Duplex Interpenetrating-Phase FeNiZn and FeNi3 Heterostructure with Low-Gibbs Free Energy Interface Coupling for Highly Efficient Overall Water Splitting.

The sluggish kinetics of both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) generate the large overpotential in water electrolysis and thus high-cost hydrogen production. Here, multidimensional nanoporous interpenetrating-phase FeNiZn alloy and FeNi3 intermetallic heterostructure is in situ constructed on NiFe foam (FeNiZn/FeNi3@NiFe) by dealloying protocol. Coupling with the eminent synergism among specific constituents and the highly efficient mass transport from integrated porous backbone, FeNiZn/FeNi3@NiFe depicts exceptional bifunctional activities for water splitting with extremely low overpotentials toward OER and HER (η1000 = 367/245 mV) as well as the robust durability during the 400 h testing in alkaline solution. The as-built water electrolyzer with FeNiZn/FeNi3@NiFe as both anode and cathode exhibits record-high performances for sustainable hydrogen output in terms of much lower cell voltage of 1.759 and 1.919 V to deliver the current density of 500 and 1000 mA cm-2 as well long working lives. Density functional theory calculations disclose that the interface interaction between FeNiZn alloy and FeNi3 intermetallic generates the modulated electron structure state and optimized intermediate chemisorption, thus diminishing the energy barriers for hydrogen production in water splitting. With the merits of fine performances, scalable fabrication, and low cost, FeNiZn/FeNi3@NiFe holds prospective application potential as the bifunctional electrocatalyst for water splitting.

Nitrogen-doped carbon encapsulated hollow ZnSe/CoSe2 nanospheres as high performance anodes for lithium-ion batteries.

Hierarchical nitrogen-doped carbon encapsulated hollow ZnSe/CoSe2 (ZnSe/CoSe2@N-C) nanospheres are fabricated by a convenient solvothermal and selenization approach, followed by a carbonization process. The as-obtained ZnSe/CoSe2@N-C possesses a multilevel nanoscale architecture composed of a thin carbon shell with a size of around 12 nm and hollow selenide nanoparticles as the core with tiny rough grains and rich voids as the subunits. The robust carbon protective shell and synergistic effect between double metal ions boost the electron and ion transportation as well as promote effective extraction and insertion of lithium ions. Hollow ZnSe/CoSe2@N-C spheres show high reversible capacity with 1153 mA h g-1 remaining over 100 cycles at 100 mA g-1. In particular, the hollow ZnSe/CoSe2@N-C spheres show an outstanding cycling stability at a high rate of 2000 mA g-1 with the reversible capacity of up to 966 mA h g-1 remaining after 500 cycles. As an advanced anode, ZnSe/CoSe2@N-C composite shows remarkable cycling stability and exceptional rate capability in the field of energy storage technologies.

Porous PtAg nanoshells/reduced graphene oxide based biosensors for low-potential detection of NADH.

A superior NADH sensing platform was constructed based on porous PtAg nanoshells supported on reduced graphene oxide (PtAg/rGO) in the absence of any enzymes and redox mediators. The PtAg/rGO composite was prepared via one-step reduction combined with galvanic replacement reaction. The as-made PtAg/rGO assembles multiple structural advantages of coherent conductive matrix, rich electroactive sites, and high specific surface area, accompanied by the unique alloying effect. The PtAg/rGO possesses adequate active reaction sites and fluent electron transport pathway towards the electrocatalytic NADH oxidation, thus presenting significantly increased oxidation current and negative shift of 330 mV in applied potential relative to the bare GCE. By virtues of the outstanding electrocatalytic activity, PtAg/rGO exhibits effective amperometric detection of NADH at 0.15 V within a wide linear concentration range of 2-2378 µM, a high sensitivity of 92.62 µA mM-1 cm-2, low detection limit of 0.2 µM, and long-term detection over 2500 s. Moreover, the as-constructed biosensors can achieve accurate NADH detection in human serum samples, indicating its promising application feasibility in fundamental and clinic research. Graphical Abstract Porous PtAg alloy nanoshells supported on reduced graphene oxide (PtAg/rGO) was prepared via a facile one-step reduction and spontaneous replacement reaction strategy. A sensitive and highly stable electrochemical biosensor based on PtAg/rGO is constructed for the quantitative detection of NADH at low applied potential.

Nanoporous platinum-copper flowers for non-enzymatic sensitive detection of hydrogen peroxide and glucose at near-neutral pH values.

Multimodal nanoporous PtCu flowers (np-PtCu) were prepared via a two-step dealloying strategy under mild conditions. The np-PtCu alloy possesses an interconnected flower-like network skeleton with multiscale pore distribution. This material was placed on a glassy carbon electrode where it shows outstanding detection performance towards hydrogen peroxide and glucose in near-neutral pH solutions. It can be attributed to the specific structure in terms of interconnected nanoscaled ligaments, rich pore openings and a synergistic alloying effect. Figures of merit for detection H2O2 assay include (a) a working voltage of 0.7 V (vs. the reversible hydrogen electrode); (b) a wide linear response range (from 0.01 to 1.7 mM), and (c) a low detection limit (0.1 µM). The respective data for the glucose assay are (a) 0.4 V, (b) 0.01-2.0 mM, and (c) 0.1 µM. The method is not interfered in the presence of common concentrations of dopamine, acetaminophen and ascorbic acid. Graphical abstract Multimodal nanoporous (np) PtCu alloy was prepared via a two-step dealloying strategy under mild conditions. Np-PtCu exhibits superior electrocatalytic activity. The assay is highly sensitive, selective, and it allows for a long-term detection of H2O2 and glucose.

Easy preparation of nanoporous Ge/Cu3Ge composite and its high performances towards lithium storage.

Nanoporous Ge/Cu3Ge composite is fabricated simply through selective dealloying of GeCuAl precursor alloy in dilute alkaline solution. The as-made Ge/Cu3Ge is characterized by three dimensional (3D) bicontinuous network nanostructure which comprises of substantial nanoscale pore voids and ligaments. Owing to the 3D porous architecture and the introduction of well-conductive Cu3Ge, the lithium storage performances of Ge are dramatically enhanced in terms of higher cycling stability and superior rate performance. Nanoporous Ge/Cu3Ge anode delivers steady capacities above 1000 mA h g-1 upon cycling for 70 loops at 400 mA g-1. In particular, after 300 cycles at the high rate of 3200 mA g-1 the capacity retention for Ge/Cu3Ge is able to reach a maximum of 99.3%. On the contrary, the pure nanoporous Ge encounters severe capacity decay. In view of the outstanding energy storage performances and easy preparation, nanoporous Ge/Cu3Ge exhibits great application potential as an advanced anode in lithium storage related technologies.

Double conductivity-improved porous Sn/Sn4P3@carbon nanocomposite as high performance anode in Lithium-ion batteries.

Carbon encapsulated porous Sn/Sn4P3 (Sn/Sn4P3@C) composite is conveniently prepared by one-step electrochemical dealloying of Sn80P20 alloy in mild conditions followed by growing one carbon layer. Controllable dealloying of the Sn80P20 alloy results in the formation of bicontinuous spongy Sn4P3 nanostructure with a part of residued metallic Sn atoms embedded in the porous skeleton. A uniform carbon layer is deposited on the nanoporous Sn/Sn4P3 to prevent the nanostructure's pulverizing and agglomerating during lithium ion insertion/extraction. Upon double conductivity modification from metallic Sn matrix and carbon layer, the as-made composite displays superior lithium-storage performances with much higher specific capacity as well as better cycling stability compared with pure porous Sn4P3. It offers a specific capacity of 837 mA h g-1 after 100 cycles at a rate of 100 mA g-1. Even after 700 cycles at the higher rate of 1000 mA g-1, the specific capacity still maintains as high as 589 mA h g-1. The Sn/Sn4P3@C material possesses promising application potential as an alternative anode in the lithium storage fields.

One-step mild fabrication of porous core-shelled Si@TiO2 nanocomposite as high performance anode for Li-ion batteries.

Nanoporous Si@TiO2 composites with the unique core-shell architecture are conveniently fabricated through one-step selective dealloying of SiTiAl ternary alloy under mild conditions. The as-prepared composites consist of bimodal Si network skeleton as the core and interconnected TiO2 nanosponge layer as the shell uniformly distribute on the Si surface to form the porous core-shelled structure. The nanoporous TiO2 as the outer protective layer not only reduce the violent volume change of electrode materials for stable cycling performance but also shorten the diffusion distance of Li+ for high rate capacities. The inner bimodal porous Si possesses an open bicontinuous network structure that can provide the enough empty space and robust backbone to relax the volume variation of composite and guarantee the sufficient electrode-electrolyte contact area. As a result, the optimized nanoporous Si@TiO2 composite delivers the reversible capacity of 1338.1 and 1174.4 mA h g-1 at the current densities of 200 and 1000 mA g-1 after continuous tests for 120 and 100 cycles, respectively. With the advantages of easy preparation, unique architecture, and high lithium storage performances, the porous core-shelled Si@TiO2 composites demonstrate the promising application potential as an anode material for LIBs.

An ultrasensitive biosensor for superoxide anion based on hollow porous PtAg nanospheres.

The accurate detection of the superoxide anion (O2•-) has vital academic and medical diagnostic significance due to its important dual roles in biological functioning. In this work, hollow porous PtAg nanospheres (PtAg HPNSs) were fabricated by a facile hydrothermal method followed by a dealloying procedure. The as-made PtAg nanospheres possessed hollow interiors and porous shells composed of interconnected ligaments and pores with the typical size around 4 nm. Benefitting from the unique hollow nanoporous architecture and the specific alloying effect, the PtAg HPNSs showed high electrocatalytic activity towards superoxide anions. The constructed biosensor based on PtAg HPNSs presented a fast and ultrasensitive response in a wide range of 0.8-1080 nM with much higher sensitivity of 4.5 × 10-2 µA cm-2 nM-1 and low detection limit of 0.2 nM (S/N = 3). Moreover, the novel biosensors can achieve electrochemical detection for O2•- released from living cells, exhibiting outstanding real time detection capability in cell environment. The facile controllable fabrication and unique sensing performance for PtAg HPNSs offers potential practical applications in developing highly sensitive and stable biosensor towards superoxide anion.