Hexagonal PtBi Intermetallic Inlaid with Sub-Monolayer Pb Oxyhydroxide Boosts Methanol Oxidation.

Engineering multicomponent nanocatalysts is effective to improve electrocatalysis in many applications, yet it remains a challenge in constructing well-defined multimetallic active sites at the atomic level. Herein, the surface inlay of sub-monolayer Pb oxyhydroxide onto hexagonal PtBi intermetallic nanoplates with intrinsically isolated Pt atoms to boost the methanol oxidation reaction (MOR) is reported. The well-defined PtBi@6.7%Pb nanocatalyst exhibits 4.0 and 7.4 times higher mass activity than PtBi nanoplates and commercial Pt/C catalyst toward MOR in the alkaline electrolyte at 30 °C. Meanwhile, it also achieves a record-high mass activity of 51.07 A mg-1 Pt at direct methanol fuel cells operation temperature of 60 °C. DFT calculations reveal that the introduction of Pb oxyhydroxide on the surface not only promotes the electron transfer efficiency but also suppresses the CO poisoning effect, and the efficient p-d coupling optimizes the electroactivity of PtBi@6.7%Pb nanoplates toward the MOR process with low reaction barriers. This work offers a nanoengineering strategy to effectively construct and modulate multimetallic nanocatalysts to improve the electroactivity toward the MOR in future research.

PtBi-ß-CD-Ce6 Nanozyme for Combined Trimodal Imaging-Guided Photodynamic Therapy and NIR-II Responsive Photothermal Therapy.

Combined photothermal/photodynamic therapy is a promising strategy to achieve an enhanced anticancer effect. However, hypoxia is one of the representative characteristics of the microenvironment of solid tumors, which not only attenuates the therapeutic effects but also promotes tumor invasion and metastasis. Herein, a PtBi-ß-CD-Ce6 nanoplatform for the generation of sustained O2 was constructed for more effective tumor therapy. In detail, the catalase (CAT)-like nanozyme, PtBi, which could decompose H2O2 to produce O2, was modified with ß-cyclodextrin (ß-CD). O2 would be converted into 1O2 by PtBi-ß-CD-Ce6 for enhanced photodynamic therapy (PDT) under 650 nm laser irradiation. In addition, by reason of excellent absorption in the near-infrared-II (NIR-II) region, PtBi-ß-CD-Ce6 was used for photoacoustic imaging (PA) and photothermal imaging (PT)-guided photothermal therapy (PTT) in the NIR-II biowindow. Furthermore, PtBi-ß-CD-Ce6 could be elected to serve as a contrast agent for X-ray computed tomography (CT) imaging due to the apparent X-ray attenuation capability of the Pt and Bi elements themselves. Therefore, by integrating the advantages of overcoming the hypoxia function and photothermal effect into a single nanoplatform, PtBi-ß-CD-Ce6 showed an immense possibility in multimodal imaging-guided combined PDT/PTT.

Directing Gold Nanoparticles into Free-Standing Honeycomb-Like Ordered Mesoporous Superstructures.

2D mesoporous materials fabricated via the assembly of nanoparticles (NPs) not only possess the unique properties of nanoscale building blocks but also manifest additional collective properties due to the interactions between NPs. In this work, reported is a facile and designable way to prepare free-standing 2D mesoporous gold (Au) superstructures with a honeycomb-like configuration. During the fabrication process, Au NPs with an average diameter of 5.0 nm are assembled into a superlattice film on a diethylene glycol substrate. Then, a subsequent thermal treatment at 180 °C induces NP attachment, forming the honeycomb-like ordered mesoporous Au superstructures. Each individual NP connects with three neighboring NPs in the adjacent layer to form a tetrahedron-based framework. Mesopores confined in the superstructure have a uniform size of 3.5 nm and are arranged in an ordered hexagonal array. The metallic bonding between Au NPs increases the structural stability of architected superstructures, allowing them to be easily transferred to various substrates. In addition, electron energy-loss spectroscopy experiments and 3D finite-difference time-domain simulations reveal that electric field enhancement occurs at the confined mesopores when the superstructures are excited by light, showing their potential in nano-plasmonic applications.

High Pressure Structural and Optical Properties of Two-Dimensional Hybrid Halide Perovskite (CH3NH3)3Bi2Br9.

Two-dimensional (2D) hybrid halide perovskite is emerging as the next generation of photoelectronic materials. Herein, a typical 2D halide perovskite of MA3Bi2Br9 (MA = CH3NH3) is chosen for high pressure research to explore the distinct structural and property characteristics of the inorganic and organic compositions therein. Upon compression above 4.3 GPa, the distortion and tilting of inorganic BiBr6 octahedra dominate the phase transition of MA3Bi2Br9 from trigonal to monoclinic. Meanwhile, exceptionally anisotropic compressibilities are observed between intra- and interlayer structures, which originate from the unique geometry of puckered layer. In addition, the presence of organic MA+ cations contributes to the flexible structural nature of MA3Bi2Br9. Meanwhile, the geometrical changes of inorganic components determine the relationships between structure and band gap under pressure. This work not only demonstrates the intriguing structure nature of MA3Bi2Br9 but also reveals the individual contributions on the structure-property diagram from inorganic (BiBr6 octahedra) and organic (MA cations) components.

Photothermal-Enhanced Dual Inhibition of Lactate/Kynurenine Metabolism for Promoting Tumor Immunotherapy.

Traditionally referred to as "metabolic junk", lactate has now been recognized as essential "energy currency" and crucial "messenger" that contributes to tumor evolution, immunosuppression, etc., thus presenting a promising strategy for antitumor interventions. Similarly, kynurenine (Kyn) also exerts an immunosuppressive function, thereby significantly compromising the effectiveness of immunotherapy. This study proposes and validates a strategy for enhancing immunotherapy through photothermal-assisted depletion of lactate sustained by cycle-like O2 supply, with blocking the tryptophan (Trp)/Kyn metabolic pathway. In brief, a nanozyme therapeutic agent (PNDPL) is constructed, which mainly consists of PtBi nanozymes, lactate oxidase (LOX) and the indoleamine 2,3-dioxygenase (IDO) inhibitor NLG919. The PtBi nanozymes, which exhibit a catalase (CAT)-like activity, form a positive feedback loop with LOX to consume lactate while self-supplying O2 . Moreover, PtBi nanozymes retain enzyme-like performance even in a slightly acidic tumor microenvironment. Under 1064 nm irradiation, photothermal therapy (PTT) not only induces tumor cell death but also accelerates lactate exhaustion. Therefore, the combination of lactate depletion-induced starvation therapy and PTT, along with the blocking of IDO-mediated immune escape, effectively inhibits tumor growth and reverses immunosuppressive microenvironment, thus preventing tumor metastasis. This study represents the first investigation into the synergistic antitumor effects by lactate metabolism regulation and IDO-related immunotherapy.

Atomic Diffusion Engineered PtSnCu Nanoframes with High-Index Facets Boost Ethanol Oxidation.

Electrochemical ethanol oxidation is crucial to directly convert a biorenewable liquid fuel with high energy density into electrical energy, but it remains an inefficient reaction even with the best catalysts. To boost ethanol oxidation, developing multimetallic nanoalloy has emerged as one of the most effective strategies, yet faces a challenge in the rational engineering of multimetallic active-site ensembles at atomic-level. Herein, starting from typical PtCu nanocrystals, an atomic Sn diffusion strategy is developed to construct well-defined Pt47Sn12Cu41 octopod nanoframes, which is enclosed by high-index facets of n (111)-(111), such as {331} and {221}. Pt47Sn12Cu41 achieves a high mass activity of 3.10 A mg-1 Pt and promotes the C-C bond breaking and oxidation of poisonous CO intermediate, representing a state-of-the-art electrocatalyst toward ethanol oxidation in acidic electrolyte. Density functional theory （DFT） calculations have confirmed that the introduction of Sn improves the electroactivity by uplifting the d-band center through the s-p-d coupling. Meanwhile, the strong binding of ethanol and the reduced energy barrier of CO oxidation guarantee a highly efficient ethanol oxidation process with improved Faradic efficiency of C1 products. This work offers a promising strategy for constructing novel multimetallic nanoalloys tailored by atomic metal sites as the efficient electrocatalysts.

Surface-Enriched Single-Bi-Atoms Tailoring of Pt Nanorings for Direct Methanol Fuel Cells with Ultralow-Pt-Loading.

Single-atom decorating of Pt emerges as a highly effective strategy to boost catalytic properties, which can trigger the most Pt active sites while blocking the smallest number of Pt atoms. However, the rational design and creation of high-density single-atoms on Pt surface remain as a huge challenge. Herein, a customized synthesis of surface-enriched single-Bi-atoms tailored Pt nanorings (SE-Bi1/Pt NRs) toward methanol oxidation is reported, which is guided by the density functional theory (DFT) calculations suggesting that a relatively higher density of Bi species on Pt surface can ensure a CO-free pathway and accelerate the kinetics of *HCOOH formation. Decorating Pt NRs with dense single-Bi-atoms is achieved by starting from PtBi intermetallic nanoplates (NPs) with intrinsically isolated Bi atoms and subsequent etching and annealing treatments. The SE-Bi1/Pt NRs exhibit a mass activity of 23.77 A mg-1 Pt toward methanol oxidation in alkaline electrolyte, which is 2.2 and 12.8 times higher than those of Pt-Bi NRs and Pt/C, respectively. This excellent activity endows the SE-Bi1/Pt NRs with a high likelihood to be used as a practical anodic electrocatalyst for direct methanol fuel cells （DMFCs） with high power density of 85.3 mW cm-2 and ultralow Pt loading of 0.39 mg cm-2.

Defect-Engineered Cu-Based Nanomaterials for Efficient CO2 Reduction over Ultrawide Potential Window.

High conversion efficiency over a wide operating potential window is important for the practical application of CO2 reduction electrocatalysis, yet that remains a huge challenge in differentiating the competing CO2 reduction and H2 evolution. Here we introduce point defects (Sn doping) and planar defects (grain boundary) into the Cu substrate. This multidimensional defect integration strategy guides the fabrication of highly diluted SnCu polycrystal, which exhibits high Faradaic efficiencies (>95%) toward CO2 electroreduction over an ultrawide potential window (ΔE = 1.3 V). The theoretical study indicates that the introduction of Sn doping and grain boundary synergistically provides an optimized electronic effect, which helps suppress H2 evolution and promotes the hydrogenation of *CO2.

Vesicle Geometries Enabled by Semiflexible Polymer.

Understanding and controlling vesicle shapes is fundamental challenge in biophysics and materials design. In this paper, we employ the Monte Carlo method to investigate the shape of soft vesicle induced by semiflexible polymer outside in two dimensions. The effect of bending stiffness κ of polymer and the strength εVP of attractive interaction between vesicle and polymer on the shape of vesicle is discussed in detail in the present paper. It is found that the shape of vesicle is influenced by κ and εVP. Typical shape of vesicles is observed, such as circular, cigar-like, double vesicle, and racquet-like. To engineer vesicle shape transformations is helpful for exploiting the richness of vesicle geometries for desired applications.

High-Entropy Intermetallic PtRhBiSnSb Nanoplates for Highly Efficient Alcohol Oxidation Electrocatalysis.

The control of multimetallic ensembles at the atomic-level is challenging, especially for high-entropy alloys (HEAs) possessing five or more elements. Herein, the one-pot synthesis of hexagonal-close-packed (hcp) PtRhBiSnSb high-entropy intermetallic (HEI) nanoplates with intrinsically isolated Pt, Rh, Bi, Sn, and Sb atoms is reported, to boost the electrochemical oxidation of liquid fuels. Taking advantage of these combined five metals, the well-defined PtRhBiSnSb HEI nanoplates exhibit a remarkable mass activity of 19.529, 15.558, and 7.535 A mg-1 Pt+Rh toward the electrooxidation of methanol, ethanol, and glycerol in alkaline electrolytes, respectively, representing a state-of-the-art multifunctional electrocatalyst for alcohol oxidation reactions. In particular, the PtRhBiSnSb HEI achieves record-high methanol oxidation reaction (MOR) activity in an alkaline environment. Theoretical calculations demonstrate that the introduction of the fifth metal Rh enhances the electron-transfer efficiency in PtRhBiSnSb HEI nanoplates, which contributes to the improved oxidation capability. Meanwhile, robust electronic structures of the active sites are achieved due to the synergistic protections from Bi, Sn, and Sb sites. This work offers significant research advances in developing well-defined HEA with delicate control over compositions and properties.

A Tensile-Strained Pt-Rh Single-Atom Alloy Remarkably Boosts Ethanol Oxidation.

The rational design and control of electrocatalysts at single-atomic sites could enable unprecedented atomic utilization and catalytic properties, yet it remains challenging in multimetallic alloys. Herein, the first example of isolated Rh atoms on ordered PtBi nanoplates (PtBi-Rh1 ) by atomic galvanic replacement, and their subsequent transformation into a tensile-strained Pt-Rh single-atom alloy (PtBi@PtRh1 ) via electrochemical dealloying are presented. Benefiting from the Rh1 -tailored Pt (110) surface with tensile strain, the PtBi@PtRh1 nanoplates exhibit record-high and all-round superior electrocatalytic performance including activity, selectivity, stability, and anti-poisoning ability toward ethanol oxidation in alkaline electrolytes. Density functional theory calculations reveal the synergism between effective Rh1 and tensile strain in boosting the adsorption of ethanol and key surface intermediates and the CC bond cleavage of the intermediates. The facile synthesis of the tensile-strained single-atom alloy provides a novel strategy to construct model nanostructures, accelerating the development of highly efficient electrocatalysts.

Novel Bi-Doped Amorphous SnOx Nanoshells for Efficient Electrochemical CO2 Reduction into Formate at Low Overpotentials.

Engineering novel Sn-based bimetallic materials could provide intriguing catalytic properties to boost the electrochemical CO2 reduction. Herein, the first synthesis of homogeneous Sn1- x Bix alloy nanoparticles (x up to 0.20) with native Bi-doped amorphous SnOx shells for efficient CO2 reduction is reported. The Bi-SnOx nanoshells boost the production of formate with high Faradaic efficiencies (>90%) over a wide potential window (-0.67 to -0.92 V vs RHE) with low overpotentials, outperforming current tin oxide catalysts. The state-of-the-art Bi-SnOx nanoshells derived from Sn0.80 Bi0.20 alloy nanoparticles exhibit a great partial current density of 74.6 mA cm-2 and high Faradaic efficiency of 95.8%. The detailed electrocatalytic analyses and corresponding density functional theory calculations simultaneously reveal that the incorporation of Bi atoms into Sn species facilitates formate production by suppressing the formation of H2 and CO.

Trimetallic Synergy in Intermetallic PtSnBi Nanoplates Boosts Formic Acid Oxidation.

Platinum is the most effective metal for a wide range of catalysis reactions, but it fails in the formic acid electrooxidation test and suffers from severe carbon monoxide poisoning. Developing highly active and stable catalysts that are capable of oxidizing HCOOH directly into CO2 remains challenging for commercialization of direct liquid fuel cells. A new class of PtSnBi intermetallic nanoplates is synthesized to boost formic acid oxidation, which greatly outperforms binary PtSn and PtBi intermetallic, benefiting from the synergism of chosen three metals. In particular, the best catalyst, atomically ordered Pt45 Sn25 Bi30 nanoplates, exhibits an ultrahigh mass activity of 4394 mA mg-1 Pt and preserves 78% of the initial activity after 4000 potential cycles, which make it a state-of-the-art catalyst toward formic acid oxidation. Density functional theory calculations reveal that the electronic and geometric effects in PtSnBi intermetallic nanoplates help suppress CO* formation and optimize dehydrogenation steps.

Controlled Synthesis of PtNi Hexapods for Enhanced Oxygen Reduction Reaction.

Well-defined PtNi nanocrystals represent one of the most efficient electrocatalysts to boost the oxygen reduction reaction (ORR), especially in the shape of octahedrons, nanoframes, and nanowires. However, the synthesis of complex PtNi nanostructure is still a great challenge. Herein, we report a new class of PtNi hexapods with high activity and stability toward ORR. The hexapods are prepared by selective capping and simultaneous corrosion. By controlling the oxidative etching, PtNi polyhedrons and nanoparticles are obtained, respectively. The intriguing hexapods are composed of six nanopods with an average length of 12.5 nm. Due to their sharp tips and three-dimensional (3D) accessible surfaces, the PtNi hexapods show a high mass activity of 0.85 A mg Pt - 1 at 0.9 V vs. RHE, which are 5.4-fold higher than commercial Pt/C, also outperforming PtNi polyhedrons and PtNi nanoparticles. In addition, the mass activity of PtNi hexapods maintains 92.3% even after 10,000 potential cycles.

Concave Platinum-Copper Octopod Nanoframes Bounded with Multiple High-Index Facets for Efficient Electrooxidation Catalysis.

Multimetallic nanoframes with three-dimensional (3D) catalytic surfaces represent an emerging class of efficient nanocatalysts. However, it still remains a challenge in engineering nanoframes via simple and economical methods. Herein, we report a facile one-pot synthetic strategy to synthesize Pt-Cu nanoframes bounded with multiple high-index facets as highly active electrooxidation catalysts. Two distinct octopod nanoframes, namely, concave PtCu2 octopod nanoframes (PtCu2 CONFs) and ultrathin PtCu octopod nanoframes (PtCu UONFs) were successfully synthesized by simply changing the feeding Pt and Cu precursors. Interestingly, the PtCu2 CONFs are constructed by eight symmetric feet with sharp tips, which are enclosed by high-index facets of n (111)-(111), such as {553}, {331}, and {221}. Benefiting from their 3D accessible surfaces and multiple high-index facets, the self-supported PtCu2 CONFs catalysts exhibit excellent electrocatalytic performance and superior CO-tolerant ability. For methanol oxidation reaction, the PtCu2 CONFs catalysts exhibit more than 7-fold increase in activities, 205 mV lower in the onset potential compared with commercial Pt/C. More importantly, when facing harsh electrochemical reaction conditions, the PtCu2 CONFs are well-preserved in the catalytic activities, architectural features, and stepped surfaces. The PtCu UONFs with 12 ultrathin edges, however, suffer from breakdown. The present work provides guidelines for the rational design and synthesis of nanoframe catalysts with both high activity and stability.

Atomic-Scale Preparation of Octopod Nanoframes with High-Index Facets as Highly Active and Stable Catalysts.

An atomic-scale engineered octopod nanoframe architecture (OFA) consisting of 3D catalytic surfaces and beneficial high-index facets is developed via a facile one-pot synthesis method. Based on the reliable recipe and general method, various complex nanoframe architectures are developed. Specially, the PtCu OFAs exhibit exceptional activity and stability for the oxygen reduction reaction and can be easily scaled up to high-quality.