Preparation of activated carbon aerogel and its application to electrode material for electric double layer capacitor in organic electrolyte: Effect of activation temperature

Advances in Carbon Xerogels: Structural Optimization for Enhanced EDLC Performance

This review explores the recent progress on carbon xerogels (CXs) and highlights their development and use as efficient electrodes in organic electric double-layer capacitors (EDLCs). In addition, this work examines how the adjustment of synthesis parameters, such as pH, polymerization duration, and the reactant-to-catalyst ratio, crucially affects the structure and electrochemical properties of xerogels. The adaptability of xerogels in terms of modification of their porosity and structure plays a vital role in the improvement of EDLC applications as it directly influences the interaction between electrolyte ions and the electrode surface, which is a key factor in determining EDLC performance. The review further discusses the substantial effects of chemical activation with KOH on the improvement of the porous structure and specific surface area, which leads to notable electrochemical enhancements. This structural control facilitates improvement in ion transport and storage, which are essential for efficient EDLC charge-discharge (C-D) cycles. Compared with commercial activated carbons for EDLC electrodes, CXs attract interest for their superior surface area, lower electrical resistance, and stable performance across diverse C-D rates, which underscore their promising potential in EDLC applications. This in-depth review not only summarizes the advancements in CX research but also highlights their potential to expand and improve EDLC applications and demonstrate the critical role of their tunable porosity and structure in the evolution of next-generation energy storage systems.

Nanoporous carbon materials as a sustainable alternative for the remediation of toxic impurities and environmental contaminants: A review

Due to rapidly deteriorating water resources, the world is looking forward to a sustainable alternative for the remediation of noxious pollutants such as heavy metals and organic and gaseous contaminants. To address this global issue of environmental pollution, nanoporous carbon materials (NPCMs) can be used as a one-stop solution. They are widely applied as adsorbents for many toxic impurities and environmental contaminants. The present review provides a detailed overview of the role of different synthesis factors on the porous characteristics of carbon materials, activating agents, reagent-precursor ratio and their potential application in the remediation. Findings revealed that synthetic parameters result in the formation of microporous NPCMs (S_BET: >4000 m³/g; V_Total (cm³/g) ≥ 2; V_Micro (cm³/g) ≥ 1), micromesoporous (S_BET: >2500 m³/g; V_Total (cm³/g) ≥ 1.5; V_Micro (cm³/g) ≥ 0.7) and mesoporous (S_BET: >2500 m³/g; V_Total (cm³/g) ≥ 1.5; V_Micro (cm³/g) ≥ 0.5) NPCMs. Moreover, it was observed that a narrow pore size distribution (0.5-2.0 nm) yields excellent results in the remediation of noxious contaminants. Further, chemical activating agents such as NaOH, KOH, ZnCl₂, and H₃PO₄ were compared. It was observed that activating agents KОН, H₃PO₄, and ZnCl₂ were generally used and played a significant role in the possible large-scale production and commercialization of NPCMs. Thus, it can be interpreted that with a well-planned strategy for the synthesis, NPCMs with a "tuned" porosity for a specific application, in particular, microporosity for the accumulation and adsorption of energetically important gases (CO₂, CH₄, H₂), micro-mesoporosity and mesoporosity for high adsorption capacity for towards metal ions and a large number of dyes, respectively.

Product Characteristics of Sludge Pyrolysis and Adsorption Performance of Metals by Char

The microwave heating system was used for sludge pyrolysis. The raw sludge and KOH-immersed sludge were pyrolyzed and their product characteristics were determined. The research results are advantageous to understand the influence of KOH activation on characteristics of pyrolysis products and the adsorption performance of metals in char. In the case of a high temperature and high KOH dose, most of the lost mass from sludge pyrolysis was converted into gaseous products instead of oil. The heat values of liquid oils were 40.86–41.39 MJ kg−1, which has the potential for use as fuels. The use of a higher KOH dose for sludge pyrolysis is beneficial to the porosity development and generates a mesopore structure. The results from adsorption tests indicate that precipitation could be the dominant adsorption mechanism due to the binding between alkaline anion and carbonate and metal ions with a strong chemical affinity. The high KOH dose sludge adsorbent has a remarkable adsorption performance and can be used as adsorbent for the removal of the studied metals.

Insight into activated carbon from different kinds of chemical activating agents: A review

Activated carbon (AC) is an important material in various fields owing to its low cost, well-developed porosity, and favorable chemical stability. Key factors for the optimal synthesis of AC are the carbon precursors, activation pathways, activating agents, and design of the procedure parameters. So far, no case studies have reviewed the activating agents used during the chemical activation process. Accordingly, the present review provides a summary of recent research, highlighting the development of activating agents during the process of AC. Detailed lists of pore-forming mechanisms by various activating agents, including alkaline, acidic, neutral, and self-activating agents, have been systematically summarized. Furthermore, the effects of activating agents on the experimental procedures have also been established. Finally, a comprehensive discussion about the influences of activating agents on the physical and chemical properties of the resultant AC is included. The objective of this study is to reveal and distinguish the individual roles of different activating agents during AC synthesis.

Preparation and application of sunlight absorbing ultra-black carbon aerogel/graphene oxide membrane for solar steam generation systems

In this study, sunlight absorbing membranes consisting of ultra-black resorcinol–formaldehyde (RF)-based carbon aerogel (CA) and hydrophilic graphene oxide (GO) suspension were fabricated. To investigate the effect of substrate structure, CA/GO ink was cast onto two different layers including 3D modified copper foam (MCF) and 2D paper sheet. The copper foam (CF) was treated with a new and simple modification method to enhance the hydrophilicity. Finally, the solar steam generation performances of the prepared membranes were evaluated. The optical analyses indicated that 2D and 3D samples respectively reflected ∼4.5% and ∼10%, and transmitted ∼0% of the incident light. The water contact angle measurements revealed a significant change in the wettability of the CF layer representing a contact angle of 139.41° before the modification. Based on the water evaporation rates, the efficiencies of 81.1% and 91.4% (at 1 kW m⁻²) were achieved for 2D and 3D absorbents, respectively. In addition to eliminating the geometrical restrictions of the monolithic absorbents, the results verified that CA/GO ink-based absorbents were promising materials for solar steam generation systems (SSG) due to the high light absorption, superhydrophilicity and porous structure.

The sunlight absorbing membrane consisting of ultra-black resorcinol-formaldehyde (RF)-based carbon aerogel (CA) and graphene oxide (GO) suspension was fabricated. The hydrophilic modified copper foam (MCF) was prepared and used as the substrate.

Self-Sacrificial Salt Templating: Simple Auxiliary Control over the Nanoporous Structure of Porous Carbon Monoliths Prepared through the Solvothermal Route

The conventional sol-gel method for preparing porous carbons is tedious and high-cost to prepare porous carbons and the control over the nanoporous architecture by solvents and carbonization is restricted. A simple and novel self-sacrificial salt templating method was first presented to adjust the microporous structure of porous carbon monoliths synthesized via the solvothermal method. Apart from good monolithic appearance, the solvothermal route allowed for ambient drying because it made sure that the polymerization reaction was completed quickly and thoroughly. The intact and crack-free porous carbon monoliths were investigated by scanning electron microscopy (SEM), thermogravimetric differential scanning calorimetry (TG-DSC), Fourier transform infrared (FT-IR), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and nitrogen sorption measurements. It was proven that the self-sacrificial salts NH₄SCN had been removed during pyrolyzing and so, porous carbon monoliths could be directly obtained after carbonization without the need of washing removal of salts. Most importantly, the microporous specific surface area of the resultant porous carbon monoliths was dramatically increased up to 770 m²/g and the Brunauer–Emmett–Teller (BET) specific surface area was up to 1131 m²/g. That was because the salts NH₄SCN as self-sacrificial templating helped to form more around 0.6 nm, 0.72 nm and 1.1 nm micropores. The self-sacrificial salt templating is also a suitable and feasible method for controlling the nanoporous structure of other porous materials.