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Increasing awareness toward environmental remediation and renewable energy has led to a vigorous demand for exploring a win-win strategy to realize the eco-efficient conversion of pollutants ("trash") into energy-storage nanomaterials ("treasure"). Inspired by the biological metabolism of bacteria, Acidithiobacillus ferrooxidans (A. ferrooxidans) is successfully exploited as a promising eco-friendly sustainable biofactory for the controllable fabrication of α-Fe 2 O 3 nanorods via the oxidation of soluble ferrous irons to insoluble ferric substances (Jarosite, KFe 3 (SO 4 ) 2 (OH) 6 ) and a facile subsequent heat treatment. It is demonstrated that the stable solid electrolyte interphase layers and marvelous cracks in situ formed in biometabolic α-Fe 2 O 3 nanorods play important roles that not only significantly enhance the structure stability but also facilitate electron and ion transfer. Consequently, these biometabolic α-Fe 2 O 3 nanorods deliver a superior stable capacity of 673.9 mAh g -1 at 100 mA g -1 over 200 cycles and a remarkable multi-rate capability that observably prevails over the commercial counterpart. It is highly expected that such biological synthesis strategies can shed new light on an emerging field of research interconnecting biotechnology, energy technology, environmental technology, and nanotechnology., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Mg2B2O5 nanowires with (010) twins were synthesized for the first time using a catalyst-free method. The microstructure of the Mg2B2O5 nanowires has been extensively studied by cross-sectional high-resolution transmission electron microscopy. Nanoindentation tests were performed directly on individual nanowires to probe their mechanical properties. It was found that the twinned Mg2B2O5 nanowires achieve comparable hardness but 19% decrease in elastic modulus compared to their bulk counterpart. The elastic softening mechanisms of the Mg2B2O5 nanowires are discussed with reference to their twin defects, size, and surface effects.

Two kinds of aluminum borate nanowires, Al(4)B(2)O(9) and Al(18)B(4)O(33), were successfully synthesized by a one-step combustion method through control of the Al:B atomic ratio and synthesis temperature. Both nanowires are single crystalline but have distinguishing growth habits. Nanoindentation tests were performed directly on individual nanowires to reveal their mechanical properties. A 70% reduction in elastic modulus was found in Al(18)B(4)O(33) nanowires compared with their bulk counterpart. Al(18)B(4)O(33) nanowires exhibited higher hardness and elastic modulus than Al(4)B(2)O(9) nanowires.

With the continuing development of bottom-up nanotechnology fabrication processes, spot welding can play a role similar to its macro counterpart for the interconnection of nano building blocks for the assembly of nanoelectronics and nanoelectromechanical systems (NEMS). Spot welding using single-crystalline copper-filled carbon nanotubes (CNTs) is investigated experimentally using nanorobotic manipulation inside a transmission electron microscope (TEM). Controlled melting and flowing of copper inside nanotube shells are realized by applying bias voltages between 1.5 and 2.5 V. The average mass flow rate of the copper was found to be 120 ag/s according to TEM video imaging (measured visually at approximately 11.6 nm/s through the CNT). Successful soldering of a copper-filled CNT onto another CNT shows promise for nano spot welding and thermal dip-pen lithography.

The rational design of high‐efficient non‐noble metal electrocatalysts for oxygen evolution reactions (OER) is of significance in electrochemical energy conversion. However, such low‐cost but highly active electrocatalysts remain poorly developed because of the daunting synthetic challenge. Here, the synthesis of NiSe2/Fe3O4 nanotubes via a facile self‐templating strategy, which manifests unique tetragonal morphology, asymmetric hollow interior, and unusual but adaptable heteroepitaxy structure, is reported. Benefiting from sufficient active sites and their improved activity around the heterointerface, accompanied by the good conductivity, the NiSe2/Fe3O4 nanotubes exhibit as a superior OER electrocatalyst, which affords the current density of 10 mA cm−2 at a very small overpotential of 199 mV, high attainable current density beyond 200 mA cm−2, and mass activity of 984.5 A g−1, as well as excellent stability for 100 h in the alkaline media. This work provides a unique synthetic pathway to fabricate superior OER electrocatalysts by optimizing their composition and architecture. [ABSTRACT FROM AUTHOR]

The additive manufacturing of structures and devices in nanoscale yields the possibility of extending the functionalities of nanoelectronics and developing the alternative nanofabrication technologies for the post-silicon era. The nanorobotic spot-welding that is implemented by the transporting of mass inter/intra through the carbon nanotube has been demonstrated in previous works. However, the continuous feeding of the metal mass in nanoscale, as well as the servo control of such mass feeding rate and 3D path of the nanotube injector is still unsolved. In this report, we demonstrated a nanotube fountain pen (NFP). It is equipped with a metal-filled carbon nanotube (m@CNT) as a pen-tip injector to “write” and a nanotube network as an “ink reservoir”. In this way, it is able to provide the possibility of fabricating 3D nanostructures in a continuous fashion. The resolution of NFP depending on the diameter of the nanotube-injector and the mass flow rate of it can be modulated by external electrical driven energy. The development and control of NFP provide a new additive manufacturing technique in nanoscale, and thereby enables potential to develop a NFP-based metallic 3D nanoprinting system for the large-scale, high-throughput manufacturing of nanodevices. [ABSTRACT FROM AUTHOR]

Abstract: Novel multi-branched carbon nanotubes (BCNTs) have been synthesized using alkali-element modified Cu/MgO catalyst. It was found that alkali-element doping to the catalyst played a key role in the synthesis of CNTs, signifying a novel approach to modify Cu catalyst. Based on the transmission electron microscopy observations, a simple model is developed to describe the growth of BCNTs. [Copyright &y& Elsevier]

Both p-Mo/MgO and r-Mo/MgO catalysts and their behaviors in the process to synthesize MWNTs with or without bundles were examined. The formation mechanism of the MWNTs bundles was specially presented where the absorption of hydrogen making the molybdenum nanoparticles separated out from inside to outside of the catalyst, then forming multilayers molybdenum nanaoparticles on the surface of the support, is assigned as the main cause of bundle growth. [Copyright &y& Elsevier]

A novel hybrid nanoarchitecture of TiO 2 nanotubes/graphene was synthetized through a facile two-step hydrothermal route. The anatase TiO 2 nanotubes with a diameter of about 20 nm show a net-like structure and high dispersion on the graphene nanosheets. The as-prepared sample (TOG2) exhibits a high average capacity of 410 mAh g −1 at 0.1 A g −1 , superior cycling stability with negligible capacity fade over 300 cycles and rate capability of 192 mAh g −1 at 1 A g −1 . The enhanced electrochemical properties can be attributed to its unique hybrid structure. One-dimensional hollow tubular structure of TiO 2 provides numerous open channels for electrolyte to access and facilitate the ultrafast diffusion of lithium ions. In addition, the graphene sheets are favorable for the fast electron transport within the electrode, as well as keep the structural integrity during long-term cycling processes. [ABSTRACT FROM AUTHOR]

Abstract: A typical naturally occurring mineral, marine manganese nodule, could be developed as a catalyst for the catalytic chemical vapor deposition synthesis of helical carbon nanotubes by changing the experimental conditions. In the product, a novel one-dimensional carbon nanostructure with triple helices was first observed. The possible origin is briefly discussed. It points out a facile method to obtain helical carbon nanostructures. [Copyright &y& Elsevier]

Anodic aluminum oxide (AAO) template was prepared by a two-step anodization method and cobalt particles were carefully deposited at the bottom of pores of the template. CVD method was used to grow carbon nanotubes (CNTs) on the template with this cobalt as catalyst and C2H2 as carbon source. Well-aligned carbon nanotubes were obtained perpendicular to the substrate. To modify the CNTs, ultrasonic treatment of the samples in alcoholic (or water) was applied and the results showed that the length of CNTs became equalized and their tips were opened without catalyst particles due to ultrasonically cutting off CNTs for the upper parts out of AAO pores. The mechanism is also discussed. [Copyright &y& Elsevier]

High-quality single-walled carbon nanotubes (SWNTs) are synthesized in gram amount on Fe–Mo/MgO catalysts by catalytic decomposition of CH4 in H2 or N2. Raman data reveal that the as-prepared SWNTs have a diameter of about 0.74–1.29 nm. It is found that the diameter of the as-prepared SWNTs can be controlled mainly by adjusting the molar ratio of Fe–Mo versus the MgO support. Several other factors that potentially influence the growth of SWNTs have been studied in detail. The experimental results show that the nature of the catalyst determines the diameter of the as-prepared SWNTs. [Copyright &y& Elsevier]