Sites For Catalytic Reaction Research Articles

A theoretical study of the twinned ZnO nanostructures

Zinc oxide (ZnO) based nanomaterials are widely used as heterogeneous catalysts. Particularly, the twinned ZnO nanomaterials have been shown to exhibit unique catalytic activities. In this work, we constructed the atomic models of three possible twinned ZnO nanostructures with different types of twinning boundaries and surface terminations (Zn-Zn-, O-O- and O-Zn-terminated). Theoretical simulations aided by evolutionary algorithm showed that the O-Zn-terminated “polar” nanostructure owns the highest stability, which is attributed to the saturated coordination numbers of the Zn and O atoms in the twinning boundary. Furthermore, structural and electronic calculations indicated that the total energies of the twinned ZnO nanostructures depend on both the surface and twinning boundary energetics, and the latter can play a more important role. From the calculated structures, we also found that the Zn-terminated surfaces of all the twinned structures can expose metallic-like Zn dimers which has the bond distance of ∼ 2.44 Å only, which may act as the active sites for catalytic reactions.

Layer-structure adjustable MoS2 catalysts for the slurry-phase hydrogenation of polycyclic aromatic hydrocarbons

Slurry-phase hydrogenation technology is the frontier topic in the efficient conversion of heavy oils into light fractions around the world. Developing highly active dispersed MoS2 catalysts is the major obstacle to realize the industrial application of upgrading heavy oils. In this work, both top-down ball-milling method and bottom-up hydrothermal method were designed to synthesize MoS2 catalysts with controllable layer structures. The stacking layers and lateral sizes for micro-scaled MoS2 catalysts by ball-milling method can be reduced to their limits and stabilize at 6 ∼ 8 layers and lateral size of ca. 30 nm. The more flexible bottom-up hydrothermal method can construct MoS2 catalysts with much smaller lateral sizes and fewer stacking layers, especially, MoS2 catalyst fabricated with ammonium tetrathiomolybdate as Mo and S precursor possesses average stacking layers of 2 and lateral size of 5 ∼ 10 nm. Polycyclic aromatic hydrocarbons anthracene, phenanthrene and naphthalene were used as model compounds of heavy oils to investigate the catalytic hydrogenation performance of designed MoS2 catalysts. The catalytic activities of MoS2 catalysts can be well correlated with their stacking layers and lateral size. The edges of top and bottom S-Mo-S atomic layers for MoS2 sheets, named rim sites, are positively correlated with the exposure of active sites for catalytic hydrogenation of PAHs. The highest catalytic activity of MoS2 catalyst results from its layer structures of 100% rim sites and the smallest lateral size of 5 ∼ 10 nm, which is beneficial to expose maximum active sites for catalytic hydrogenation reactions. This work can guide us to design the highly active hydrogenation catalysts, and promote the industrial application of upgrading heavy oils.

Enhancing Effect of Fe2+ Doping of Ni/NiO Nanocomposite Films on Catalytic Hydrogen Generation.

Highly active and stable non-noble metal catalysts are expected to play a critical role in future hydrogen storage and conversion applications. The design of active sites with composite oxides provides a new approach for developing high-performance catalysts. In this study, an Fe-doped Ni/NiO nanocomposite film was constructed on an ionic liquid/water interface to promote hydrogen generation. The optimized Ni/FeNiOx-25 catalyst showed excellent catalytic activity toward ammonia borane hydrolysis, with a turnover frequency of 72.3 min-1. The enhancing effect of Fe2+ doping on Ni/NiO films was confirmed by the improved intrinsic activity and theoretical simulations. Fe ion doping stabilized NiO and prevented NiO from becoming Ni. The interfacial Ni-Fe2+ dual active sites on the FeNiOx and Ni interfaces participated in the targeted adsorption and effective activation of water and NH3BH3 molecules, respectively. The sufficiently exposed plane surface of the nanofilms provided abundant active sites for catalytic reactions. This significant advance will inspire development in the ambient liquid hydrogen storage field.

Structural and biochemical characterization of the Clostridium perfringens-specific Zn2+-dependent amidase endolysin, Psa, catalytic domain

Phage-derived endolysins, enzymes that degrade peptidoglycans, have the potential to serve as alternative antimicrobial agents. Psa, which was identified as an endolysin encoded in the genome of Clostridium perfringens st13, was shown to specifically lyse C. perfringens. Psa has an N-terminal catalytic domain that is homologous to the Amidase_2 domain (PF01510), and a novel C-terminal cell wall-binding domain. Here, we determined the X-ray structure of the Psa catalytic domain (Psa-CD) at 1.65 Å resolution. Psa-CD has a typical Amidase_2 domain structure, consisting of a spherical structure with a central β-sheet surrounded by two α-helix groups. Furthermore, there is a Zn2+ at the center of Psa-CD catalytic reaction site, as well as a unique T-shaped substrate-binding groove consisting of two grooves on the molecule surface. We performed modeling study of the enzyme/substrate complex along with a mutational analysis, and demonstrated that the structure of the substrate-binding groove is closely related to the amidase activity. Furthermore, we proposed a Zn2+-mediated catalytic reaction mechanism for the Amidase_2 family, in which tyrosine constitutes part of the catalytic reaction site.

Colorimetric determination of phenolic compounds using peroxidase mimics based on biomolecule-free hybrid nanoflowers consisting of graphitic carbon nitride and copper.

Hybrid nanoflowers consisting of graphitic carbon nitride (GCN) and copper were successfully constructed without the involvement of any biomolecule, by simply mixing them at room temperature to induce proper self-assembly to achieve a flower-like morphology. The resulting biomolecule-free GCN-copper hybrid nanoflowers (GCN-Cu NFs) exhibited an apparent peroxidase-mimicking activity, possibly owing to the synergistic effect from the coordination of GCN and copper, as well as their large surface area, which increased the number of catalytic reaction sites. The peroxidase-mimicking GCN-Cu NFs were then employed in the colorimetric determination of selected phenolic compounds hydroquinone (HQ), methylhydroquinone (MHQ), and catechol (CC). For samples without phenolic compounds, GCN-Cu NFs catalyzed the oxidation of the peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2, producing an intense blue color signal. Conversely, in the presence of phenolic compounds, the oxidation of TMB was inhibited, resulting in a significant reduction ofthe color signal. Using this strategy, HQ, MHQ, and CC were selectively and sensitively determined in a linear range up to 100μM with detection limits down to 0.82, 0.27, and 0.36μM, respectively. The practical utility of this assay system was also validated by using it to detect phenolic compounds spiked in tap water, yielding a good recovery of 97.1-108.9% and coefficient of variation below 3.0%, demonstrating the excellent reliability and reproducibility of this strategy. Colorimetric determination of phenolic compounds using peroxidase mimics based on biomolecule-free hybrid nanoflowers consisting of graphitic carbon nitride and copper.

Study on the Mechanism of Selective Catalytic Reduction of NOx by NH3 over Mn-Doped CoCr2O4

In this paper, the first-principles calculation method based on density functional theory is used to calculate the structure of CoCr2O4 and Mn-doped Mn0.1Co0.9Cr2O4 low-refractive-index surface (100) and the adsorption model of NH3 and other molecules. Moreover, the process of the NOx removal reaction with NH3 was studied in detail. The results showed that the adsorption energy of NH3 and the amount of Mulliken charge transfer increased after Mn doping. The projected density of states indicates that the interactions between the adsorbed molecule and the substrate are stronger. It is worth noting that the doped Mn sites are also favorable sites for catalytic reactions. Based on the calculation results, we know that NH3 molecules are easily adsorbed on the surface of the catalyst and then dehydrogenated to produce NH2, NH, and other products. The next major step is the reaction of NH2 with gaseous NO to form an intermediate product of NH2NO, which is then decomposed into N2 and H2O. However, the route of N2O as an intermediate is energetically infeasible. Among them, NH3 dehydrogenation is a rate-determining step, and the activation energy barrier is 1.01 eV. However, under aerobic conditions, the activation energy barrier (0.71 eV) from NH3 to NH2 is significantly reduced. In addition, the adsorbed NO reacts with the active O atoms to generate NO2 on the surface, and NO2 can undergo a “fast selective catalytic reduction” process. To sum up, doping manganese on the surface of the CoCr2O4 catalyst can improve the catalytic activity of denitration, and the Mn0.1Co0.9Cr2O4 catalyst has a good selectivity.

Fabrication of trimodal porous silica/g-C[formula omitted]N[formula omitted] nanotubes for efficient visible light photocatalytic reduction of CO[formula omitted] to ethanol

The novel composite photocatalyst of trimodal porous silica (TPS)/g-C3N4 nanotubes was fabricated via a two-step hydrothermal synthesis method with intermediate pretreatment. The TPS was extracted from rice husk, which is agricultural waste, to further reduce the cost of photocatalyst preparation. A series of characterization results, including X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, N2 adsorption–desorption, and pore size analysis, illustrated the properties of crystal, pore structure, and morphology of the composite photocatalyst. The TPS/g-C3N4 presented a hollow tubular shape with a large surface area and CO2 adsorption capacity, so there were more catalytic active reaction sites. The photocatalytic activity measurement was operated, and only ethanol was detected when g-C3N4 NT and composite TGNT were used as photocatalysts. In particular, the ethanol yield of TGNT2 was 196μm/g, and after 10 cycles of running, the photocatalytic activity decreased by less than 5%. UV–Vis diffuse reflectance spectra, photoluminescence spectra, and photoelectrochemical analysis revealed the mechanism of the photocatalytic activity enhancement from the aspects of visible light absorption, photo-generated electron–hole pair separation and transfer, and charges recombination. It theoretically explained the prospect of this fabrication strategy. It demonstrated that TGNT is a low-cost, stable, efficient, and promising photocatalyst to reduce CO2 to ethanol under visible light.

In-situ reconstruction of non-noble multi-metal core-shell oxyfluorides for water oxidation

The electrochemical anodic behavior of transition metal compounds plays an undeniably non-negligible role across many electrooxidation reactions. In this work, a chronopotentiometric technique was employed to activate the multicomponent non-noble metal oxyfluorides in-situ for oxygen evolution reaction (OER). It is interesting to unravel that the increasing applied current density helps to reconstruct the catalyst into nanoporous core–shell structure and introduce metal oxyhydroxide on the surface, which guarantees more channels for efficient ion/mass transportation and thus contributes to exposing more active sites for catalytic reaction. The activated five-membered oxyfluoride shows the best catalytic activity with overpotential of 348 ± 2 mV to achieve the current density of 10 mA/cm2 and a Tafel slope of 110.3 ± 0.1 mV/dec, in contrast with the pristine one (532 ± 2 mV & 240.2 ± 0.1 mV/dec). It still maintains high stability after long time OER measurement, making it a promising succedaneum for noble metal catalysts. The high-entropy effect, amorphous state and high active sites density jointly contribute to its enhanced OER performance. This work provides new ideas for realizing the potential of inactive elements via entropy engineering and using electrochemical self-reconstruction to modify semiconductors for advanced water oxidation.

Active site synergy of the mixed-phase cobalt diselenides with slight lattice distortion for highly reversible and stable lithium oxygen batteries

Many non-precious metal-based catalysts with high intrinsic activity for catalytic reactions are prone to structural degradation in practical application, which leads to poor stability. In this work, we propose c-CoSe2/o-CoSe2 as the oxygen electrode of lithium-oxygen batteries (LOBs) to improve its cycle stability. The heterogeneous interface inside c-CoSe2/o-CoSe2 leads to an increase in the covalence bonds between Co and Se ions, which greatly enhances the robustness of the crystal lattice, thereby improving the stability of the catalyst. In addition, the strong interaction between the mixed phases is favorable for adjusting the electron density around the active sites and boosting oxygen electrode kinetics. Moreover, the epitaxial growth of o-CoSe2 on c-CoSe2 will cause abundant heterogeneous interfaces and slight lattice distortion along the interfaces, thereby providing sufficient catalytic reaction sites. The DFT calculation results show that the optimized adsorption of intermediates at the heterogeneous interface plays an important role in boosting oxygen electrode reactions and improving the electrochemical performance of LOBs. The experimental results show that LOBs with the c-CoSe2/o-CoSe2 electrodes exhibit outstanding performance, including large specific capacity of about 23,878 mA h g − 1, high coulombic efficiency of up to 93.66%, and excellent stability of over 176 cycles (1410 h).

Screen-printed analytical strip constructed with bacteria-templated porous N-doped carbon nanorods/Au nanoparticles for sensitive electrochemical detection of dopamine molecules

Dopamine (DA) as an important neurotransmitter plays an important role in physiological activities, and its abnormal level can cause diseases such as Parkinson's disease. However, the clinical analysis of DA mainly relies on time-consuming and expensive liquid chromatography and molecular spectrometer. We present here a design and fabrication of inexpensive strip sensor constructed from screen printed electrodes for sensitive and selective detection of DA. The ink used for printing the strips contains Shewanella putrefaciens-templated porous N-doped carbon nanorods (N-doped CN) and Au nanoparticles (Au NPs), in which the N-doping enhances CN's negative charge to electrostatically attract the positively charged DA with strong adsorption for achieving fast electron transfer. Moreover, results indicate that the Au NPs impregnation in N-doped CN renders much more catalytic reaction sites toward DA oxidation current. The strip sensor exhibits high sensitivity for DA detection with a broad linear range of 0.02–700 μM and a low detection limit of 0.007 μM as well as good selectivity and superior flexibility for great potential in wearable applications. The strip sensor further performs an accurate detection of DA in human serum, providing a powerful analytical tool for diagnosis of DA related diseases in clinical analysis.

Promotional effect of surface treated N-TiO2 as support for VOx-based catalysts on the selective catalytic reduction of NO using NH3

Selective catalytic reduction (SCR) catalysts, which are widely used to mitigate rising nitrogen oxide (NOx) pollution originating from fine dust, are associated with issues such as a limited operating temperature range and the demand for a higher NOx conversion efficiency. Specifically, to increase NOx conversion efficiency, increasing catalytic reaction sites by improving specific surface area (SSA) and dispersing catalytic active particles across the catalyst are of great significance. When active materials have low dispersibility, their activity is lowered owing to aggregation and crystallisation as the catalytic material content increases. To address this issue, it is necessary to realize the dispersion of active materials, while ensuring that no aggregation via the surface occurs. In this study, we investigated the use of N-doped TiO2 (N-TiO2) to disperse the active particles. Approximately 17 at.% N-doped was into the TiO2 support. The results obtained showed that the addition of these supports resulted in the even dispersion of the active materials on the catalyst surface, yielding abundant anchoring sites, which improved SSA, as confirmed by the transmission electron microscopy analysis of the textural properties of the catalysts. Further, these catalysts exhibited high catalytic activity over a wide temperature range (200–400 °C).

Enhanced Photo–Fenton Removal Efficiency with Core-Shell Magnetic Resin Catalyst for Textile Dyeing Wastewater Treatment

Heterogeneous photo–Fenton reactions have been regarded as important technologies for the treatment of textile dyeing wastewaters. In this work, an efficient core-shell magnetic anion exchange resin (MAER) was prepared through in situ polymerization and used to remove reactive brilliant red (X-3B) in a UV–Fenton system. The MAER exhibited satisfactory removal efficiency for X-3B because of its highly effective catalytic activity. More than 99% of the X-3B (50 mg/L) was removed within 20 min in the UV–Fenton reaction. This is because the uniformly dispersed core-shell magnetic microsphere resin could suppress the aggregation of Fe3O4 nanoparticles and, thus, enhance the exposure of Fe reaction sites for catalytic reaction with H2O2. The good adsorption capacity of MAER also played an important role in promoting contact between X-3B and reactive radicals during the reaction. Mechanism research showed that hydroxyl radical (•OH) was the main reactive radicals for the removal of X-3B in the MAER UV–Fenton system. The MAER can be easily separated by a magnet after catalytic reactions. Moreover, the matrix effects of different substrates (Cl−, NO3−, SO42−, and humic acid) were investigated. The results showed that SO42− could be beneficial to improve the removal of X-3B but that the others decrease the removal. The MAER UV–Fenton also removed significant amounts of total organic carbon (TOC) for the X-3B solution and an actual textile dyeing industrial wastewater. The heterogeneous oxidation system established in this work may suggest prospects for practical applications in the treatment of textile dyeing wastewater.

Co-Ni alloy nanoparticles supported by carbon nanofibers for hydrogen evolution reaction

Abstract Alloying, a general strategy to improve the electrocatalytic performance of non-precious metal catalysts. Herein, we adopt a simple method to in-situ grow a cobalt-nickel alloy on a three-dimensional network of N-doped carbon fibers that put spatial restriction to the alloy particles, making the size smaller and uniformly distributed. The electronic synergy between nickel and cobalt and the confinement effect of in-situ growth can make Co-Ni/NCNFs provide more feasible reaction sites for catalytic hydrogen evolution reaction. Simultaneously, the formation of cobalt-nickel alloys inhibits the generation of oxides during the synthesis process, so as to promote the quality of alloys with better activity. Co-Ni/NCNFs exhibits excellent electrocatalytic properties with only 61 mV overpotential and 152.3 dec−1 at 10 mA cm−2 current density and excellent long-term stability due to the in-situ growth approach. This research also provides a feasible method for designing self-supporting alloy catalysts by in-situ growth.

Pt Nanoparticles Confined by Zirconium Metal-Organic Frameworks with Enhanced Enzyme-like Activity for Glucose Detection.

Metal nanozymes hold promise for chemical and biological applications, and their implementation relies on high catalytic efficiency and stability. Using the metal–organic framework as an ideal carrier for well-dispersed ultra-small metal nanoparticles (NPs) is beneficial for improving the catalytic efficiency of nanozymes. In this study, a zirconium-based metal organic framework (UiO-66) with good chemical stability and high porosity was synthesized and used to construct Pt/UiO-66 nanocomposites. The percentage of Pt in UiO-66 can be tuned easily by adjusting the feeding amount of PtCl42–. Because of the confinement effect of mesopores, the Pt particles with an average diameter of 3.8 nm are formed and dispersed throughout the pores of the UiO-66 particle. The Pt/UiO-66 composites show efficient oxidase- and peroxidase-like activity. Both the oxidase- and peroxidase-like activities are dependent on the Pt percentage. Pt/UiO-66-6% exhibits enhanced peroxidase-like activity, ∼3.9 times higher than that of commercial Pt/C with 10 wt % Pt. We propose that the construction of Pt/UiO-66 increased the utilization efficiency and stability of Pt NPs and provided more active sites for catalytic reactions. Using the peroxidase-like activity of Pt/UiO-66, a colorimetric method that can be used for actual blood glucose detection was developed for the specific detection of glucose with a limit of detection of 0.033 mM.

Active Site Engineering on Two-Dimensional-Layered Transition Metal Dichalcogenides for Electrochemical Energy Applications: A Mini-Review

Two-dimensional-layered transition metal dichalcogenides (2D-layered TMDs) are a chemically diverse class of compounds having variable band gaps and remarkable electrochemical properties, which make them potential materials for applications in the field of electrochemical energy. To date, 2D-layered TMDs have been wildly used in water-splitting systems, dye-sensitized solar cells, supercapacitors, and some catalysis systems, etc., and the pertinent devices exhibit good performances. However, several reports have also indicated that the active sites for catalytic reaction are mainly located on the edge sites of 2D-layered TMDs, and their basal plane shows poor activity toward catalysis reaction. Accordingly, many studies have reported various approaches, namely active-site engineering, to address this issue, including plasma treatment, edge site formation, heteroatom-doping, nano-sized TMD pieces, highly curved structures, and surface modification via nano-sized catalyst decoration, etc. In this article, we provide a short review for the active-site engineering on 2D-layered TMDs and their applications in electrochemical energy. Finally, the future perspectives for 2D-layered TMD catalysts will also be briefly discussed.

Unexpected Facet-Selective TiO2 Surface Modification and Photoelectrochemical Property

Interface of the Group X metal oxides and TiO2 nanostructure has been examined regarding the photoelectrochemical water splitting reaction. Deposition of NiO-only nanoparticles covered the rutile (110) side of TiO2 nanostructure. However, application of the Group X hetero-metal oxides somewhat opened the rutile (110) side. Thermal post-treatment of the hetero-metal oxides at medium temperature readily generated mixed valence states of a metallic site and the high oxidation states on the TiO2-Group X hetero-metal oxides interface. The thermal post-treatment simultaneously generated the both catalytic sites for water splitting reactions, of which surface successfully facilitated the photoelectrochemical water splitting in the absence of a redox mediator. In addition to the formation of p-n heterojunction, the co-existing catalytic sites surely promoted the overall water splitting. The TiO2 surface decoration with the Group X hetero-metal oxides modulates band structure, as well provides an effective method to control the surface charge recombination. The size controlled TiO2 nanostructure and its surface decoration by the Group X hetero-metal oxides provided beneficial pathways for both of the photo-generated electrons and holes. In this talk, I will discuss the synthetic methods and analytical data for the photoelectrode materials.

Catalytic ozonation of norfloxacin using Co3O4/C composite derived from ZIF-67 as catalyst

In this study, Co3O4-carbon composite was synthesized by calcined metal organic framework (MOF) ZIF-67 and used as efficient catalysts for ozonation of norfloxacin (NOF). The MOF-derived Co3O4–C composite remained similar polyhedrons structure of ZIF-67, suggesting that Co3O4 was well-dispersed in Co3O4–C composite. Furthermore, a larger amount of surface carbon-oxygen functional groups were distributed on Co3O4–C composite, which resulted in the diversification of active sites for catalytic ozonation reaction. NOF degradation and mineralization could be effectively enhanced in Co3O4–C/O3 process. Moreover, NOF mineralization by catalytic ozonation strongly depended on the solution pH, while other operational conditions, such as O3 concentration and catalyst dosage had not obvious influence on it. Co3O4–C composite could significantly accelerate O3 decomposition to produce active free radicals (such as •OH), which enhanced the mineralization of NOF. The possible catalytic mechanism of Co3O4–C composite was proposed. Additionally, after five consecutive use of Co3O4–C composite in catalytic ozonation process, there was no obvious decrease in TOC removal efficiency, indicating a stable performance of Co3O4–C composite, which was suitable for the catalytic ozonation for wastewater treatment.

Grain Boundaries Boost Oxygen Evolution Reaction in NiFe Electrocatalysts.

In a polycrystalline material, the grain boundaries (GBs) can be effective active sites for catalytic reactions by providing an electrodynamically favorable surface. Previous studies have shown that grain boundary density is related to the catalytic activity of the carbon dioxide reduction reaction, but there is still no convincing evidence that the GBs provide surfaces with enhanced activity for oxygen evolution reaction (OER). Combination of various electrochemical measurements and chemical analysis reveals the GB density at surface of NiFe electrocatalysts directly affects the overall OER. In situ electrochemical microscopy vividly shows that the OER occurs mainly at the GB during overall reaction. It is observed that the reaction determining steps are altered by grain boundary densities and the meaningful work function difference between the inside of grain and GBs exists. High-resolution transmission electron microscopy shows that extremely high index planes are exposed at the GBs, enhancing the oxygen evolution activity. The specific nature of GBs and its effects on the OER demonstrated in this study can be applied to the various polycrystalline electrocatalysts.

Multiple catalytic reaction sites induced non-radical/radical pathway with graphene layers encapsulated Fe-N-C toward highly efficient peroxymonosulfate (PMS) activation

Understanding the origin of high activity of graphene layers encapsulated Fe-N-C catalysts in Fenton-like reaction is critical, but still challenging for developing catalysts with high activity and durability. Therefore, we prepared a highly active Fe-N-C catalyst (FexMny-Fe@NCs) containing FeN4 coordination to activate peroxymonosulfate (PMS) toward 4-aminobenzoic acid ethyl ester (ABEE) degradation, and revealed the multiple catalytic reaction sites by investigating the composition and the structure of the catalyst. The relationship between the catalytic degradation performance and multiple catalytic reaction sites was performed on the basis of both experiments and density functional theory (DFT) calculations. The catalytic performance of Fe2Mn1-Fe@NCs was found to show optimal catalytic degradation performance. Pyrrolic N served as adsorption site as well as singlet oxygen generation site to promote the catalytic degradation. Fe-pyridinic N-C acted as hydroxyl radical and sulfate radical generation site. Both singlet oxygen and superoxide radical were dominated the catalytic reaction. The insight achieved from this study may be further applied to other Fe-N-C catalysts design and further efficient organic pollution remediation.

Activated Carbons from Fast Pyrolysis Biochar as Novel Catalysts for the Post-Treatment of Pyrolysis Vapors, Studied by Analytical Pyrolysis

Biochars are attractive materials for carbon catalysts since their carbon content and surface area are relatively high and minerals present in biochar can act as active sites for catalytic reactions. In this study, biochars from the fast pyrolysis of birch, pine, and unbarked willow were activated and acid washed. These materials were tested as catalysts for a post-treatment of pine wood pyrolysis vapors, aiming at stabilizing the vapors before their condensation. All the unmodified biochars had high content of minerals, those being highest in willow due to the bark. After the activation treatments, the surface areas and pore volumes of all biochars significantly increased. All studied biochars and activated carbon catalysts reduced the oxygen content of the pyrolysis degradation products. This effect was more pronounced for compounds derived from polysaccharides vs. lignin. The most promising catalyst for vapor upgrading was unwashed activated carbon from willow, having high surface areas and pore volumes together with high mineral contents. These properties together promoted the high conversion of polysaccharide-derived products (anhydrosugars, acids, and pyrans) into CO2. Release of highly oxidized degradation products may indicate that reductive stabilization takes place via hydrogen migration from the polysaccharide-derivatives to lignin derivatives, mediated by the carbon catalyst.