Carbon capture and sequestration from point sources is an important component in the CO2 emission mitigation portfolio. In particular, sorbents with both high capacity and selectivity are required for reducing the cost of carbon capture. Although physisorbents have the advantage of low energy consumption for regeneration, it remains a challenge to obtain both high capacity and sufficient CO2/N2 selectivity at the same time. Here, we report the controlled synthesis of a novel N-doped hierarchical carbon that exhibits record-high Henry’s law CO2/N2 selectivity among physisorptive carbons while having a high CO2 adsorption capacity. Specifically, our synthesis involves the rational design of a modified pyrrole molecule that can co-assemble with the soft Pluronic template via hydrogen bonding and electrostatic interactions to give rise to mesopores followed by carbonization. The low-temperature carbonization and activation processes allow for the development of ultrasmall pores (d < 0.5 nm) and preservation o...

Hierarchical N-Doped Carbon as CO2 Adsorbent with High CO2 Selectivity from Rationally Designed Polypyrrole Precursor.

Recent progress in advanced nanostructures synthesized from biomass resources for the oxygen reduction reaction (ORR) is reviewed. The ORR plays a significant role in the performance of numerous energy-conversion devices, including low-temperature hydrogen and alcohol fuel cells, microbial fuel cells, as well as metal-air batteries. The viability of such fuel cells is strongly related to the cost of the electrodes, especially the cathodic ORR electrocatalyst. Hence, inexpensive and abundant plant and animal biomass have become attractive options to obtain electrocatalysts upon conversion into active carbon. Bioresource selection and processing criteria are discussed in light of their influence on the physicochemical properties of the ORR nanostructures. The resulting electrocatalytic activity and durability are introduced and compared to those from conventional Pt/C-based electrocatalysts. These ORR catalysts are also active for oxygen or hydrogen evolution reactions.

Advanced Biomass-Derived Electrocatalysts for the Oxygen Reduction Reaction

Biomass derived porous carbon for CO2 capture

Nitrogen-doped porous carbons obtained from coconut shell by urea modification and KOH activation are found to exhibit very high CO2 uptake at 1 bar, almost 5 mmol g–1 at 25 °C and over 7 mmol g–1 at 0 °C, respectively. The high CO2 uptake of the sorbent can be ascribed to its high microporosity and nitrogen content. In addition, these sorbents possess high CO2/N2 selectivity, stable cyclic ability, high initial heat of CO2 adsorption, fast adsorption kinetics, and high dynamic CO2 capture capacity under simulated flue gas conditions. When combined with the low cost of the coconut-shell precursor, these properties make them exceptionally attractive sorbent candidates for CO2 capture.

Enhanced CO2 Capture Capacity of Nitrogen-Doped Biomass-Derived Porous Carbons

This study introduces a new, environmentally-friendly method to synthesize N,P-doped porous carbon by high conversion (46% yield) of coconut shell residues for the reduction of oxygen in alkaline media. The obtained materials display an excellent electrocatalytic activity, making them suitable as cathode catalyst for alkaline fuel cells. The synthesis procedure included an efficient single-step activation with phosphoric acid to achieve high surface area (1216 m 2  g −1 ) and pore volume (1.15 cm 3  g −1 with 72% mesopores). Urea was used as a low-cost and ecologically-sound source for nitrogen doping of the as-synthesized porous carbon. Remarkably, the biomass-derived electroactive carbon demonstrates a superior performance compared to a reference material, the state-of-the-art commercial Pt-C catalyst: (a) comparable electrocatalytic activity; (b) better tolerance to methanol crossover effects and, (c) improved long-term durability towards oxygen reduction reaction in alkaline media.

https://research.aalto.fi/files/14102192/Manuscript_AppCatB_Maryam_2017.pdf

Porous N,P-doped carbon from coconut shells with high electrocatalytic activity for oxygen reduction: Alternative to Pt-C for alkaline fuel cells

The objective of this research is to develop a cost-effective carbonaceous CO2 sorbent. Highly nanoporous N-doped carbons were synthesized with coconut shell by combining ammoxidation with KOH activation. The resultant carbons have characteristics of highly developed porosities and large nitrogen loadings. The prepared carbons exhibit high CO2 adsorption capacities of 3.44–4.26 and 4.77–6.52 mmol/g at 25 and 0 °C under atmospheric pressure, respectively. Specifically, the sample NC-650-1 prepared under very mild conditions (650 °C and KOH/precursor ratio of 1) shows the CO2 uptake 4.26 mmol/g at 25 °C, which is among the best of the known nitrogen-doped porous carbons. The high CO2 capture capacity of the sorbent can be attributed to its high microporosity and nitrogen content. In addition, the CO2/N2 selectivity of the sorbent is as high as 29, higher than that of many reported CO2 sorbents. Finally, this N-doped carbon exhibits CO2 heats of adsorption as high as 42 kJ/mol. The multiple advantages of the...

Highly Cost-Effective Nitrogen-Doped Porous Coconut Shell-Based CO2 Sorbent Synthesized by Combining Ammoxidation with KOH Activation.

The goal of our research is developing an efficient and cost-effective carbonaceous CO2 sorbent. Using petroleum coke as the precursor, porous nitrogen-doped carbons were prepared by combining ammoxidation with KOH activation. The as-synthesized samples possess highly developed microporosities and large nitrogen loadings. High CO2 adsorption capacities of 3.76–4.57 mmol/g at 25 °C and 5.80–6.62 mmol/g at 0 °C under atmospheric pressure were achieved. Specifically, the sample prepared under mild temperature (650 °C) and low KOH/precursor ratio (KOH/precursor = 2) shows a CO2 uptake of 4.57 mmol/g at 25 °C, among the highest achieved for nitrogen-doped porous carbons. This high CO2 capture capacity can be attributed to the synergistic effect of nitrogen doping and high narrow microporosity of the sorbent. However, experimental evidence suggests that nitrogen doping contributes less than narrow microporosity. Additionally, the CO2/N2 selectivity and CO2 heats of adsorption of the sorbent are as high as 22 an...

Adsorption of CO2 by Petroleum Coke Nitrogen-Doped Porous Carbons Synthesized by Combining Ammoxidation with KOH Activation

Tetraethylenepentamine modified protonated titanate nanotubes for CO2 capture

High-entropy oxides (HEOs) have gained great attention as an emerging kind of high-performance anode materials for lithium-ion batteries (LIBs) due to the entropy stabilization and multi-principal synergistic effect. Herein, the porous perovskite-type RE(Co0.2Cr0.2Fe0.2Mn0.2Ni0.2)O3 (RE=La, Sm and Gd) HEOs&nbsp; were successfully synthesized by a solution combustion synthesis method. Owing to the synergistic effect of lattice distortion and oxygen vacancies, the Gd(Co0.2Cr0.2Fe0.2Mn0.2Ni0.2)O3 electrode exhibits superior high-rate lithium-ion storage performance and excellent cycling stability. A reversible capacity of 403 mAh g-1 at a current rate of 0.2 A g -1 after 500 cycles, and a superior high-rate capacity of 394 mAh g-1 even at 1.0 A g -1 after 500 cycles are achieved. Meanwhile, Gd(Co0.2Cr0.2Fe0.2Mn0.2Ni0.2)O3 electrode also exhibits pronounced pseudo-capacitive behavior, contributing to additional capacity. By adjusting and balancing the lattice distortion and oxygen vacancies of the electrode materials, the lithium-ion storage performance can be further regulated.

https://www.sciopen.com/article_pdf/1645977020378128385.pdf

Jie Chen

Papers

Enhanced CO2 Capture Capacity of Nitrogen-Doped Biomass-Derived Porous Carbons

Highly Cost-Effective Nitrogen-Doped Porous Coconut Shell-Based CO2 Sorbent Synthesized by Combining Ammoxidation with KOH Activation.

Adsorption of CO2 by Petroleum Coke Nitrogen-Doped Porous Carbons Synthesized by Combining Ammoxidation with KOH Activation

Tetraethylenepentamine modified protonated titanate nanotubes for CO2 capture

Synergetic effect of lattice distortion and oxygen vacancies on high-rate lithium-ion storage in high-entropy perovskite oxide