Nitrogen-doped graphene has been demonstrated to be an excellent multifunctional material due to its intriguing features such as outstanding electrocatalytic activity, high electrical conductivity, and good chemical stability as well as wettability. However, synthesizing the nitrogen-doped graphene with a high nitrogen content and large specific surface area is still a challenge. In this study, we prepared a nitrogen-doped graphene aerogel (NGA) with high porosity by means of a simple hydrothermal reaction, in which graphene oxide and ammonia are adopted as carbon and nitrogen source, respectively. The microstructure, morphology, porous properties, and chemical composition of NGA were well-disclosed by a variety of characterization methods, such as scanning electron microscopy, nitrogen adsorption-desorption measurements, X-ray photoelectron spectroscopy, and Raman spectroscopy. The as-made NGA displays a large Brunauer-Emmett-Teller specific surface area (830 m(2) g(-1)), high nitrogen content (8.4 atom %), and excellent electrical conductivity and wettability. On the basis of these features, the as-made NGA shows superior capacitive behavior (223 F g(-1) at 0.2 A g(-1)) and long-term cycling performance in 1.0 mol L(-1) H2SO4 electrolyte. Furthermore, the NGA also possesses a high carbon dioxide uptake capacity at 1.0 bar and 273 K (11.3 wt %).

Porous graphene, which features nano-scaled pores on the sheets, is mostly investigated by computational studies. The pores on the graphene sheets may contribute to the improved mass transfer and may show potential applications in many fields. To date, the preparation of porous graphene includes chemical bottom-up approach via the aryl-aryl coupling reaction and physical preparation by high-energy techniques, and is generally conducted on substrates with limited yields. Here we show a general and scalable synthesis method for porous graphene that is developed through the carbothermal reaction between graphene and metal oxide nanoparticles produced from oxometalates or polyoxometalates. The pore formation process is observed in situ with the assistance of an electron beam. Pore engineering on graphene is conducted by controlling the pore size and/or the nitrogen doping on the porous graphene sheets by varying the amount of the oxometalates or polyoxometalates, or using ammonium-containing oxometalates or polyoxometalates.

Human hair, a biowaste composed of protein, is converted into nitrogen and sulfur co-doped porous carbonaceous materials via a facile degradation and carbonization/activation process. The resulting carbon materials possess large specific surface area value (2700 m 2 g -1 ) as well as high nitrogen and sulfur contents (around 8.0 and 4.0 wt %, respectively). The morphology, composition, porous structure of the obtained materials were thoroughly characterized by scanning and transmission electron microscopy, elemental analysis, nitrogen and carbon dioxide sorption analysis, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy, etc. It is confirmed that both the degradation and the carbonization/activation procedures play important roles in the porous structure formation. Furthermore, these materials are proven to exhibit good performances in gas adsorption: carbon dioxide uptake (up to 24.0 wt %, at 273 K and 1.0 bar), methane adsorption (up to 3.04 wt %, at 273 K and 1.0 bar) and hydrogen adsorption (up to 2.03 wt %, at 77 K and 1.0 bar). The high gas adsorption capacities could be attributed to the microporous structure combined with the functionalities. In addition, we believe that this synthesis process offers a facile and effective way for transforming protein-containing biowastes into functionalized porous carbonaceous materials. 4 processes, typically involving high temperature treatment and often leading to the generation of quantities of waste. Furthermore, the conventional precursors are non-sustainable and relatively expensive as compared with biomass-derived materials, especially biowastes, such as watermelon, 7 silk waste, 30 waste tea-leaves, 31 animal bone, 32 wood resources, 33,34 and corncob. 35 Human hair, as we all know, is a biowaste consisting of carbon, nitrogen, oxygen, sulfur, and hydrogen elements owing to the abundant proteins. Therefore, human hair could be treated as scrap material for the preparation of valuable carbon materials. [36][37][38][39] For instance, Qian et al have reported the production of carbon materials from human hair with carbonization (300 °C) and sequent KOH activation (800 °C). The obtained HMC-800 had a BET surface area of 1306 m 2 g -1 and a high specific capacitance of 340 F g -1 in 6 M KOH at a current density of 1 A g -1 as well as good stability over 20 000 cycles. 36 Similarly, Si and co-workers have reported the production of carbon materials from human hair and glucose via hydrothermal carbonization procedure at 180 °C and KOH activation at 600 °C, the supercapacity properties were also tested. 38 Yu and co-workers have synthesized human hair-derived carbon via a three-step process:pre-carbonization, sequent NaOH activation (600 °C) and further graphitization (900 °C). The obtained HC-900 had a higher BET surface area (about 1810 m 2 g -1 ), and exhibited as a good electrocatalyst for oxygen reduction reaction. 39Herein, the human hair-derived materials were synthesized via a facile degradation and carbonization/activation process...

No abstract