Structure–performance relationship of Au nanoclusters in electrocatalysis:Metal core and ligand structure

Remarkable progress has characterized the field of electrocatalysis in recent decades,driven in part by an enhanced comprehension of catalyst structures and mechanisms at the nanoscale.Atomically precise metal nanoclusters,serving as exemplary models,significantly expand the range of accessible structures through diverse cores and ligands,creating an exceptional platform for the investigation of catalytic reactions.Notably,ligand‐protected Au nanoclusters(NCs)with precisely defined core numbers offer a distinct advantage in elucidating the correlation between their specific structures and the reaction mechanisms in electrocatalysis.The strategic modulation of the fine microstructures of Au NCs presents crucial opportunities for tailoring their electrocatalytic performance across various reactions.This review delves into the profound structural effects of Au NC cores and ligands in electrocatalysis,elucidating their underlying mechanisms.A detailed exploration of the fundamentals of Au NCs,considering core and ligand structures,follows.Subsequently,the interaction between the core and ligand structures of Au NCs and their impact on electrocatalytic performance in diverse reactions are examined.Concluding the discourse,challenges and personal prospects are presented to guide the rational design of efficient electrocatalysts and advance electrocatalytic reactions.

Using Electrodeposition of Carboxylated Chitosan for Green Preparation of Copper Nanoclusters and Nanocomposite Films

On the basis of coordinated electrodeposition of carboxylated chitosan(CCS),we presented a green method to prepare Cu NCs and Cu NCs/CCS nanocomposite films.The method shows a range of benefits,such as the convenient and eco-friendly process,mild conditions,and simple post-treatment.The experimental results reveal that a homogeneous deposited film(Cu NCs/CCS nanocomposite film)is generated on the Cu plate(the anode)after electrodeposition,which exhibits an obvious red florescence.The results from TEM observation suggest there are nanoparticles(with the average particle size of 2.3 nm)in the deposited film.Spectral analysis results both demonstrate the existence of Cu NCs in the deposited film.Moreover,the Cu NCs/CCS film modified electrode is directly created through electrodeposition of CCS,which enables promising application in the electrochemical sensing.By means of fluorescence properties of Cu NCs,the Cu NCs/CCS film also owns the potential in fluorescence detection.Therefore,this work builds a novel method for the green synthesis of Cu NCs,meanwhile it offers a convenient and new electrodeposition strategy to prepare polysaccharide-based Cu NCs nanocomposites for uses in functional nanocomposites and bioelectronic devices.

Pt nanoclusters modified porous g-C_(3)N_(4)nanosheets to significantly enhance hydrogen production by photocatalytic water reforming of methanol

For the use of green hydrogen energy,it is crucial to have efficient photocatalytic activity for hydrogen generation by water reforming of methanol under mild conditions.Much attention has been paid to gC_(3)N_(4)as a promising photocatalyst for the generation of hydrogen.To improve the separation of photogenerated charge,porous nanosheet g-C_(3)N_(4)was modified with Pt nanoclusters(Pt/g-C_(3)N_(4))through impregnation and following photo-induced reduction.This catalyst showed excellent photocatalytic activity of water reforming of methanol fo r hydrogen production with a 17.12 mmol·g^(-1)·h^(-1)rate at room temperature,which was 311 times higher than that of the unmodified g-C_(3)N_(4).The strong interactions of Pt-N in Pt/g-C_(3)N_(4)constructed effective electron transfer channels to promote the separation of photogenerated electrons and holes effectively.In addition,in-situ infrared spectroscopy was used to investigate the intermediates of the hydrogen production reaction,which proved that methanol and water eventually turn into H_(2)and CO_(2)via formaldehyde and formate.This study provides insights for understanding the photocatalytic hydrogen production in the water reforming of methanol.

A Single-chain Antibody for One-pot Fabrication of Luminescent Gold Nanoclusters and Rabies Virus Imaging in Cells

The fragile antibody leads to a great challenge as a scaffold to fabricate the luminescent metal nanoclusters using one-pot method.This study presents a stable single-chain anti-body(scFv57R-ATS)for the fabrication of luminescent gold nanoclusters(AuNCs@scFv57R-ATS)and a quick,sensitive rabies virus detection in living cells.In this paper,AuNCs@scFv57R-ATS was designed to specifically recognize antigen RV in modified HeLa cells,which promoted the demonstration of metal nanocluster fluorescent probes for antigen targeting and therapy.

Marrying luminescent metal nanoclusters to C_(3)N_(4) for efficient photocatalytic hydrogen peroxide production

Photocatalytic oxygen(O_(2))reduction has been considered a promising method for hydrogen peroxide(H_(2)O_(2))production.However,the poor visible light harvesting and low-efficient separation and generation of charge carriers of conventional photocatalysts strongly limited their photocatalytic H_(2)O_(2) generation performance.Herein,we design a highly efficient photocatalyst in this work by marrying luminescent gold-silver nanoclusters(AuAg NCs)to polyethyleneimine(PEI)modified C_(3)N_(4)(C3N4-PEI).The key design in this work is the utilization of highly luminescent AuAg NCs as photosensitizers to promote the generation and separation of charge carriers of C_(3)N_(4)-PEI,thereby ultimately producing abundant e−for O_(2) reduction under visible light illumination(λ≥400 nm).As a result,the as-designed photocatalyst(C3N4-PEI-AuAg NCs)exhibits excellent photocatalytic activity with an H_(2)O_(2) production capability of 82μM in pure water,which is 3.5 times higher than pristine C_(3)N_(4)(23μM).This interesting design provides a paradigm in developing other high-efficient photocatalysts for visible-light-driven H_(2)O_(2) production.

Controllably partial removal of thiolate ligands from unsupported Au_(25) nanoclusters by rapid thermal treatments for electrochemical CO_(2)reduction

Colloidal synthesis of metal nanoclusters will inevitably lead to the blockage of catalytically active sites by organic ligands.Here,taking[Au_(25)(PET)_(18)]-(PET=2-phenylethanethiol)nanocluster as a model catalyst,this work reports a feasible procedure to achieve the controllably partial removal of thiolate ligands from unsupported[Au_(25)(PET)_(18)]-nanoclusters with the preservation of the core structure.This procedure shortens the processing duration by rapid heating and cooling on the basis of traditional annealing treatment,avoiding the reconfiguration or agglomeration of Au_(25)nanoclusters,where the degree of dethiolation can be regulated by the control of duration.This work finds that a moderate degree of dethiolation can expose the Au active sites while maintaining the suppression of the competing hydrogen evolution reaction.Consequently,the activity and selectivity towards CO formation in electrochemical CO_(2)reduction reaction of Au_(25)nanoclusters can be promoted.This work provides a new approach for the removal of thiolate ligands from atomically precise gold nanoclusters.

Atomically precise gold nanoclusters for healthcare applications

The potential application of gold nanoparticles(GNPs)in biomedicine has been extensively reported.However,there is still too much puzzle about their real face and potential health risks in comparison with the commercial drug molecules.The emergence of atomically precise gold nanoclusters(APGNCs)provides the opportunity to address the puzzle due to their ultrasmall size,defined molecular formula,editable surface engineering,available structures and unique physicochemical properties including excellent biocompatibility,strong luminescence,enzyme-like activity and efficient renal clearance,et al.Recently,these advantages of APGNCs also endow them promising performances in healthcare such as bioimaging,drug delivery,antibacterial and cancer therapy.Especially,their clear composition and structures like the commercial drug molecules facilitate the study of their functions and the structure-activity relationship in healthcare,which is essential for the guided design of APGNC nanomedicine.Therefore,this review will focus the advantages and recent progress of APGNCs in health care and envision their prospects for the future.

Activation of Transition Metal(Fe,Co and Ni)-Oxide Nanoclusters by Nitrogen Defects in Carbon Nanotube for Selective CO_(2) Reduction Reaction

The electrochemical carbon dioxide reduction reaction(CO_(2)RR),which can produce value-added chemical feedstocks,is a proton-coupled-electron process with sluggish kinetics.Thus,highly efficient,cheap catalysts are urgently required.Transition metal oxides such as CoO_(x),FeO_(x),and NiO_(x)are low-cost,low toxicity,and abundant materials for a wide range of electrochemical reactions,but are almost inert for CO_(2)RR.Here,we report for the first time that nitrogen doped carbon nanotubes(N-CNT)have a surprising activation effect on the activity and selectivity of transition metal-oxide(MO_(x)where M=Fe,Ni,and Co)nanoclusters for CO_(2)RR.MO_(x)supported on N-CNT,MO_(x)/N-CNT,achieves a CO yield of 2.6–2.8 mmol cm−2 min−1 at an overpotential of−0.55 V,which is two orders of magnitude higher than MO_(x)supported on acid treated CNTs(MO_(x)/O-CNT)and four times higher than pristine N-CNT.The faraday efficiency for electrochemical CO_(2)-to-CO conversion is as high as 90.3%at overpotential of 0.44 V.Both in-situ XAS measurements and DFT calculations disclose that MO_(x)nanoclusters can be hydrated in CO_(2)saturated KHCO_(3),and the N defects of N-CNT effectively stabilize these metal hydroxyl species under carbon dioxide reduction reaction conditions,which can split the water molecules and provide local protons to inhibit the poisoning of active sites under carbon dioxide reduction reaction conditions.

Fabrication of High Color Rendering Index White Light Emitting Diodes from Gold Nanoclusters

We demonstrated gold nanoclusters as color tunable emissive light converters for the application of white light emitting diodes (WLEDs). A blue LED providing 460 nm to excite gold nanoclusters mixed with UV curable material generates broad bandwidth emission at the visible range. Increasing the amount of gold nanoclusters, the correlated color temperature of WLEDs tuned from cold white to warm white, and also results in the variation of color rendering index (CRI). The highest CRI in the experiment is 92.

Ag7(MBISA)6 Nanoclusters Conjugated with Quinacrine for FRET-Enhanced Photodynamic Activity under Visible Light Irradiation

Singlet oxygen(1 O2) plays an important role in various applications, such as in the photodynamic therapy(PDT) of cancers,photodynamic inactivation of microorganisms, photo-degradation of toxic compounds, and photo-oxidation in synthetic chemistry. Recently,water-soluble metal nanoclusters(NCs) have been utilized as photosensitizers for the generation of highly reactive 1 O2 because of their high water solubility, low toxicity, and surface functionalizability for targeted substances. In the case of metal NC-based photosensitizers, the photo-physical properties depend on the core size of the NCs and the core/ligand interfacial structures. A wide range of atomically precise gold NCs have been reported; however, reports on the synthesis of atomically precise silver NCs are limited due to the high reactivity and low photostability(i.e., easy oxidation) of Ag NCs. In addition, there have been few reports on what kinds of metal NCs can generate large amounts of 1 O2. In this study, we developed a new one-pot synthesis method of water-soluble Ag7(MBISA)6(MBISA= 2-mercapto-5-benzimidazolesulfonic acid sodium salt) NCs with highly efficient 1 O2 generation ability under the irradiation of white light emitting diodes(LEDs). The molecular formula and purity were determined by electrospray ionization mass spectrometry and gel electrophoresis. To the best of our knowledge, this is the first report on atomically precise thiolate silver clusters(Agn(SR)m) for efficient 1 O2 generation under visible light irradiation. The 1 O2 generation efficiency of Ag7(MBISA)6 NCs was higher than those of the following known water-soluble metal NCs: bovine serum albumin(BSA)-Au25 NCs,BSA-Ag8 NCs, BSA-Ag14 NCs,Ag25(dihydrolipoic acid)14 NCs,Ag35(glutathione)18 NCs,and Ag75(glutathione)40 NCs. The metal NCs examined in this study showed the following order of 1 O2 generation efficiency under white light irradiation: Ag7(MBISA)6 > BSA-Ag14 > Ag75(SG)40 > Ag35(SG)18 >BSA-Au25 >>BSA-Ags(not detected) and Ag2 s(DHLA)14(not detected). For further improving the 1 O2 generation of Ag7(MBISA)6 NCs, we developed a novel fluorescence resonance energy transfer(FRET) system by conjugating Ag7(MBISA)6 NCs with quinacrine(QC)(molar ratio of Ag NCs to QC is 1 : 0.5). We observed the FRET process,from QC to Ag7(MBISA)6 NCs,occurring in the conjugate. That is,the QC works as a donor chromophore,while the Ag NCs work as an acceptor chromophore in the FRET process. The FRET-mediated process caused a 2.3-fold increase in 1 O2 generation compared to that obtained with Ag7(MBISA)6 NCs alone. This study establishes a general and simple strategy for improving the PDT activity of metal NC-based photosensitizers.

Re nanoclusters anchored on nanosheet supports: Formation of Re-O-matrix bonding and evaluation as all-pH-range hydrogen evolution reaction (HER) electrocatalysts

Although the water splitting-based generation of hydrogen as an energy carrier can help to mitigate the global problems of energy shortage and climate change,the practical implementation of this strategy is hindered by the absence of inexpensive high-performance electrocatalysts for the hydrogen evolution reaction (HER).Re-based HER electrocatalysts exhibit predictable high performance within the entire pH range but suffer from arduous formation (i.e.,vulnerability to oxidation) and uncontrollable aggregation,which strongly discourages the maximisation of active site exposure required for activity enhancement.To overcome these limitations,we herein hydrothermally synthesise Re nanoclusters uniformly distributed on nanosheet supports,such as reduced graphene oxide nanosheets (Re NCs@rGO),revealing that this hybrid features abundant exposed active sites and high oxidation resistance.The obtained electrocatalysts were elaborately characterized by microscopic and spectroscopic analyses.Also,density functional theory calculations confirm the optimised synthesis of Re NCs@rGO and indicate the crucial role of Re–O–C junction formation in securing durability.The effective suppression of Re nanocluster detachment/dissolution under HER conditions endows Re NCs@rGO with high electron conductivity and electrochemical stability,resulting in a durability superior to that of commercial Pt/C and an activity similar to that of this reference.As a result,Re NCs@rGO exhibited remarkably small HER overpotentials of 110,130,and 93 m V to deliver a current density of 10 mA cm^(-2) in 0.5 M H_(2)SO_(4),1 M PBS,and 1 M KOH,respectively.Thus,Re NCs@rGO is a promising alternative to conventional Pt-group-metal catalysts and should find applications in next-generation high-performance water splitting systems.

Kinetically controlled synthesis of atomically precise Ag nanoclusters for the catalytic reduction of 4-nitrophenol

Synthesizing atomically precise Ag nanoclusters(NCs),which is essential for the general development of NCs,is quite challenging.In this study,we report the synthesis of high-purity atomically precise Ag NCs via a kinetically controlled strategy.The Ag NCs were prepared using a mild reducing agent via a one-pot method.The as-prepared Ag NCs were confirmed to be Ag_(49)(D-pen)_(24)(D-pen:D-penicillamine)on the basis of their matrix-assisted laser desorption ionization time-of-flight mass spectrometric and thermogravimetric characteristics.The interfacial structures of the Ag NCs were illustrated by proton nuclear magnetic resonance and Fourier-transform infrared spectroscopy.The Ag NCs were supported on activated carbon(AC)to form Ag NCs/AC,which displayed excellent activity for the catalytic reduction of 4-nitrophenol with a kinetic reaction rate constant k of 0.21 min^(-1).Such a high k value indicates that the composite could outperform several previously reported catalysts.Moreover,the catalytic activity of Ag NCs/AC remained nearly constant after six times of recycle,which suggests its excellent stability.

Ultrasmall AuPd nanoclusters on amine-functionalized carbon blacks as high-performance bi-functional catalysts for ethanol electrooxidation and formic acid dehydrogenation

The synthesis of ultrasmall metal nanoclusters(NCs) with high catalytic activities is of great importance for the development of clean and renewable energy technologies but remains a challenge. Here we report a facile wet-chemical method to prepare ~1.0 nm Au Pd NCs supported on amine-functionalized carbon blacks. The Au Pd NCs exhibit a specific activity of 5.98 mA cm_(AuPd)^(-2)and mass activity of 5.25 A mg_(auPd)^(-1) for ethanol electrooxidation, which are far better than those of commercial Pd/C catalysts(1.74 mAcm_(AuPd)^(-2) and 0.54 A mg_(Pd)^(-1) ). For formic acid dehydrogenation, the Au Pd NCs have an initial turn over frequency of 49339 h^(-1) at 298 K without any additive, which is much higher than those obtained for most of reported Au Pd catalysts. The reported synthesis may represent a facile and low-cost approach to prepare other ultrasmall metal NCs with high catalytic activities for various applications.

MoC nanoclusters anchored Ni@N‐doped carbon nanotubes coated on carbon fiber as three‐dimensional and multifunctional electrodes for flexible supercapacitor and self‐heating device

With the rapid development of different kinds of wearable electronic devices,flexible and high‐capacity power sources have attracted increasing attention.In this study,a facile strategy to fabricate Ni nanoparticles embedded in N‐doped carbon nanotubes(CNTs)(Ni@NCNTs)homogeneously coated on the surface of carbon fiber with a multistructural component of molybdenum carbide(MoC/Ni@NCNTs/CC)was synthesized.There are two forms of MoC in MoC/Ni@NCNTs/CC,including the MoC nanoclusters in a size of 2 to 4 nm anchored on Ni@N‐doped CNTs and the MoC nanoparticles as an interface between MoC/Ni@NCNTs and carbon cloth(CC).Multifunctional MoC/Ni@NCNTs/CC served as both positive and negative electrode and a heater in flexible supercapacitors and in wearable devices,which exhibited excellent electrochemical and heating performance.Besides,an all‐solid‐state supercapacitor consists of two pieces of MoC/Ni@NCNTs/CC that exhibited extraordinary energy storage performance with high‐energy density(78.7μWh/cm2 at the power density of 2.4 mW/cm2)and excellent cycling stability(≈91%capacity retention after 8000 cycles).Furthermore,all‐solid‐state flexible supercapacitors were incorporated with an MoC/Ni@NCNTs/CC electrode into self‐heating flexible devices for keeping the human body warm.Thus,MoC/Ni@NCNTs/CC is a promising electrode material for flexible and wearable storage systems and heating electronic application.

Cytochrome-c aptamer functionalized Pt nanoclusters for enhanced chemodynamic therapy

Catalysis-based chemodynamic therapy(CDT)is an emerging cancer treatment strategy which uses a Fenton-like reaction to kill tumor cells by catalyzing endogenous hydrogen peroxide(H_(2)O_(2))into a toxic hydroxyl radical(·OH).The performance of CDT is greatly dependent on PDT agent.Herein,mitochondria-targeting Pt nanoclusters were synthesized using cytochrome c aptamer(CytcApt)as template.The obtained CytcApt-PtNCs can produce.OH by H_(2)O_(2)under the acidic conditions.Moreover,CytcApt-PtNCs could kill 4T1 tumor cells in a pH-dependent manner,but had no side effect on normal 293T cells.Therefore,CytcApt-PtNCs possess excellent therapeutic effect and good biosafety,indicating their great potential for CDT.

Tuning the Electrochemical Property of the Ultrafine Metal-oxide Nanoclusters by Iron Phthalocyanine as Efficient Catalysts for Energy Storage and Conversion

Nanoclusters(NCs)have been demonstrated of outstanding performance in electrochemical energy storage and conversion technologies due to their strong quantum confinement effects and strong interaction with supports.Here,we developed a class of ultrafine metal-oxide(MOx,M=Fe,Co and Ni)NCs incorporated with iron phthalocyanine(FePc),MOx/FePc-G,supported on graphene as high-performance catalysts for oxygen reduction reaction(ORR),oxygen evolution reaction(OER),and carbon dioxide reduction(CO2RR).The high activities for ORR and OER are attributed to the electron donation and accepting ability of the highly redox active of FePc-G that could tune the properties of MOx.The FeOx/FePc-G exhibits an extremely positive half-wave potential(E1/2)of 0.888 and 0.610 V for ORR in alkaline and neutral conditions,respectively,which is around 60 mV more positive than that of Pt/C.And NiOx/FePc-G shows similar OER activity with the state-of-the-art catalysts,Ir/C,and better performance than NiFeO NCs supported on graphene.Remarkably,the CoOx/FePc-G and NiOx/FePc-G show high activity and selectivity to reduce CO2 into CO with a low onset potential of-0.22 V(overpotential is 0.11 V).

Ratiometric Fluorescence Detection of 6-Mercaptopurine Based on the Nanohybrid of Fluorescence Carbon Dots and Gold Nanoclusters

The development of a simple and accurate quantitative method for the determination of 6-mercaptopurine (6-MP) is of great importance because of its serious side effects. Ratiometric fluorescence (RF) sensors are not subject to interference from environmental factors, and exhibit enhanced precision and accuracy. Therefore, a novel RF sensor for the selective detection of 6-MP was developed. The present work reports a sensitive and selective RF sensor for the detection of 6-mercaptopurine, by hybridizing carbon nanodots (CDots) and gold nanoclusters (AuNCs) capped with bovine serum albumin (BSA). The CDots serve as the reference signal and the AuNCs as the reporter. On addition of the 6-MP, AuNCs formed aggregates, because the existing cross-links within the AuNCs and BSA structure were broken in favour of the Au-S bonds, which can enhance the fluorescence of AuNCs, while the fluorescence of CDots is stable against 6-MP, leading to distinct ratiometric fluorescence changes when exposed to 6-MP. 6-MP could be detected in the range of 0 - 30.22 μM with a detection limit of 54 nM. The developed sensor was applied for the determination of 6-MP in human serum samples and satisfactory results were obtained.

Structural Evolution Patterns of FCC-Type Gold Nanoclusters

Recent progress in the research of atomically-precise metal nanoclusters has identified a series of exceptionally stable nanoclusters with specific chemical compositions. Structural determination on such "magic size" nanoclusters revealed a variety of unique structures such as decahedron, icosahedron, as well as hexagonal close packing(hcp) and body-centered cubic(bcc) packing arrangements in gold nanoclusters, which are largely different from the face-centered cubic(fcc) structure in conventional gold nanoparticles. The characteristic geometrical structures enable the nanoclusters to exhibit interesting properties, and these properties are in close correlation with their atomic structures according to the recent studies. Experimental and theoretical analyses have been applied in the structural identification aiming to clarify the universal principle in the structural evolution of nanoclusters. In this mini-review, we summarize recent studies on periodic structural evolution of fcc-based gold nanoclusters protected by thiolates. A series of nanoclusters exhibit one-dimensional growth along the [001] direction in a layer-by-layer manner from Au_(23)(TBBT)_(20) to Au_(36)(TBBT)_(24),Au_(44)(TBBT)_(28), and to Au_(52)(TBBT)_(32)(TBBT: 4-tert-butylbenzenethiolate). The optical properties of these nanoclusters also evolve periodically based on steady-state and ultrafast spectroscopy. In addition, two-dimensional growth from Au_(44)(TBBT)_(28) toward both [100] and [010] directions leads to the Au_(92)(TBBT)_(44) nanocluster, and the recently reported Au_(52)(PET)_(32)(PET: 2-phenylethanethiol) also follows this growth pattern with partial removal of the layer. Theoretical predictions of relevant fcc nanoclusters include Au_(60)(SCH_3)_(36), Au_(68)(SCH_3)_(40), Au_(76)(SCH_3)_(44), etc, for the continuation of 1 D growth pattern, as well as Au_(68)(SR)_(38)mediating the 2 D growth pattern from Au_(44)(TBBT)_(28) to Au_(92)(TBBT)_(44). Overall, this mini-review provides guidelines on the rules of structural evolution of fcc gold nanoclusters based on 1 D, 2 D and 3 D growth patterns.

Synthesis, Growing Processes and Physical Properties of CdS Nanoclusters in Y-Zeolite Studied by Positron Annihilation

Direct synthesis of CdS nanoclusters within the pore structure of Y zeolite was made. The location of CdS nanoclusters inside Y zeolite hosts was confirmed by the blue-shifted reflection absorption spectra with respected to that of bulk CdS materials. In this paper, we conducted Positron Annihilation Lifetime Spectrum (PALS) measurements on a series of CdS/Y zeolite samples and concluded that CdS clusters were not located in supercages but in smaller sodalite cages; as the CdS loading concentration increases to 5 wt%, the discrete CdS cubes begin to form bigger superclusters through interaction. The stability of CdS clusters inside the sodalite units is due to the coordination of Cd atoms with the framework oxygen atoms of the double six-ring windows. Moreover, PALS reveals some important information of surface states existing on the interfacial layers between CdS clusters and Y zeolite.

Oxygen vacancy-rich amorphous FeNi hydroxide nanoclusters as an efficient electrocatalyst for water oxidation

In this work,a one-pot strategy is presented to directly synthesize amorphous Fe_(x)Ni_(y) hydroxide nanoclusters(denoted as ANC-Fe_(x)Ni_(y),<2 nm)with oxygen vacancies induced by ionic liquids.The ANC-Fe_(x)Ni_(y) catalyst presents abundant catalytic sites and high intrinsic conductivity.As such,the optimized ANC-Fe_(1)Ni_(2) exhibits high activity in oxygen evolution reaction(OER)with a Tafel slope of 39 m V dec^(–1) and an overpotential of 266 m V at 10 m A cm^(-2).Notably,the optimized ANC-Fe_(1)Ni_(2) shows an extraordinarily large mass activity of 3028 Ag_(FeNi)^(–1) at the overpotential of 300 m V,which is~24-fold of commercial RuO_(2) catalyst.The superior activity of these Fe_(x)Ni_(y) hydroxide nanoclusters is ascribed to(i)the amorphous and distorted structure with abundant oxygen vacancies,and(ii)enhanced active site density by downsizing the ANC-FexNiyclusters.This strategy provides a novel route for enhancing OER electrocatalytic performance and highly encouraging for the future application of amorphous metal hydroxides in catalysis.