Ultrathin Cu9S5 Nanosheets with Sulfur Vacancy for Multimodal Tumor Therapy.

Multimodal tumor therapy with nanotechnology is an effective and integrative strategy to overcome the limitations of therapeutic efficacy and possible side effects associated with monotherapy. However, the construction of multimodal treatment nanoplatforms often involves various functional components, leading to certain challenges, such as time-consuming synthesis processes, low product yield, and inadequate biocompatibility. To address these issues, we have developed a straightforward method for preparing ultrathin Cu9S5 nanosheets (NSs) with surface defects for photothermal/photodynamic/chemodynamic therapy. The ultrathin morphology of the Cu9S5 NSs (with 2-3 nm) not only confers excellent biocompatibility but also enables broad-spectrum absorption with a remarkable photothermal conversion efficiency (58.96%) under 1064 nm laser irradiation. Moreover, due to the presence of a S vacancy, these Cu9S5 NSs exhibit favorable enzyme-like properties, including reactive oxygen species generation and glutathione consumption, particularly under laser irradiation. The efficacy of related tumor therapy and antibacterial treatment is significantly enhanced by the synergistic activation of photothermal/photodynamic/chemodynamic therapy through 1064 nm laser irradiation, as demonstrated by both in vitro and in vivo experiments. This study presents a novel strategy for multimodal tumor therapy with the prepared ultrathin Cu9S5 NSs, which holds promising pathways for photodynamic therapy in the NIR-II region.

Large-scale synthesis, mechanism, and application of a luminescent copper hydride nanocluster.

Elucidating the structure-property relationships of ultra-small metal nanocluster with basic nuclear is of great significance for understanding the evolution mechanism in both the structures and properties of polynuclear metal nanoclusters. In this study, an ultra-small copper hydride (CuH for short) nanocluster was simply synthesized with high yield, and the large-scale preparation was also achieved. Single crystal X-ray diffractometer (SC-XRD) analysis shows that this copper NC contains a tetrahedral Cu4 core co-capped by four PPh2Py ligands and two Cl in which the existence of the central H atom in tetrahedron was further identified experimentally and theoretically. This CuH nanocluster exhibits bright yellow emission, which is proved to be the mixture of phosphorescence and fluorescence by the sensitivity of both emission intensity and lifetime to O2. Furthermore, the temperature-dependent emission spectra and density functional theory (DFT) calculations suggest that the luminescence of CuH mainly originates from the metal-to-ligand charge transfer and cluster-centered triplet excited states. This work offers new insights into understanding the structure-property relationship of basic nuclear CuH nanocluster.

Electrochemical Reversible Reforming between Ethylamine and Acetonitrile on Heterostructured Pd-Ni(OH)2 Nanosheets.

Rational design of electrocatalysts is essential to achieve desirable performance of electrochemical synthesis process. Heterostructured catalysts have thus attracted widespread attention due to their multifunctional intrinsic properties, and diverse catalytic applications with corresponding outstanding activities. Here, we report an in situ restoration strategy for the synthesis of ultrathin Pd-Ni(OH)2 nanosheets. Such Pd-Ni(OH)2 nanosheets exhibit excellent activity and selectivity towards reversible electrochemical reforming of ethylamine and acetonitrile. In the acetonitrile reduction process, Pd acts as reaction center, while Ni(OH)2 provide proton hydrogen through promoting the dissociation of water. Also ethylamine oxidation process can be achieved on the surface of the heterostructured nanosheets with abundant Ni(II) defects. More importantly, an electrolytic cell driven by solar cells was successfully constructed to realize ethylamine-acetonitrile reversible reforming. This work demonstrates the importance of heterostructure engineering in the rational synthesis of multifunctional catalysts towards electrochemical synthesis of fine chemicals.

Ammonia-assisted synthesis of low-crystalline FeCo hydroxides for efficient electrochemical overall water splitting.

Low-crystalline FeCo hydroxides were synthesized on a gram scale with the aid of ammonia, and they exhibited impressive catalytic activity for both the HER and OER. We utilized these catalysts to assemble a water splitting cell, which functions efficiently. The electrolytic cell can produce a consistent current density of 200 mA cm-2 for over 20 hours while operating at a voltage of 1.95 V.

Mesoporous PtPb Nanosheets as Efficient Electrocatalysts for Hydrogen Evolution and Ethanol Oxidation.

Using a one-pot hydrothermal method with ethylenediamine, we have synthesized mesoporous PtPb nanosheets that exhibit exceptional activity in both hydrogen evolution and ethanol oxidation. The resulting PtPb nanosheets have a Pt-enriched structure with up to 80 % atomic content of Pt. The synthetic method generated a significant mesoporous structure, formed through the dissolution of Pb species. These advanced structures enable the mesoporous PtPb nanosheets to achieve a current density of 10 mA cm-2 with an extreme low overpotential of 21 mV for hydrogen evolution under alkaline conditions. Furthermore, the mesoporous PtPb nanosheets exhibit superior catalytic activity and stability for ethanol oxidation. The highest catalytic current density of PtPb nanosheets is 5.66 times higher than that of commercial Pt/C. This research opens up new possibilities in designing mesoporous, two-dimensional noble-metal-based materials for electrochemical energy conversion with excellent performance.

Heterostructured Ru/Ni(OH)2 Nanomaterials as Multifunctional Electrocatalysts for Selective Reforming of Ethanol.

The electrochemical reforming of ethanol into hydrogen and hydrocarbons can reduce the electric potential energy barrier of hydrogen production from electrochemical water splitting, obtaining high value-added anode products. In this work, Ru/Ni(OH)2 heterostructured nanomaterials were synthesized successfully by an in situ reduction strategy with remarkable multifunctional catalytic properties. In the hydrogen evolution reaction, Ru/Ni(OH)2 exhibits a smaller overpotential of 31 mV to obtain a current density of 10 mA/cm2, which is better than that of commercial Pt/C. Notably, such heterostructured Ru/Ni(OH)2 nanomaterials also perform an outstanding catalytic selectivity toward an acetaldehyde product in the oxidation of ethanol. DFT calculations reveal that abundant Ru(0)-Ni(II) heterostructured sites are the key factor for the excellent performances. As a result, an ethanol-selective reforming electrolyzer driven by a 2 V solar cell is constructed to produce hydrogen and acetaldehyde in the cathodic and anodic part, respectively, via using Ru/Ni(OH)2 heterostructured catalysts. This work provides a forward-looking technical guidance for the design of novel energy conversion systems.

In-plane strain engineering in ultrathin noble metal nanosheets boosts the intrinsic electrocatalytic hydrogen evolution activity.

Strain has been shown to modulate the electronic structure of noble metal nanomaterials and alter their catalytic performances. Since strain is spatially dependent, it is challenging to expose the active strained interfaces by structural engineering with atomic precision. Herein, we report a facile method to manipulate the planar strain in ultrathin noble metal nanosheets by constructing amorphous-crystalline phase boundaries that can expose the active strained interfaces. Geometric-phase analysis and electron diffraction profile demonstrate the in-plane amorphous-crystalline boundaries can induce about 4% surface tensile strain in the nanosheets. The strained Ir nanosheets display substantially enhanced intrinsic activity toward the hydrogen evolution reaction electrocatalysis with a turnover frequency value 4.5-fold higher than the benchmark Pt/C catalyst. Density functional theory calculations verify that the tensile strain optimizes the d-band states and hydrogen adsorption properties of the strained Ir nanosheets to improve catalysis. Furthermore, the in-plane strain engineering method is demonstrated to be a general approach to boost the hydrogen evolution performance of Ru and Rh nanosheets.

Upconversion nanoparticles@AgBiS2 core-shell nanoparticles with cancer-cell-specific cytotoxicity for combined photothermal and photodynamic therapy of cancers.

UCNPs@AgBiS2 core-shell nanoparticles that AgBiS2 coated on the surface of upconversion nanoparticles (UCNPs) was successfully prepared through an ion exchange reaction. The photothermal conversion efficiency of AgBiS2 can be improved from 14.7% to 45% due to the cross relaxation between Nd ions and AgBiS2. The doping concentration of Nd ions played a critical role in the production of reactive oxygen species (ROS) and enhanced the photothermal conversion efficiency. The NaYF4:Yb/Er/Nd@NaYF4:Nd nanoparticles endows strong upconversion emissions when the doped concentration of Nd ions is 1% in the inner core, which excites the AgBiS2 shell to produce ROS for photodynamic therapy (PDT) of cancer cells. As a result, the as-prepared NaYF4:Yb/Er/Nd@NaYF4:Nd@AgBiS2 core-shell nanoparticles showed combined photothermal/photodynamic therapy (PTT/PDT) against malignant tumors. This work provides an alternative near-infrared light-active multimodal nanostructures for applications such as fighting against cancers.

Ultrathin Amorphous/Crystalline Heterophase Rh and Rh Alloy Nanosheets as Tandem Catalysts for Direct Indole Synthesis.

Heterogeneous noble-metal-based catalysis plays an essential role in the production of fine chemicals. Rh-based catalysts are one of the most active candidates for indole synthesis. However, it is still highly desired to develop heterogeneous Rh-based catalysts with high activity and selectivity. In this work, a general, facile wet-chemical method is reported to synthesize ultrathin amorphous/crystalline heterophase Rh and Rh-based bimetallic alloy nanosheets (NSs), including RhCu, RhZn, and RhRu. Impressively, the amorphous/crystalline heterophase Rh NSs exhibit enhanced catalytic activity toward the direct synthesis of indole compared to the crystalline counterpart. Importantly, the obtained amorphous/crystalline heterophase RhCu alloy NSs can further enhance the selectivity to indole of >99.9% and the conversion is 100%. This work demonstrates the importance of phase engineering and metal alloying in the rational design and synthesis of tandem heterogeneous catalysts toward fine chemical synthesis.

Ultrathin Ni(0)-Embedded Ni(OH)2 Heterostructured Nanosheets with Enhanced Electrochemical Overall Water Splitting.

The efficiency of splitting water into hydrogen and oxygen is highly dependent on the catalyst used. Herein, ultrathin Ni(0)-embedded Ni(OH)2 heterostructured nanosheets, referred to as Ni/Ni(OH)2 nanosheets, with superior water splitting activity are synthesized by a partial reduction strategy. This synthetic strategy confers the heterostructured Ni/Ni(OH)2 nanosheets with abundant Ni(0)-Ni(II) active interfaces for hydrogen evolution reaction (HER) and Ni(II) defects as transitional active sites for oxygen evolution reaction (OER). The obtained Ni/Ni(OH)2 nanosheets exhibit noble metal-like electrocatalytic activities toward overall water splitting in alkaline condition, to offer 10 mA cm-2 in HER and OER, the required overpotentials are only 77 and 270 mV, respectively. Based on such an outstanding activity, a water splitting electrolysis cell using the Ni/Ni(OH)2 nanosheets as the cathode and anode electrocatalysts has been successfully built. When the output voltage of the electrolytic cell is 1.59 V, a current density of 10 mA cm-2 can be obtained. Moreover, the durability of Ni/Ni(OH)2 nanosheets in the alkaline electrolyte is much better than that of noble metals. No obvious performance decay is observed after 20 h of catalysis. This facile strategy paves the way for designing highly active non-precious-metal catalyst to generate both hydrogen and oxygen by electrolyzing water at room temperature.

Construction of highly accessible single Co site catalyst for glucose detection.

The development of high-performance glucose sensors is an urgent need, especially for diabetes mellitus diagnosis. However, the glucose monitoring is conventionally operated in an invasive finger-prick manner and their noninvasive alternatives largely suffered from the relatively poor sensitivity, selectivity, and stability, resulted from the lack of robust and efficient catalysts. In this paper, we design a concave shaped nitrogen-doped carbon framework embellished with single Co site catalyst (Co SSC) by selectively controlling the etching rate on different facet of carbon substrate, which is beneficial to the diffusion and contact of analyte. The Co SSC prompts a significant improvement in the sensitivity of the solution-gated graphene transistor (SGGT) devices, with three orders of magnitude better than those of SGGT devices without catalysts. Our findings expand the field of single site catalyst in the application of biosensors, diabetes diagnostics and personalized health-care monitoring.

Engineering the Electronic Structure of Submonolayer Pt on Intermetallic Pd3Pb via Charge Transfer Boosts the Hydrogen Evolution Reaction.

The efficient electrochemical hydrogen evolution reaction (HER) plays a key role in accelerating sustainable H2 production from water electrolysis, but its large-scale applications are hindered by the high cost of the state-of-the-art Pt catalyst. In this work, submonolayer Pt was controllably deposited on an intermetallic Pd3Pb nanoplate (AL-Pt/Pd3Pb). The atomic efficiency and electronic structure of the active surface Pt layer were largely optimized, greatly enhancing the acidic HER. AL-Pt/Pd3Pb exhibits an outstanding HER activity with an overpotential of only 13.8 mV at 10 mA/cm2 and a high mass activity of 7834 A/gPd+Pt at -0.05 V, both largely surpassing those of commercial Pt/C (30 mV, 1486 A/gPt). In addition, AL-Pt/Pd3Pb shows excellent stability and robustness. Theoretical calculations show that the improved activity is mainly derived from the charge transfer from Pd3Pb to Pt, resulting in a strong electrostatic interaction that can stabilize the transition state and lower the barrier.

Single Cobalt Atoms with Precise N-Coordination as Superior Oxygen Reduction Reaction Catalysts.

A new strategy for achieving stable Co single atoms (SAs) on nitrogen-doped porous carbon with high metal loading over 4 wt % is reported. The strategy is based on a pyrolysis process of predesigned bimetallic Zn/Co metal-organic frameworks, during which Co can be reduced by carbonization of the organic linker and Zn is selectively evaporated away at high temperatures above 800 °C. The spherical aberration correction electron microscopy and extended X-ray absorption fine structure measurements both confirm the atomic dispersion of Co atoms stabilized by as-generated N-doped porous carbon. Surprisingly, the obtained Co-Nx single sites exhibit superior ORR performance with a half-wave potential (0.881 V) that is more positive than commercial Pt/C (0.811 V) and most reported non-precious metal catalysts. Durability tests revealed that the Co single atoms exhibit outstanding chemical stability during electrocatalysis and thermal stability that resists sintering at 900 °C. Our findings open up a new routine for general and practical synthesis of a variety of materials bearing single atoms, which could facilitate new discoveries at the atomic scale in condensed materials.

Modulating fcc and hcp Ruthenium on the Surface of Palladium-Copper Alloy through Tunable Lattice Mismatch.

Herein, we report an epitaxial-growth-mediated method to grow face-centered cubic (fcc) Ru, which is thermodynamically unfavorable in the bulk form, on the surface of Pd-Cu alloy. Induced by the galvanic replacement between Ru and Pd-Cu alloy, a shape transformation from a Pd-Cu@Ru core-shell to a yolk-shell structure was observed during the epitaxial growth. The successful coating of the unconventional crystallographic structure is critically dependent on the moderate lattice mismatch between the fcc Ru overlayer and PdCu3 alloy substrate. Further, both fcc and hexagonal close packed (hcp) Ru can be selectively grown through varying the lattice spacing of the Pd-Cu substrate. The presented findings provide a new synthetic pathway to control the crystallographic structure of metal nanomaterials.

Ultrathin Icosahedral Pt-Enriched Nanocage with Excellent Oxygen Reduction Reaction Activity.

Cost-efficient utilization of Pt in the oxygen reduction reaction (ORR) is of great importance for the potential industrial scale demand of proton-exchange membrane fuel cells. Designing a hollow structure of a Pt catalyst offers a great opportunity to enhance the electrocatalytic performance and maximize the use of precious Pt. Herein we report a routine to synthesize ultrathin icosahedral Pt-enriched nanocages. In detail, the Pt atoms were conformally deposited on the surface of Pd icosahedral seeds, followed by selective removal of the Pd core by a concentrated HNO3 solution. The icosahedral Pt-enriched nanocage that is a few atomic layers thick includes the merits of abundant twin defects, an ultrahigh surface/volume ratio, and an ORR-favored Pt{111} facet, all of which have been demonstrated to be promoting factors for ORR. With a 10 times higher specific activity and 7 times higher mass activity, this catalyst shows more extraordinary ORR activity than the commercial Pt/C. The ORR activity of icosahedral Pt-enriched nanocages outperforms the cubic and octahedral nanocages reported in the literature, demonstrating the superiority of the icosahedral nanocage structure.

Hydrogel-derived non-precious electrocatalysts for efficient oxygen reduction.

The development of highly active, cheap and robust oxygen reduction reaction (ORR) electrocatalysts to replace precious metal platinum is extremely urgent and challenging for renewable energy devices. Herein we report a novel, green and especially facile hydrogel strategy to construct N and B co-doped nanocarbon embedded with Co-based nanoparticles as an efficient non-precious ORR catalyst. The agarose hydrogel provides a general host matrix to achieve a homogeneous distribution of key precursory components including cobalt (II) acetate and buffer salts, which, upon freeze-drying and carbonization, produces the highly active ORR catalyst. The gel buffer containing Tris base, boric acid and ethylenediaminetetraacetic acid, commonly adopted for pH and ionic strength control, plays distinctively different roles here. These include a green precursor for N- and B-doping, a salt porogen and a Co(2+) chelating agent, all contributing to the excellent ORR activity. This hydrogel-based process is potentially generalizable for many other catalytic materials.

Multifunctional electroactive heteroatom-doped carbon aerogels.

The design and synthesis of highly active, durable, and cheap nanomaterials for various renewable energy storage and conversion applications is extremely desirable but remains challenging. Here, a green and efficient strategy to produce CoOx nanoparticles and surface N-co-doped carbon aerogels (Co-N-CAs) is reported by multicomponent surface self-assembly of commercially melamine sponge (CMS). In the methodology, the CMS simultaneously function as green N precursor for surface N doping and 3D support. The resulting Co-N-CAs exhibit 3D hierarchical, interconnected macro- and bimodal meso-porosity (6.3 nm and <4 nm), high surface area (1383 m(2) g(-1)), and highly dispersed, semi-exposured CoOx nanoparticles (diameter of 12.5 nm). The surface doping of N, semi-exposured configuration of CoOx nanoparticles and the penetrated complementary pores (<4 nm) in the carbon walls provide highly accessibility between electroactive components and electrolytes to improve reactivity. With their tailored architecture, the Co-N-CAs show superior electrocatalytic oxygen reduction (ORR) activities comparable to the commercially Pt/C catalysts, high specific capacitance (433 F g(-1)), excellent lithium storage (938 mAh g(-1)), and outstanding durability, making them very promising for advanced energy conversion and storage. In addition, the presented strategy can be extended to fabricate other metal oxide- and N-co-doped carbon aerogels for diverse energy-related applications.

Synthesis and photocatalytic performance of ZnIn2S4 nanotubes and nanowires.

ZnIn2S4 nanotubes and nanowires have been selectively fabricated via a convenient one-step wet-chemical approach by using porous polycarbonate membrane as a hard template. The wall of nanotubes is as thin as 5 nm, and the diameter of them is 200 nm. Formation mechanism of ZnIn2S4 nanotubes and nanowires is also discussed according to the experimental results. The structure, morphology, and composition properties of the as-prepared samples were characterized using X-ray powder diffraction, UV-vis spectrophotometer, transmission electron microscopy, energy dispersive X-ray spectrometry, and scanning electron microscopy.

Phosphate-free synthesis, optical absorption and photoelectric properties of Cu2ZnGeS4 and Cu2ZnGeSe4 uniform nanocrystals.

Copper-based quaternary chalcogenide semiconductor Cu2ZnGeS4 and Cu2ZnGeSe4 nanocrystals have been synthesized successfully via a simple and convenient one-pot phosphine-free solution approach. Oleylamine was used as both the solvent and reductant for Se or S and benefited the formation of homogeneous quaternary nanocrystals. Scanning transmission electron microscopy-EDS elemental mapping confirms the uniform spatial distribution of four elements in nanocrystals. UV-Vis absorption spectra of Cu2ZnGeS4 and Cu2ZnGeSe4 nanocrystals show strong photon absorption in the entire visible range. The photoresponsive behavior indicates the potential application of Cu2ZnGeSe4 nanocrystals in solar energy conversion systems.

Synthesis and photoelectric properties of Cu2ZnGeS4 and Cu2ZnGeSe4 single-crystalline nanowire arrays.

Cu2ZnGeS4 (CZGS) and Cu2ZnGeSe4 (CZGSe) single crystalline nanowire arrays have been prepared via a convenient one-step nanoconfined solvothermal approach. The porous anodic aluminum oxide was used as a morphology directing template by offering nanospace in the AAO pores for confined solvothermal reaction. The structure, morphology, composition, and optical absorption properties of the as-prepared samples were characterized using X-ray powder diffraction, transmission electron microscopy, energy dispersive X-ray spectrometry, scanning electron microscopy, and a UV-vis spectrophotometer. The CZGS and CZGSe films are found to have obvious photoelectric response, indicating their potential in the application of photovoltaic devices.