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In this study, a green synthesis route was developed to prepare Ca and Co oxides supported carbon aerogel from renewable alginate. The sodium alginate was adopted as a template and carbon source, and a hydrogel with a three-dimensional and core-shell structure was chelated by introducing calcium and cobalt bimetals. The synthesized Ca Co oxides supported carbon aerogel can completely remove Hg0 in the HCl-containing waste gasification gas at room temperature. The Hg0 adsorption capacity on the 4Ca-1Co/CA adsorbent is as high as 4.02 mg/g when the 5% breakthrough occurs. At a 20% breakthrough of HCl, the captured amount of HCl could reach 175.37 mg/g. We concluded that the introduction of calcium and cobalt on the adsorbent provides sufficient active sites for the removal of HCl in a large amount, at the same time, the excellent oxygen supply capacity of Co species in an oxygen-free atmosphere can form active chlorine sites, which is conductive to enhance the removal of Hg0. Additionally, the 4Ca-1Co/CA adsorbent has the characteristics of wide temperature window and wide application range of space velocity, which can meet the needs of various working conditions. [Display omitted] • A green synthesis route to prepare Ca and Co oxides supported carbon aerogel from renewable alginate is provided. • There is a synergistic effect on removing HCl and Hg0 at 4Ca-1Co/CA adsorbent. • The introduction of Ca and Co provides sufficient active sites for the highly efficient removal of HCl and Hg0. • A wide temperature window and high space velocity could be performed on 4Ca-1Co/CA adsorbent. [ABSTRACT FROM AUTHOR]

Bio-based aerogels are sustainable and eco-friendly materials that have gained increasing attention. However, their development is hindered by complex technological processes and unsatisfactory mechanical properties. To obtain a multi-scale hierarchical micro-meso porous composite aerogel with extraordinary thermal insulation and mechanical properties via simple and facile preparation process, we used oxidized cotton linter fiber (CF) as the skeleton and reinforcement, oxidized microcrystalline cellulose (MCC) as the supporting and filling matrix, and PVA as the crosslinking agent and a good glue to enhance the interaction between CF and MCC, and the porous network of the composite aerogel. The composite aerogel is very light, strong, and flexible. The best obtained composite aerogel has a apparent density of only 67.5% of the pure cotton fiber composite aerogel (CF 0), a maximum compressive stress of 1.22 MPa, which is 22 times higher than the pure microcrystalline composite aerogel (MCC 0), and a thermal conductivity of 0.0335 W/m.K, which is 89% lower than CF 0. These properties make the composite aerogel suitable for various thermal insulation applications, such as protective clothing for extremely cold environment. [Display omitted] • Cotton linter composite aerogels were facilely prepared in an environmental-friendly strategy. • The composite aerogels have a multi-scale hierarchical micro-meso structure with enhanced hydrogen bonding. • The composite aerogels have enhanced mechanical properties and thermal insulation. [ABSTRACT FROM AUTHOR]

[Display omitted] • A 3D network structure carbon aerogel of PPD-Cu/CA for deep removal of COS from natural gas. • Para-phenylenediamine doping improves the pore structure of the adsorbent and introduces basic pyridine nitrogen. • The introduction of p-phenylenediamine increases the number of moderate basic sites on the adsorbent. • The adsorbent exhibits excellent high space velocity resistance and water resistance. • The COS adsorption capacity of the optimized PPD-Cu/CA adsorbent can reach 18.6 mg/g at 40 °C. For the purpose of overcoming the difficulty of low removal rate of COS at low temperatures, N-doped copper oxide-supported carbon aerogels were prepared with sodium alginate as a carbon source for deep removal of COS (about 20 ppm) from natural gas. By exploring the effects of different nitrogen sources (urea, melamine and p-phenylenediamine), carbon–nitrogen ratio and carbonization temperature, p-phenylenediamine-doped copper oxide-loaded carbon aerogels (PPD-Cu/CA) with both excellent catalytic hydrolysis of COS and adsorption were prepared. The COS adsorption capacity of optimized PPD-Cu/CA was 18.6 mg·g−1 with 0.94 %Vol of water content at 40 °C, meanwhile, the COS removal efficiency at 40,000 and 70,000 mL·g−1·h−1 could reach 100 % and 94.6 %, respectively, showing excellent high space velocity resistance. Combined with characterization and experimental results, the introduction of p-phenylenediamine enriched the pore structure of the carbon carrier, increased the neutral base site, and played a positive role in the adsorption and hydrolysis of COS. This study provides a new insight into the removal of carbonyl sulfur from natural gas. [ABSTRACT FROM AUTHOR]

• At low temperature the 5%K 2 O-Cu/CA achieved good COS conversion performance. • The surface hydroxyl group is enriched by K loading. • The escaped H 2 S could be adsorbed to be S2- and SO 4 2- on 5 %K 2 O-Cu/CA. • The adsorbent could be regenerated by N 2 regeneration process. COS in natural gas is difficult to be effectively removed at room temperature. Catalytic hydrolysis is a promising method, however, the discrepancy of catalytic active site as well as deactivation factors are the restricting factors. In this paper, the CuO load and alkali metal modification was successfully prepared on carbon aerogel with more mesoporous structure(5 %K 2 O-Cu/CA). The doping of K could improve the pore structure of the sample and is more conducive to the storage of sulfate, obtaining good anti-poisoning properties. Meanwhile, the K load achieved enriched surface hydroxyl groups, which played an important role in COS conversion, and provided enough electronic electron transfers to accelerate the H 2 O dissociation, producing more hydroxyl groups. Then the adsorbed COS could be efficiently captured by the increasing number of weak basic sites at low temperature. Furthermore, after COS transformation the escaped H 2 S could be subsequently adsorbed on 5 %K 2 O-Cu/CA surface and converted to be S2- and SO 4 2- on CuO surface. Finally, the adsorbent capacity and deactivation were studied, and the N 2 regeneration method owns the higher sulfur capacity of 6.01 mg/g with a COS removal efficiency of 100 % for the first time. [ABSTRACT FROM AUTHOR]

The development of anode materials with a high capacity, excellent rate capability, and acceptable stability for sodium-ion batteries (SIBs) is still an urgent issue. Here, we fabricated FeS nanoparticle (NP)/three-dimensional (3D) carbon nanofiber aerogels (CNA) composites utilizing Fe-alginate aerogels as the renewable precursor. In the FeS/CNA sample, well-distributed FeS NPs were embedded on a 3D-CNA network with high electron conductivity and a large specific surface area. Impressively, the FeS/CNA sample was evaluated as an anode electrode material for SIBs, and exhibited an excellent specific capacity (473 mA h g−1 at 0.1 A g−1) and outstanding rate capacity (291 mA h g−1 at 5 A g−1). In addition, 97.4% of the capacity, 385 mA h g−1, was retained over 400 cycles at 2 A g−1, indicating the prominent cycling stability of the FeS/CNA sample. The results were ascribed to the unique structure of the FeS particles embedded on interconnected CNAs, which could boost sodium ion diffusion and facilitate electrolyte access. • Fe-alginate aerogels assure uniform dispersion of FeS NPs on porous carbon matrix. • 1D carbon fibers as transport channels can constitute porous 3D porous network. • FeS NPs and 3D network CNAs have a synergistic effect on sodium storage. • The FeS/CNA electrode reveals an excellent and stable electrochemical performance. [ABSTRACT FROM AUTHOR]

Abstract The key challenge for high-performance sodium-ion batteries is the exploitation of appropriate electrode materials with a long cycling stability and high rate capability. This study reports the synthesis of a composite of ultrafine FeSe nanoparticles (NPs) and carbon nanofiber aerogel (CNFA) as anode material for SIBs. The composite features ultra-small (∼5 nm) NPs of FeSe uniformly embedded in interconnect three dimensional (3D) carbon nanofiber with large surface area, highly conductive network, and robust structural stability. As expected, the FeSe-CNFA-700 sample delivers a capacity as high as ∼313 mA h g−1 at 2000 mA g−1 after 1000 cycles and ultrahigh rate capability up to 20000 mA g−1. The significantly improved electrochemical performance could be attributed to the unique structure that combines a variety of advantages: easy access of electrolyte to the 3D network structure, pseudocapacitve charge storage and fast Na ion diffusion processes. The results confirm the intercalation of Na+ into the 3D ultrafine FeSe nanoparticles/carbon nanofiber aerogel is enhanced through the strong interaction between FeSe nanocrystals and the carbon layer. The density functional theory calculations demonstrate that the unique FeSe/carbon layer interface in 3D network structure can enhance Na storage due to the small energy barrier and negative adsorption energy. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) carbonaceous aerogels assembled by one-dimensional (1D) carbon nanofibers (CNF) have attracted much attention, because their unique interconnected and hierarchical porous structure can offer a wide range of applications in environmental remediation and energy storage. Herein, the residue of gelidium amansii (mainly endofibers, ∼1.6 μm) after extraction of agar were used as precursor to fabricate nanofibrilated cellulose by using facile ultrosonication treatment. The nanofibrilated celluloses are highly engineered nanofibers with average diameter of ∼90 nm. Then the 1D cellulose nanofibers could be assembled into 3D nanofiber aerogels after freeze drying. The subsequent pyrolysis in NH 3 and activition could result in the formation of N-doped CNF areogel (N-PCNFA), where the oxygen-containing groups in cellulose macromolecules converted to H 2 O, CO, and CO 2 . The N-PCNFA with hierarchically porous structure, high surface area (2290 m 2  g −1 ), N-doping, and 3D interconnected channels are beneficial to electrolyte ions and electron transportation. The N-PCNFA displayed high capacity and long-term stability as energy storage material. This work highlights a new strategy in highly efficient utilizing the marine biomass waste for developing low-cost and functional carbon aerogel for multiple energy storage. [ABSTRACT FROM AUTHOR]

In order to overcome the deficiencies of low adsorption capacity and poor tolerance to high space velocities of commercial adsorbents for H 2 S removal, core-shell structured Cu-Fe/carbon aerogels (CA) with mixed valence of Cu and Fe were synthesized. The doping of Cu decreased the average size of Fe nanoparticles and enhanced the dispersion of nanoparticles. In addition, parts of oxides were reduced to Cu0 and Fe0 by carbon shell during carbonization process, resulting in the coexistence of mixed valence Cu Fe doped nanoparticles in CA. The existence of Cu0 and Fe0 nanoparticles is the key contributor for excellent tolerance to high space velocities, where the H 2 S could be easily adsorbed and dissociated to form reactive intermediate such as HS− and S2−. The well dispersed Cu Fe doping oxides are the active sites for H 2 S capture, benefiting for the high H2S adsorption capacity. The adsorbed water can be dissociated to hydroxyl groups over iron oxide, which is more conducive to the removal of H 2 S. The H 2 S (200 ppm H 2 S in CH 4) adsorption capacity of optimized adsorbent was 221.1 mg∙g−1 at 100% relative humidity. This study provided a new insight into the synthesis of Cu-based and Fe-based adsorbents for the removal of H 2 S. [Display omitted] • 1Cu1Fe/CA adsorbent can effectively remove H 2 S and has excellent tolerance to high space velocity at room temperature. • Cu and Fe in the core-shell structured adsorbent enhance the ability to H 2 S adsorption and dissociation. • The doping of Cu significantly reduces the average size of Fe nanoparticles and enhances their dispersion. • The reaction mechanism of mixed-valence 1Cu1Fe/CA is proposed by comparing the DFT theoretical calculations. [ABSTRACT FROM AUTHOR]

Hydrogen evolution reaction (HER), is considered as an ideal alternative approachs to settle the energy crisis. Therefore, we need to explore efficient and stable non-Pt-based electrocatalysts for hydrogen production from water electrolysis. In this work, S-doped ultrafine molybdenum carbide anchored on cellulose nanocrystals (CNC) derived carbon composite aerogels (Mo 2 C@S-CA) were synthesized for HER by a simple one-step carbonization method, utilizing inorganic-organic hybrid ammonium molybdate/CNC (AMM/CNC) as precursor. The obtained Mo 2 C@S-CA aerogels can not only provide plenty of active sites, but also accelerate the hydrogen release from the reaction surface of the electrocatalysts. The as-synthesized catalysts exhibit superior HER activity with a small overpotential value of 176 mV vs . RHE at 10 mA cm −2 and excellent long-term stability after 10,000 cycles in 0.5 M H 2 SO 4 . These superb properties make the catalyst be a promising electrocatalyst for the HER. This work highlights the importance of biomass-derived multifunctional value-added composite aerogels in enhancing the electrolysis of water. [ABSTRACT FROM AUTHOR]