Efficient Acidic Photoelectrochemical Water Splitting Enabled by Ru Single Atoms Anchored on Hematite Photoanodes.

Photoelectrochemical (PEC) water splitting in acidic media holds promise as an efficient approach to renewable hydrogen production. However, the development of highly active and stable photoanodes under acidic conditions remains a significant challenge. Herein, we demonstrate the remarkable water oxidation performance of Ru single atom decorated hematite (Fe2O3) photoanodes, resulting in a high photocurrent of 1.42 mA cm-2 at 1.23 VRHE under acidic conditions. Comprehensive experimental and theoretical investigations shed light on the mechanisms underlying the superior activity of the Ru-decorated photoanode. The presence of single Ru atoms enhances the separation and transfer of photogenerated carriers, facilitating efficient water oxidation kinetics on the Fe2O3 surface. This is achieved by creating additional energy levels within the Fe2O3 bandgap and optimizing the free adsorption energy of intermediates. These modifications effectively lower the energy barrier of the rate-determining step for water splitting, thereby promoting efficient PEC hydrogen production.

Ir Single Atoms Boost Metal-Oxygen Covalency on Selenide-Derived NiOOH for Direct Intramolecular Oxygen Coupling.

This investigation probes the intricate interplay of catalyst dynamics and reaction pathways during the oxygen evolution reaction (OER), highlighting the significance of atomic-level and local ligand structure insights in crafting highly active electrocatalysts. Leveraging a tailored ion exchange reaction followed by electrochemical dynamic reconstruction, we engineered a novel catalytic structure featuring single Ir atoms anchored to NiOOH (Ir1@NiOOH). This novel approach involved the strategic replacement of Fe with Ir, facilitating the transition of selenide precatalysts into active (oxy)hydroxides. This elemental substitution promoted an upward shift in the O 2p band and intensified the metal-oxygen covalency, thereby altering the OER mechanism toward enhanced activity. The shift from a single-metal site mechanism (SMSM) in NiOOH to a dual-metal-site mechanism (DMSM) in Ir1@NiOOH was substantiated by in situ differential electrochemical mass spectrometry (DEMS) and supported by theoretical insights. Remarkably, the Ir1@NiOOH electrode exhibited exceptional electrocatalytic performance, achieving overpotentials as low as 142 and 308 mV at current densities of 10 and 1000 mA cm-2, respectively, setting a new benchmark for the electrocatalysis of OER.

Wafer Scale Gallium Nitride Integrated Electrode Toward Robust High Temperature Energy Storage.

Gallium Nitride (GaN), as the representative of wide bandgap semiconductors, has great prospects in accomplishing rapid charge delivery under high-temperature environments thanks to excellent structural stability and electron mobility. However, there is still a gap in wafer-scale GaN single-crystal integrated electrodes applied in the energy storage field. Herein, Si-doped GaN nanochannel with gallium oxynitride (GaON) layer on a centimeter scale (denoted by GaN NC) is reported. The Si atoms modulate electronic redistribution to improve conductivity and drive nanochannel formation. Apart from that, the distinctive nanochannel configuration with a GaON layer provides adequate active sites and extraordinary structural stability. The GaN-based supercapacitors are assembled and deliver outstanding charge storage capabilities at 140 °C. Surprisingly, 90% retention is maintained after 50 000 cycles. This study opens the pathway toward wafer-scale GaN single-crystal integrated electrodes with self-powered characteristics that are compatible with various (opto)-electronic devices.

Chiral Superlattices Self-Assembled from Post-Modified Metal-Organic Polyhedra.

Metal-organic polyhedra (MOPs) are inherently porous, discrete, and solvent-dispersive, and directing them into chiral superlattices through direct self-assembly remains a considerable challenge due to their nanoscale size and structural complexity. In this work, we illustrate a postmodification protocol to covalently conjugate a chiral cholesteryl pendant to MOPs. Postmodification retained the coordination cores and allowed for reaction-induced self-assembly in loosely packed nanosized columns without supramolecular chirality. Solvent-processed bottom-up self-assembly in aqueous media facilitated the well-defined packing into twisted superlattices with a 5 nm lattice parameter. Experimental and computational results validated the role of intercholesteryl forces in spinning the nanosized MOPs, which achieved the chirality transfer to supramolecular scale with chiral optics. This work establishes a novel protocol in rational design of MOP-based chiroptical materials for potential applications of enantioselective adsorption, catalysis, and separation.

Unveiling pH-Dependent Adsorption Strength of *CO2 - Intermediate over High-Density Sn Single Atom Catalyst for Acidic CO2-to-HCOOH Electroreduction.

The acidic electrochemical CO2 reduction reaction (CO2RR) for direct formic acid (HCOOH) production holds promise in meeting the carbon-neutral target, yet its performance is hindered by the competing hydrogen evolution reaction (HER). Understanding the adsorption strength of the key intermediates in acidic electrolyte is indispensable to favor CO2RR over HER. In this work, high-density Sn single atom catalysts (SACs) were prepared and used as catalyst, to reveal the pH-dependent adsorption strength and coverage of *CO2 - intermediatethat enables enhanced acidic CO2RR towards direct HCOOH production. At pH=3, Sn SACs could deliver a high Faradaic efficiency (90.8 %) of HCOOH formation and a corresponding partial current density up to -178.5 mA cm-2. The detailed in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopic studies reveal that a favorable alkaline microenvironment for CO2RR to HCOOH is formed near the surface of Sn SACs, even in the acidic electrolyte. More importantly, the pH-dependent adsorption strength of *CO2 - intermediate is unravelled over the Sn SACs, which in turn affects the competition between HER and CO2RR in acidic electrolyte.

A Bioinspired Atomically Thin Nanodot Supported Single-Atom Nanozyme for Antibacterial Textile Coating.

Surface antibacterial coatings with outstanding antibacterial efficiency have attracted increasing attention in medical protective clothing and cotton surgical clothing. Although nanozymes, as a new generation of antibiotics, are used to combat bacteria, their catalytic performance remains far from satisfactory as alternatives to natural enzymes. Single-atom nanodots provide a solution to the low catalytic activity bottleneck of nanozymes. Here, atomically thin C3 N4 nanodots supported single Cu atom nanozymes (Cu-CNNDs) are developed by a self-tailoring approach, which exhibits catalytic efficiency of 8.09 × 105 M-1 s-1 , similar to that of natural enzyme. Experimental and theoretical calculations show that excellent peroxidase-like activity stems from the size effect of carrier optimizing the coordination structure, leading to full exposure of Cu-N3 active site, which improves the ability of H2 O2 to generate hydroxyl radicals (•OH). Notably, Cu-CNNDs exhibit over 99% superior antibacterial efficacy and are successfully grafted onto cotton fabrics. Thus, Cu-CNNDs blaze an avenue for exquisite biomimetic nanozyme design and have great potential applications in antibacterial textiles.

New Approach to Low-Power-Consumption, High-Performance Photodetectors Enabled by Nanowire Source-Gated Transistors.

Power consumption makes next-generation large-scale photodetection challenging. In this work, the source-gated transistor (SGT) is adopted first as a photodetector, demonstrating the expected low power consumption and high photodetection performance. The SGT is constructed by the functional sulfur-rich shelled GeS nanowire (NW) and low-function metal, displaying a low saturated voltage of 0.61 V ± 0.29 V and an extremely low power consumption of 7.06 pW. When the as-constructed NW SGT is used as a photodetector, the maximum value of the power consumption is as low as 11.96 nW, which is far below that of the reported phototransistors working in the saturated region. Furthermore, benefiting from the adopted SGT device, the photodetector shows a high photovoltage of 6.6 × 10-1 V, a responsivity of 7.86 × 1012 V W-1, and a detectivity of 5.87 × 1013 Jones. Obviously, the low power consumption and excellent responsivity and detectivity enabled by NW SGT promise a new approach to next-generation, high-performance photodetection technology.

Phase Transition to Heptagonal-Cluster-Packed Structure of Gold Nanoribbons.

Transforming periodic crystals into packing of atomic clusters is attracting enormous interest for both fundamental research and potential application, but it still remains a big challenge for noble metals. Here, we have observed gold nanoribbons packed with heptagonal clusters, where every two or three constituent clusters connect edge-to-edge with their neighbors. This is the first reported metallic structure packed from building blocks with heptagonal symmetry. The cluster-packed nanoribbons transited from two-dimensional hexagonal structure under tensile condition and a reverse transition occurred by compression, resolved by in situ observation. The cluster-packed structure was stabilized by the s-d orbital hybridization. Theoretical calculations demonstrate that the conductance of the ribbons undergoes a quantized change from 6 to 4 G0 (G0 = 2e2/h) during the phase transition and backward for the reverse transition.

Direct atomic-scale imaging of a screw dislocation core structure in inorganic halide perovskites.

Topological defects such as dislocations in crystalline materials usually have major impacts on materials' mechanical, chemical and physical properties. Detailed knowledge of dislocation core structures is essential to understand their impacts on materials' properties. However, compared with imaging of core structures of edge dislocations, direct imaging of a screw dislocation core is challenging from the traditional edge-on direction because the atomic displacements are parallel to the screw dislocation line. Here, a screw dislocation with a Burgers vector 1/2[110] in orthorhombic CsPbBr3 nanocrystals is directly imaged at the atomic scale with the incident electron beam perpendicular to the dislocation line using aberration-corrected scanning transmission electron microscopy (STEM). The dislocation core is characterized by helical atomic planes along the dislocation line. Quantitative assessments of the change rate of the screw displacements reveal the dislocation line locate at a plane containing Cs and Br atoms. This study reveals the atomic structure of screw dislocation cores in CsPbBr3 and provides useful information for the understanding of structure-property relations of halide perovskites.

An Ultrastable 155-Nuclei Silver Nanocluster Protected by Thiacalix[4]arene and Cyclohexanethiol for Photothermal Conversion.

Thiacalix[4]arenes have emerged as a family of macrocyclic ligands to protect metal nanoparticles, but it remains a great challenge to solve the mystery of their structures at the atomic level, especially for those larger than 2 nm. Here, we report the largest known mixed-valence silver nanocluster [Ag155 (CyS)40 (TC4A)5 Cl2 ] (Ag155) protected by deprotonated cyclohexanethiol (CySH) and macrocyclic ligand p-tert-butylthiacalix[4]arene (H4 TC4A). Its single-crystal structure consists of a metallic core of four concentric shells, Ag13 @Ag42 @Ag30 @Ag70 , lined with a organic skin of 40CyS- and 5TC4A4- and 2Cl- . Ag155 manifests an unusual pseudo-5-fold symmetry dictated by the intrinsic metal atom packing and the regioselective distribution of mixed protective ligands. This work not only reveals a macrocyclic ligand effect on the formation of a large silver nanocluster, but also provides a new structural archetype for comprehensively perceiving their interface and metal kernel structures.

Low-Coordination Single Au Atoms on Ultrathin ZnIn2 S4 Nanosheets for Selective Photocatalytic CO2 Reduction towards CH4.

Selective CO2 photoreduction to hydrocarbon fuels such as CH4 is promising and sustainable for carbon-neutral future. However, lack of proper binding strengths with reaction intermediates makes it still a challenge for photocatalytic CO2 methanation with both high activity and selectivity. Here, low-coordination single Au atoms (Au1 -S2 ) on ultrathin ZnIn2 S4 nanosheets was synthesized by a complex-exchange route, enabling exceptional photocatalytic CO2 reduction performance. Under visible light irradiation, Au1 /ZnIn2 S4 catalyst exhibits a CH4 yield of 275 µmol g-1 h-1 with a selectivity as high as 77 %. As revealed by detailed characterizations and density functional theory calculations, Au1 /ZnIn2 S4 with Au1 -S2 structure not only display fast carrier transfer to underpin its superior activity, but also greatly reduce the energy barrier for protonation of *CO and stabilize the *CH3 intermediate, thereby leading to the selective CH4 generation from CO2 photoreduction.

A 34-Electron Superatom Ag78 Cluster with Regioselective Ternary Ligands Shells and Its 2D Rhombic Superlattice Assembly.

Herein, we report a 78-nuclei silver nanocluster (NC) [Ag78 (i PrPhS)30 (dppm)10 Cl10 ]4+ (SD/Ag78a; dppm=bis-(diphenylphosphino)methane) that was synthesized through a one-pot reaction using [Ag(pz)]n as precursor (Hpz=pyrazole) and further characterized by X-ray crystallography. SD/Ag78a shows a core-shell structure comprised of an all-metallic Ag53 kernel surrounded by an Ag25 discontinuous metal-organic shell. The Ag53 kernel is an Ag13 Ino decahedron encaged by an Ag40 drum-like shell, while the Ag25 shell consists of two Ag10 S10 P10 Cl5 rings and five S-Ag-S staples. Three types of ligands regioselectively cap on the surface of the Ag78 NC, forming diverse metal-ligand interfacial structures. The NC is a closed-shell 34-electron superatom with +4 charge state and shows highly featured molecule-like absorption spectra in the UV/Vis region with a maximum around 493 nm. The rhombic superlattice assembled from SD/Ag78a through intercluster C-H⋅⋅⋅π interactions can be formed by a simple drop-casting treatment.

Investigating the Origin of Enhanced C2+ Selectivity in Oxide-/Hydroxide-Derived Copper Electrodes during CO2 Electroreduction.

Oxide-/hydroxide-derived copper electrodes exhibit excellent selectivity toward C2+ products during the electrocatalytic CO2 reduction reaction (CO2RR). However, the origin of such enhanced selectivity remains controversial. Here, we prepared two Cu-based electrodes with mixed oxidation states, namely, HQ-Cu (containing Cu, Cu2O, CuO) and AN-Cu (containing Cu, Cu(OH)2). We extracted an ultrathin specimen from the electrodes using a focused ion beam to investigate the distribution and evolution of various Cu species by electron microscopy and electron energy loss spectroscopy. We found that at the steady stage of the CO2RR, the electrodes have all been reduced to Cu0, regardless of the initial states, suggesting that the high C2+ selectivities are not associated with specific oxidation states of Cu. We verified this conclusion by control experiments in which HQ-Cu and AN-Cu were pretreated to fully reduce oxides/hydroxides to Cu0, and the pretreated electrodes showed even higher C2+ selectivity compared with their unpretreated counterparts. We observed that the oxide/hydroxide crystals in HQ-Cu and AN-Cu were fragmented into nanosized irregular Cu grains under the applied negative potentials. Such a fragmentation process, which is the consequence of an oxidation-reduction cycle and does not occur in electropolished Cu, not only built an intricate network of grain boundaries but also exposed a variety of high-index facets. These two features greatly facilitated the C-C coupling, thus accounting for the enhanced C2+ selectivity. Our work demonstrates that the use of advanced characterization techniques enables investigating the structural and chemical states of electrodes in unprecedented detail to gain new insights into a widely studied system.

Direct Imaging of Tunable Crystal Surface Structures of MOF MIL-101 Using High-Resolution Electron Microscopy.

Metal-organic frameworks (MOFs) are often synthesized using various additives to modulate the crystallization. Here, we report the direct imaging of the crystal surface of MOF MIL-101 synthesized with different additives, using low-dose high-resolution transmission electron microscopy (HRTEM), and identify three distinct surface structures, at subunit cell resolution. We find that the mesoporous cages at the outermost surface of MIL-101 can be opened up by vacuum heating treatment at different temperatures, depending on the MIL-101 samples. We monitor the structural evolution of MIL-101 upon vacuum heating, using in situ X-ray diffraction, and find the results to be in good agreement with HRTEM observations, which leads us to speculate that additives have an influence not only on the surface structure but also on the stability of framework. In addition, we observe solid-solid phase transformation from MIL-101 to MIL-53 taking place in the sample synthesized with hydrofluoric acid.

Oxygen-Assisted Cathodic Deposition of Zeolitic Imidazolate Frameworks with Controlled Thickness.

Processing metal-organic frameworks (MOFs) as films with controllable thickness on a substrate is increasingly crucial for many applications to realize function integration and performance optimization. Herein, we report a facile cathodic deposition process that enables the large-area preparation of uniform films of zeolitic imidazolate frameworks (ZIF-8, ZIF-71, and ZIF-67) with highly tunable thickness ranging from approximately 24 nm to hundreds of nanometers. Importantly, this oxygen-reduction-triggered cathodic deposition does not lead to the plating of reduced metals (Zn and Co). It is also operable cost-effectively in the absence of supporting electrolyte and facilitates the construction of well-defined sub-micrometer-sized heterogeneous structures within ZIF films.

Size-Dependent Grain-Boundary Structure with Improved Conductive and Mechanical Stabilities in Sub-10-nm Gold Crystals.

Low-angle grain boundaries generally exist in the form of dislocation arrays, while high-angle grain boundaries (misorientation angle >15°) exist in the form of structural units in bulk metals. Here, through in situ atomic resolution aberration corrected electron microscopy observations, we report size-dependent grain-boundary structures improving both stabilities of electrical conductivity and mechanical properties in sub-10-nm-sized gold crystals. With the diameter of a nanocrystal decreasing below 10 nm, the high-angle grain boundary in the crystal exists as an array of dislocations. This size effect may be of importance to a new generation of interconnects applications.

Absorptive Hydrogen Scavenging for Enhanced Aromatics Yield During Non-oxidative Methane Dehydroaromatization on Mo/H-ZSM-5 Catalysts.

Addition of Zr metal particles to MoCx /ZSM-5 in interpellet mixtures (2:1 weight ratio) resulted in maximum single-pass methane conversion of 27 % for dehydroaromatization at 973 K (in significant excess of the equilibrium prescribed circa 10 % conversion at these conditions) and a concurrent 1.4-5.6-fold increase in aromatic product yields due to circumvention of thermodynamic equilibrium limitations by absorptive H2 removal by Zr while retaining cumulative aromatic product selectivity. The absorptive function of the polyfunctional catalyst formulation can be regenerated by thermal treatment in He flow at 973 K, yielding above-equilibrium methane conversion in successive regeneration cycles. H2 uptake experiments demonstrate formation of bulk ZrH1.75 on hydrogen absorption by Zr at 973 K. Cooperation between absorption and catalytic centers distinct in location and function enables circumvention of persistent thermodynamic challenges in non-oxidative methane dehydrogenation.

Carbon-coated Na3V2(PO4)3 embedded in porous carbon matrix: an ultrafast Na-storage cathode with the potential of outperforming Li cathodes.

Sodium ion batteries are one of the realistic promising alternatives to the lithium analogues. However, neither theoretical energy/power density nor the practical values reach the values of Li cathodes. Poorer performance is expected owing to larger size, larger mass, and lower cell voltage. Nonetheless, sodium ion batteries are considered to be practically relevant in view of the abundance of the element Na. The arguments in favor of Li and to the disadvantage of Na would be completely obsolete if the specific performance data of the latter would match the first. Here we present a cathode consisting of carbon-coated nanosized Na3V2(PO4)3 embedded in a porous carbon matrix, which not only matches but even outshines lithium cathodes under high rate conditions. It can be (dis)charged in 6 s with a current density as high as 22 A/g (200 C), still delivering a specific capacity of 44 mAh/g, while up to 20 C, the polarization is completely negligible.

Self-supported Li4Ti5O12-C nanotube arrays as high-rate and long-life anode materials for flexible Li-ion batteries.

Self-supported Li4Ti5O12-C nanotube arrays with high conductivity architectures are designed and fabricated for application in Li-ion batteries. The Li4Ti5O12 nanotube arrays grow directly on stainless steel foil by a facile template-based solution route, further enhancing electronic conductivity by uniform carbon-coating on the inner and outer surfaces of Li4Ti5O12 nanotubes. Owing to the shortened Li(+) diffusion distance, high contact surface area, sufficient conductivity, and very good structure stability of the nanotube arrays, the self-supported Li4Ti5O12-C nanotube arrays exhibit remarkable rate capability (a reversible capability of 135 mA h g(-1), 105 mA h g(-1), and 80 mA h g(-1) at 30C, 60C, and 100C, respectively) and cycling performance (approximate 7% capacity loss after 500 cycles at 10C with a capacity retention of 144 mA h g(-1)).

Structure and Charge Carrier Separation Promotion Effects of Antiphase Boundaries in Cesium Lead Bromide.

Defects in lead halide perovskites (LHPs) may have a significant impact on charge carrier separation, but the roles of the defects are not fully understood. Here, using aberration-corrected scanning transmission electron microscopy (STEM), different types of antiphase boundaries (APBs) are discovered in CsPbBr3 platelets. APBs with a displacement vector of 1/4[111] are characterized by double layers of CsBr layers at the (110) or (001) planes, while APBs at the (112) planes are formed through edge sharing of PbBr6 ̵octahedra. Significant lattice distortions are determined at (001) and (110) APBs on the basis of quantitative analyses of STEM images. Density functional theory calculations demonstrate that all three types of APBs can induce band offsets at their valence bands and conduction bands. The APBs are intended to promote the separation of photogenerated charge carriers in LHPs. These findings provide a crystal engineering technique for enhancing the optoelectronic properties of LHPs by controlling defects.