Recent Progress in Carbonaceous and Redox-Active Nanoarchitectures for Hybrid Supercapacitors: Performance Evaluation, Challenges, and Future Prospects.

Due to advancements in technology, the energy demand is becoming more intense with time. The rapid fossil fuels consumption and environmental concerns triggered intensive research for alternative renewable energy resources, including sunlight and wind. Yet, due to their time-dependent operations, significant electric energy storage systems are required to store substantial energy. In this regard, electrochemical energy storage devices, like batteries and supercapacitors (SCs), have recently attracted much research attention. Recent developments in SCs demonstrated that hybrid SCs (HSCs), which combine the excellent properties of batteries and SCs, increase the specific energy, specific power, specific capacitance, and life span. Carbonaceous and redox-active materials have been explored as efficient electrode materials for applications in HSCs, ultimately enhancing their electrochemical performances. The HSCs performance significantly depends on the porosity, specific surface area, and conductivity of the electrode materials. This review article gives an overview of recent advances in developing HSCs with high specific power, specific energy, and long cyclic-life. The fabrication of various HSCs materials using carbonaceous and redox-active nanoarchitectures and their characterization are explored in-depth, including electrode development, basic principles, and device engineering. A proper investigation has been conducted regarding state-of-the-art materials as HSC electrodes. This review focuses on the most up-to-date, cutting-edge, electrode materials for HSCs and their performance. The possibilities for novel electrode materials and their impact on the HSCs performance for future energy storage are also discussed.

Sorption of naphthalene and 2-naphthol onto porous carbonaceous materials as a function of pore size, metals, and oxygen-containing groups.

The important role of oxygen-containing groups of porous carbonaceous materials (PCMs) on sorption of organic compounds has been realized, but whether these groups can generate different joint effects, especially when oxidized PCMs with different pore sizes are complexed with heavy metals (Cu2+), remains ambiguous. The present study aimed to determine how pore sizes, metal ions, and oxygen-containing groups as a function affect the sorption of naphthalene and 2-naphthol to PCMs (e.g., activated carbons/ACs and mesoporous carbon/CMK-3). The H2-reduced oxidized PCMs were used as the control of low oxygen content to avoid changes in the pore structure properties compared with the oxidized PCMs. Oxygen-containing groups considerably decreased the sorption of naphthalene and 2-naphthol to PCMs because of their weaker hydrophobic interaction and fewer sorption sites. Notably, naphthalene sorption on oxidized AC was inhibited with Cu2+ because of the steric constraint of Cu2+ hydration shells of the micropores. However, pore blockage by Cu2+ reduced the mesopore size of oxidized CMK-3, leading to enhanced pore filling effect and cation-π bonding, and therefore increased naphthalene sorption. For 2-naphthol, the sorption to oxidized PCMs initially increased and then decreased with increasing Cu2+ concentration attributed to the fewer Cu2+ acting as a bridging agent and excess Cu2+ competing for sorption sites.

Different effects of surface heterogeneous atoms of porous and non-porous carbonaceous materials on adsorption of 1,1,2,2-tetrachloroethane in aqueous environment.

The surface heterogeneous atoms of carbonaceous materials (CMs) play an important role in adsorption of organic pollutants. However, little is known about the surface heterogeneous atoms of CMs might generate different effect on adsorption of hydrophobic organic compounds by porous carbonaceous materials - activated carbons (ACs) and non-porous carbonaceous materials (NPCMs). In this study, we observed that the surface oxygen and nitrogen atoms could decrease the adsorption affinity of both ACs and NPCMs for 1,1,2,2-tetrachloroethane (TeCA), but the degree of decreasing effects were very different. The increasing content of surface oxygen and nitrogen ([O + N]) caused a sharper decrease in adsorption affinity of ACs (slope of lg (kd/SA) vs [O + N]: -0.098∼-0.16) than that of NPCMs (slope of lg (kd/SA) vs [O + N]: -0.025∼-0.059) for TeCA. It was due to the water cluster formed by the surface hydrophilic atoms that could block the micropores and generate massive invalid adsorption sites in the micropores of ACs, while the water cluster only occupied the surface adsorption sites of NPCMs. Furthermore, with the increasing concentration of dissolved TeCA, the effect of surface area on adsorption affinity of NPCMs for TeCA kept constant while the effect of [O + N] decreased due to the competitive adsorption between water molecule and TeCA on the surface of NPCMs, meanwhile, both the effects of micropore volume and [O + N] on adsorption affinity of ACs for TeCA were decreased due to the mechanism of micropore volume filling. These findings are valuable for providing a deep insight into the adsorption mechanisms of CMs for TeCA.

Highly Efficient Oxygen Reduction Electrocatalyst Derived from a New Three-Dimensional PolyPorphyrin.

Metal-encapsulated nitrogen-doping porous carbonaceous materials (NDPCs) prepared from metalloporphyrin-based covalent organic frameworks (MP-COFs) have become very promising candidates for highly effective oxygen reduction electrocatalysts. To enhance the ORR performance and durability of these NDPCs in novel energy conversion and storage devices, we develop a new type of metal-encapsulated NDPCs (HBY-COF-900) composed of FeN4 active sites by introduction of metalloporphyrin into porous COFs. Comparable to the benchmark 20% Pt/C, HBY-COF-900 in acidic solutions exhibits higher oxygen reduction electrocatalytic activity, long-term durability, and good CO tolerance. These properties can be attributed to a synergistic effect of FeN4 active sites, high graphitization, and porous structure. This work opens an avenue for the development of metal-encapsulated NDPCs from three-dimensional polyporphyrin prepared by one-step polymerization.

Asphalt-derived high surface area activated porous carbons for carbon dioxide capture.

Research activity toward the development of new sorbents for carbon dioxide (CO2) capture have been increasing quickly. Despite the variety of existing materials with high surface areas and high CO2 uptake performances, the cost of the materials remains a dominant factor in slowing their industrial applications. Here we report preparation and CO2 uptake performance of microporous carbon materials synthesized from asphalt, a very inexpensive carbon source. Carbonization of asphalt with potassium hydroxide (KOH) at high temperatures (>600 °C) yields porous carbon materials (A-PC) with high surface areas of up to 2780 m(2) g(-1) and high CO2 uptake performance of 21 mmol g(-1) or 93 wt % at 30 bar and 25 °C. Furthermore, nitrogen doping and reduction with hydrogen yields active N-doped materials (A-NPC and A-rNPC) containing up to 9.3% nitrogen, making them nucleophilic porous carbons with further increase in the Brunauer-Emmett-Teller (BET) surface areas up to 2860 m(2) g(-1) for A-NPC and CO2 uptake to 26 mmol g(-1) or 114 wt % at 30 bar and 25 °C for A-rNPC. This is the highest reported CO2 uptake among the family of the activated porous carbonaceous materials. Thus, the porous carbon materials from asphalt have excellent properties for reversibly capturing CO2 at the well-head during the extraction of natural gas, a naturally occurring high pressure source of CO2. Through a pressure swing sorption process, when the asphalt-derived material is returned to 1 bar, the CO2 is released, thereby rendering a reversible capture medium that is highly efficient yet very inexpensive.