Porous Carbon Catalyst Research Articles

Oxygen Reduction Reaction of Block Copolymer Template-Directed Porous Carbon Catalysts

Oxygen Reduction Reaction of Block Copolymer Template-Directed Porous Carbon Catalysts

Watermelon Peel‐Derived Nitrogen‐Doped Porous Carbon as a Superior Oxygen Reduction Electrocatalyst for Zinc‐Air Batteries

AbstractMetal‐free carbon materials derived from biomass wastes are considered as prospective electrocatalysts applied in the oxygen reduction reaction (ORR) field on account of their extremely low costs and good stabilities. Herein, we develop a watermelon peel‐derived nitrogen‐doped hierarchically porous carbon (N‐WPAC) catalyst by using a simple chemical method without additional templates. The N‐WPAC catalyst exhibits an excellent ORR activity and more outstanding durability than the commercial Pt/C catalyst. The superior ORR performances of N‐WPAC are mainly ascribed to its hierarchically porous carbon structure with abundant defects, which is beneficial to expose sufficient active sites and accelerate the mass‐transfer process. Moreover, the Zn‐air battery based on N‐WPAC displays eminent discharge performances, which are close to those of the Zn‐air battery based on Pt/C. This work broadens our horizon to design efficient ORR catalysts derived from biomass wastes by a facile and scalable approach.

Covalent organic frameworks-derived hierarchically porous N-doped carbon for 2,4-dichlorophenol degradation by activated persulfate: The dual role of graphitic N

A series of hierarchically porous carbon catalysts with high N content and large surface area were prepared via self-templated carbonization of covalent organic frameworks (COFs). The catalyst was used to activate persulfate (PS) for degrading 2,4-dichlorophenol (2,4-DCP). Experimental results demonstrated that the prepared catalyst treated at 700 °C (PNC-700) showed both strong adsorption ability and enhanced PS activity for 2,4-DCP degradation. A variety of characterization techniques were used to investigate the properties of prepared catalysts. We found that the graphitic N functional groups acted as both activity sites and electron transfer access. The activity of the catalyst was also closely related to the hierarchical pore structure and good electrical conductivity. The influencing factors of PNC-700/PS system in 2,4-DCP degradation were discussed. In addition, PNC-700 displayed excellent recyclability. The activation process especially non-radical pathway was promoted by increasing graphitic N contents. The possible reaction mechanism and degradation pathways were also proposed.

Facile fabrication of cobalt (Co) nanoparticles anchored magnetic porous carbon for efficient catalytic reduction of nitrophenols

The preparation of efficient, low-cost and easily recycled catalyst for the reduction of nitrophenol (NP) to corresponding aminophenol (AP) remains a challenge. Herein, we present a facile strategy for preparing cobalt nanoparticles anchored magnetic porous carbon (Co-MPC) catalyst, which involves first formation of Co(OH)2-crosslinked peach gum polysaccharide (Co(OH)2-PGP) gel and followed by carbonization treatment. As a natural macromolecule, PGP contains numerous oxygen-containing groups, which can interact Co2+ to form Co(OH)2-PGP gel. The resulted Co-MPC not only shows high catalytic activity for the reduction of diverse NPs to the corresponding APs, but also can be easily recovered by magnetic separation after catalytic reaction. Moreover, it also exhibits superior reusability. Even if it is reused for 5 times, it still maintains high catalytic activity. Considering the easy preparation process and superior catalytic performance of Co-MPC, this work provides a viable strategy for preparation of low-cost and high-performance catalysts from natural biomass.

One-pot green synthesis of Zero-Valent iron particles supported on N-Doped porous carbon for efficient removal of organic pollutants via Persulfate Activation: Low iron leaching and degradation mechanism

In this work, zero-valent iron particles supported on nitrogen doped porous carbon (Fe-NPC) was successfully prepared by a green and convenient one-pot method through pyrolysis. In Fe-NPC/PS system, 96.44% orange II (OGII) was almost removed within 35 min, which was much higher than NPC and Fe-PC of 53.27% and 54.67%, respectively. Factors influencing the degradation process of OGII were investigated, including PS concentration, catalyst dosage, initial pH and ions disturbance. The radical quenching studies, electron paramagnetic resonance (EPR) measurements and chronoamperometry experiments verified the degradation mechanism of OGII in Fe-NPC/PS system included both radical and non-radical pathways in which •HO and SO4-· were the dominant active radicals and electron transfer was involved. Fe-NPC exhibited excellent tolerance toward a wide pH conditions with only 88 µg/L iron leaching in initial pH of 3.1, which was much lower than literature reported. The low iron leaching of Fe-NPC was attributed to the protection of carbon matrix and doped nitrogen in catalyst. Moreover, the surface CO group of the catalyst contributed to better performance in alkaline system. Furthermore, the supported iron species introduced magnetism into the catalyst for easily separation. The Fe-NPC/PS system also exhibited high removal efficiencies for Congo red (CR), Reactive blue 19 (RB 19), 4-Nitrophenol (4-NP) and tetracycline (TC). These results provided a sight for economically and efficiently fabricating stable iron based nitrogen doped porous carbon catalyst for water contaminant degradation.

A telluride-doped porous carbon as highly efficient bifunctional catalyst for rechargeable Zn-air batteries

The development of high-efficiency, low-cost, and stable bifunctional catalysts towards oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is of great significance to the large-scale application of zinc–air batteries. Here we synthesized a telluride (Te)-doped porous carbon catalyst (ZnCo-Te@NC) through pyrolyzing ZnCo-MOF-coated Te nanotubes. The as-prepared ZnCo-Te@NC exhibited excellent bifunctional electrocatalytic performance with an impressive half-wave potential (E1/2) of 0.873 V for ORR and a low overpotential of 400 mV at 10 mA cm−2 for OER, outperforming most non-noble metal-based catalysts previously reported. When using ZnCo-Te@NC as the air cathode catalyst in a self-assembled battery, it demonstrated smaller charge-discharge voltage gap (0.932 V at 50 mA cm−2) and higher peak power density (259.7 mW cm−2) with robust long-term (100 h) cycle stability, surpassing the benchmark precious metal catalyst-based batteries. This is the first report that telluride has been doped into a highly graphitized porous carbon for use in zinc-air batteries. This work provides an effective strategy to develop high graphitized carbon materials by telluride modification to enhance the performance of bifunctional electrocatalysts for Zn–air batteries.

Simultaneous brine recovery and water depollution in highly saline leather industry wastewater using a united halophiles supported nano porous carbon catalyst

The united water depollution of organic compounds and simultaneous brine recovery from leather industry saline wastewater (soak liquor contains 4–5% NaCl) using halophiles immobilized carbon reactors are investigated in this study. Initially, three active halophilic organisms such as Serratia marcescenssp., Citrobacter freundiisp., and Salmonella typhimuriumsp., were screened from the NaCl-organics acclimatized leather industry deep soil. The halophilic organism's growth parameters such as incubation time, pH, and temperature, salinity, and substrate concentrations were optimized. The halophiles united carbon catalyst was used in fluidized bed reactor (FICCO) and packed bed reactor (CAACO). The FICCO and CAACO reactors used to recover the brine from soak liquor which is free from the organics such as amino acids, glycerol, fatty acids, glucosamine and glucuronic acid derived from the treatment of protein, lipids and mucopolysaccharides containing soak liquor depolluted by SOAR- En-NPAC reactors. The SEM and AFM images reinforced the halophiles integrated on the surface of carbon matrix. The maximum retention time of 6 h, for water depollution from the organic compounds achieved by FICCO reactor at highly saline medium and the COD, 98%; BOD, 95%; TOC, 92%; TN, 93%; TSS, 85% and 92% of VS eliminated using FICCO and CAACO reactors. The final treated wastewater evaporated under solar incubation and the recovered brine was characterized by the analytical techniques such as SEM, XRD and ICP-OES used to verify the purity.

Atomically dispersed iron atoms on nitrogen-doped porous carbon catalyst with high density and accessibility for oxygen reduction

• AD-Fe-NPC was successfully developed as oxygen reduction catalysts. • HAADF-STEM images confirmed the atomic dispersion of Fe on AD-Fe-NPC catalysts. • The optimized AD-Fe-NPC structure exhibited superior ORR activity to Pt/C. The development of high-performance, low-cost and high-stability oxygen reduction reaction (ORR) non-platinum catalysts has become one of the main research directions on fuel cells and metal-air batteries. Here, we developed porous carbon catalysts with atomically dispersed nitrogen coordinated iron atoms (Fe-N x ) as the active sites (AD-Fe-NPC) using Fe-doped ZIF-8 and 1,10-phenanthroline as precursors. The additional nitrogen coordinated sites from 1,10-phenanthroline, together with a special structure of ZIF-8 can suppress the agglomeration of Fe atoms, leading to isolated Fe atoms with high density on graphitic carbon during the pyrolysis. As a result, the sample prepared using 50 mg of 1,10-phenanthroline (AD-Fe-NPC-50) exhibited a high activity towards oxygen reduction with a half-wave potential of 0.91 V versus reversible hydrogen electrode in 0.1 M KOH, which is attributed to the high porosity (1011.2 m 2 g −1 ) and density of Fe-N x active sites (1.1 at%). Furthermore, as an air electrode in zinc-air batteries, the AD-Fe-NPC-50 demonstrated a maximum power density of about 201 mA cm −2 and a specific capacity of 782 mA h g Zn −1 at 10 mA cm −2 , which outperformed commercial Pt/C and many state-of-the-art non-precious metal catalysts.

Synthesis and application in oxygen reduction reaction of N-doping porous graphitic carbon from biomass waste

In order to enhance the corrosion resistance of carbon supported electrocatalyst under harsh operating conditions for Zn-air battery, a new type of 3D porous graphitic carbon catalysts are developed through catalytic graphitization of biomass waste combing with metal and nitrogen introduction. The obtained catalyst exhibits outstanding ORR (oxygen reduction reaction) performance by exhibiting same half-wave potential than that of commercial 20 wt% Pt/C in alkaline condition and higher current density, better stability, and better methanol tolerance. When assembled for rechargeable Zn-air batteries, the samples show a power density as high as 154 mW cm−2 with an excellent cycling stability greater than 90 h/270 cycles. A series of control experiments provide a new insight into the coupling role of porosity and the degree of graphitization in ORR catalytic process, that is, the balance of graphitization and porosity contributes to both high activity and good stability.

Green synthesis of nitrogen and fluorine co-doped porous carbons from sustainable coconut shells as an advanced synergistic electrocatalyst for oxygen reduction

Abstract Exploring a convenient and sustainable strategy to fabricate inexpensive and efficient electrocatalysts for oxygen reduction reaction (ORR) is one of the main challenges to achieve the goal of large-scale commercial application of fuel cells. Herein, an environmental and convenient strategy is presented to ingeniously fabricate nitrogen and fluorine co-doped porous carbon (NF-PC) catalyst using coconut shells as a green carbon source. In particular, the integration of N and F atoms into the coconut shells-derived carbon framework plays a significant role in boosting the ORR catalytic performance, since the synergistic catalysis introduced by the co-doping of N and F. Benefiting from the favorable characteristics of microporous conductive carbon framework, moderate N and F co-doping, as well as synergistic effect between N and F dopants, the developed NF-PC catalyst possesses remarkable catalytic activity, methanol resistance and cycle stability, even surpassing than that of commercial Pt/C. In addition to providing a promising metal-free ORR catalysts, most importantly, the sustainable and convenient strategy explored in this research offers great potential for commercial applications in fuel cells and other clean energy technologies.

A dual ligand coordination strategy for synthesizing drum-like Co, N co-doped porous carbon electrocatalyst towards superior oxygen reduction and zinc-air batteries

We herein propose a dual ligand coordination strategy for deriving puissant non-noble metal electrocatalysts to substitute valuable platinum (Pt)-based materials toward oxygen reduction reaction (ORR), a key reaction in metal-air batteries and fuel cells. In brief, cobalt ions are firstly double-coordinated with proportionate 2-methylimidazole (2-MeIm) and benzimidazole (BIm) to obtain drum-like zeolitic imidazolate frameworks (D-ZIFs), which are then carbonized to output the final Co, N co-doped porous carbon (Co–N–PCD) catalyst inheriting the drum-like morphology of D-ZIFs. The Co–N–PCD is featured by mesopores and exhibits superb electrocatalytic behavior for ORR. Impressively, the half-wave potential of Co–N–PCD catalysts is 0.886 V with finer methanol-tolerance and stability than those of commercial Pt/C. Additionally, a zinc-air battery assembled from the Co–N–PCD displays an open-circuit voltage of 1.413 V, comparable to that of commercial Pt/C (1.455 V), suggesting the potentials of Co–N–PCD in practical energy conversion devices.

Co/N-codoped porous carbons derived from poly(Schiff base)/Co(II) complex as ultrahighly efficient catalysts for CTH of nitroarenes

Herein we report the scalable synthesis of Co/N-codoped porous carbon (Co/N-C) catalysts by pyrolyzing poly(Schiff base)/Co(II) complex. The strong Co(II)-binding affinity of poly(Schiff base) leads to the formation of uniformly distributed Co(0) nanoparticles, Co-Nx species, and N–C configurations, in which their catalytic contributions are confirmed and estimated by ligand-poisoning and acid-etching experiments and the Co-Nx species has been proved to be highly active for catalytic transfer hydrogenation (CTH) reaction. Consequently, the as-prepared Co-N/C-950 catalyst exhibits an ultrahigh activity for the CTH of 4-nitrophenol (4-NP) with a TOF of 226 mol4-NP molCo−1 min−1 (13560 h−1) together with an excellent selectivity for CTH of challenging nitroarenes. Moreover, the Co(0) nanoparticles embedded in the Co-N/C-950 catalyst can be further transformed to Co4N phase by a facile nitridation reaction, yielding Co4N-N/C-950 catalyst with even higher activity for the CTH of 4-NP (TOF up to 310 mol4-NP molCo−1 min−1).

Waste pig blood-derived 2D Fe single-atom porous carbon as an efficient electrocatalyst for zinc–air batteries and AEMFCs

Biomass is a useful precursor for manufacturing electrocatalysts because it is highly abundant, eco-friendly, and is composed of organic materials that include Fe and nitrogen precursors. Among the numerous waste biomass types, slaughtered pig blood contains a high concentration of Fe-porphyrin inside the hemoglobin, and this characteristic makes it an ideal precursor for fabricating a bio-inspired Fe-N-C oxygen reduction reaction (ORR) catalyst. Here, Zinc (Zn)-hydrolysates are obtained from purified waste pig blood was used as a porous carbon source for two-dimensional (2D) sheet-like porous single-atom electrocatalysts. In addition, pig blood provides Fe single-atom catalytic sites derived from hemoglobin in (Zn)-hydrolysates and shows excellent ORR activity by retaining excellent mass transfer due to the presence of mesopores generated by Zn activation under NH3 pyrolysis Furthermore, one of the catalytic materials is a Zn-incorporated Fe single-atom porous carbon catalyst (designated Zn/FeSA-PC)/950/NH3, was successfully integrated as an Anion Exchange Membrane Fuel Cells (AEMFCs) and Zn‐Air Batteries (ZABs) where it supported maximum power densities of 352 and 220 mW/cm2, respectively. This study demonstrates the new designs and preparation procedures for high-performance electrocatalysts that can be manufactured at low cost from abundant and renewable blood biomass.

Effect of Na, Cu and Ru on metal-organic framework-derived porous carbon supported iron catalyst for Fischer-Tropsch synthesis

• Fe was highly dispersed on MIL-100(Fe) derived porous carbon with a high loading (>37 wt%). • XRD and HRTEM show particle size decrease for Na, Cu, and Ru-promoted catalysts. • Cu-promoted catalysts show a high CO conversion and a stable FT activity. • Na addition increased O/P ratio and C 5+ selectivity in product distribution. • Ru-promoted catalysts show a deactivation at high reaction temperature (340 °C). Fischer-Tropsch synthesis (FTS) is studied over Metal-organic framework (MOF) based porous carbon supported iron catalysts promoted with Na, Cu and Ru metals. The FTS results showed that all promoters can enhance CO conversion, FT product yield (FTY), and CO 2 selectivity is also increased. Among all promoters, Cu-based sample exhibits the best promoting effect in activity (FTY=0.154 mol CO g Fe −1 h − 1 ). Interestingly, the activity is about 2 times higher to that of unpromoted catalysts. Ru-contained sample exhibits the most significant influence on the light hydrocarbon production, with the C 1–4 hydrocarbon selectivity above 70%. Na-contained sample performed the highest C 5+ selectivity of 66% with a medium CO conversion of 51%. The improved FTS activity and selectivity of promoted catalysts is related to the decrease in iron particle size as confirmed by X-ray diffraction (XRD), and transmission electron microscopy (TEM). It is confirmed, the small iron particles of the promoted catalyst are stabilized on the surface of carbon matrix, preventing further aggregation at high temperature, which is contributed to the improved FTS performance. Our research study showed that Na, Cu and Ru can not only affect the distribution of resulting products but also improve the activity of FTS. In short, the effect of Cu is remarkable on the MOF-derived catalyst. Similarly, the MOF-derived porous carbon catalysts confined the iron species during the reaction process, provide a clear structure-activity relationship between the promoters and the catalytic performance. Finally, this novel work can provide a new pathway for metal-organic framework-derived Fe-embedded porous carbon catalysts for Fischer-Tropsch synthesis.

Extending synchrotron SAXS instrument ranges through addition of a portable, inexpensive USAXS module with vertical rotation axes.

Ultra-SAXS can enhance the capabilities of existing synchrotron SAXS/WAXS beamlines. A compact ultra-SAXS module has been developed, which extends the measurable q-range with 0.0015 ≤ q (nm-1) ≤ 0.2, allowing structural dimensions in the range 30 ≤ D (nm) ≤ 4000 to be probed in addition to the range covered by a high-end SAXS/WAXS instrument. By shifting the module components in and out on their respective motor stages, SAXS/WAXS measurements can be easily and rapidly interleaved with USAXS measurements. The use of vertical crystal rotation axes (horizontal diffraction) greatly simplifies the construction, at minimal cost to efficiency. In this paper, the design considerations, realization and synchrotron findings are presented. Measurements of silica spheres, an alumina membrane, and a porous carbon catalyst are provided as application examples.

Large-scale fabrication of biomass-derived N, S co-doped porous carbon with ultrahigh surface area for oxygen reduction

Low-cost biomass-derived carbon nanomaterials hold great promise as catalysts for the oxygen reduction reaction. Here, we have successfully prepared an N, S co-doped metal-free porous carbon catalyst through the synchronous pore-forming/doping technology. The thiourea plays dual roles as a porogen and dopant in the synthesis process. After coupling with thiourea, the successful doping of N and S elements in NSMP-I increase their defects, specific surface area, and pyridine nitrogen groups. These advantages result in a significant increase in the property of the catalyst. The ORR test result of NSMP-I shows that the four-electron transfer pathway is followed, and the onset potential and the half-wave potential are increased to 0.92 and 0.78 V vs. RHE, respectively. The result achieved may help contribute to provide a way and theoretical guidance for the sustainability and efficiency of agricultural and forestry waste resources.

Sn and N co-doped porous carbon catalyst electrochemically reduce CO2 into tunable syngas

Electrocatalytic CO2 reduction into syngas (CO and H2 mixture) is one of the most sustainable strategies for recycling CO2 into value-added products. In this study, a non-noble Sn, N co-doped porous carbon (Sn-NC) catalysts were prepared. The results show that the products of CO2 electroreduction on as-obtained Sn-NC catalysts are CO and H2, which would be a cheap, stable and efficient syngas production route. Notably, as-prepared Sn-NC exhibits a good activity at -0.6 V, with FECO of 63 % and FEH2 of 37 %. By adjusting the reduction potentials, the H2 / CO ratio of the generated syngas can be adjusted from 8.15 to 0.60. This work would be a good reference for production of tunable syngas from CO2 via low-cost catalysts.

A hierarchically ordered porous nitrogen-doped carbon catalyst with densely accessible Co-N active sites for efficient oxygen reduction reaction

Abstract Reasonable design and construction of efficient and stable catalysts with abundant metal-Nx active sites are the focus of oxygen reduction reaction (ORR) research. In this work, a type of catalyst with isolated single-atomic Co sites embedded in the ultra-thin pore walls of hierarchically ordered porous N-doped carbon (ISA-Co/HOPNC) by a simple single template pyrolysis strategy has been successfully synthesized. The interconnected macropores introduced by the silica colloidal crystal template (CCT) not only improve the mass transmission of molecules and ions to achieve the accessibility of internal Co-Nx active sites, but also promote the complete removal of inactive Co species nanoparticles (NPs) inside the catalyst. Removal of inactive Co species NPs that form mesopores in the ultra-thin walls of the macropores increases the specific surface area to expose more active sites. In comparison with the commercial 20 wt% Pt/C, the optimal ISA-Co/HOPNC-0.3 catalyst shows comparable ORR activity, but much higher methanol tolerance and cycle stability. The remarkable ORR performance of ISA-Co/HOPNC-0.3 can be attributed to the numerous exposed single-atomic Co-Nx active sites, as well as the high surface area and efficient mass transport from the 3D hierarchically ordered porous structure.

Fabrication of Porous N-rich Carbon Electrocatalysts from Pyrolysis of PANI-Encapsulated CeO2 for Enhanced Oxygen Reduction Reaction

The oxygen reduction reaction (ORR) is a crucial cathodic process and a technology providing renewable energy. It is essential to create ORR catalysts not containing noble metals yet still affordable and possessing high-efficiency and long-term durability. Therefore, this work developed a highly porous N-doped carbon catalyst embedded with CeO2 nanoparticles (NPs). This composite catalyst was synthesized by pyrolysis of PANI-encapsulated CeO2 NPs (CeO2/PANI) combined with in situ polymerization. The resulting catalyst exhibited an outstanding ORR performance with 0.94 and 0.81 mV onset and positive half-wave potentials, respectively, and 5.52 mA cm−2 diffusion-limited current density. The catalyst also demonstrated excellent stability. These exceptional characteristics indicate that a synergy of the N-doped carbon and CeO2 NPs provide a novel strategy of fabrication of novel ORR catalysts without using noble-metals for applications related to fuel cells and metal-air batteries.

Atomic metal, N, S co-doped 3D porous nano-carbons: Highly efficient catalysts for HT-PEMFC

A new strategy for fabricating atomically dispersed heteroatom-doped nanoporous carbon materials is reported. Through the self-assembly of dopamine, triblock copolymer F127, and metal ions, different three-dimensional atomic metal-N/S doped carbon catalysts are obtained after pyrolysis. Noble metal salts with ferrous sulfate induce the bimetallic monatomic FeM (M = Pd, Pt) N, S-doped carbon catalysts. Minute amounts of Pt or Pd single atoms in the catalysts greatly improve the oxygen reduction reaction (ORR) activity both in acidic and alkaline conditions. Typically, the obtained Fe, Pt–N/S co-doped carbon (FePt-NSC) catalyst exhibits superior ORR performance with positive half-wave potentials (E1/2) of 0.89 and 0.80 V in alkaline and acidic solutions, respectively. In addition, FePt-NSC displays dominant four electron catalytic process and excellent electrocatalytic stability. The high temperature proton exchange membrane fuel cell (HT-PEMFC) test (160 °C) illustrates that FePt-NSC reaches 0.67 V at 400 mA/cm2 and achieves the peak power density of 628 mW/cm2, better than most of the catalysts reported at the similar conditions. These results indicate the atomic metal-N/S doped porous carbon catalysts to be highly promising low-Pt catalysts for HT-PEMFC.