Institutional Repository of GuangZhou Institute of Energy Conversion, CAS
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Molecular insight into the dual effect of salts: Promoting or inhibiting the nucleation and growth of carbon dioxide clathrate hydrates
No full textFacing the huge gap between the growing CO2 emissions and net-zero emissions target to mitigate global warming, the long-term storage of excess CO2 becomes an intractable issue. Sequestering CO2 in the oceans as clathrate hydrates is a promising solution. Many unanswered questions still exist at the molecular level regarding how ions in seawater kinetically affect the formation of CO2 hydrates, particularly the dual effect: as the concentration rises, salt ions shift from being a promoter of hydrate formation to becoming an inhibitor. Herein, we report the homogeneous nucleation process of CO2 hydrates in saline solutions via molecular dynamics simulations. Consistent with experimental findings, our results show that nucleation is promoted within certain salt concentration ranges; however, the evidence suggests that ions do not act as nucleation sites. Multiple ion-induced variations in the aqueous phase are analyzed, including changes in the mobility, structure, and CO2 solubility. We find that the presence of ions strengthens the hydrophobic interactions among the dissolved CO2 molecules, which are associated with the salting-out phenomenon, accounting for the promoting effect of salts at low concentrations. However, as the salt concentration increases, this advantage is offset, leading to the inhibiting effect at high salt concentrations. We demonstrate that anions are inevitably involved in the construction of the solid hydrate phase. Their presence disrupts the native tetrahedral connectivity of water molecules and imparts negative charges to the solid phase, thereby attracting cations. In addition to advancing our understanding of the intricate interactions among water, guest, and additive molecules to germinate ordered solid structures, these findings can accelerate the development and utilization of sustainable hydrate-based applications
Advances in porous carbon materials for a sustainable future: A review
No full textDeveloping clean and renewable energy sources is key to a sustainable future. For human society to progress sustainably, environmentally friendly energy conversion and storage technologies are critical. The use of nanostructured advanced functional materials heavily influences the functionality of these systems. Porous carbons are multifunctional materials boasting considerable industrial utility. They possess many remarkable physiochemical and mechanical characteristics which have garnered interest in various fields. In this review, the application of porous carbon materials in electrocatalysis (HER, OER, ORR, NARR, and CO2RR) 2 RR) and rechargeable batteries (LIBs, Li-S - S batteries, NIBs, and KIBs) for renewable energy conversion and storage are discussed. The suitability of porous carbon materials for these applications is discussed, and some recent works are reviewed. Finally, a few viewpoints on developing porous carbons in electrocatalysis and rechargeable batteries are given. This review aims to generate interest in current and upcoming researchers in porous carbon application for a sustainable future
Innovative iron-manganese modified microalgae biochar for efficient phosphate iron removal from water: Preparation and adsorption mechanisms
No full textThis study developed a novel FeMn composite biochar (FMBC) with the pyrolysis raw resource of Chlorella, applying for phosphates removal from the aqueous. Under optimal conditions, the FMBC prepared from microalgae achieved a phosphate removal rate of approximately 91.6 % (adsorption capacity: 23.23 mg/g) within 120 min, demonstrating superior adsorption performance compared to the pristine biochar. Response Surface Methodology (RSM) was applied for FMBC preparation optimization. To improve the metal loading capacity of biochar, Ethylene Diamine Tetraacetic Acid (EDTA) was used as a chelating agent during the preparation process. The optimum preparation conditions for FMBC were Fe/biomass(w/w) ratio of 1.25, Mn/biomass(w/w) ratio of 1.10, pyrolysis time of 120 min, and pyrolysis temperature of 650 degrees C, which presented a large specific surface area (14.681 m(2)/g), pore volume (0.036 cm(3)/g) with the rich oxygen-containing functional groups. Phosphorus removal kinetic and isotherm process were better described by pseudo-second-order model and the Dubinin-Radushkevinch (D-R) isotherm. In addition, the optimal adsorption conditions for FMBC were as follows: biochar dosage of 0.1 g, initial pH of 7.0, adsorption temperature of 25 degrees C, and initial phosphate concentration of 50 mg/L. Physical adsorption, surface complexation, precipitation, electrostatic attractions, and ion exchange were responsible for phosphate adsorption process by FMBC. The main innovation of this study is the use of explosive growth algae to prepare metal-modified biochar for phosphorus removal from water bodies, to realize the goals of resource utilization of waste biomass and eutrophication control in water, which are significant for sustainable development
Facile synthesis of MOF-derived carbon-supported LaZn@C nanocomposite as an efficient electrode material for supercapacitor
No full textMOF-derived transition metal alloys have attracted researcher's interest in energy storage devices due to their vast surface area, high porosity, adjustable pore sizes, ease of modification, abundant active sites, and 3D tunable structure. Metal alloys covered with carbon can stabilize conductivity and ease charge accumulation, and they are suitable candidates for electrode materials for supercapacitor application. In this research article, core-shell LaZn@C nanocomposites were fabricated at different pyrolysis times via a hydrothermal approach. The materials that pyrolysis for two hours have a remarkable specific capacitance of 1024 Fg(- 1) at 1 Ag- 1 and an impressive energy density of 36.9 Whkg(-1). In addition, it has lower Rp similar to 0.8 Omega and Rs similar to 0.2 Omega resistance due to the large surface area's high carbon content with cylindrical particles. Moreover, it shows an outstanding retention rate of (94.5 % over 4500 cycles at 1 Ag- 1). Finally, this research showed the novelty of advanced MOF-derived materials that suggest an efficient electrode material for the electrochemical performance of energy storage devices and supercapacitor applications
Ionic double-shell magnetic covalent organic framework for sharp and fast adsorption of critical metals
No full textThe recovery of critical metals (CMs) from waste streams has garnered increasing attention in recent years due to their increased demand, engineering applications, and vulnerability to supply disruptions. Herein, we synthesize two novel ionic materials, namely GIEC(704a) (magnetic covalent organic framework consisting of Fe3O4/TAGH-Dha) and GIEC(704b) (double-shell magnetic material formed of Fe3O4/TAGH-Dha/TpPa) using the solvothermal method for the recovery of CMs. The experimental data supported Langmuir's isotherm model, and the results showed that both GIEC(704a) and GIEC(704b) exhibited remarkable adsorption capacities (q(max)). GIEC(704a) exhibited adsorption capacities of 1531.8, 884.9, and 729.9 mg/g, while GIEC(704b) had 1681.5, 854.7, and 800 mg/g (Al3+, Fe3+ and Cu2+) capacities, respectively. Furthermore, GIEC(704a) and GIEC(704b) demonstrated approximately 80 % adsorption of REEs with high adsorption capacities of 53.6, 52.3, 41.2 mg/g and 55.3, 55.4, and 43.4 mg/g (Lanthanum, Yttrium, and Neodymium), respectively with excellent selectivity. The large surface areas of GIEC(704a) and GIEC(704b)-147.9 m(2)/g and 2143.1 m(2)/g, respectively-explain their excellent performance. The results of the kinetic study support the pseudo-second-order model with a high coefficient of (R-2 = 0.9999), and an efficiency of over 90 % was achieved within 5 min. The findings of the thermodynamic analysis indicated that the adsorption process was spontaneous and endothermic. Furthermore, the outstanding reusability of GIEC(704a) and GIEC(704b) confirmed their suitability for environmental chemical engineering and industrial applications
Synthesis of ultra-low freezing point alkane by self-aldol condensation of n-butyraldehyde over MgO-SiO<sub>2</sub>catalyst followed by hydrodeoxygenation over Pd/C and HZSM-5 catalyst
No full textProduction of jet fuel is not only promising but challenging in the field of biomass utilization. Here we proposed a novel route to produce highly branched alkanes with ultra-low freezing point using n-butyraldehyde as feedstock by self-aldol condensation and subsequent hydrodeoxygenation (HDO). The catalyst characterization revealed that the MgO-SiO2 catalyst played an acid-base synergetic effect role in the self-aldol condensation of n-butyraldehyde using n-butanol as solvent, which obtained C8 oxygenate and C12 oxygenate with yield of 69.3 % and 26.8 % respectively. The medium Br & oslash;nsted base site of the catalyst captured alpha-H to promote the formation of enolate from n-butyraldehyde, and the Lewis acid sites promoted the dehydration of intermediate products. DFT simulation showed that n-butanol activated alpha-C in enolate in aldol condensation, and deactivated the oxygen atoms in enolate by hydrogen bonds to inhibit side reactions. Finally, the obtained condensation products were subjected to HDO reaction over the 5 wt% Pd/C and HZSM-5 catalysts, obtaining the highly branched alkanes with an ultra-low freezing point of -120.7 degrees C for C8 alkane and -78.7 degrees C for C12 alkane suitable for bio-jet fuels
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