, represent a particularly interesting topic from both fundamental research as well as practical application points of view. For example, ethanol, ethylene, propanol, etc. are among the most produced chemicals by the industry and are widely used for various applications. Distributive CO2RR by recycling locally emitted CO2 to manufacture these chemicals for the local consumption could substantially reduce the cost of CO2 storage and transport while producing economic income.Electrocatalytic reduction of CO2 involves a fundamental reaction step – proton couple electron transfer (PCET). CO2RR to CO or formic acid requires only two PCET steps, rendering them highly effective with fast kinetics. CO2RR to C2+ chemicals are significantly more challenging due to the rapid escalation of required PCET steps (for example, 12 for ethanol and 18 for propanol), as well as the C-C bond coupling reaction. These increased PCET steps substantially complicate the electrochemical reaction coordinate, leading to a high probability of branching reactions, which lower the single product Faradaic efficiency (FE). [1]At Argonne, we developed an amalgamated lithium metal (ALM) synthesis method of preparing highly selective and active electrocatalysts through collaboration with Northern Illinois U. For example, we derived a Cu-based CO2RR catalyst that yielded > 90% FE for conversion of CO2 to ethanol [2]. More recently, we expanded the approach to metal Sn and prepared a family of CO2RR catalysts with Sn size varying from single atom, ultra-small clusters to nano-crystallite. High single-product FEs and low onset potential of CO2 conversion to acetate (FE = 90 % @ -0.6 V), ethanol (FE = 92% @ - 0.4 V), and formate (FE = 91% @ -0.6 V) were achieved over the catalysts of different active site dimensions. [3]In this presentation, we will discuss in detail on the CO2 conversion mechanism behind these highly selective, size-modulated p-block element (Sn) catalysts. We will elucidate the catalytic reaction path using first-principle computation, advanced material characterizations, together with kinetic isotope effect (KIE) study. To our surprise, we found that PCET reaction paths over these catalysts can be completely altered by switching from H2O to D2O in the electrolyte, an important experimental observation to support future theoretical exploration on the transition state theory of CO2RR. Acknowledgement: This work is supported by U. S. Department of Energy, Office of Energy Efficiency and Renewable Energy - Industrial Efficiency & Decarbonization Office and by Office of Science, U.S. Department of Energy under Contract DE-AC02-06CH11357.[1] “Electrochemical conversion of CO2 to long-chain hydrocarbons”, Di-Jia Liu, Joule 2022 6, 1969–1980[2] “Highly selective electrocatalytic CO2 reduction to ethanol by metallic clusters dynamically formed from atomically dispersed copper”, Haiping Xu, Dominic Rebollar, Haiying He, Lina Chong, Yuzi Liu, Cong Liu, Cheng-Jun Sun, Tao Li, John V. Muntean, Randall E. Winans, Di-Jia Liu and Tao Xu, 2020 Nature Energy, 5, 623–632[3] “Modulating CO2 electrocatalytic conversion to organics pathway by the catalytic site dimension”, Haiping Xu, Haiying He, Jianxin Wang, Inhui Hwang, Yuzi Liu, Chengjun Sun, Tao Li, John V. Muntean, Tao Xu, Di-Jia Liu,* J. Am. Chem. Soc. 2024, 146, 10357−10366

Pt‐Sn/Sb Interaction Induces Reversed Charge Transfer and Selective Hydroxyl Adsorption for Enhanced Hydrogen Electro‐Oxidation

AbstractThe challenges encountered by Pt‐based electrocatalysts in alkaline hydrogen oxidation reaction include high Pt dosage and conflicting demands for modulating adsorption strengths among diverse intermediates. Here, an ultrasmall Pt cluster grafted on antimony tin oxide nanocrystalline with strong electron donor ability to minimal Pt dosage yet maximized electrocatalytic performance is developed. Mechanism studies show that the formation of Pt–Sn/Sb interaction at the heterointerface and the resultant reversed electron transfer selectively enhance the adsorption for OH‐ while concurrently weakening the binding strength for *H and CO toward Pt clusters. This accelerates the kinetics of H2/CO oxidation by promoting the binding of OH species with *H/*CO, yielding the catalyst with up to 5.7‐fold higher mass‐specific activity than benchmark Pt/C and increased resistance to CO poisoning. This work demonstrates the rational design of the synergistic multi‐site interactions towards advanced Pt‐based catalysts.

Stabilizing ultra-small bimetallic PtSn clusters within S-1 crystals for effective propane dehydrogenation with low Pt loading

It’s a great challenge for enhancing the stability over Pt-based catalysts with low Pt loading during propane dehydrogenation based upon the manipulation of ultra-small PtSn clusters and their compositions. Here, we developed a novel strategy to produce and stabilize sub-nanometer PtSn clusters even atomical dispersion within Silicalite-1 crystals via tailoring calcination atmosphere from air to argon, which could achieve a stable performance of propane dehydrogenation with only 0.15 wt% Pt loading. Argon calcination atmosphere of PtSn@Silicalite-1 significantly decreased the size of PtSn clusters, which further presented a strikingly catalytic performance with the high formation of propylene over 8.0 mol[C3H6]·g[Pt]−1·h−1 even after 3840 min at 600 °C (WHSV=760 g[C3H8]·g[Pt]−1·h−1). Hardly any deactivation was obtained over PtSn8@S-1-Ar-50 after long-term runs for 3840 min with an extremely low deactivation constant of 0.0001 h−1 so far, which was mainly derived from the outstanding stability of PtSn sub-nanometers within S-1 crystals through appropriate flow rate of argon calcination atmosphere.

Efficient removal of plasticiser dibutyl phthalate on CoP cluster anchored MXene via boosting peroxymonosulfate activation: Catalytic performance and decomposition mechanism

A novel Ti3C2 synthesis method via strong alkaline etching (MXeneba) was developed to degrade dibutyl phthalate (DBP) using a CoP/MXeneba + peroxymonosulfate (PMS) system. The MXeneba's modified surface properties enabled stable Co2+ adsorption and homogeneous loading of ultrasmall CoP clusters post-phosphatisation. Complete DBP degradation was achieved within 30 min, facilitated by reactive oxygen species (ROS: SO4·-, ·OH, O2·-, and 1O2) and the highly reduced titanium atoms promoting Co3+ to Co2+ conversion. Density functional theory (DFT) calculations elucidated PMS adsorption sites and active species for DBP degradation. This study clarifies the activation mechanism, linking catalyst structure to performance, and provides insights for future advanced oxidation processes in environmental remediation. The findings emphasize the practical application and significance of the CoP/MXeneba catalyst in treating harmful plasticisers in water, contributing to efficient and sustainable water purification methods. The research also highlights this novel catalyst system's robustness and versatility in tackling diverse pollutants.

Graphene-supported MN4 single-atom catalysts for multifunctional electrocatalysis enabled by axial Fe tetramer coordination

Multifunctional electrocatalysts for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) are crucial for development of the key electrochemical energy storage and conversion devices, for which single-atom catalyst (SAC) has present great promises. Very recently, some experimental works showed that structurally well-defined ultra-small transition-metal clusters (such as Fe and Co tetramers, denoted as Fe4 and Co4, respectively), can efficiently modulate the catalytic behavior of SACs by axial coordination. Herein, taking the graphene-supported MN4 SACs as representatives, we theoretically explored the feasibility of realizing multifunctional SACs for ORR, OER and HER by this novel axial coordination engineering. Through extensive first-principles calculations, from 23 candidates, IrN4 decorated with Fe4 (IrN4/Fe4) is identified as the promising trifunctional catalyst with the theoretical overpotential of 0.43, 0.51 and 0.30 V for OER, ORR and HER, respectively. RhN4/Fe4 and CoN4/Fe4 are recognized as potential OER and ORR bifunctional catalysts. In addition, NiN4/Fe4 exhibits the best ORR activity with an overpotential of 0.30 V, far superior to the pristine NiN4 SAC (0.88 V). Electronic structure analyses reveal that the significantly enhanced ORR/OER activity can be ascribed to the orbital and charge redistribution of Ni/Ir active center, resulting from its electronic interaction with Fe4 cluster. This work could stimulate and guide the rational design of graphene-based multifunctional SACs realized by axial coordination of small TM clusters, and provide insights into the modulation mechanism.

TS-1 zeolite encapsulated Pt clusters with enhanced electronic metal-support interaction of Pt−O(H)−Ti for nearly-zero-carbon-emitting photocatalytic hydrogen production from methanol

Photocatalytic H2 production from methanol is sustainable, yet challenges remain in avoiding carbon-containing gaseous by-products. Titanium silicalite-1 (TS-1) zeolite possesses attractive photocatalytic performance, but lack of modification strategies due to its microporous framework. Herein, we developed a pre-anchoring strategy to confine ultra-small Pt clusters inside TS-1 with ultra-low loading (0.2 mol%), in which Pt were anchored in Ti−OH nests by electronic metal-support interaction (EMSI). The optimal catalyst achieved a remarkable H2 generation rate of 63.2 mmol g–1 h–1 in CH3OH solutions, along with the production of high-value chemical HCHO as the oxidation product with 96.9% selectivity. Investigations reveal that the EMSI between Pt and Ti facilitated the selective decomposition of CH3OH to H2 and HCHO, leading to a nearly zero-carbon-emission process. Accordingly, we propose a light-driven carbon-negative "CO2→CH3OH→H2" route, coupling CO2 utilization and green H2 production with CH3OH as the intermediate, therefore offering a new perspective for "liquid sunshine".

Size-Dependent Catalysis in Fenton-like Chemistry: From Nanoparticles to Single Atoms.

State-of-the-art Fenton-like reactions are crucial in advanced oxidation processes (AOPs) for water purification. This review explores the latest advancements in heterogeneous metal-based catalysts within AOPs, covering nanoparticles (NPs), single-atom catalysts (SACs), and ultra-small atom clusters. A distinct connection between the physical properties of these catalysts, such as size, degree of unsaturation, electronic structure, and oxidation state, and their impacts on catalytic behavior and efficacy in Fenton-like reactions. In-depth comparative analysis of metal NPs and SACs is conducted focusing on how particle size variations and metal-support interactions affect oxidation species and pathways. The review highlights the cutting-edge characterization techniques and theoretical calculations, indispensable for deciphering the complex electronic and structural characteristics of active sites in downsized metal particles. Additionally, the review underscores innovative strategies for immobilizing these catalysts onto membrane surfaces, offering a solution to the inherent challenges of powdered catalysts. Recent advances in pilot-scale or engineering applications of Fenton-like-based devices are also summarized for the first time. The paper concludes by charting new research directions, emphasizing advanced catalyst design, precise identification of reactive oxygen species, and in-depth mechanistic studies. These efforts aim to enhance the application potential of nanotechnology-based AOPs in real-world wastewater treatment.

Ultrasmall and Highly Dispersed Pt Entities Deposited on Mesoporous N-doped Carbon Nanospheres by Pulsed CVD for Improved HER.

Vapor-based deposition techniques are emerging approaches for the design of carbon-supported metal powder electrocatalysts with tailored catalyst entities, sizes, and dispersions. Herein, a pulsed CVD (Pt-pCVD) approach is employed to deposit different Pt entities on mesoporous N-doped carbon (MPNC) nanospheres to design high-performance hydrogen evolution reaction (HER) electrocatalysts. The influence of consecutive precursor pulse number (50-250) and deposition temperature (225-300°C) are investigated. The Pt-pCVD process results in highly dispersed ultrasmall Pt clusters (≈1nm in size) and Pt single atoms, while under certain conditions few larger Pt nanoparticles are formed. The best MPNC-Pt-pCVD electrocatalyst prepared in this work (250 pulses, 250°C) reveals a Pt HER mass activity of 22.2 ± 1.2Amg-1 Pt at -50mV versus the reversible hydrogen electrode (RHE), thereby outperforming a commercially available Pt/C electrocatalyst by 40% as a result of the increased Pt utilization. Remarkably, after optimization of the Pt electrode loading, an ultrahigh Pt mass activity of 56 ± 2Amg-1 Pt at -50mV versus RHE is found, which is among the highest Pt mass activities of Pt single atom and cluster-based electrocatalysts reported so far.

Enhanced Proximity of Rh1,2-Rhn Ensembles Encaged in UiO-67 Boosting Catalytic Conversion of Syngas to Oxygenates.

Maintaining high conversion under the premise of high oxygenates selectivity in syngas conversion is important but a formidable challenge in Rh catalysis. Monometallic Rh catalysts provide poor oxygenate conversion efficiency, and efforts have been focused on constructing adjacent polymetallic sites; however, the one-pass yields of C2+ oxygenates over the reported Rh-based catalysts were mostly <20 %. In this study, we constructed a monometallic Rh catalyst encapsulated in UiO-67 (Rh/UiO-67) with enhanced proximity to dual-site Rh1,2-Rhn ensembles. Unexpectedly, this catalyst exhibited high efficacy for oxygenate synthesis from syngas, giving a high oxygenate selectivity of 72.0 % with a remarkable CO conversion of 50.4 %, and the one-pass yield of C2+ oxygenates exceeded 25 %. The state-of-the-art characterizations further revealed the spontaneous formation of an ensemble of Rh single atoms/dimers (Rh1,2) in the proximity of ultrasmall Rh clusters (Rhn) confined within the nanocavity of UiO-67, providing adjacent Rh+-Rh0 dual sites dynamically during the reaction that promote the relay of the undissociated CHO species to the CHx species. Thus, our results open a new route for designing highly efficient Rh catalysts for the conversion of syngas to oxygenates by precisely tuning the ensemble and proximity of the dual active sites in a confined space.

Enhanced Proximity of Rh1,2‐Rhn Ensembles Encaged in UiO‐67 Boosting Catalytic Conversion of Syngas to Oxygenates

AbstractMaintaining high conversion under the premise of high oxygenates selectivity in syngas conversion is important but a formidable challenge in Rh catalysis. Monometallic Rh catalysts provide poor oxygenate conversion efficiency, and efforts have been focused on constructing adjacent polymetallic sites; however, the one‐pass yields of C2+ oxygenates over the reported Rh‐based catalysts were mostly &lt;20 %. In this study, we constructed a monometallic Rh catalyst encapsulated in UiO‐67 (Rh/UiO‐67) with enhanced proximity to dual‐site Rh1,2‐Rhn ensembles. Unexpectedly, this catalyst exhibited high efficacy for oxygenate synthesis from syngas, giving a high oxygenate selectivity of 72.0 % with a remarkable CO conversion of 50.4 %, and the one‐pass yield of C2+ oxygenates exceeded 25 %. The state‐of‐the‐art characterizations further revealed the spontaneous formation of an ensemble of Rh single atoms/dimers (Rh1,2) in the proximity of ultrasmall Rh clusters (Rhn) confined within the nanocavity of UiO‐67, providing adjacent Rh+‐Rh0 dual sites dynamically during the reaction that promote the relay of the undissociated CHO species to the CHx species. Thus, our results open a new route for designing highly efficient Rh catalysts for the conversion of syngas to oxygenates by precisely tuning the ensemble and proximity of the dual active sites in a confined space.

Modulating CO2 Electrocatalytic Conversion to the Organics Pathway by the Catalytic Site Dimension.

Electrochemical reduction of carbon dioxide to organic chemicals provides a value-added route for mitigating greenhouse gas emissions. We report a family of carbon-supported Sn electrocatalysts with the tin size varying from single atom, ultrasmall clusters to nanocrystallites. High single-product Faradaic efficiency (FE) and low onset potential of CO2 conversion to acetate (FE = 90% @ -0.6 V), ethanol (FE = 92% @ -0.4 V), and formate (FE = 91% @ -0.6 V) were achieved over the catalysts of different active site dimensions. The CO2 conversion mechanism behind these highly selective, size-modulated p-block element catalysts was elucidated by structural characterization and computational modeling, together with kinetic isotope effect investigation.

Soluble individual metal atoms and ultrasmall clusters catalyze key synthetic steps of a natural product synthesis

Metal individual atoms and few-atom clusters show extraordinary catalytic properties for a variety of organic reactions, however, their implementation in total synthesis of complex organic molecules is still to be determined. Here we show a 11-step linear synthesis of the natural product (±)-Licarin B, where individual Pd atoms (Pd1) catalyze the direct aerobic oxidation of an alcohol to the carboxylic acid (steps 1 and 6), Cu2-7 clusters catalyze carbon-oxygen cross couplings (steps 3 and 8), Pd3-4 clusters catalyze a Sonogashira coupling (step 4) and Pt3-5 clusters catalyze a Markovnikov hydrosylilation of alkynes (step 5), as key reactions during the synthetic route. In addition, the new synthesis of Licarin B showcases an unexpected selective alkene hydrogenation with metal-free NaBH4 and an acid-catalyzed intermolecular carbonyl-olefin metathesis as the last step, to forge a trans-alkene group. These results, together, open new avenues in the use of metal individual atoms and clusters in organic synthesis, and confirm their exceptional catalytic activity in late stages during complex synthetic programmes.

Constructing superparaelectric polar structure for dielectric energy storage

To meet the miniaturization demands of next-generation electronics and electrical systems, energy storage capacitors with both high energy density and efficiency have become a research hotspot. Ferroelectric-based dielectrics are primary candidates due to the existence of spontaneous polarization and versatile domain structures. Since domains are fundamental structure units that respond to the external electric field, domain engineering is a general route to realizing high energy storage performance. In this perspective, we introduce a type of dielectrics, proposed recently and termed superparaelectrics, which has ultrasmall polar clusters (several unit cells) and exhibits nearly zero hysteresis and relatively high polarization due to the highly dynamical polar structure. Fundamental concepts of superparaelectricity are overviewed, and representative examples with state-of-the-art energy storage performance are reviewed to demonstrate the advantages of superparaelectrics. Finally, perspectives are provided about the future development of superparaelectric and electrostatic energy storage fields.

Design engineering of MOF-derived ZnO porous nanofibers functionalized with Pt clusters: Significantly improved acetone sensing properties

For high-performance gas sensors to be used in practical applications, high sensitivity and ultrafast response are essential. Herein, metal–organic framework (MOF)-derived Pt@ZnO porous nanofibers (PNFs) were constructed by using Pt@ZIF-8 as an electrospun precursor. This brand-new Pt@ZnO PNFs combined the benefits of the two classes of porous materials (MOFs and PNFs) and therefore exhibited open porous characteristics. This mesh fiber structure also prevented the growth and aggregation of ultra-small Pt clusters of about 2 nm. As a typical case study, the 0.5 mL Pt@ZnO PNFs demonstrated good sensing performances characterized by high acetone responses (12.2-fold improvement @ 20 ppm) and fast response/recovery times (2 s/5 s) in comparison with ZnO nanocubes. The Pt@ZnO PNFs also displayed good stability and selectivity towards acetone. We credited these improved sensing signals to synergic interactions between Pt clusters and ZnO nanoparticles, the catalytic spillover effect of Pt clusters, and unique mesh nanofiber structure with open porous characteristics. This work provides a novel design method to construct MOF-derived ultra-small noble metal cluster modified mesh metal oxide PNFs with high gas-sensing performance.

Ru clusters anchored on N-doped porous carbon-alumina matrix as efficient catalyst toward primary amines via reductive amination

Efficient synthesis of primary amines via reductive amination from carbonyl compounds using NH3 and H2 as nitrogen and hydrogen sources is promising and challenging. Herein, we reported the ultrasmall Ru clusters bonded to the nitrogen atoms encapsulated in nitrogen-dopped carbon layers supported on alumina (Ru@NC-Al2O3) derived from metalated Al-MOF containing atomically dispersed Ru species, which served as highly active, selective, and reusable catalyst for the facile synthesis of primary amines. A series of carbonyl compounds including aliphatic and aryl ketones or aldehydes were converted to their corresponding primary amines under mild conditions. The excellent catalytic performance was attributed to the Ru-N coordination which could help to stabilize the Ru species and prevent their aggregation and leaching, and also ascribed to the proper Ru0 percentage that was facilitate the hydrogenation step, as well as originated from the Lewis acid sites that was beneficial to the activation of CN bond in intermediates.

Atomically precise ultrasmall copper cluster for room-temperature highly regioselective dehydrogenative coupling

Three-component dehydrogenative coupling reactions represent important and practical methodologies for forging new C–N bonds and C–C bonds. Achieving highly all-in-one dehydrogenative coupling functionalization by a single catalytic system remains a great challenge. Herein, we develop a rigid-flexible-coupled copper cluster [Cu3(NHC)3(PF6)3] (Cu3NC(NHC)) using a tridentate N-heterocyclic carbene ligand. The shell ligand endows Cu3NC(NHC) with dual attributes, including rigidity and flexibility, to improve activity and stability. The Cu3NC(NHC) is applied to catalyze both highly all-in-one dehydrogenative coupling transformations. Mechanistic studies and density functional theory illustrate that the improved regioselectivity is derived from the low energy of ion pair with copper acetylide and endo-iminium ions and the low transition state, which originates from the unique physicochemical properties of the Cu3NC(NHC) catalyst. This work highlights the importance of N-heterocyclic carbene in the modification of copper clusters, providing a new design rule to protect cluster catalytic centers and enhance catalysis.

Covalently anchoring silver nanoclusters Ag44 on modified UiO-66-NH2 with Bi2S3 nanorods and MoS2 nanoparticles for exceptional solar wastewater treatment activity

For the first time, covalently anchoring size selected silver nanoclusters [Ag44(MNBA)30] on the Bi2S3@UiO-66-NH2 and MoS2@UiO-66-NH2 heterojunctions were constructed as novel photocatalysts for photodegradation of methylene blue (MB) dye. The anchoring of Ag44 on MoS2@UiO-66-NH2 and Bi2S3@UiO-66-NH2 heterojunctions extended the light absorption of UiO-66-NH2 to the visible region and improved the transfer and separation of photogenerated charge carriers through the heterojunctions with a unique band gap structure. The UV–Vis-NIR diffuse reflectance spectroscopic analysis confirmed that the optical absorption properties of the UiO-66-NH2 were shifted from the UV region at 379 nm to the visible region at ~ 705 nm after its doping with Bi2S3 nanorods and Ag44 nanoclusters (Bi2S3@UiO-66-NH-S-Ag44). The prepared Bi2S3@UiO-66-NH-S-Ag44 and MoS2@UiO-66-NH-S-Ag44 photocatalysts exhibited exceptional photocatalytic activity for visible light degradation of MB dye. The photocatalysts exhibited complete decolorization of the MB solution (50 ppm) within 90 and 120 min stirring under visible light irradiation, respectively. The supper photocatalytic performance and recycling efficiency of the prepared photocatalysts attributed to the covalent anchoring of the ultra-small silver clusters (Ag44) on the heterojunctions surface. The X-ray photoelectron spectroscopic analysis confirmed the charge of the silver clusters is zero. The disappearance of the N–H bending vibration peak of primary amines in the FTIR analysis of Bi2S3@UiO-66-NH-S-Ag44 confirmed the covalent anchoring of the protected silver nanoclusters on the UiO-66-NH2 surface via the condensation reaction. The Bi2S3@UiO-66-NH-S-Ag44 catalyst exhibited excellent recyclability efficiency more than five cycles without significant loss in activity, indicating their good potential for industrial applications. The texture properties, crystallinity, phase composition, particle size, and structural morphology of the prepared photocatalysts were investigated using adsorption–desorption N2 isotherms, X-ray diffraction (XRD), HR-TEM, and FE-SEM, respectively.