Oxygen reduction reaction and hydrogen evolution reaction are two key reactions involved in several renewable energy technologies. Herein, a nonprecious bifunctional electrocatalyst for oxygen ...reduction reaction and hydrogen evolution reaction is facilely synthesized through directly pyrolyzing the mixture of Prussian blue analogues, graphene oxide and graphitic carbon nitride in the presence of silica colloids. Post-synthesis removal of silica hard templates leads to a cobalt and nitrogen co-doped reduced graphene oxide composite with Co nanoparticles, which comprises abundant mesoporous textures and a high specific surface area of 703.26 cm2 g−1. The resultant composite shows marked oxygen reduction reaction activity, with a more positive half-wave potential of +0.848 V, a higher limiting current, a stronger immunity to fuel crossover effect and higher operation stability, as compared with commercial Pt/C catalyst in alkaline solution. Besides, such composite can also serve as efficient and stable hydrogen evolution reaction catalyst in alkaline electrolyte, and an overpotential of only 180 mV is required to reach 10 mA cm−2. The remarkable bifunctional catalytic activities are attributed to the synergistic effects of Co nanoparticles and graphene substrate. These results highlight the high potential of present strategy in synthesis of multifunctional nonprecious electrocatalysts.
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•Porous cellulose carbon aerogels were obtained via carbonized and activated simultaneously.•Cellulose carbon aerogel had a high specific surface area of 1364m2/g and a high specific ...capacitance of 328Fg−1.•For the first time, we showed that the cellulose carbon aerogel had a good CO2 adsorption capacity.
Fabrication of cost-effective and eco-friendly hierarchical porous carbons from the most abundant and widely available biomass cellulose represents a critical and sustainable way to solve the crisis of fossil resources. In this work, a hierarchical porous carbon aerogel with desirable macropores, mesopores, and micropores was obtained via dissolving-gelling and subsequent carbonizing-activating process. The CO2 activated carbon aerogel had a high specific surface area of 1364m2/g and a high specific capacitance of 328Fg−1 (0.5Ag−1, 1.0M H2SO4) as well as an outstanding cycling stability with 96% of the capacitance retention after 5000 charge/discharge cycles. More importantly, for the first time, we demonstrated that the cellulose-derived hierarchical porous carbon aerogel showed a good CO2 adsorption capacity of 3.42mmol/g (at 1atm and 298K), which indicates the possibility of using this carbon aerogel for CO2 capture.
3D monoliths have undergone great progress in the past decades in scientific and engineering fields. Especially, compressible and elastic 3D monoliths (CEMs) hold great promise in a series of ...applications, such as pressure/strain sensing, energy storage, oil/water separation, and thermal insulation, attributed to their unique mechanical properties and multifunctionality (e.g., conductivity, thermal stability, and high adsorption capacity). Recently, plenty of advanced CEMs have been developed from 1D and 2D building blocks, polymers, and biomass via various methods. Herein, the latest progress in controllable design and preparation of advanced CEMs, which mainly refer to aerogels, sponges, and foams, are reviewed in terms of their structural units and applications. The relationship between structure and mechanical performances of CEMs is discussed. Moreover, their applications in sensing, energy storage and conversion, water treatment, fire‐resistance, and electromagnetic interface shielding are presented. Finally, the challenges and future opportunities of CEMs are also discussed.
Recently, plenty of advanced three‐dimensional (3D) compressible and elastic monoliths (CEMs) have been developed. Herein, the latest progress in controllable design and preparation of CEMs beyond hydrogels is summarized. The relationship between structure and mechanical performances of CEMs is discussed, and their applications in sensing, energy storage and conversion, water treatment, fire‐resistance, and electromagnetic interface shielding are presented.
Hierarchical porous N-doped carbons have attracted great interest in energy storage and CO
2
capture applications due to their unique porous structure and physicochemical properties. Fabrication of ...cost-effective and eco-friendly hierarchical porous N-doped carbons from renewable biomass resources is a sustainable route for future energy storage. However, it is still a big challenge to produce N-doped carbons with hierarchical porous structure from cellulose, which is the most abundant and widely available renewable resource on earth. Here, we designed a facile and effective strategy to produce hierarchical porous N-doped carbons from cellulose for high-performance supercapacitor and CO
2
capture applications. In this method, hierarchical porous cellulose aerogels were first obtained
via
a dissolving-gelling process and then carbonized in NH
3
atmosphere to give hierarchical porous N-doped carbon aerogels with more interconnected macropores and micropores. Due to the unique porous structure and physicochemical properties, the as-prepared N-doped carbon aerogels had a high specific capacitance of 225 F g
−1
(0.5 A g
−1
) and an outstanding cycling stability. For the first time, we also demonstrated that this N-doped carbon aerogel exhibited a exceptional CO
2
adsorption capacity of 4.99 mmol g
−1
, which is much higher than those of other porous carbons. This novel hierarchical porous N-doped carbon has great potential applications in CO
2
capture, energy storage, porous supports, and electrochemical catalysis.
3D hierarchical porous N-doped carbon aerogel from renewable cellulose: an attractive carbon for high-performance supercapacitor electrode and CO
2
adsorption.
High theoretical energy density, low cost, and environment‐friendly flexible metal‐air batteries (MABs) are expected to become one of the best candidate energy storage devices for small‐scale, ...intelligent, flexible, and wearable electronic products/technology. This review discusses the flexible components of different flexible MABs, focusing on flexible air cathodes and flexible electrolytes, and prospects for future research directions.
Novel thiol functionalized xylose hydrochar microspheres supported palladium nanoparticles (C–SH–Pd) were synthesized by gentle heating of palladium (II) acetate and thiol functionalized xylose ...hydrochar (C–SH) in ethanol. The as-prepared C–SH–Pd exhibited high catalytic activity towards Suzuki reactions with a yield of high up to 100%. Moreover, it could be reused for at least five times without heavily loss of the catalytic activity. The amount of palladium entrapped on C-SH microspheres was measured by AAS and found to be 1.42 mmol/g. Leaching studies showed that the filtrate contained less than 0.2 ppm Pd. Due to the superior catalytic performance and stability of the C–SH–Pd catalyst, it can be exploited in other cross coupling reactions in the long run.
Graphic Abstract
► The zeta potential greatly influenced the colloidal stability of CNC. ► Ca2+ showed more prominent influence on the colloidal stability of CNC than Na+. ► Anionic organic electrolytes with low Mw ...favored the colloidal stability of CNC. ► Cation polyelectrolyte easily caused CNC aggregation.
Colloidal stability of negatively charged cellulose nanocrystalline (CNC) in the presence of inorganic and organic electrolytes was investigated by means of dynamic light scattering and atomic force microscopy. CNC could be well dispersed in distilled water due to the electrostatic repulsion among negatively charged sulfate ester groups. Increasing the concentration of inorganic cation ions (Na+ and Ca2+) resulted in CNC aggregation. CNC in divalent cation ion Ca2+ solution exhibited less stability than that in monovalent cation ion Na+ solution. Organic low-molecular-weight electrolyte sodium dodecyl sulfate (SDS) favored the stability of CNC suspension, whereas organic high-molecular-weight electrolyte sodium carboxymethyl cellulose (CMC) induced CNC particle aggregation due to intermolecular bridging interaction or entanglement. Cationic polyacrylamide (CPAM) caused a serious aggregation of CNC particles even at low concentration of CPAM. At low ionic strength (Na+, 1mM), CNC were stable in aqueous solution at the pH range of 2–11.
•A novel plasticizer ChCl/urea was found to effectively plasticize cellulose films.•ChCl/urea showed good compatibility with cellulose.•No chemical reaction and crystallization occurred to ChCl/urea ...plasticized cellulose film.•ChCl/urea was comparable to glycerol and sorbitol, and could be used as a potential plasticizer for cellulose film.
Recently, choline chloride/urea (ChCl/urea), a typical deep eutectic solvent (DES), has been found to possess various applications in organic synthesis, electrochemistry, and nanomaterial preparation. Herein we reported the first attempt to plasticize regenerated cellulose film (RCF) using ChCl/urea as an effective plasticizer. Meanwhile, RCFs plasticized with glycerol and sorbitol were also prepared for comparison. The plasticized RCFs were investigated by Fourier transform infrared (FT-IR) spectroscopy, wide-angle X-ray diffraction (XRD), atomic force microscopy (AFM), and mechanical testing. Transparent and soft RCFs could be successfully prepared in the presence of ChCl/urea, and high elongation at break (34.88%) suggested a significant plasticizing efficiency. No new crystal and phase separation occurred to ChCl/urea plasticized RCFs. The thermal stability of ChCl/urea plasticized RCF was lowered. These results indicated that ChCl/urea was an effective plasticizer for producing cellulose films.
Abstract
Deuterium labeling is of great value in organic synthesis and the pharmaceutical industry. However, the state-of-the-art C–H/C–D exchange using noble metal catalysts or strong bases/acids ...suffers from poor functional group tolerances, poor selectivity and lack of scope for generating molecular complexity. Herein, we demonstrate the deuteration of halides using heavy water as the deuteration reagent and porous CdSe nanosheets as the catalyst. The deuteration mechanism involves the generation of highly active carbon and deuterium radicals via photoinduced electron transfer from CdSe to the substrates, followed by tandem radicals coupling process, which is mechanistically distinct from the traditional methods involving deuterium cations or anions. Our deuteration strategy shows better selectivity and functional group tolerances than current C–H/C–D exchange methods. Extending the synthetic scope, deuterated boronic acids, halides, alkynes, and aldehydes can be used as synthons in Suzuki coupling, Click reaction, C–H bond insertion reaction etc. for the synthesis of complex deuterated molecules.
Biomass-based protic ionic liquids (BILs), green solvents with inherent properties, have the potential as precursors of functionalized catalytic carbon materials. Simple one-step design and ...preparation of BILs-based porous carbon-based materials remains a challenge. Our demonstration here was to use BIL as an important precursor for synthesizing porous carbon-coated CoP nanocrystals by facile one-pot carbonization process. The as-prepared CoP@NPC-900 has a specific surface area of 979.67 m
2
g
−1
without activator and simultaneously exhibits excellent hydrogen evolution reaction (HER) performance with a low overpotential of 181 mV at 10 mA cm
−2
and small Tafel slope of 59 mV dec
−1
in acid solution. In addition, density functional theory (DFT) calculations indicate lower adsorption free energy and rapid electron transfer between CoP nanocrystals and N, P co-doped porous carbon (NPC) are key factors of improving the HER performance. Our research opens up a new use of BILs, as well as provides a facile strategy to promote practical application of transition metal phosphides for HER.
Graphical abstract
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