Transforming Nickel Hydroxide into 3D Prussian Blue Analogue Array to Obtain Ni2P/Fe2P for Efficient Hydrogen Evolution Reaction

For the first time, a 3D Prussian blue analogue (PBA) with well‐defined spatial organization is fabricated by using a nickel hydroxide array as a precursor. The nickel hydroxide arrays are synthesized in titanium foil and reacted with K₃[Fe(CN)₆]. The plate‐like morphology of the nickel hydroxide is perfectly preserved and combined with abundant PBA nanocubes. After phosphidation at 350 °C, the obtained sample demonstrated excellent hydrogen evolution reaction (HER) activity in both acid and alkaline solutions to reach a current density of 10 mA cm^?2 with an overpotential of only 70 and 121 mV, respectively. With an overpotential of 266 mV, it can reach a larger current density of 500 mA cm^?2 in acid. The efficient HER activity of the obtained sample is mainly ascribed to its structural advantage with various active metal sites derived from the nickel hydroxide and PBA precursor. In addition, long‐term stability measurements have verified the good performance of the obtained sample in acid and alkaline solutions. An increment of overpotential of only 8 and 9 mV is observed, in the acid and alkaline solutions respectively. Beyond these assets, it is supposed that the strategy to synthesize 3D PBA arrays from nickel hydroxide can be extended to other metal–organic frameworks arrays for more electrochemical applications.     

A Nanosheet Array of Cu2Se Intercalation Compound with Expanded Interlayer Space for Sodium Ion Storage

Intercalation chemistry/engineering has been widely investigated in the development of electrochemical energy storage. Graphite, as an old intercalation host, is receiving vigorous attention again via a new halogen intercalation. Whereas, exploiting new intercalation hosts and optimizing the intercalation effect still remains a great challenge. This study fabricates a Cu₂Se intercalation compound showing expanded interlayer space and nanosheet array features by using a green growth approach, in which cetyltrimethyl ammonium bromide (CTAB) is inserted into Cu₂Se at an ambient temperature. When acting as an electrode material for sodium‐ion batteries, the Cu₂Se–CTAB nanosheet arrays exhibit excellent discharge capacity and rate capability (426.0 mAh g^?1 at 0.1 A g^?1 and 238.1 mAh g^?1 at 30 A g^?1), as well as high capacity retention of ≈90% at 20 A g^?1 after 6500 cycles. Benefiting from the porous array architecture, the transport of electrolytes is facilitated on the surface of Cu₂Se nanosheets. In particular, the CTAB intercalated in the interlayer space of Cu₂Se can increase its buffer space, stabilize the polyselenide shuttle, and prevent the fast growth of Cu nanoparticles during its electrochemical process.     

Template‐Free Construction of Self‐Supported Sb Prisms with Stable Sodium Storage

Antimony (Sb) is a promising anode material for sodium‐ion batteries owing to its large capacity of 660 mAh g^?1. However, its practical application is restricted by the rapid capacity decay resulted from a large volume expansion up to 390% upon Na alloying. Herein, construction of a self‐supported Sb array that has enough space allowing for effective accommodation of the volume change is reported. The array of Sb prisms is directly grown on a Cu substrate via a template‐free electrodeposition, followed by mild heating to consolidate the structural integrity between Sb and Cu. The resulting 3D architecture endows the Sb array with excellent sodium storage performance, exhibiting a reversible capacity of 578 mAh g^?1 and retaining 531 mAh g^?1 over 100 cycles at 0.5 C. The potential of Sb array in sodium‐ion full cells by pairing it with a Na_0.67(Ni_0.23Mg_0.1Mn_0.67)O₂ cathode is further demonstrated. This full cell affords a specific energy of 197 Wh kg^?1 at 0.2 C and a specific power of 1280 W kg^?1 at 5 C. Considering its low cost and scale‐up capability, the template‐free route may find extensive applications in designing electrode architectures.     

Quantum dot-based protein micro- and nanoarrays for detection of prostate cancer biomarkers

In this article, we demonstrate the fabrication and detection of cancer protein biochips consisting of micro- and nanoarrays whereby pegylated quantum dots (QDs) conjugated to antibodies (Abs) of prostate specific antigens (PSA) were used for the detection of clinical biomarkers such as PSA. BSA which acts as an efficient blocking layer in microarrays, tends to show an interaction with QDs. In view of this fact, we investigated two series of samples which were fabricated in the presence and absence of BSA blocking layer. Variation in the incubation time required for the antigen-antibody interaction to take place, different proteins as controls and the effect of bare QDs on these microarrays, were the three main parameters which were studied in these two series. Samples fabricated in the absence of BSA blocking layer exhibited an extremely high specificity in the detection of cancer proteins and were also marked by negligible nonspecific binding effects of QDs, in stark contrast to the samples fabricated using BSA as a blocking layer. Fabrication of nanoarrays of QD-conjugated PSA Abs having a spot size of nearly 900 nm has also been demonstrated. Thus, we show the potential offered by QDs in in vitro analysis of cancer biomarker imaging.