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Chromium-free passivation of Zn coating on NdFeB magnets becomes a research hotspot due to the serious harm of chromium ions to the human body. Chromium-based and cerium-based passivation technologies are conducted on electroplating Zn/NdFeB respectively. Morphologies, elemental compositions and phase structures of the two passivated coatings are characterized by scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy, respectively. The corrosion resistances of the two passivated specimens are compared by neutral salt spray test, accelerated aging test and electrochemical measurements. A complete and smooth passivation film can be obtained on the surface of Zn/NdFeB, filling the gaps and pores in Zn coating. Compared with un-passivated Zn/NdFeB, Zn(Ce)/NdFeB and Zn(Cr)/NdFeB possess excellent corrosion resistance. In comparison, Zn(Ce)/NdFeB possesses excellent anti-corrosion performance, increasing the red-rust appearing time from 288 to 432 h, which is still lower than that of Zn(Cr)/NdFeB (528 h). Therefore, the self-repair effect of cerium passivation technology during the corrosion process should be further studied to achieve the purpose of replacing chromium passivation technology.

High-yielding preparation of branched N-doping carbon nanotubes can be realized by carbonizing ZnCo-ZIF nanotubes. Due to the unique architecture and N-doping, such branched carbon nanotubes show excellent electrochemical K+ storage performance.

Dendrite-free lithium deposition for lithium metal anodes enabled by a 3D lithiophilic host of vertically aligned TiO2 nanotubular arrays decorated with Ag nanocrystals.

We propose a strategy to rebuild the extended π-delocalized network in a Z-scheme polymeric heterojunction to improve the photon utilization efficiency, engendering an unprecedentedly high photocatalytic performance.

High performance NiOx nanoplatelet porous films were prepared and successfully applied in EC/energy storage bifunctional devices and flexible films (where the presence of Ni vacancies enhances the performance of films in Li+ electrolytes).

The modulated electronic structure of FeS2/MoS2 nanosheets with ultrathin features (∼3 nm) was designed by a one-step hydrothermal process for efficient electrochemical nitrogen reduction reaction.

Hierarchical NiO nanosheet@nanowire arrays serve as a high-performance electrochromic energy storage material.

N-doped carbon-based single-atom catalysts (NC-SACs) are widely researched in various electrochemical reactions due to high metal atom utilization and catalytic activity. The catalytic activity of NC-SACs originates from the coordinating structure between single metal site (M) and the doped nitrogen (N) in carbon matrix by forming M-Nx-C structure (1≤ x≤ 4). The M-N4-C structure is widely considered to be the most stable and effective catalytic site. However, there is no in-depth research for the “x” modulation in Pt-Nx-C structure and the corresponding catalytic properties. Herein, atomically dispersed Pt on N-doped carbon (Pt-NC) with Pt-Nx-C structure (1≤ x≤ 4), as a research model, is fabricated by a ZIF-8 template and applied to catalytic oxygen reduction. Different carbonization temperatures are used to control N loss, and then modulate the N coordination of Pt-Nx-C structure. The Pt-NC has the predictable low half-wave potential (E1/2) of 0.72 V vs RHE compared to the Pt/C 20% of 0.81V due to low Pt content. Remarkably, the Pt-NC shows a high onset potential (1.10 V vs RHE, determined for j = -0.1 mA cm2) and a high current density of 5.2 mA cm−2, more positive and higher than that of Pt/C 20% (0.96 V) and 4.9 mA cm−2, respectively. As the structural characterization and DFT simulation confirmed, the reducing Pt-N coordination number induces low valence of Pt atoms and low free energy of oxygen reduction, which is responsible for the improved catalytic activity. Furthermore, the Pt-NC shows high mass activity (172 times higher than that of Pt/C 20%), better stability and methanol crossover resistance.

To exploit next-generation high-energy Li metal batteries, it is vitally important to settle the issue of dendrite growth accompanied by interfacial instability of the Li anode. Applying 3D current collectors as hosts for Li deposition emerges as a prospective strategy to achieve uniform Li nucleation and suppress Li dendrites. Herein, well-aligned and spaced TiO

Developing efficient ammonia synthesis technology under ambient conditions is of vital importance. In this work, an FeS

Construction of heterostructures is one of the most promising strategies for designing photocatalysts for highly efficient solar hydrogen (H

Nanoporous carbon derived from metal–organic frameworks (MOFs) is an attractive electrode material for potassium ion batteries, but carbon electrodes fabricated using single MOF precursors cannot balance all the demands. In view of the core–shell nanostructure that can complement the advantages of the core and shell materials, we here demonstrate a facile and general synthesis strategy for synthesizing a series of core–shell MOF hybrids. The prepared core–shell MOF hybrids are applied as precursors for nanoporous carbon which maintain a core–shell hybrid structure after carbonization, having electrically conducting carbon as the core and N-doped carbon as the shell. Due to the unique core–shell structure which offers more active sites and fast reaction kinetics, the electrochemical K+ storage properties of all core–shell MOF hybrid-derived nanoporous carbon are superior to those of single MOF-derived counterparts. Our synthesis strategy of core–shell MOF hybrids is expected to provide a useful reference for other MOF nanostructures, and the enhanced K+ storage performance also reveals the significance of MOF structural engineering.

Heteroatom co-doping has been considered as an effective strategy to simultaneously overcome intrinsic shortcomings of g-C3N4 to achieve enhanced photocatalytic properties, in which the involved dopants could play its role in altering electronic structure, optical absorption and charge separation of the catalyst. Herein, W/O co-doped hollow g-C3N4 tubular structures are successfully obtained for the first time via a one-step thermal decomposition. By W/O co-doping, architecture of g-C3N4 is able to be modulated with enhanced optical absorption towards visible region. In addition, narrowed band gap and restrained charge recombination are conducive for the excitation of electron-hole pairs and transportation. Photocatalytic water splitting tests indicate that the co-doped hollow tubular g-C3N4 structures enable superior activity for generating hydrogen up to 403.57 μmol g−1 h−1 driven by visible light, nearly 2.5 times as high as that of pristine g-C3N4. This work presents a rational strategy to design co-doped g-C3N4 as an efficient visible-light-driven photocatalyst.

Niobium pentoxide (Nb2O5) with the advantages of high working potential and negligible volume expansion has been an attractive canditate for lithium-ion battery (LIB) applications. Unfortunately, t...

Three-dimensional (3D) hierarchical Pt/TiO2@C core-shell nanowire networks with high surface area have been constructed via wet chemical approaches. The 3D TiO2 nanowire framework was in situ synthesized within a porous titanium foam by hydrothermal method followed by carbon coating and self-assembled growth of ultrathin Pt nanowires. Structural characterization indicates that single crystalline ultrathin Pt nanowires of 3–5 nm in diameter were vertically distributed on the anatase TiO2 nanowires covered with a 2–4 nm thin carbon layer. The 3D hierarchical Pt/TiO2@C nanostructure demonstrates evidently higher catalytic activities towards methanol oxidation than the commercial Pt/C catalyst. The catalytic current density of the hierarchical catalyst is 1.6 times as high as that of the commercial Pt/C, and the oxidation onset potential (0.35 V vs. Ag/AgCl) is more negative than the commercial one (0.46 V vs. Ag/AgCl). Synergistic effect between the ultrathin Pt nanowires and the TiO2@C core-shell nanostructure accounts for the enhanced catalytic properties, which can be determined by X-ray photoelectron spectroscopy (XPS) investigation. The obtained hierarchical Pt/TiO2@C nanowire networks promise great potential in producing anode catalysts for direct methanol fuel cells applications.

Lithium-ion capacitor (LIC) is an efficient hybrid electrochemical energy storage device, which dominates high power and energy density simultaneously. In this work, a method of liquid phase fragme...

Optimizing the architecture and tailoring the phase composition are useful approaches to increasing electrochemical capacitor energy storage performance. In this work, a novel three-dimensional (3D...

Efficient exfoliation of layered materials has attracted considerable attention in various applications due to their superior photoelectric, physical and chemical properties. Here, we report a universal, rapid approach to prepare the two-dimensional (2D) nanosheets and zero-dimensional (0D) quantum dots (QDs) using a simple cryo-mediation liquid phase exfoliation of layered materials (graphite, MoS2, WS2). The QDs decorated nanosheets 0D/2D homostructure can be subsequently formed by the self-assembly of the as-exfoliated QDs and nanosheets. The unique structural properties of the mono- or few-layer mesoporous nanosheets interspersed with QDs can expose abundant active edge sites as well as improve the conductivity, which exhibits excellent activity and stability towards electrocatalytic hydrogen evolution reaction (HER). This work offers a powerful methodology to prepare 2D homostructures from a variety of layered materials.

Atomically thin 2D materials with high surface areas allow engineering its physical and chemical properties with help of combining or decorating with different classes of materials. The hybrid or heterostructure of two different atomically thin materials exhibits completely different chemical and electronics behavior as compared to its parent components. Here, MoS2 quantum dots (QDs) are decorated onto ultrathin NiO nanosheets (NSs) by using a one-pot hydrothermal process. Uniformly dispersed MoS2 QDs and ultrathin NiO NSs hybrid/heterostructure can provide more active reaction sites and accelerate the charge transfer rate. Benefiting from the heterointerfaces synergistic effect between MoS2 QDs and NiO NSs, the MoS2 QDs/NiO NSs electrode exhibits excellent electrocatalytic activity towards both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). As a bifunctional electrocatalyst, the MoS2 QDs/NiO NSs electrode has achieved highly efficient overall water splitting activity, which needs a low voltage of 1.61 V to deliver a 10 mA cm−2 with superior stability.

Sulfur-doping of non-noble metal Fe-N-C single-atom catalysts (SACs) shows a key bifunctional role in promoting ORR and OER activity. The controversial claims about the enhanced ORR activity and the ambiguity of the OER activity brought about by S-doping demand in-depth investigation. Here, systematic theoretical investigation was carried out. Unlike previously believed, coordinative S-doping gives rise to a precisely regulated OOH* stabilization effect, which is revealed to be the origin of the bifunctional ORR/OER activity. The fine regulation is reflected in two aspects: (1) Compared with other intermediates, the regulation of OOH* adsorption is more obvious. (2) More sulfur-doping leads to excessive strong or weak stabilization, which is not conducive to ORR/OER. The single S doping elevates the charge density and opens the metallic spin channels of Fe-N

In this work, a strategy of using fast co-precipitation method has been developed to synthesize stable Al doped α-phase NiCo layered double hydroxides (NCA-LDH). A subsequent surface sulphuration of NCA-LDH (S-NCA-LDH) was carried out to improve the conductivity. The as-synthesized S-NCA-LDH exhibits a good electrochemical performance with a specific capacity of 727.1C g

Porous carbon is regarded as one of the most promising anode candidates for Li-ion battery and Na-ion battery. We herein demonstrate a series of nitrogen-doped porous carbon (NPC) by simply carbonizing bimetallic ZnCo-containing zeolitic imidazolate frameworks (ZnCo-ZIFs). The nitrogen content, specific surface area, pore size distribution and microstructure of prepared NPC are balanced by adjusting Zn2+/Co2+ molar ratio of ZnCo-ZIFs and carbonization process parameters. It is found that the optimized ZnCo-ZIF-derived NPC shows promise for electrochemical Li+/Na+ storage, which could be attributed to the hierarchical porous structure, large specific surface area and relatively high N-doping content.

Lithium ion hybrid capacitors (LIHCs) have a capacitor-type cathode and a battery-type anode and are a prospective energy storage device that delivers high energy/power density. However, the kinetic imbalance between the cathode and the anode is a key obstacle to their further development and application. Herein, we prepared TiNb

Single crystalline strontium titanate (SrTiO3) submicron cubes have been synthesized based on a molten salt method. The submicron cubes showed superior photocatalytic activity towards both water splitting and carbon dioxide reduction, in which methane (CH4) and hydrogen (H2) were simultaneously produced. The average production rate of methane up to 8 h is 4.39 μmol g−1 h−1 but drops to 0.46 μmol g−1 h−1. However, the average production rate of hydrogen is 14.52 before 8 h but then increases to 120.23 μmol g−1 h−1 after 8 h. The rate change of the two processes confirms the competition between the H2O splitting and CO2 reduction reactions. Band structure and surface characteristics of the SrTiO3 submicron cubes were characterized by diffuse reflective UV-Vis spectroscopy, Mott–Schottky analysis, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The results reveal that the simultaneous and competitive production of methane and hydrogen is due to a thermodynamics factor, as well as the competition between the adsorption of carbon dioxide and water molecules on the surface of the faceted SrTiO3. This work demonstrates that SrTiO3 photocatalysts are efficient in producing sustainable fuels via water splitting and carbon dioxide reduction reactions.

A carbon microtube aerogel (CMA) with hydrophobicity, strong adsorption capacity, and superb recyclability was obtained by a feasible approach with economical raw material, such as kapok fiber. The CMA possesses a great adsorption capacity of 78-348 times its weight. Attributed to its outstanding thermal stability and excellent mechanical properties, the CMA can be used for many cycles of distillation, squeezing, and combustion without degradation, which suggests a potential practical application in oil-water separation. In addition, the adsorption capacity still retained 98% by distillation, 97% by squeezing, and 90% by combustion after 10 cycles. Therefore, the obtained CMA has a broad prospect as an economical, efficient, and environmentally friendly adsorbent. National Research Foundation (NRF) This work was financially supported by Singapore National Research Foundation under NRF RF Award No. MOE2016- T2-1-131, Tier 1 2017-T1-001-075.

Three-dimensional (3D) carbon-coated NiCo2S4 nanowires structures doped with nitrogen are used for energy storage and conversions. The nitrogen doping in both the carbon layer and NiCo2S4 nanowires enhances the electrochemical performances. Here, an easily scalable and simple temperature treatment has been used to decorate carbon-coated NiCo2S4 nanowires with nitrogen doping (NC@NiCo2S4 NWs) in 3D carbon architecture (carbon cloth). Benefiting from the nitrogen doping and ultrathin carbon layer, the as-prepared 3D NC@NiCo2S4 NWs electrode exhibits the superior electrochemical performance for both asymmetric supercapacitor and electrocatalytic water splitting. An asymmetric supercapacitor assembled by the NC@NiCo2S4 NWs and active carbon electrodes achieves a high energy density of 1.72?mWh?cm?3 (68.87?Wh?kg?1) under a power density of 10.63?mW?cm?3 (425?W?kg?1) with 90.1% retention of initial capacitance after 10,000 cycles. When employed as the electrocatalyst, the NC@NiCo2S4 NWs show high activities towards electrocatalytic water splitting., by Chandra Sekhar Tiwary et al.

As CO2 emissions are sharply increasing, processes for converting CO2 into value-added products are becoming more desirable. Ruthenium-based catalysts are the most active for CO2 methanation; howev...

Rational construction of binder-free electrode is regarded as a promising way to improve the electrochemical performance of supercapacitor. Herein, we synthesize a hierarchical NiCo2O4/MnO2 core–shell nanosheets arrays by two-step cathodic electrodeposition method. The optimized NiCo2O4/MnO2 electrode prepared by the electrodeposition potential of − 1.8 V for 240 s shows a large specific capacitance of 3.81 F cm−2 at 2 mA cm−2. The enhanced electrochemical performance is attributed to the unique core–shell structure of NiCo2O4/MnO2 nanosheets arrays with appropriate interspaces between nanosheets that can offer more active sites and accelerate ion/electron transfer rate. Besides, the NiCo2O4/MnO2//AC flexible asymmetric supercapacitor achieves a high energy density of 2.55 mWh cm−3 with good stability (86.1% of initial capacitance can remain after 10000 cycles), indicating the perfect energy storage features.

Crystalline WO3/Ti-doped WO3 bi-layer nanopore arrays were constructed by the template synthesis of a WO3 nanopore layer modified by a magnetron sputtering of an amorphous Ti-doped/WO3 layer. The obtained bi-layer nanopore array shows a remarkable electrochromic performance with large dual-band optical modulation in both visible (VIS) and near infrared (NIR) regions (optical modulation of over 70% in the wavelength range from 600 to 1600 nm) and the fast response speed (coloring for 3.4 s and bleaching for 6.6 s). In addition, the bi-layer WO3/Ti-doped WO3 nanopore array also present superior energy-storage properties (areal capacitance of 44.0 mF cm−2 and good rate capability), better than that of titanium-free thin films. The special bifunctional characteristics of electrochromism and pseudocapacitance can be ascribed to the large specific surface area provided by the architectural design, rich ion channels in the amorphous layer as well as proper titanium doping, which bestows the bi-layer nanopore array a great potential in clean energy applications.

As a typical wide bandgap semiconductor material, silicon carbide (SiC) has been widely used in the field of electrical and electronic materials due to its excellent electron transport characteristics. In this paper, two-dimensional (2D) ultrathin SiC nanosheets (SiC NSs) were for the first time achieved directly through an improved cryo-mediated liquid phase exfoliation process. Then three-dimensional (3D) SiC/rGO hybrid aerogels were assembled by a facile hydrothermal treatment followed by freeze drying. The supercapacitive performance of the as-obtained 3D SiC/rGO hybrid aerogels is systematically investigated by the combined use of cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). The specific energy of 53.22 Wh kg−1 at a current density of 1 A g−1 could be achieved with outstanding long-term cycling stability, demonstrating that ultrathin SiC NSs may be developed as promising electrode materials for high performance supercapacitors.

Nitrogen-doped hierarchical porous carbon with a high-specific surface area has been successfully synthesized via a one-step template carbonization-activation of nicotinic acid. The mass ratio of Mg (OH)2 and KOH to carbon precursor plays a crucial role in controlling porosity and nitrogen content of the product. Our optimized sample shows a hierarchical porous structure with a high surface area (2608 m2 g−1), large pore volume (4.0 cm3 g−1), and reasonable incorporation of nitrogen (2.2%). In addition, the electrode made using this optimized material shows a maximum specific capacitance of 282 F g−1 at a current density of 1 A g−1 and outstanding rate performance (64% capacitance retention at 20 A g−1). An assembled symmetric capacitor using this material displays a maximum energy density of 21.5 Wh kg−1 and 95% retention over 5000 cycles at 5 A g−1 at 25 °C. Moreover, our facile, simple, and efficient method of fabrication paves the way large-scale application of these porous carbon materials for high-performance supercapacitors.

In this work, we report a facile cryo-mediated liquid phase exfoliation method to synthesize water-soluble defect-rich MoS2 ultrathin nanosheets (d-MoS2 NSs) with the assistance of NaBH4 in the sol...

Highly sensitive analysis of cancer biomarkers demonstrates an important impact in early diagnosis and therapies of cancer. A novel surface-enhanced Raman scattering (SERS) based immunoassay using microfluidic technique was reported for rapid analysis of prostate-specific antigen (PSA) biomarker. It is a useful screening test to discriminate prostate cancer and other diseases related to prostate. A "sandwich" immunoassay based on SERS nanotags, PSA biomarkers, and magnetic beads was applied on a pump-free microfluidic sensor. Magnetic immunocomplexes are isolated and trapped at the detection chamber by a permanent magnet integrated into the chip. The PBS buffer washed magnetic immunocomplexes and brought the free gold nanoparticles to the downsteam channel for waste. Our results show a good linear response in the range from 0.01 to 100 ng mL-1. The limit of detection of the PSA level is estimated to be below 0.01 ng mL-1 using this chip. This detection level of PSA biomarker in human serum can be accomplished in 5 min without manual incubation and a heavy syringe pump. To the best of our knowledge, this is the first SERS-based immunoassay which applied a pump-free microfluidic chip as a detection platform. We believe that the proposed method reveals a valuable potential tool for the diagnosis of prostate cancer.