Power-to-decarbonization: Mesoporous carbon-MgO nanohybrid derived from plasma-activated seawater salt-loaded biomass for efficient CO2 capture

Accelerated Synthesis of Ordered Mesoporous Carbons Using Plasma

Conventional ordered mesoporous carbon (OMC) production usually requires long processing times in the carbonization step to achieve desired temperatures through controlled ramps. To enable expedited materials discovery, developing advanced manufacturing capability with significantly improved throughput is highly desired. Current approaches for accelerating the synthesis of OMCs include using microwave and Joule heating. However, both methods rely on the introduction of additional components, such as microwave absorbers and electrically conductive agents, within the bulk materials to impart the ability to reach high carbonization temperatures. This work demonstrates accelerated synthesis and functionalization of OMCs through the use of a dielectric barrier discharge plasma, where carbonization can be accomplished within 15 min using 30 W plasma sources, representing more than an order of magnitude increase in polymer-to-carbon conversion kinetics compared to that of a traditionally pyrolyzed analogue. Particularly, the ability of performing rapid carbonization without the use of additional substrates within the OMC precursor systems is advantageous. A systematic investigation of how plasma power, time, and gas atmosphere impact the resulting OMC pore textures and properties is performed, demonstrating the broad applicability of plasma-enabled carbonization methods. Furthermore, we demonstrate that the plasma treatment strategy can be extended to incorporate heteroatoms into the carbon framework by introducing ammonia gas, resulting in OMCs with a nitrogen content up to 4.7 at %, as well as non-Pluronic templating systems for synthesizing OMC with pore sizes larger than 10 nm. As employing a plasma source for materials pyrolysis is an industrially relevant approach, our system can be extended toward scaled synthesis of OMCs with much faster production rates.

Mesoporous carbon nitride supported MgO for enhanced CO2 capture

The growing concern about the environmental consequences of anthropogenic CO2 emissions significantly stimulated the research of low-cost, efficient, and recyclable solid adsorbents for CO2 capture. In this work, a series of MgO-supported mesoporous carbon nitride adsorbents with different MgO contents (xMgO/MCN) was prepared using a facile process. The obtained materials were tested for CO2 capture from 10 vol% CO2 mixture gas with N2 using a fixed bed adsorber at atmospheric pressure. At 25 ºC, the bare MCN support and unsupported MgO samples demonstrated CO2 capture capacities of 0.99, and 0.74 mmol g-1, respectively, which were lower than those of the xMgO/MCN composites.The incorporation of MgO into the MCN improved the CO2 uptake, and the 20MgO/MCN exhibited the highest CO2 capture capacity of 1.15 mmol g-1 at 25 °C. The improved performance of the 20MgO/MCN nanohybrid can be possibly assigned to the presence of high content of highly dispersed MgO NPs along with its improved textural properties in terms of high specific surface area (215 m2g-1), large pore volume (0.22 cm3g-1), and abundant mesoporous structure. The efffects of temperature and CO2 flow rate were also investigated on the CO2 capture performance of 20MgO/MCN. Temperature was found to have a negative influence on the CO2 capture capacity of the 20MgO/MCN, which decreased from 1.15 to 0.65 mmol g-1with temperature rise from 25 C to 150º C, due to the endothermicity of the process. Similarly, the capture capacity decreased from 1.15 to 0.54 mmol g-1 with the increase of the flow rate from 50 to 200 ml minute-1 respectively. Importantly, 20MgO/MCN showed excellent reusability with consistent CO2 capture capacity over five sequential sorption-desorption cycles, suggesting its suitability for the practical capture of CO2.

Potential capture and conversion of CO2 from oceanwater through mineral carbonation

Carbon dioxide (CO₂) emitted by human activities not only brings about a serious greenhouse effect but also accelerates global climate change. This has resulted in extreme climate hazards that can obstruct human development in the near future. Hence, there is an urgent need to achieve carbon neutrality by increasing negative emissions. The ocean plays a vital role in absorbing and sequestering CO₂. Current research on marine carbon storage and sink enhancement mainly focuses on biological carbon sequestration using carbon sinks (macroalgae, shellfish, and fisheries). However, seawater inorganic carbon accounts for more than 95 % of the total carbon in marine carbon storage. Increasing total alkalinity at a constant dissolved inorganic carbon shifts the balance of existing seawater carbonate system and prompts a greater absorption of atmospheric CO₂, thereby increasing the ocean's "carbon sink". This review explores two main mechanisms (i.e., enhanced weathering and ocean alkalinization) and materials (e.g., silicate rocks, metal oxides, and metal hydroxides) that regulate marine chemical carbon sink (MCCS). This work also compares MCCS with other terrestrial and marine carbon sinks and discusses the implementation of MCCS, including the following aspects: chemical reaction rate, cost, and possible ecological and environmental impacts.