14Rod-shape porous carbon was prepared from aniline modified lignin via KOH activation and 15 used as electrode materials for supercapacitors. The specific surface area, pore size and shape 16 could be modulated by the carbonization temperature, which significantly affected the 17 electrochemical performance. Unique rod-shape carbon with massive pores and a high BET 18 surface area of 2265 m 2 g -1 were obtained at 700 in contrast to irregular morphology created at 19 other carbonization temperatures. In 6 mol L -1 KOH electrolyte, a specific capacitance of 336 F 20 g -1 , small resistance of 0.9 Ω and stable charge/discharge at current density of 1 A g -1 after 1, 000 21 cycles were achieved using rod-shape porous carbon as electrodes in an electrical double layer 22 capacitor.23 a Z R. Gu Tel./fax: + 1 605 688 5372. from abundant, renewable biomass feedstock can be produced sustainably at low cost 47 [15]. So far, carbon materials derived from biomass such as rice husk, coffee grounds, grape seed, 48 cornstalk, banana peel [16-20], have been explored as electrode materials in EDLC and 49promising electrochemical performance has been demonstrated. 50Recent research showed that introducing nitrogen into activated carbon could induce additional 51 pseudo-capacitance via reversible redox reactions and improve the wettability between the 52 electrodes and electrolytes [21]. As a result, the capacitance performance of EDLC was greatly 53 promoted. Therefore, biomass derived carbon materials with nitrogen may be promising 54 electrode materials for EDLC. Since biochar typically contains low nitrogen content, we 55 hypothesize that combination of nitrogen rich compounds with biomass will lead to biochar with 56 high nitrogen content. Furthermore, there may be opportunities to tune the physicochemical 57 properties of the nitrogen rich biochar, such as morphology, surface area, and conductance. 58Regarding the source of nitrogen, aniline appears a promising candidate because it is easy to 59 polymerize, and the polymer can be grown into different shapes such as wires, tubes and spheres 60 [22-24] by controlling the synthetic conditions. 61 Herein, we present aniline modified lignin as the raw materials to prepare rod-shape porous 62 carbon as EDLC electrode materials. It is shown that the chemical activation plays a key role in 63 achieving large specific surface area, uniform pore size distribution and good conductivity, 64 which lead to excellent electrochemical performance. 65 2. Experimental 66 2.1 Preparation of activated carbon 67 Solvent lignin (3 g), aniline (1.5 ml) and 30 ml ethanol were added into a flask with 30 ml 68 ethanol, followed by stirring at 80 until the ethanol was evaporated. Then the mixture was 124 temperature. At high temperatures, the activation agent KOH reacted with carbon, producing 125 gases (CO, H 2 O and CO 2 ), forming pores and leaving behind potassium salts (K, KOH and 126 K 2 CO 3 ) [26]. The interconnected cavities in the porous carbon might serve as reservoirs for the 127 electr...

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N-doped porous carbon materials derived from urea-modified lignin were prepared via efficient KOH activation under carbonization. The synthesized N-doped carbon materials, which displayed a well-developed porous morphology with high specific surface area of 3130 m 2 g-1 , was used as electrode materials in symmetric supercapacitors with aqueous and solid electrolytes. In consistent with the observed physical structures and properties, the supercapacitors exhibited specific capacitances of 273 and 306 F g-1 , small resistances of 2.6 and 7.7 Ω, stable charge/discharge at different current densities for over 5000 cycles and comparable energy and power density in 6 mol L-1 KOH liquid and KOH-PVA solid electrolytes, respectively.

Oxygen evolution reaction is an enabling process of energy storage, metal extraction, and nature photosynthesis. Bubble growth on the electrode surface can block the reaction. Here, we present the use of a magnet to remove bubbles from the catalytic sites, reducing the activation overpotential in the electrochemical reaction. The results demonstrate that the directional migration of oxygen or hydrogen bubbles during water electrolysis can be achieved by the magnetic field, uncovering the transport mechanism of gas bubbles in oriented motion induced by Lorentz force and buoyancy. Increase of magnetic strength can speed up bubble shedding especially at large currents, inhibiting dendrite growth of electrodeposited metal. Moreover, the charging threshold would be lowered at the action of isotropy of Ni magnetic domains. Removal of bubbles absorbed at the electrode using the magnet would be beneficial for energy saving, surface quality of electrodeposited metal, and hydrogen production.