5104 www.MaterialsViews.com wileyonlinelibrary.comof heteroatom-doped carbon nanomaterials. In the past decades, there has been certain success in developing effective approaches for synthesizing heteroatomdoped carbon nanomaterials. [ 10,12,[16][17][18][19][20][21] However, despite great progress has been made, the preparation of different heteroatom-doped carbon materials is rarely a general strategy; furthermore, the preparation of these existing heteroatomdoped carbon materials, specifi cally 3D network monolith, usually involves either complicated and expensive instruments, or harsh, complex, and time-consuming synthesis routes, or hazardous chemicals (e.g., concentrated sulfuric acid), all that have seriously restricted their practical applications. Accordingly, it is highly desirable to exploit a simple, renewable, scalable, but multifunctional and general strategy to effectively engineer 3D heteroatom-doped carbon nanomaterials, which is crucial for widespread implementation and commercialization.Bacterial cellulose (BC), a bio-product produced from fermentation, has attracted much attention due to its wide availability, low cost, renewability, and porous nature. [ 6,14,22,23 ] Herein, we demonstrate a highly effi cient, convenient, lowcost, and general strategy to fabricate heteroatom-doped carbon nanomaterials based on the characteristic abundant surface functional groups (hydroxy/carboxylic groups) of BC, [ 24 ] in which the BC serves as an excellent platform for introducing different heteroatoms into the framework of carbon nanomaterials. Specifi cally, P-doped, N,P-co-doped, and B,P-co-doped carbon nanofi bers were successfully prepared by impregnating H 3 PO 4 , NH 4 H 2 PO 4 , and H 3 BO 3 / H 3 PO 4 into the BC pellicle, respectively, followed by carbonization in an inert atmosphere at 800 °C. Compared with previous reports, our approach has three signifi cant advantages for constructing 3D macroscopic heteroatom-doped carbon materials, namely, i) the raw materials are abundant and cheap, ii) the preparation process is easy handling, versatile, and general, and iii) the fabrication is generally suitable for an industrial scale-up. To demonstrate the application potential of the as-prepared heteroatom-doped carbon nanomaterials, here we show the utilization of N,P-co-doped carbon nanofi bers in electrode materials of supercapacitor devices. The as-constructed supercapacitor exhibits high power density and excellent cycling stability.Recently, heteroatom-doped three-dimensional (3D) nanostructured carbon materials have attracted immense interest because of their great potential in various applications. Hence, it is highly desirable to exploit a simple, renewable, scalable, multifunctional, and general strategy to engineer 3D heteroatom-doped carbon nanomaterials. Herein, a simple, eco-friendly, general, and effective way to fabricate 3D heteroatom-doped carbon nanofi ber networks on a large scale is reported. Using this method, 3D P-doped, N,Pco-doped, and B,P-co-doped carbon nanofi ber networks are...

A new kind of high-performance asymmetric supercapacitor is designed with pyrolyzed bacterial cellulose (p-BC)-coated MnO₂ as a positive electrode material and nitrogen-doped p-BC as a negative electrode material via an easy, efficient, large-scale, and green fabrication approach. The optimal asymmetric device possesses an excellent supercapacitive behavior with quite high energy and power density.

To meet the pressing demands for portable and flexible equipment in contemporary society, it is strongly required to develop next-generation inexpensive, flexible, lightweight, and sustainable supercapacitor systems with large power densities, long cycle life, and good operational safety. Here, we fabricate a flexible all-solid-state supercapacitor device with nitrogen-doped pyrolyzed bacterial cellulose (p-BC-N) as the electrode material via a low-cost, eco-friendly, low-temperature, and scalable fabrication hydrothermal synthesis. The pliable device can reversibly deliver a maximum power density of 390.53 kW kg À1 and exhibits a good cycling durability with $95.9% specific capacitance retained after 5000 cycles. Therefore, this nitrogen-doped carbon nanofiber electrode material holds significant promise as a flexible, efficient electrode material. Broader contextThe ever-growing requirements of portable and exible electronic devices spark the intense interests in developing next-generation low-cost, pliable, and sustainable supercapacitor systems with high power densities, long-term life span, and operation security. We engineered and fabricated a exible all-solid-state supercapacitor using the nitrogen-doped carbon nanober as the electrode materials via a low-cost, eco-friendly, and highly scalable hydrothermal method with pyrolyzed bacterial cellulose (p-BC) and aqueous ammonia. The exible device exhibits a maximum power density of 390.53 kW kg À1 and long life span with $95.9% of the initial specic capacitance aer 5000 cycles. Therefore, this device holds signicant prospect for commercial applications.