Sustainable Route for Molecularly Thin Cellulose Nanoribbons and Derived Nitrogen-Doped Carbon Electrocatalysts

Abstract

Ultrathin cellulose nanoribbons were extracted from earth-abundant biomass using 2,2,6,6-tetramethylpiperidine-1-oxyl-catalyzed (TEMPO-catalyzed) oxidation and sonication processes. By two TEMPO-oxide systems with different processing times, TEM and AFM observations indicate the obtained cellulose nanoribbons (Cel-NRs) with dimensions of 400–800 nm in length, 1.72–2.54 nm in width, and 0.78–2.67 nm in thickness. The dimension data indicate that the Cel-NRs from the TEMPO/NaBr/NaClO system are much shorter but contain more cellulose chains than those from the TEMPO/NaClO/NaClO2 system. Moreover, these abundant biomass nanoribbons were fabricated from direct pyrolysis with NH3 activation. The obtained highly active nitrogen-doped carbon nanoribbons (N-CNRs) and metal-free oxygen reduction reaction (ORR) electrocatalysts show superb ORR activity (half-wave potential of 0.71 and 0.73 V versus reversible hydrogen electrode) and high selectivity (electron-transfer number of 3.26 and 3.74 at 0.8 V), comparable current density and onset potential (0.906 and 0.926 V), excellent electrochemical stability (higher than 89.5% and 91.6% after 20 000 potential cycles) in alkaline media, and better resistance to crossover effects in the ORR. More importantly, when used as a cathode catalyst for constructing the air electrode of the Zn–air battery, the N-CNRs exhibit super long-term stability and a capacity of 587 and 583 mAh g–1 at the discharge current densities of 5 and 20 mA cm–2, respectively, which are highly comparable with those of the state-of-the-art Pt/C catalyst (20 wt % Pt, Hispec 3000). This indicates that our present work is the first example of using atomically thin carbon nanoribbons as the metal-free electrocatalyst substitution to Pt for developing high-performance metal–air batteries from earth-abundant terrestrial plants.

Pseudosolvent Intercalator of Chitin: Self‐Exfoliating into Sub‐1 nm Thick Nanofibrils for Multifunctional Chitinous Materials

“…also found that the mean thickness of cellulose nanofibrils extracted by using TEMPO/NaClO 2 /NaClO oxidation systems was around 0.8 nm, which is related to few layers cellulose molecular sheet. [ 7 ] More recently, Zhang et al. reported that the basic building block of the natural silkworm silk was 0.4 nm thick nanoribbons consisting of single β‐sheet layer and amorphous silk chains.…”

“…On the other hand, ChNFs prepared with elevated swelling time exhibits similar surface zeta potential while gradually growing carboxylate content from 1.34 to 1.78 mmol g −1 , also indicating that more hydroxyl groups along the inner (010) planar are esterified by MAH (Figure S15, Supporting Information). [ 7 ] After dispersing esterified β‐chitin in NaOH aqueous solution (pH = 11), nanofibrils with few molecular layers thick is exfoliated from elementary nanofibrils, as driven by the strong electrostatic repulsion between molecular sheets (Stage II). Longer incubation time in the pseudosolvent of DMSO/KOH tends to widen more (010) planar and thereby a decrease of nanofibrils thickness (Figure 3C; and Figure S16, Supporting Information).…”

Natural sliced wood veneer as a universal porous lightweight substrate for supercapacitor electrode materials

“…The application of cellulose-based energy storage materials for lithium-ion batteries and supercapacitors has received unprecedented attention in recent years. [1][2][3][4][5] In particular, the use of nanocellulose as a carrier or a shaped material in combination with an electrochemically active material (e.g., a conductive polymer or carbon nanomaterial) to form energy storage materials, [6][7][8][9] and the direct carbonisation of nanocellulose into activated carbon materials [10][11][12][13][14] have been examined in detail. This increased attention regarding nanocellulose is closely related to its excellent properties, which are derived from its biomass source, i.e., wood.…”

Turning gelidium amansii residue into nitrogen-doped carbon nanofiber aerogel for enhanced multiple energy storage

“…Lu et al controllably synthesized a series of 3D porous CNF aerogel with different dimeters using earth-abundant bamboo as precursors [12]. With the fast exploration of ocean, the abundant algae resources, mainly including browm, red, and green algas, have been extensively concerned [16][17][18][19][20][21][22][23][24][25]. Similar to bamboo, some of abundant seaweed (~ 30,000,000 tons per year) contain high cellulose, making them possible to produce CNF aerogel via a sustainable route.…”