Revisiting the activity origin of the PtAu24(SR)18 nanocluster for enhanced electrocatalytic hydrogen evolution by combining first-principles simulations with the experimental in situ FTIR technique.

Thiolate-protected metal nanoclusters (NCs) have been widely used in various electrocatalytic reactions, yet the dynamic evolution of metal NCs during electrocatalysis has been rarely explored and the activity origin remains largely ambiguous. Herein, using a PtAu24(SCH3)18 NC as a prototype model, we combined advanced first-principles calculations and attenuated total reflection surface-enhanced infrared spectroscopy (ATR-SEIRAS) to re-examine its active site and reaction dynamics in the hydrogen evolution reaction (HER). It has been previously assumed that the central Pt is the only catalytic center. However, differently, we observed the spontaneous desorption of thiolate ligands under moderate potential, and the dethiolated PtAu24 exhibits excellent HER activity, which is contributed not only by the central Pt atom but also by the exposed bridged Au sites. Particularly, the exposed Au exhibits high activity even comparable to Pt, and the synergistic effect between them makes dethiolated PtAu24 an extraordinary HER electrocatalyst, even surpassing the commercial Pt/C catalyst. Our predictions are further verified by electrochemical activation experiments and in situ FTIR (ATR-SEIRAS) characterization, where evident adsorption of Au-H* and Pt-H* bonds is monitored. This work detected, for the first time, the Au-S interfacial dynamics of the PtAu24 nanocluster in electrocatalytic processes, and quantitatively evaluated the essential catalytic role of the exposed Au sites that has been largely overlooked in previous studies.

Atomically precise alkynyl-protected Ag19Cu2 nanoclusters: synthesis, structure analysis, and electrocatalytic CO2 reduction application.

We report the synthesis, structure analysis, and electrocatalytic CO2 reduction application of Ag19Cu2(CCArF)12(PPh3)6Cl6 (abbreviated as Ag19Cu2, CCArF: 3,5-bis(trifluoromethyl)phenylacetylene) nanoclusters. Ag19Cu2 has characteristic absorbance features and is a superatomic cluster with 2 free valence electrons. Single-crystal X-ray diffraction (SC-XRD) revealed that the metal core of Ag19Cu2 is composed of an Ag11Cu2 icosahedron connected by two Ag4 tetrahedra at the two terminals of the Cu-Ag-Cu axis. Notably, Ag19Cu2 exhibited excellent catalytic performance in the electrochemical CO2 reduction reaction (eCO2RR), manifested by a high CO faradaic efficiency of 95.26% and a large CO current density of 257.2 mA cm-2 at -1.3 V. In addition. Ag19Cu2 showed robust long-term stability, with no significant drop in current density and FECO after 14 h of continuous operation. Density functional theory (DFT) calculations disclosed that the high selectivity of Ag19Cu2 for CO in the eCO2RR process is due to the shedding of the -CCArF ligand from the Ag atom at the very center of the Ag4 unit, exposing the active site. This study enriches the potpourri of alkynyl-protected bimetallic nanoclusters and also highlights the great advantages of using atomically precise metal nanoclusters to probe the atomic-level structure-performance relationship in the catalytic field.

Cu Nanowires Encapsulated by ZIF67 for Efficient Ammonia Electrosynthesis from Nitrate.

Electrochemical NO3- reduction reaction (NO3RR) represents a green and sustainable way to produce valuable NH3 for both NH3 production and nitrate contaminant removal, and developing efficient, durable, highly selective catalyst is the key. Herein, we report a facile method to fabricate a catalyst composed of ultrafine Cu nanowires (Cu NWs) encapsulated by ZIF67, namely, CuNW@ZIF67, for efficient NH3 electrosynthesis from nitrate. The CuNW@ZIF67 catalyst exhibited excellent catalytic performance toward NO3RR in alkaline electrolyte, manifested by a large NH3 Faradaic efficiency of 93.7% at -0.5 V versus reversible hydrogen electrode (RHE), a high energy efficiency over 30% at -0.7 V, and robust long-term stability. Such intriguing catalytic properties are mainly ascribed to its structural merits and the strong electronic interaction between Cu NWs and ZIF67. DFT calculations revealed that, the Cu site can easily convert NO3- into NO2-, while the Co site plays a critical role in catalyzing the NO2--to-NH3 process. The study can shed light on rational design of efficient, durable, and highly selective catalysts for NO3RR and beyond.

Rational Design Toward Advanced Non-Flow Aqueous Zinc-Bromine Systems Boosted by Alkaline-Neutral Decoupling Electrolytes.

Non-flow aqueous zinc-bromine batteries (AZBBs) are highly attractive owing to their lightweight construction and largely reduced cost compared with the flow ones. Yet, their development is restricted by the sluggish reaction kinetics of Br2/Br-, the shuttle of soluble polybromide species (Brn -, n is odd), and the poor stability of Zn-based anode. Herein, an effective alkaline-neutral electrolyte decoupling system is constructed to mitigate these issues, where nitrogen-doped carbon felt with high catalytic activity to Br2/Br- reaction is developed for cathode, a cost-effective cation exchange membrane (CEM) of polyethersulfone/sulfonated polyether ether ketone (PES/SPEEK-M) that can stop Brn - is used as separator, and glucose that can inhibit dendrites is introduced as anolyte additive. The constructed flowless AZBB mainly consists of two separate redox couples, including Zn/Zn(OH)4 2- in alkaline anolyte and Br2/Br- in neutral media, where non-cations (e.g. OH-, Zn(OH)4 2-, H2O,  and Brn -) can be restricted to their respective chamber by the PES/SPEEK-M while cations can pass by. In the optimized system, good electrochemical performance is achieved, mainly including a surprising discharge voltage of 2.01 V, a high average Coulombic efficiency of 96.7%, and a good cycling life of ≈1000 cycles without obvious capacity decay at a fixed charge capacity of 2 mAh cm-2.

-SR removal or -R removal? A mechanistic revisit on the puzzle of ligand etching of Au25(SR)18 nanoclusters during electrocatalysis.

Accurate identification of active sites is highly desirable for elucidation of the reaction mechanism and development of efficient catalysts. Despite the promising catalytic performance of thiolated metal nanoclusters (NCs), their actual catalytic sites remain elusive. Traditional first-principles calculations and experimental observations suggested dealkylated S and dethiolated metal, respectively, to be the active centers. However, the real kinetic origin of thiolate etching during the electrocatalysis of NCs is still puzzling. Herein, we conducted advanced first-principles calculations and electrochemical/spectroscopic experiments to unravel the electrochemical etching kinetics of thiolate ligands in prototype Au25(SCH3)18 NC. The electrochemical processes are revealed to be spontaneously facilitated by dethiolation (i.e., desorption of -SCH3), forming the free HSCH3 molecule after explicitly including the solvent effect and electrode potential. Thus, exposed under-coordinated Au atoms, rather than the S atoms, serve as the real catalytic sites. The thermodynamically preferred Au-S bond cleavage arises from the selective attack of H from proton/H2O on the S atom under suitable electrochemical bias due to the spatial accessibility and the presence of S lone pair electrons. Decrease of reduction potential promotes the proton attack on S and significantly accelerates the kinetics of Au-S bond breakage irrespective of the pH of the medium. Our theoretical results are further verified by the experimental electrochemical and spectroscopic data. At more negative electrode potentials, the number of -SR ligands decreased with concomitant increase of the vibrational intensity of S-H bonds. These findings together clarify the atomic-level activation mechanism on the surface of Au25(SR)18 NCs.

Synthesis, structure anatomy, and catalytic properties of Ag14Cu2 nanoclusters co-protected by alkynyl and phosphine ligands.

We report the synthesis, structure anatomy, and catalytic properties of Ag14Cu2(CCArF)14(PPh3)4 (CCArF: 3,5-bis(trifluoromethyl)phenylacetylene) nanoclusters, denoted as Ag14Cu2. Ag14Cu2 has a robust electronic structure with two free valence electrons, and it has a distinctive absorbance feature. Single-crystal X-ray diffraction (SC-XRD) disclosed that Ag14Cu2 possesses an octahedral Ag6 metal kernel capped by two Ag4Cu1(CCArF)7(PPh3)2 metal-ligand units. Remarkably, it exhibits excellent bifunctional catalytic performance for 4-nitrophenol reduction and the electrochemical CO2 reduction reaction (eCO2RR). In 4-nitrophenol reduction, it adopts first-order reaction kinetics with a rate constant of 0.137 min-1, while in the eCO2RR, it shows a CO faradaic efficiency (FECO) of 83.71% and a high current density of 92.65 mA cm-2 at -1.6 V vs. RHE. Moreover, Ag14Cu2 showed robust long-term stability with no significant decay in current density and FECO over 10 h of continuous operation in the eCO2RR. This study not only enriches the potpourri of alkynyl-protected bimetallic AgCu nanoclusters, but also demonstrates the great potential of employing metal nanoclusters for bifunctional catalytic applications.

Alkynyl-protected Ag20 Rh2 Nanocluster with Atomic Precision: Structure Analysis and Tri-functionality Catalytic Application.

We report the overall structure and trifunctionality catalytic application of an atomically precise alloy nanocluster of Ag20 Rh2 (C≡C-t Bu)16 (CF3 CO2 )6 (H2 O)2 (abbreviated as Ag20 Rh2 hereafter). Ag20 Rh2 has a twisted rod-like structure, where a Ag4 @Rh2 kernel is connected by two twisted Ag8 cubes on two sides. Ag20 Rh2 is a superatomic cluster with four free valence electrons, and it has characteristic absorbance feature. Interestingly, Ag20 Rh2 exhibited superior catalytic performance than the larger AgRh nanoparticle counterparts in electrochemical hydrogen evolution reaction (HER), reduction of 4-nitrophenol, and the methyl orange degradation reaction. Such intriguing catalytic properties are attributed to the more exposed active sites from the ultrasmall nanoclusters than relatively large nanoparticles. This study not only enriches the family member of alkynyl-protected AgRh nanoclusters with atomic precision, but also highlights the great advantages of employing nanoclusters as efficient catalysts for multiple functionalities.

Structure, optical properties, and catalytic applications of alkynyl-protected M4Rh2 (M = Ag/Au) nanoclusters with atomic precision: a comparative study.

We report two atomically precise alloy nanoclusters of Ag4Rh2(CCArF)8(PPh3)2 and Au4Rh2(CCArF)8(PPh3)2 (Ar = 3,5-(CF3)2C6H3, abbreviated as Ag4Rh2 and Au4Rh2, respectively) co-protected by alkynyl and phosphine ligands. Both clusters have identical octahedral metal core configurations and can be termed superatoms with two free electrons. However, they possess different optical features, manifested by totally different absorbance peaks, and drastically different emission peaks, and also, Ag4Rh2 has a much higher fluorescence quantum yield (18.43%) than Au4Rh2 (4.98%). Moreover, Au4Rh2 exhibited markedly superior catalytic performance in the electrochemical hydrogen evolution reaction (HER), manifested by a much lower overpotential at 10 mA cm-2 and better stability. Density functional theory (DFT) calculations revealed that the free energy change of Au4Rh2 for the adsorption of two H* (0.64 eV) is lower than that of Ag4Rh2 for the adsorption of one H* (-0.90 eV) after stripping a single alkynyl ligand from the cluster. In contrast, Ag4Rh2 demonstrated much stronger catalytic capability for catalyzing 4-nitrophenol reduction. The present study provides an exquisite example to understand the structure-property relationship of atomically precise alloy nanoclusters, and emphasizes the importance of fine-tuning of the physicochemical properties and catalytic performance of the metal nanoclusters through modulating the metal core and beyond.

Electrochemical NO3- Reduction Catalyzed by Atomically Precise Ag30Pd4 Bimetallic Nanocluster: Synergistic Catalysis or Tandem Catalysis?

Electrochemically converting NO3- compounds into ammonia represents a sustainable route to remove industrial pollutants in wastewater and produce valuable chemicals. Bimetallic nanomaterials usually exhibit better catalytic performance than the monometallic counterparts, yet unveiling the reaction mechanism is extremely challenging. Herein, we report an atomically precise [Ag30Pd4 (C6H9)26](BPh4)2 (Ag30Pd4) nanocluster as a model catalyst toward the electrochemical NO3- reduction reaction (eNO3-RR) to elucidate the different role of the Ag and Pd site and unveil the comprehensive catalytic mechanism. Ag30Pd4 is the homoleptic alkynyl-protected superatom with 2 free electrons, and it has a Ag30Pd4 metal core where 4 Pd atoms are located at the subcenter of the metal core. Furthermore, Ag30Pd4 exhibits excellent performance toward eNO3-RR and robust stability for prolonged operation, and it can achieve the highest Faradaic efficiency of NH3 over 90%. In situ Fourier-transform infrared study revealed that a Ag site plays a more critical role in converting NO3- into NO2-, while the Pd site makes a major contribution to catalyze NO2- into NH3. The bimetallic nanocluster adopts a tandem catalytic mechanism rather than a synergistic catalytic effect in eNO3-RR. Such finding was further confirmed by density functional theory calculations, as they disclosed that Ag is the most preferable binding site for NO3-, which then binds a water molecule to release NO2-. Subsequently, NO2- can transfer to the vicinal exposed Pd site to promote NH3 formation.

Heterostructure of NiFe@NiCr-LDH for Active and Durable Oxygen Evolution Reactions in Alkaline Media.

Developing cost-effective, efficient, and durable catalysts for oxygen evolution reactions (OER) is the key for promoting large-scale H2 production through electrochemical water splitting. Herein, we report a facile method for fabricating an NiFe@NiCr-LDH catalyst toward alkaline OER. The electronic microscopy technique revealed that it has a well-defined heterostructure at the interface between the NiFe and NiCr phases. In 1.0 M KOH, the as-prepared NiFe@NiCr-LDH catalyst shows excellent catalytic performance, evidenced by an overpotential of 266 mV at the current density of 10 mA cm-2 and a small Tafel slope of 63 mV dec-1; both are comparable with the RuO2 benchmark catalyst. It also exhibits robust durability in long-term operation, manifested by a 10% current decay in 20 h, which is superior to that of the RuO2 catalyst. Such excellent performance is attributed to the interfacial electron transfer that occurs at the interfaces of the heterostructure, and the Fe(III) species facilitate the formation of Ni(III) species as active sites in NiFe@NiCr-LDH. This study offers a feasible strategy for preparing a transition metal-based LDH catalyst for OER toward H2 production and other electrochemical energy technologies.

Effects of prenatal exposure to bisphenols on newborn leucocyte telomere length: a prospective birth cohort study in China.

Telomere length (TL) at birth is related to diseases that may arise in the future and long-term health. Bisphenols exhibit toxic effects and can cross the placenta barrier. However, the effects of prenatal exposure to bisphenols on newborn TL remain unknown. We aimed to explore the effects of prenatal exposure to bisphenols (i.e., bisphenol A [BPA], bisphenol B [BPB], bisphenol F [BPF], bisphenol S [BPS] and tetrabromobisphenol A [TBBPA]) on relative TL in newborns. A total of 801 mother-infant pairs were extracted from the Guangxi Zhuang Birth Cohort. The relationship between bisphenol levels in maternal serum and relative TL in cord blood was examined by generalized linear models and restricted cubic spline (RCS) models. After adjusting for confounders, we observed a 3.19% (95% CI: -6.08%, -0.21%; P = 0.037) reduction in relative cord blood TL among mothers ≥ 28 years old, with each onefold increase in BPS. However, in each onefold increase of TBBPA, we observed a 3.31% (95% CI: 0.67%, 6.01%; P = 0.014) increase in relative cord blood TL among mothers < 28 years old. The adjusted RCS models revealed similar results (P overall < 0.05, P non-linear > 0.05). This study was the first to establish a positive association between serum TBBPA levels and relative TL in newborns born to young mothers. However, BPS levels were inversely correlated with TL in fetus born to old mothers. The results suggested that the fetus of old pregnant women may be more sensitive to BPS exposure. Moreover, BPS exposure early in life may accelerate aging or increase the risk of developing BPS-related diseases in later life.

Electrochemical CO2 reduction catalyzed by atomically precise alkynyl-protected Au7Ag8, Ag9Cu6, and Au2Ag8Cu5 nanoclusters: probing the effect of multi-metal core on selectivity.

Doping metal nanoclusters (NCs) with another metal usually leads to superior catalytic performance toward CO2 reduction reaction (CO2RR), yet elucidating the metal core effect is still challenging. Herein, we report the systematic study of atomically precise alkynyl-protected Au7Ag8, Ag9Cu6, and Au2Ag8Cu5 NCs toward CO2RR. Au2Ag8Cu5 prepared by a site-specific metal exchange approach from Ag9Cu6 is the first case of trimetallic superatom with full-alkynyl protection. The three M15 clusters exhibited drastically different CO2RR performance. Specifically, Au7Ag8 demonstrated high selectivity for CO formation in a wide voltage range (98.1% faradaic efficiency, FE, at -0.49 V and 89.0% FE at -1.20 V vs. RHE), while formation of formate becomes significant for Ag9Cu6 and Au2Ag8Cu5 at more negative potentials. DFT calculations demonstrated that the exposed, undercoordinated metal atoms are the active sites and the hydride transfer as well as HCOO* stabilization on the Cu-Ag site plays a critical role in the formate formation. Our work shows that, tuning the metal centers of the ultrasmall metal NCs via metal exchange is very useful to probe the structure-selectivity relationships for CO2RR.

Alkynyl and halogen co-protected (AuAg)44 nanoclusters: a comparative study on their optical absorbance, structure, and hydrogen evolution performance.

We report the synthesis, structure, and electrochemical hydrogen evolution reaction (HER) performance of two alkynyl and halogen coprotected AuAg alloy nanoclusters, namely Au24Ag20(tBuPh-CC)24Cl2 (NC 1 for short) and Au22Ag22(tBuCC)16Br3.28Cl2.72 (NC 2 for short). Single crystal X-ray structural analysis revealed that the two nanoclusters possess a rather similar core@shell@shell keplerate metal core configuration to M12@M20@M12 with the main difference in the outermost shell (Au12vs. Au10Ag2). Interestingly, such a subtle difference in the two-metal-atoms results in different optical absorbance features and drastically different HER performances. Both NCs have excellent long-term stability for the HER, but NC 1 possesses superior activity to NC 2, and density functional theory calculations disclosed that the binding energy of hydrogen to form the key *H intermediate for NC 1 is much lower and hence it adopts a more energetically feasible HER pathway.

Engineering Gold Nanostructures for Cancer Treatment: Spherical Nanoparticles, Nanorods, and Atomically Precise Nanoclusters.

Cancer is a major global health issue and is a leading cause of mortality. It has been documented that various conventional treatments can be enhanced by incorporation with nanomaterials. Thanks to their rich optical properties, excellent biocompatibility, and tunable chemical reactivities, gold nanostructures have been gaining more and more research attention for cancer treatment in recent decades. In this review, we first summarize the recent progress in employing three typical gold nanostructures, namely spherical Au nanoparticles, Au nanorods, and atomically precise Au nanoclusters, for cancer diagnostics and therapeutics. Following that, the challenges and the future perspectives of this field are discussed. Finally, a brief conclusion is summarized at the end.

Mangrove Root-Inspired Carbon Nanotube Film for Micro-Direct Methanol Fuel Cells.

The functional microporous layer, acting as a mass-transfer control medium with a rational structure and surface morphology as well as high electrical conductivity, significantly affects the performance of micro-direct methanol fuel cells (µDMFCs). Bioinspired by the architecture and multi-functional properties of mangrove roots, this study develops a simple and versatile strategy based on magnetron sputtering and chemical vapor deposition to fabricate a mangrove root-inspired carbon nanotube film (MR-CNTF) as the functional interface in µDMFCs. It has features such as ultralightweight, high porosity, and good electrical conductivity. During the synthesis process, an apex-growth model of CNTF is identified. The results indicate that the MR-CNTF used as a cathodic microporous layer can remarkably facilitate the oxygen transport and water management. Because of its multi-functional structure and excellent material characteristics, the passive µDMFC displays a peak power density of 14.9 mW cm-2 at 68 mA cm-2. This value is 88.6% higher than the highest power density of the one based on a carbon nanotube array (7.9 mW cm-2) and 45% higher than that of the conventional carbon black (10.7 mW cm-2). We believe that this novel material with its multi-functional structure illuminates a promising application for fuel cells and other energy storage and conversion devices.

A homoleptic alkynyl-protected [Ag9Cu6( t BuC[triple bond, length as m-dash]C)12]+ superatom with free electrons: synthesis, structure analysis, and different properties compared with the Au7Ag8 cluster in the M15 + series.

We report the first homoleptic alkynyl-protected AgCu superatomic nanocluster [Ag9Cu6( t BuC[triple bond, length as m-dash]C)12]+ (NC 1, also Ag9Cu6 in short), which has a body-centered-cubic structure with a Ag1@Ag8@Cu6 metal core. Such a configuration is reminiscent of the reported AuAg bimetallic nanocluster [Au1@Ag8@Au6( t BuC[triple bond, length as m-dash]C)12]+ (NC 2, also Au7Ag8 in short), which is also synthesized by an anti-galvanic reaction (AGR) approach with a very high yield for the first time in this study. Despite a similar Ag8 cube for both NCs, structural anatomy reveals that there are some subtle differences between NCs 1 and 2. Such differences, plus the different M1 kernel and M6 octahedron, lead to significantly different optical absorbance features for NCs 1 and 2. Density functional theory calculations revealed the LUMO and HOMO energy levels of NCs 1 and 2, where the characteristic absorbance peaks can be correlated with the discrete molecular orbital transitions. Finally, the stability of NCs 1 and 2 at different temperatures, in the presence of an oxidant or Lewis base, was investigated. This study not only enriches the M15 + series, but also sets an example for correlating the structure-property relationship in alkynyl-protected bimetallic superatomic clusters.

Homoleptic Alkynyl-Protected Ag15 Nanocluster with Atomic Precision: Structural Analysis and Electrocatalytic Performance toward CO2 Reduction.

We report the fabrication of homoleptic alkynyl-protected Ag15 (C≡C-t Bu)12 + (abbreviated as Ag15 ) nanocluster and its electrocatalytic properties toward CO2 reduction reaction. Crystal structure analysis reveals that Ag15 possesses a body-centered-cubic (BCC) structure with an Ag@Ag8 @Ag6 metal core configuration. Interestingly, we found that Ag15 can adsorb CO2 in the air and spontaneously self-assembled into one-dimensional linear material during the crystal growth process. Furthermore, Ag15 can convert CO2 into CO with a faradaic efficiency of ca. 95.0 % at -0.6 V and a maximal turnover frequency of 6.37 s-1 at -1.1 V along with excellent long-term stability. Finally, density functional theory (DFT) calculations disclosed that Ag15 (C≡C-t Bu)11 + with one alkynyl ligand stripping off from the intact cluster can expose the uncoordinated Ag atom as the catalytically active site for CO formation.

Single-atom catalyst for high-performance methanol oxidation.

Single-atom catalysts have been widely investigated for several electrocatalytic reactions except electrochemical alcohol oxidation. Herein, we synthesize atomically dispersed platinum on ruthenium oxide (Pt1/RuO2) using a simple impregnation-adsorption method. We find that Pt1/RuO2 has good electrocatalytic activity towards methanol oxidation in an alkaline media with a mass activity that is 15.3-times higher than that of commercial Pt/C (6766 vs. 441 mA mg‒1Pt). In contrast, single atom Pt on carbon black is inert. Further, the mass activity of Pt1/RuO2 is superior to that of most Pt-based catalysts previously developed. Moreover, Pt1/RuO2 has a high tolerance towards CO poisoning, resulting in excellent catalytic stability. Ab initio simulations and experiments reveal that the presence of Pt‒O3f (3-fold coordinatively bonded O)‒Rucus (coordinatively unsaturated Ru) bonds with the undercoordinated bridging O in Pt1/RuO2 favors the electrochemical dehydrogenation of methanol with lower energy barriers and onset potential than those encountered for Pt‒C and Pt‒Ru.

Controllable synthesis and formation mechanism study of homoleptic alkynyl-protected Au nanoclusters: recent advances, grand challenges, and great opportunities.

In the past decade, atomically precise coinage metal nanoclusters have been a subject of major interest in nanoscience and nanotechnology because of their determined compositions and well-defined molecular structures, which are beneficial for establishing structure-property relationships. Recently ligand engineering has been extended to alkynyl molecules. Homoleptic alkynyl-protected Au nanoclusters (Au NCs) have emerged as a hotspot of research interest, mainly due to their unique optical properties, molecular configuration, and catalytic functionalities, and more importantly, they are used as a counterpart object for fundamental study to compare with the well-established thiolate Au NCs. In this review, we first summarize the recently reported various controllable synthetic strategies for atomically precise homoleptic-alkynyl-protected Au NCs, with particular emphasis on the ligand exchange method, direct reduction of the precursor, one-pot synthesis, and the synchronous nucleation and passivation strategy. After that, we switch our focus to the formation mechanism and structure evolution process of homoleptic alkynyl-protected Au NCs, where Au144(PA)60 and Au36(PA)24 (PA = phenylacetylide) are given as examples, along with the prediction of the possible formation mechanism of some other cluster molecules. In the end of this review, the outlook and perspective of this rapidly developing field including grand challenges and great opportunities are discussed. This review can stimulate more research efforts towards developing new synthetic strategies to enrich the limited examples and unravel the formation/growth mechanism of homoleptic alkynyl-protected Au NCs.

Fast and high-yield synthesis of thiolate Ag44 and Au12Ag32 nanoclusters via the CTAB reverse micelle method.

To advance the development of atomically precise Ag and Ag-alloyed nanoclusters, it is critical to develop effective synthetic methods. Herein, we successfully extend the CTAB (cetyl trimethyl ammonium bromide) reverse micelle method to synthesize a high-purity Ag44(p-MBA)30 (p-MBA = para-mercaptobenzoic acid) nanocluster and its corresponding alloy cluster Au12Ag32(p-MBA)30 in a short time (15 min and 5 min), with a high yield of ∼83% and ∼85%, respectively. Furthermore, the mechanism regarding the reverse micelle method has been clearly elucidated. Through characterizing the reaction system by Raman spectroscopy and NMR spectroscopy techniques, it can be revealed that employing CTAB to form reverse micelles to construct a sealed chemical environment is critical for realizing the fast and high-yield synthesis.