Sustainable Carbon Materials toward Emerging Applications

It is desirable for a sustainable society that the production and utilization of renewable materials are net-zero in terms of carbon emissions. Carbon materials with emerging applications in CO₂ utilization, renewable energy storage and conversion, and biomedicine have attracted much attention both academically and industrially. However, the preparation process of some new carbon materials suffers from energy consumption and environmental pollution issues. Therefore, the development of low-cost, scalable, industrially and economically attractive, sustainable carbon material preparation methods are required. In this regard, the use of biomass and its derivatives as a precursor of carbon materials is a major feature of sustainability. Recent advances in the synthetic strategy of sustainable carbon materials and their emerging applications are summarized in this short review. Emphasis is made on the discussion of the original intentions and various sustainable strategies for producing sustainable carbon materials. This review provides basic insights and significant guidelines for the further design of sustainable carbon materials and their emerging applications in catalysis and the biomedical field.

Polyacrylamide hydrogel-derived three-dimensional hierarchical porous N,S co-doped carbon frameworks for electrochemical capacitors

Polyacrylamide hydrogel-derived 3D porous hierarchical N,S co-doped carbon frameworks are purposefully fabricated, and exhibit superior electrochemical capacitance in both alkaline and acidic electrolytes.

A biomass derived porous carbon for broadband and lightweight microwave absorption

With the continuous progress of science and technology, the traditional magnetic material is no longer able to meet the new complex electromagnetic (EM) environment due to its high bulk density. Therefore, the novel excellent EM absorber with the feature of thin thickness, low density, broad absorption bandwidth and strong absorption intensity is highly desired. Herein, we fabricated a porous carbon with ultrahigh porosity through a facile KOH activation from biomass waste pumpkin seed shell for lightweight EM wave absorption application. By optimizing the porous structures, the strong absorption intensity of -50.55 dB is achieved at thin thickness of 1.85 mm under low filler content of only 10 wt %. More interestingly, a broad frequency bandwidth of 7.4 GHz could cover the whole Ku band. These outstanding microwave absorption performances, couple with low cost ingredients and ease of fabrication process enable the porous carbon framework as the next generation promising candidate for lightweight and remarkable EM absorber.

Foxtail millet-derived highly fluorescent multi-heteroatom doped carbon quantum dots towards fluorescent inks and smart nanosensors for selective ion detection

Foxtail millet-derived highly fluorescent nitrogen/sulfur/phosphrous (N/S/P) co-doped CQDs were efficiently fabricated via a green strategy, and were found to hold potential towards fluorescent inks and smart detection.

Sustainable rose multiflora derived nitrogen/oxygen-enriched micro-/mesoporous carbon as a low-cost competitive electrode towards high-performance electrochemical supercapacitors

Cost-efficient carbonaceous materials have been utilized extensively for advanced electrochemical supercapacitors. However, modest gravimetric/volumetric capacitances are the insuperable bottleneck in their practical applications. Herein, we develop a simple yet scalable method to fabricate low-cost micro-/mesoporous N/O-enriched carbon (NOC-K) by using natural rose multiflora as a precursor with KOH activation. The biomass-derived NOC-K is endowed with a large surface area of ∼1646.7 m² g⁻¹, micro-/mesoporosity with ∼61.3% microporosity, high surface wettability, and a high content of N (∼1.2 at%)/O (∼26.7 at%) species. When evaluated as an electroactive material for supercapacitors, the NOC-K electrode (5 mg cm⁻²) yields large gravimetric/volumetric specific capacitances of ∼340.0 F g⁻¹ (∼238.0 F cm⁻³) at 0.5 A g⁻¹, and even ∼200.0 F g⁻¹ (∼140.0 F cm⁻³) at 5.0 A g⁻¹, a low capacitance decay of ∼4.2% after 8200 consecutive cycles, and a striking specific energy of ∼8.3 W h kg⁻¹ in aqueous KOH electrolyte, benefiting from its intrinsic structural and compositional superiorities. Moreover, a remarkable specific energy of ∼52.6 W h kg⁻¹ and ∼96.6% capacitance retention over 6500 cycles for the NOC-K based symmetric cell are obtained with the organic electrolyte. More promisingly, the competitive NOC-K demonstrates enormous potential towards advanced supercapacitors both with aqueous and organic electrolytes as a sustainable electrode candidate.

Hierarchical micro-/mesoporous N/O-enriched carbon was scalably fabricated, and exhibited high gravimetric/volumetric capacitances, a large energy density and long-term cycling stability for supercapacitors with aqueous and organic electrolytes.

Hierarchical Micro/Mesoporous Carbons Synthesized with a ZnO Template and Petroleum Pitch via a Solvent-Free Process for a High-Performance Supercapacitor

Hierarchical micro/mesoporous carbons were prepared using ZnO nanoparticles as hard templates and a petroleum industrial-residual pitch as the carbon source via a solvent-free process. The ZnO templates can be easily removed using HCl(aq), thereby avoiding limitations present in conventional porous silica templating approaches that require highly corrosive HF(aq) for template removal. Notably, the proposed solvent-free synthetic method from low-cost pitch to high-value porous carbons is a friendly process with respect to our overexploited environment. With the combination of ZnO nanoparticles and pitch, the surface area (76-548 m² g^-1) of the resultant mesoporous carbons increases with an increase in the weight ratios of ZnO to pitch. Furthermore, the hierarchical micro/mesoporous carbons with a large surface area (854-1979 m² g^-1) can be feasibly fabricated by only adding an appropriate amount of an activating agent. Meanwhile, N-doped hierarchical porous carbons can be achieved by carbonizing the blend of these materials with melamine. For supercapacitor application, the resultant carbons exhibit a high capacitance up to 200.5 F g^-1 at 5 mV s^-1 using LiClO₄/PC as the electrolyte in a symmetrical two-electrode cell. More importantly, the coin-cell supercapacitor based on porous carbons achieved a capacitance of 94 F g^-1 at 5 mV s^-1 and 63% capacitance retention at 500 mV s^-1, thereby holding the potential for commercialization.

Porous high specific surface area-activated carbon with co-doping N, S and P for high-performance supercapacitors

Porous high specific surface area activated carbon with co-doping N, S and P for high-performance supercapacitors.