Increasing the utilization efficiency of platinum is critical for advancing proton exchange-membrane fuel cells (PEMFCs). Despite extensive research on catalysts for the cathodic oxygen reduction reaction (ORR), developing highly active and durable Pt-based catalysts that can suppress surface dealloying in corrosive acid conditions remains challenging. Herein, we report a facile synthesis of bimetallic ultrathin PtM (M = Mo, W, and Cr) nanowires (NWs) composed of group VI B transition metal atomic sites anchored on the surface. These NWs possess uniform sizes and well-controlled atomic arrangements. Compared to PtW and PtCr catalysts, the PtMo_0.05 NWs exhibit the highest half-wave potential of 0.935 V and a mass activity of 1.43 A·mg_Pt⁻¹. Remarkably, they demonstrate a remarkable 23.8-fold enhancement in mass activity compared to commercial Pt/C for ORR, surpassing previously reported Pt-based catalysts. Additionally, the PtMo NWs cathode in membrane electrode assembly tests achieves a remarkable peak power density of 1.443 W·cm⁻² (H₂-O₂ conditions at 80 °C), which is 1.09 times that of commercial Pt/C. The ligand effect in the bimetallic surface not only facilitates strong coupling between Mo (4d) and Pt (5d) atomic orbitals to hinder atom leaching but also modulates the d-states of active site, significantly optimizing the adsorption of key oxygen (*O and *OH) species and accelerating the rate-determining step in ORR pathways.

The ethanol oxidation reaction (EOR) is crucial in direct alcohol fuel cells and chemical production. However, the electro-oxidation of ethanol molecules to produce acetaldehyde and carbon monoxide can poison the active sites of nanocatalysts, resulting in reduced performance and posing challenges in achieving high activity and selectivity for ethanol oxidation. In this study, we employed a dynamic seed-mediated method to precisely modify highly dispersed Ru sites onto well-defined Pd nanocrystals. The oxyphilic Ru sites serve as "OH valves", regulating water dissociation, while the surrounding Pd atomic arrangements control electronic states for the oxidation dehydrogenation of carbonaceous intermediates. Specifically, Ru_0.040@Pd nanocubes (Ru:Pd = 0.04 at.%), featuring (100) facets in Ru-Pd₄ configurations, demonstrate an outstanding mass activity of 6.53 A·mg_Pd⁻¹ in EOR under alkaline conditions, which is 6.05 times higher than that of the commercial Pd/C catalyst (1.08 A·mg_Pd⁻¹). Through in-situ experiments and theoretical investigations, we elucidate that the hydrophilic Ru atoms significantly promote the dynamic evolution of H₂O dissociation into OH_ads species, while the electron redistribution from Ru to adjacent Pd concurrently adjusts the selective oxidation of C₂ intermediates. This host–guest interaction accelerates the subsequent oxidation of carbonaceous intermediates (CH₃CO_ads) to acetate, while preventing the formation of toxic *CH_x and *CO species, which constitutes the rate-determining step.

Fine regulation of geometric structures has great promise to acquire specific electronic structures and improve the catalytic performance of single-atom catalysts, yet it remains a challenge. Herein, a novel seed encapsulation–decomposition strategy is proposed for the geometric distortion engineering and thermal atomization of a series of Cu-N_x/S moieties anchored on carbon supports. During pyrolysis, seeds (Cu²⁺, CuO, or Cu₇S₄ nanoparticles) confined in metal organic framework can accommodate single Cu atoms with Cu–N or Cu–S coordination bonds and simultaneously induce C–S or C–N bond cleavage in the second coordination shell of Cu centers, which are identified to manipulate the distortion degree of Cu-N_x/S moieties. The severely distorted Cu-N₃S molecular structure endows the resultant catalyst with excellent oxygen reduction reaction activity (E_1/2 = 0.885 V) and zinc-air battery performance (peak power density of 210 mW·cm⁻²), outperforming the asymmetrical and symmetrical Cu-N₄ structures. A combined experimental and theoretical study reveals that the geometric distortion of Cu-N_x/S moieties creates uneven charge distribution by a unique topological correlation effect, which increases the metal charge and shifts the d-band center toward the Fermi level, thereby optimizing the inter-mediate adsorption energy.

Photocathode with superior catalytic activity, long-term stability, and fast mass/electron transfer is highly desirable but challenging for dye-sensitized solar cell (DSC). Herein, the ZIF-67 grown on carbon cloth is successfully transformed into CoSe₂ embedded in N-doped carbon nanocage (CoSe₂/N-C) via a growth-carbonization-selenization process. The carbon cloth supported CoSe₂/N-C, as photocathode of DSC, demonstrates a good long-term stability and high photovoltaic efficiency (8.40%), outperforming Pt. The good efficiency can be attributed to the high catalytic activity of CoSe₂, fast mass transfer of porous three-dimensional (3D) structure, and good electron transport derived from the intimate contact between CoSe₂ and highly conductive carbon cloth. The high stability would be ascribed to N-doped carbon coating that perfectly prevents CoSe₂ from decomposition. This work will pave the way to develop highly efficient and stable Pt-free photocathode for DSC.

We develop a unique ternary Pd–Ni–P nanocatalyst for the sensitive enzymefree electrooxidation detection of glucose under alkaline conditions. By reducing the distance between the Pd and Ni active sites in the Pd–Ni–P nanoparticles (NPs) via atom engineering, the catalyst structure is transformed from Pd@Ni–P dumbbells into spherical NPs, greatly enhancing the catalyst sensitivity. The glassy carbon electrode modified with Pd–Ni–P ternary NPs, which behaves as an efficient nonenzymatic glucose sensor, offers excellent electrocatalytic performance with a high sensitivity of 1, 136 μA·mM^-1·cm^-2, a short response time of 2 s, a wide linear range of 0.5 μM to 10.24 mM, a low limit of detection of 0.15 μM (signal-to-noise ratio = 3), and good selectivity and reproducibility. Moreover, owing to its superior catalytic performance, the Pd–Ni–P modified electrode has excellent reliability for glucose detection in real samples of human serum. Our study provides a promising alternative strategy for designing and constructing high-performance multicomponent nanocatalyst-based sensors.

Copper sulfide (Cu₇S₄) nanoparticles coated with an ultra-high payload (~5.0 × 10⁷ fluorine atoms per particle) of fluorinated ligands (oleylamine functionalized 3, 5-bis(trifluoromethyl)benzaldehyde, ¹⁹F_OAm) exhibited a single intense 19F magnetic resonance (MR) signal and efficient near infrared photothermal performance in water medium. In vivo assessment revealed strong ¹⁹F MR signals at cancerous lesions and effective inhibition of tumor growth after photothermal treatment, indicating the great potential of these fabricated nanoprobes for simultaneous ¹⁹F MR imaging and photothermal therapy.

Thermosensitive drug delivery systems (DDSs) face major challenges, such as remote and repeatable control of in vivo temperature, although these can increase the therapeutic efficacy of drugs. To address this issue, we coated near-infrared (NIR) photothermal Cu_1.75S nanocrystals with pH/thermos-sensitive polymer by in situ polymerization. The doxorubicine (DOX) loading content was up to 40 wt.%, with less than 8.2 wt.% of DOX being leaked under normal physiological conditions (pH = 7.4, 37 ℃) for almost 48 h in the absence of NIR light. These nanocapsules demonstrate excellent photothermal stability by continuous longterm NIR irradiation. Based on the stable and high photothermal efficiency (55.8%), pre-loaded drugs were released as desired using 808-nm light as a trigger. Both in vitro and in vivo antitumor therapy results demonstrated that this smart nanoplatform is an effective agent for synergistic hyperthermia-based chemotherapy of cancer, demonstrating remote and noninvasive control.

Highly luminescent upconversion nanoparticles (UCNPs) with small sizes are highly desirable for bioapplications. A facile in situ cation exchange strategy has been developed to greatly enhance the UC luminescence of hexagonal phase NaYF₄ NPs while maintaining their small particle size and shape. Via a cation exchange treatment by hot-injecting Gd³⁺ precursors into the as-prepared NPs solution without pre-separation, the naked-eye visible UC emission of the NPs was enhanced about 29 times under 980 nm near infrared (NIR) excitation with unchanged particle size. The cation exchange process was further demonstrated for the case of NaYF₄ nanorods (NRs). After the cation exchange, the nanorod was broken into two NPs with stronger emission. The cation exchanged hydrophobic UCNPs were further encapsulated with poly(amino acid) and successfully applied for targeted cancer cell UC luminescence imaging.

A facile strategy using cheap and readily available precursors has been successfully developed for the synthesis of rare-earth doped hexagonal phase NaYF₄ nanocrystals with uniform shape and small particle size as well as strong photoluminescence. Due to their optical properties and good biocompatibility, these multicolor nanocrystals were successfully used as a bio-tag for cancer cell imaging. This novel synthetic method should also be capable of extension to the synthesis of other fluoride nanocrystals such as YF₃ and LaF₃.

This paper describes the synthesis of new upconverting luminescent nanoparticles that consist of YF₃: Yb³⁺/Er³⁺ functionalized with poly(acrylic acid) (PAA). Unlike the upconverting nanocrystals previously reported in the literature that emit visible (blue–green–red) upconversion fluorescence, these as-prepared nanoparticles emit strong near-infrared (NIR, 831 nm) upconversion luminescence under 980 nm excitation. Scanning electron microscopy, transmission electron microscopy, and powder X-ray diffraction were used to characterize the size and composition of the luminescent nanocrystals. Their average diameter was about 50 nm. The presence of the PAA coating was confirmed by infrared spectroscopy. The particles are highly dispersible in aqueous solution due to the presence of carboxylate groups in the PAA coating. By carrying out the synthesis in the absence of PAA, YF₃: Yb³⁺/Er³⁺ nanorice materials were obtained. These nanorice particles are larger (~700 nm in length) than the PAA-functionalized nanoparticles and show strong typical visible red (668 nm), rather than NIR (831 nm), upconversion fluorescence. The new PAA-coated luminescent nanoparticles have the pottential be used in a variety of bioanalytical and medical assays involving luminescence detection and fluorescence imaging, especially in vivo fluorescence imaging, due to the deep penetration of NIR radiation.