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Introducing heating function to oil sorbents opens up a new pathway to the fast cleanup of viscous crude oil spills in situ. The oil sorption speed increases with the rise of the temperature, thus oil sorbents with high heating temperature are desirable. Besides, the oil sorbents also need to be produced environment-friendly. Here we present carbonized melamine-formaldehyde sponges (CMSs) that exhibited superior heating performance and the CMSs could be massively fabricated through a non-polluting pyrolysis process. The conductive CMSs could be heated over 300 °C with a low applied voltage of 6.9 V and keep above 250 °C for 30 min in the air without obvious damage. Such high heating performance enabled heating up the oil spills with a high rate of 2.65 °C·s−1 and 14% improvement of oil sorption coefficient compared with the state-of-the-art value. We demonstrated that one joule-heated CMS could continuously and selectively collect viscous oil spills (9,010 mPa·s) 690 times its own weight in one hour. The CMSs will be a highly competitive sorbent material for the fast remediation of future crude oil spills.

Printable elastic conductors promote the wide application of consumable electronic textiles (e-textiles) for pervasive healthcare monitoring and wearable computation. To assure a clean appearance, the e-textiles require a washing process to clean up the dirt after daily use. Thus, it is crucial to develop low-cost printable elastic conductors with strong adhesion to the textiles. Here, we report a composite elastic conductor based on Ag nanowires (NWs) and polyurethane elastomer. The composite could be dispersed into ink and easily printed onto textiles. One-step print could form robust conductive coatings without sealing on the textiles. Interestingly, the regional concentration of Ag NWs within the polyurethane matrix was observed during phase inversion, endowing the elastic conductor with a low percolation threshold of 0.12 vol.% and high conductivity of 3,668 S·cm−1. Thanks to the high adhesion of the elastic conductors, the resulted e-textiles could withstand repeated stretching, folding, and machine washing (20 times) without obvious performance decay, which reveals its potential application in consumable e-textiles.

The anode oxygen evolution reaction (OER) is known to largely limit the efficiency of electrolyzers owing to its sluggish kinetics. While crystalline metal oxides are promising as OER catalysts, their amorphous phases also show high activities. Efforts to produce amorphous metal oxides have progressed slowly, and how an amorphous structure benefits the catalytic performances remains elusive. Now the first scalable synthesis of amorphous NiFeMo oxide (up to 515 g in one batch) is presented with homogeneous elemental distribution via a facile supersaturated co-precipitation method. In contrast to its crystalline counterpart, amorphous NiFeMo oxide undergoes a faster surface self-reconstruction process during OER, forming a metal oxy(hydroxide) active layer with rich oxygen vacancies, leading to superior OER activity (280 mV overpotential at 10 mA cm-2 in 0.1 m KOH). This opens up the potential of fast, facile, and scale-up production of amorphous metal oxides for high-performance OER catalysts.

By virtue of their extraordinarily high surface areas, ordered pore structures, various compositions, and rich functionality, metal-organic frameworks (MOFs) are of great interest in diverse fields such as gas separation, sensing, catalysis, energy, environment science, and biomedicine. However, the difficulty in processing MOF crystals and controlling the MOF superstructure is emerging as a critical issue in their application. Herein, it is reported that a robust template, i.e., nanofibrillated cellulose (NFC), can be used for the synthesis of MOF materials with 1D nanofiber morphology. NFC@MOF core-shell nanofibers with a uniform network structure and high aspect ratios can be prepared by use of this template. The small crystal size, flexibility, and good dispersity of the NFC@MOF nanofibers make it convenient for the macroscale assembly and solution processing of MOF materials. A proof-of-concept study is demonstrated wherein freestanding MOF nanofiber membranes represent good performance in applications of water treatment and heterogeneous catalysis reaction. This general synthesis and solution-processing strategy may herald a new era in promoting the industrial application of MOFs.

The development of efficient and low-cost bifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is crucial for the successful implementation of water splitting technologies, which represents a promising and appealing solution to the sustainable-energy conversion. In this work, a nanocomposite electrocatalyst based on partially oxidized Ni nanoparticles supported on Ni-N co-doped carbon nanofibers (PO-Ni/Ni-N-CNFs) was developed using low-cost hydrothermal carbonaceous nanofibers, pyrrole, and NiCl2 as precursors. Benefiting from effective active sites, mesoporous structure, and interlinked nanofiber network, the as-obtained nanocomposite electrocatalyst exhibited superior catalytic activity and durability for both HER and OER in alkaline media. Furthermore, the practical application of PO-Ni/Ni-N-CNFs as a bifunctional catalyst for overall water splitting was demonstrated, with a current density of 10 mA cm−2 achieved at the voltage of 1.69 V.

Carbon aerogels with 3D networks of interconnected nanometer-sized particles exhibit fascinating physical properties and show great application potential. Efficient and sustainable methods are required to produce high-performance carbon aerogels on a large scale to boost their practical applications. An economical and sustainable method is now developed for the synthesis of ultrathin carbon nanofiber (CNF) aerogels from the wood-based nanofibrillated cellulose (NFC) aerogels via a catalytic pyrolysis process, which guarantees high carbon residual and well maintenance of the nanofibrous morphology during thermal decomposition of the NFC aerogels. The wood-derived CNF aerogels exhibit excellent electrical conductivity, a large surface area, and potential as a binder-free electrode material for supercapacitors. The results suggest great promise in developing new families of carbon aerogels based on the controlled pyrolysis of economical and sustainable nanostructured precursors.

Electrocatalytic reduction of oxygen plays a crucial role in many energy storage and conversion devices. Currently, the development of high-performance carbon-based non-precious-metal (NPM) oxygen reduction reaction (ORR) catalysts in acidic media still remains a great challenge. Herein, we report a highly active meso/microporous Fe–N-doped carbon nanofiber (Fe–N-CNF) catalyst prepared via a SiO2-protected shell mediated template method. The SiO2-protected shell not only restricts the free migration of iron species but also traps volatile gaseous substances during the pyrolysis process at high temperature, thus leading to a simultaneous optimization of both the surface functionalities and porous structures of the Fe–N-CNF catalysts. Compared to catalysts prepared without a SiO2-protected shell, the Fe–N-CNF catalysts exhibit a much enhanced ORR activity in an acidic medium, along with a superior long-term stability.

Forming alloys with transition metal remarkably decreases the u sage of noble metal and offers benefits for electrocatalysis. Here we introduced a mixed-solvent strategy to synthesize unique PtAuCu ternary nanotubes (NTs) with porous and rough surface, using high quality Cu nanowires (NWs) as the partial sacrificial templates. We found that Au plays a key role in the enhancement of e lectrocatalytic performance for both methanol oxidation reaction (MOR) and formic acid oxidation reaction (FAOR). The mass activities of PtAuCu NTs after acid leaching for MOR and FAOR reach 1698.8 mA mg-1Pt at 0.9 V and 1170 mA mg-1Pt at 0.65 V, respectively. Such ternary NTs show impressive stability due to the irreversibly adsorption of CO* on the Au surface instead of the active Pt surface and the excellent structure stability. The present method could be extended to prepare other new multi-functional electrocatalysts.

Two-dimensional inorganic nanomaterials have drawn much attention due to their excellent properties and wide applications associated with unique 2D structures. However, an efficient and versatile chemical synthesis method using ambient conditions for 2D nanomaterials, especially with secondary structures (e.g. mesopores), has still not been reported. Herein, we report a versatile method to synthesize a family of ultrathin and mesoporous nanosheets of metal selenides based on a precursor so-called “red Se remaining Zn” (RSRZ). The principle of our synthesis is based on a template-assisted chemical transformation process via acidification of inorganic–organic hybrid ZnSe(DETA)0.5 nanosheets (DETA: diethylenetriamine). An appropriate amount of acid was added into an aqueous dispersion of ZnSe(DETA)0.5 nanosheets under air for activation. The acidification induced chemical transformation mechanism was studied by tracking the acidification process. This acid controlled reactivity of lamellar hybrids allows it to be possible to capture the highly reactive intermediates, which will provide a new platform for the synthesis of various mesoporous metal selenides.

Three dimensional (3D) carbon nanomaterials exhibit great application potential in environmental protection, electrochemical energy storage and conversion, catalysis, polymer science, and advanced sensors fields. Current methods for preparing 3D carbon nanomaterials, for example, carbonization of organogels, chemical vapor deposition, and self-assembly of nanocarbon building blocks, inevitably involve some drawbacks, such as expensive and toxic precursors, complex equipment and technological requirements, and low production ability. From the viewpoint of practical application, it is highly desirable to develop a simple, cheap, and environmentally friendly way for fabricating 3D carbon nanomaterials in large scale. On the other hand, in order to extend the application scope and improve the performance of 3D carbon nanomaterials, we should explore efficient strategies to prepare diverse functional nanomaterials based on their 3D carbon structure. Recently, many researchers tend to fabricate high-performance 3D carbon-based nanomaterials from biomass, which is low cost, easy to obtain, and nontoxic to humans. Bacterial cellulose (BC), a typical biomass material, has long been used as the raw material of nata-de-coco (an indigenous dessert food of the Philippines). It consists of a polysaccharide with a β-1,4-glycosidic linkage and has a interconnected 3D porous network structure. Interestingly, the network is made up of a random assembly of cellulose nanofibers, which have a high aspect ratio with a diameter of 20-100 nm. As a result, BC has a high specific surface area. Additionally, BC hydrogels can be produced on an industrial scale via a microbial fermentation process at a very low price. Thus, it can be an ideal platform for design of 3D carbon-based functional nanomaterials. Before our work, no systematic work and summary on this topic had been reported. This Account presents the concepts and strategies of our studies on BC in the past few years, that is, converting cheap biomass into high value-added 3D carbon nanomaterials and designing diverse functional materials on 3D carbon structure. We first briefly introduce the history, constituent, and microstructure features of BC and discuss its advantages as a raw material for preparing the CNF aerogels. Then, we summarize the methods and strategies for preparing various 3D carbon-based nanomaterials from BC. In addition, the potential applications of the developed CNF aerogel based functional materials are also highlighted in this Account, including stretchable conductors, oxygen reduction reaction catalysts, supercapacitors, lithium-ion battery, and oil cleanup. Finally, we give some prospects on the future challenges in this emerging research area of designing CNF aerogel based functional nanomaterials from BC.

Carbon aerogels that are typically prepared using sol-gel chemistry have unique three dimensional networks of interconnected nanometer-sized particles and thus exhibit many fascinating physical properties and great application potentials in widespread fields. To boost the practical applications, it is necessary to develop efficient and low-cost methods to produce high-performance carbon aerogels on a large-scale, preferably in a sustainable way. In 2012, two new classes of aerogels consisting of carbon-nanofiber (CNF) networks were prepared from biomass-derived precursors by chemosynthesis (i.e. template-directed hydrothermal carbonization of carbohydrate) and biosynthesis (i.e. use of bacterial cellulose as precursor), respectively. This Review gives a critical overview of this emerging and rapidly developing field, focusing on the synthetic strategies of the carbon-nanofiber aerogels and their outstanding physical properties. We also discuss the multifunctional application potentials of the two sorts of carbon aerogels and their nanocomposites, and highlight the challenges and future opportunities in this field.

Improving heteroatomic interactions via alloying or forming heterogeneous catalysts is of importance to the enhancement in terms of electrocatalytic activity and stability. In this work, a simple galvanic replacement reaction was utilized to synthesize low Pt-based quaternary nanotubes (NTs). It is easy to obtain PtPdRuTe NTs with different composition and controlled shape using ultrathin Te nanowires (NWs) as sacrificial templates for its high activity. The NT wall thickness and formed NPs on the surface are closely related with the composition, especially Pd content. The optimized incorporation of Pd atoms into ternary PtRuTe NTs formed a uniform protecting PtPd surface and modified the Pt electronic structure to improve the methanol oxidation reaction (MOR) performance. X-ray photoelectron spectroscopy (XPS) reveals a larger extent of electron transfer from neighboring atoms to Pt on PtPdRuTe, consequently leading to a weaker bonding of the intermediate on Pt. As a result, the quaternary PtPdRuTe NTs exhibit enhanced activity and stability toward efficient MOR.

The energy crisis and environmental pollution are serious challenges that humanity will face for the long-term. Despite tremendous efforts, the development of environmentally friendly methods to fabricate new energy materials is still challenging. Here we report, for the first time, a new strategy to fabricate various doped carbon nanofiber (CNF) aerogels by pyrolysis of bacterial cellulose (BC) pellicles which had adsorbed or were dyed with different toxic organic dyes. The proposed strategy makes it possible to remove the toxic dyes from waste-water and then synthesize doped CNF aerogels using the dyed BC pellicles as precursors. Compared with other reported processes for preparing heteroatom doped carbon (HDC) nanomaterials, the present synthetic method has some significant advantages, such as being green, general, low-cost and easily scalable. Moreover, the as-prepared doped CNF aerogels exhibit great potential as electrocatalysts for the oxygen reduction reaction (ORR) and as electrode materials for supercapacitors.

Superelastic and fatigue-resistant materials that can work over a wide temperature range are highly desired for diverse applications. A morphology-retained and scalable carbonization method is reported to thermally convert a structural biological material (i.e., bacterial cellulose) into graphitic carbon nanofiber aerogel by engineering the pyrolysis chemistry. The prepared carbon aerogel perfectly inherits the hierarchical structures of bacterial cellulose from macroscopic to microscopic scales, resulting in remarkable thermomechanical properties. In particular, it maintains superelasticity without plastic deformation even after 2 × 106 compressive cycles and exhibits exceptional temperature-invariant superelasticity and fatigue resistance over a wide temperature range at least from -100 to 500 °C. This aerogel shows unique advantages over polymeric foams, metallic foams, and ceramic foams in terms of thermomechanical stability and fatigue resistance, with the realization of scalable synthesis and the economic advantage of biological materials.

A new catalyst for the oxygen reduction reaction in fuel cells and metal—air batteries is prepared from aqueous solutions of carbonaceous nanofibers, pyrrole, and FeCl3 (room temperature, 4 h, followed by pyrolysis under flowing N2).

Molybdenum carbide (Mo2C) has been considered as a promising non-noble-metal hydrogen evolution reaction (HER) electrocatalyst for future clean energy devices. In this work, we report a facile, green, low-cost and scalable method for the synthesis of a Mo2C-based HER electrocatalyst consisting of ultrafine Mo2C nanoparticles embedded within bacterial cellulose-derived 3D N-doped carbon nanofiber networks (Mo2C@N-CNFs) using 3D nanostructured biomass as a precursor. The electrocatalyst exhibits remarkable HER activity (an overpotential of 167 mV achieves 10 mA cm−2 and a high exchange current density of 4.73 × 10−2 mA cm−2) and excellent stability in acidic media as well as high HER activity in neutral and basic media. Further theoretical calculations indicate a strong synergistic effect between Mo2C nanoparticles and N-CNFs in the Mo2C@N-CNF catalyst, which leads to an impressive HER performance. Embedding metal-based nanoparticles in bacteria-generated aerogels is a promising way to produce hydrogen fuel using water and electricity. Most water electrolysis methods use platinum catalysts to make hydrogen–oxygen bond splitting easier. But platinum's scarcity has prompted investigations into alternatives such as molybdenum carbide (Mo2C), a catalyst that shows increased activity when coupled with carbon nanofibers. Shu-Hong Yu and colleagues from Hefei, University of Science and Technology of China, now report that bacterial cellulose — a low-cost biomass synthesized by microbes — can act as a favorable support for Mo2C nanocatalysts. Straightforward immersion of bacterial cellulose in an ammonium molybdate precursor solution, followed by freeze drying and pyrolysis, yielded a three-dimensional porous network dotted with spatially separated Mo2C nanoparticles and nitrogen dopants. Tests showed the catalyst had excellent water splitting capabilities over the pH range 0 to 14. A new type of non-noble-metal hydrogen evolution reaction (HER) electrocatalyst based on ultrafine Mo2C nanoparticles embedded within 3D N-doped carbon nanofiber networks was fabricated by using a cheap, green, 3D nanostructured biomass (bacterial cellulose) as precursor. It exhibits remarkable electrocatalytic HER performance from pH 0 to pH 14.