Showing papers by "Changbin Zhang published in 2023"
TL;DR: In this paper , a simple strategy was provided to regulate the morphology and microstructure of δ-MnO2 via the hydrothermal reaction temperature, and the effects of the reaction temperature and the ozone to toluene concentration ratio on the catalyst performance were investigated.
Abstract: To improve the reactivity and lifetime of catalysts in the catalytic ozonation of toluene, a simple strategy was provided to regulate the morphology and microstructure of δ-MnO2 via the hydrothermal reaction temperature. The effects of the reaction temperature and the ozone to toluene concentration ratio on the catalyst performance were investigated. The optimized MnO2-260 catalyst prepared at the limiting hydrothermal temperature (260 °C) showed high catalytic activity (XTol = 95%) and excellent stability (1200 min) at the approximately ambient temperature of 40 °C, which was superior to the results in previous studies. The structure and morphology of δ-MnO2 were characterized by extended X-ray absorption fine structure, X-ray diffraction, scanning electron microscopy, positron annihilation lifetime spectroscopy, electron spin resonance, and other techniques. Experimental results and density functional theory calculations were in agreement that surface oxygen vacancy clusters, especially surface oxygen dimer vacancies, are critical in ozone activation. Oxygen vacancies can facilitate the adsorption and activation of O3 to generate reactive oxygen species (ROS, including 1O2, O2-, and •OH), leading to superior ozonation activity to degrade toluene and intermediates. Meanwhile, free radical detection and scavenger tests indicated that •OH is the primary ROS during toluene ozonation rather than 1O2 or O2-.
5 citations
TL;DR: In this article , the electrode by electrodeposited manganese dioxide on the Zn metal has been designed, which can guide uniform deposition of zinc on the electrode, and then greatly extend the service life and improve the long cycling stability of ARZIBs.
3 citations
TL;DR: In this paper , the reduced catalysts were tested for o-xylene oxidation and characterized by power X-ray diffraction (XRD), transmission electron microscopy (TEM), Xray photoelectron spectroscopy (XPS) and temperature-programmed decomposition of TPDH.
Abstract: Pd/Al2O3 was pretreated by CO, H2 and NaBH4 reduction, respectively. The reduced catalysts were tested for o-xylene oxidation and characterized by power X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and temperature-programmed decomposition of palladium hydride (TPDH). The characterizations indicate the pretreatments lead to distinct Pd particle sizes and amount of surface activated oxygen species, which are responsible for the catalytic performance. Compared with H2 and NaBH4 reduction methods, CO reduction shows a strong interaction between Pd and Al2O3 with smaller Pd particle size and more surface activated oxygen. It exhibited excellent catalytic performance, complete oxidation of 50 ppmV o-xylene at 85°C with a WHSV of 60,000 mL/(g∙hr).
3 citations
TL;DR: In this article , a series of α-MnO2 nanowire catalysts were prepared via thermal annealing treatment at various temperatures to tailor defect species, including surface oxygen vacancy clusters.
Abstract: Catalytic ozonation has gained considerable interest in volatile organic compound (VOC) elimination due to its mild reaction conditions. However, the low activity and mineralization rate of VOCs over catalysts hinder its practical application. Herein, a series of α-MnO2 nanowire catalysts were prepared via thermal annealing treatment at various temperatures to tailor defect species. Numerous characterization techniques were used and combined to investigate the relationship between activity and microstructure. PALS and XAFS indicated that more unsaturated manganese and oxygen vacancies, especially surface oxygen vacancy clusters, were produced in α-MnO2 under the optimal high calcination temperature. As a result, MnO2-600 was found to exhibit the best-ever performance in toluene conversion (95%) and mineralization rate (89.5%) at 20 °C, making it a promising candidate for practical use. The roles of these defects in manipulating the reactive oxygen species of α-MnO2 were clarified by quantifying the amounts of reactive oxygen species by quenching experiments and density functional theory calculations. 1O2 and ·OH species generated in the vicinity of oxygen vacancy clusters, especially the dimer oxygen vacancy cluster, were identified as key oxygen species in the abatement of toluene. This study provides a facile method to engineer the microstructure of MnO2 by means of the manipulation of oxygen vacancies and an in-depth understanding of their roles in the catalytic ozonation of VOC.
2 citations
TL;DR: In this paper , a suite of complementary characterizations revealed that the catalyst activated with CO created the highly dispersed Pt nanoparticles to maintain a more positively charged state of Pt, which appropriately weakens the Mn-O bonding strength in the adjacent region of Pt for efficient supply of active oxygen during the reaction.
Abstract: Formaldehyde (HCHO) and carbon monoxide (CO) are both common air pollutants and hazardous to human body. It is imperative to develop the catalyst that is able to efficiently remove these pollutants. In this work, we activated Pt-MnO2 under different conditions for highly active oxidation of HCHO and CO, and the catalyst activated under CO displayed superior performance. A suite of complementary characterizations revealed that the catalyst activated with CO created the highly dispersed Pt nanoparticles to maintain a more positively charged state of Pt, which appropriately weakens the Mn-O bonding strength in the adjacent region of Pt for efficient supply of active oxygen during the reaction. Compared with other catalysts activated under different conditions, the CO-activated Pt-MnO2 displays much higher activity for oxidation of HCHO and CO. This research contributes to elucidating the mechanism for regulating the oxidation activity of Pt-based catalyst.
1 citations
TL;DR: In this paper , a nitrogen-doped biomass litchi-shell derived porous carbon (marked as N-LPC) was used as the iodine host for ZIBs.
Abstract: Zinc-iodine batteries (ZIBs) have attracted widespread attention because of their efficient capacity for ion transport and safety. However, the shuttle effect and physical properties of iodine species tremendously hinder their practical applications. Herein, we report a nitrogen-doped biomass litchi-shell derived porous carbon (marked as N-LPC) as the iodine host for ZIBs. The porous-rich structure of N-LPC is favorable for iodine loading and electron/ion transfers. Furthermore, the doping of heteroatomic nitrogen provides abundant anchoring sites to achieve strong interaction with iodine, thus the self-discharge can be suppressed effectively. Accordingly, the N-LPC/I2 composite cathode exhibits a specific capacity of 127 mAh/g at 100 mA g−1, as well as excellent rate capability and cycle stability. This study provides a strategy for discovering the cost-effective carbonaceous iodine host material.
1 citations
TL;DR: In this paper , the authors showed that the Pt-Ni bimetallic catalyst was composed of Pt nanoparticles with surrounding Ni atoms, and the results of in situ diffuse reflectance Fourier transform infrared spectroscopy showed the direct disassociation of CO2 to CO on the Pt/γ-Al2O3 and the decomposition of formate species to CO.
Abstract: Catalytic CO2 hydrogenation is a promising way to produce chemicals and has recently received much attention; however, designing catalysts with special product selectivity still remains a challenge. Here, we interestingly found that the Pt–Ni/γ-Al2O3 catalyst tended to have high CH4 selectivity, while both Pt/γ-Al2O3 and Ni/γ-Al2O3 had high CO selectivity. The characterization results showed that the Pt–Ni bimetallic catalyst was composed of Pt nanoparticles with surrounding Ni atoms. The results of in situ diffuse reflectance Fourier transform infrared spectroscopy showed the direct disassociation of CO2 to CO on the Pt/γ-Al2O3 and the decomposition of formate species to CO on Ni/γ-Al2O3. However, the presence of Pt–Ni bimetallic sites changed the hydrogenation pathway, in which the electronic interaction between Pt particles and surrounding Ni atoms promoted the further hydrogenation of formate species to CH4. This study provides insights into the understanding of the mechanisms of CO2 hydrogenation on bimetallic catalysts.
1 citations
TL;DR: In this paper , a NiCo2 O4 nanozyme with self-adaptive hierarchical nanostructure was developed to capture bacteria of various morphotypes via the physico-mechanical interaction between the nanostructures and bacteria.
Abstract: Along with the rapid development and ever-deepening understanding of nanoscience and nanotechnology, nanomaterials hold promise to mimic the highly evolved biological exquisite nanostructures and sophisticated functions. Here, inspired by the ubiquitous antibacterial nanostructures on the wing surfaces of some insects, we develop a NiCo2 O4 nanozyme with self-adaptive hierarchical nanostructure that can capture bacteria of various morphotypes via the physico-mechanical interaction between the nanostructure and bacteria. Moreover, the developed biomimetic nanostructure further exhibits superior peroxidase-like catalytic activity, which can catalytically generate highly toxic reactive oxygen species that disrupt bacterial membranes and induce bacterial apoptosis. Therefore, the mechano-catalytic coupling property of this NiCo2 O4 nanozyme allows for an extensive and efficient antibacterial application, with no concerns of antimicrobial resistance. This work suggests a promising strategy for the rational design of advanced antibacterial materials by mimicking biological antibiosis. This article is protected by copyright. All rights reserved.
1 citations
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TL;DR: In this article , an Ag-MnOx-based catalysts were prepared and activated under different atmosphere (i.e., air, hydrogen (H2) and carbon monoxide (CO)) for efficient oxidation of HCHO.
Abstract: Formaldehyde (HCHO) is a common indoor pollutant that is detrimental to human health. Its efficient removal has become an urgent demand to reduce the public health risk. In this work, Ag-MnOx-based catalysts were prepared and activated under different atmosphere (i.e., air, hydrogen (H2) and carbon monoxide (CO)) for efficient oxidation of HCHO. The catalyst activated with CO (Ag/Mn-CO) displayed the highest activity among the tested samples with 90% conversion at 100 °C under a gas space velocity of 75,000 mL/(gcat·h). Complementary characterizations demonstrate that CO reduction treatment resulted in synergically regulated content of surface oxygen on support to adsorb/activate HCHO and size of Ag particle to dissociate oxygen to oxidize the adsorbed HCHO. In contrast, other catalysts lack for either abundant surface oxygen species or metallic silver with the appropriate particle size, so that the integrate activity is limited by one specific reaction step. This study contributes to elucidating the mechanisms regulating the oxidation activity of Ag-based catalysts.
TL;DR: In this article , the influence of surface fluorine (F) on TiO2 for the photocatalytic oxidation (PCO) of toluene was investigated and the results showed that the presence of the appropriate amount of surface Ti-F on the surface of TiO 2 improved the separation of photogenerated carriers, which facilitated the generation of ·OH and promoted the activity for the PCO.
Abstract: In the present study, we investigated the influence of surface fluorine (F) on TiO2 for the photocatalytic oxidation (PCO) of toluene. TiO2 modified with different F content was prepared and tested. It was found that with the increasing of F content, the toluene conversion rate first increased and then decreased. However, CO2 mineralization efficiency showed the opposite trend. Based on the characterizations, we revealed that F substitutes the surface hydroxyl of TiO2 to form the structure of Ti-F. The presence of the appropriate amount of surface Ti-F on TiO2greatly enhanced the separation of photogenerated carriers, which facilitated the generation of ·OH and promoted the activity for the PCO of toluene. It was further revealed that the increase of only ·OH promoted the conversion of toluene to ring-opening containing intermediates, causing the accumulation of intermediates and then conversely inhibited the ·OH generation, which led to the decrease of the CO2 mineralization efficiency. The above results could provide guidance for the rational design of photocatalysts for toluene oxidation.
TL;DR: In this paper , a novel lignin-based poly(tetraethylene pentamine-pyrogallol) (AL-PTAP) was used for removal of Cr(vi) using a Mannich reaction and catechol-amine reaction.
Abstract: In this work, a novel alkali lignin-based adsorption material, alkali lignin-based poly(tetraethylene pentamine-pyrogallol) (AL-PTAP), was prepared using a Mannich reaction and catechol-amine reaction for removal of Cr(vi). It was characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The effects of tetraethylene pentamine (TEPA) dosage, pyrogallol (PL) dosage, contact time, pH, temperature and other factors on the adsorption behavior of the adsorbent were systematically investigated. These experimental data show that the adsorption behavior conforms to the pseudo-second-order kinetic model and the Langmuir isotherm model. The maximum adsorption capacity is 769.2 mg g−1 at 303 K, which is much higher than that of alkali lignin (AL). AL-PTAP can achieve a removal rate of almost 100% for Cr(vi) solutions with a concentration of less than 90 mg L−1 at 1 min. Furthermore, the toxic Cr(vi) is partly reduced to nontoxic Cr(iii) during the adsorption process. Therefore, AL-PTAP is a fast and efficient alkali lignin-based adsorbent, which is expected to improve the utilization value of alkali lignin in Cr(vi) wastewater treatment.
TL;DR: In this article , a 1% Ag/Al2O3 (Ag/Al-fresh) catalyst with Ag species in a uniform state and then reduced with H2 at 600 °C to obtain the Ag/al-600H2 catalyst.
Abstract: Ag-based catalysts have been extensively investigated in HCHO oxidation on account of the low price of the Ag precursor and their considerable low-temperature activity. It is known that H2 pretreatment has a remarkable promotion effect on Pt- and Pd- catalysts for HCHO oxidation, whereas the effect of H2 reduction on Ag-based catalysts has been rarely reported, probably due to the coexistence of multiple states of Ag species resulting from the high Ag loading. Herein, we prepared a 1% Ag/Al2O3 (Ag/Al-fresh) catalyst with Ag species in a uniform state and then reduced Ag/Al-fresh with H2 at 600 °C to obtain the Ag/Al-600H2 catalyst. We observed that H2 reduction had a significant influence on the performance of Ag/Al2O3 nanocatalysts in HCHO oxidation. In a dry reaction atmosphere, Ag/Al-fresh and Ag/Al-600H2 exhibited comparable HCHO conversion levels, but Ag/Al-600H2 showed much higher CO2 selectivity than Ag/Al-fresh. The presence of water vapor severely suppressed the HCHO conversion of the Ag/Al-fresh catalyst, while Ag/Al-600H2 showed high water resistance, maintaining high HCHO conversion and CO2 selectivity at 35% RH. Characterization results showed that the Ag species on Ag/Al-fresh and Ag/Al-600H2 were single-atom cationic Ag and metallic Ag nanoparticles, respectively. It was revealed that the Ag0 nanoparticles were more conducive than single-atom Ag+ to formate decomposition, as well as O2 and H2O activation, thus accelerating the conversion of HCOO– and CO intermediates to CO2 and contributing to the higher activity and water resistance of the Ag/Al-600H2 catalyst.
TL;DR: In this article , the authors showed that toluene on S-TiO2 was initially oxidized to benzene-ring-containing intermediate species by ROS, which suppressed the ROS production and blocked the ring-opening reaction, resulting in low CO2 selectivity.
TL;DR: In this article , a nanosized SrTiO3 film was proposed as a highly selfadapting protective coating to facilitate fast Zn2+ kinetics and guarantee even ion flux.
Abstract: Rechargeable aqueous zinc ion batteries, featuring as high specific capacity, low cost and high safety, are considered one of the most promising alternatives to lithium-ion batteries for the next-generation energy storage system. Nevertheless, the undesired dendrite formation and serious side reaction of Zn metal anode significantly hinder the usage of Zn-based metal batteries. Here, we propose a nanosized SrTiO3 film as a highly self-adapting protective coating to facilitate fast Zn2+ kinetics and guarantee even ion flux, leading to endow homogeneous Zn deposition under the SrTiO3 layer. Consequently, the symmetric batteries equipped with SrTiO3-coated Zn electrodes obtain a long-term cycling lifespan for 1000h with a fixed capacity of 1 mA h cm−2 without the formation of zinc dendrites. Furthermore, the Zn@SrTiO3||MnO2 full battery displays excellent cycling stability and rate performance. This study emphasizes the important role of SrTiO3 layer in designing the interfacial stability during zinc redox process for stable aqueous Zn metal batteries.
TL;DR: In this paper , a strontium titanate (SrTiO3) coated separator was used to improve the deposition behavior of Zn2+ and represses Zn dendrite.
TL;DR: In this paper , the authors tuned SMSI on Pd/TiO2 catalysts through inducing surface defects of TiO2 by pretreating with different atmospheres (H2/N2, N2, O2/O2), at the high temperature (800 °C).
TL;DR: In this paper , the authors investigated the activity and selectivity of the transition metals (Fe, Co, and Ni) supported on a CeO2 catalyst for CO2 hydrogenation at atmospheric pressure.
TL;DR: In this article , a comprehensive oxidation pathway of toluene is refined by using in situ diffuse reflectance infrared Fourier transform spectroscopy and Vocus proton transfer reaction mass spectrometry (Vocus-PTR-MS).
Abstract: Catalytic oxidation has been extensively studied as a promising technology for the removal of toluene from industrial waste gases and indoor air. However, the debate regarding the oxidation mechanism is far from resolved. CexMn1-xO2 catalysts with different mixing ratios are prepared by the sol-gel method and found to exhibit better catalytic activities for toluene oxidation than a single oxide. Characterizations and theoretical calculations reveal that the doped Mn increases the number of oxygen vacancies and the ability of oxygen vacancies to activate aromatic rings, which promotes the rate-determining step of toluene oxidation, i.e., ring-opening reactions. The oxidation products detected by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and Vocus proton transfer reaction mass spectrometry (Vocus-PTR-MS) show that the doped Mn significantly improves the ring-opening efficiency and subsequently yields more short-chain products, such as pyruvic acid and acetic acid. A comprehensive oxidation pathway of toluene is refined in this work.
17 Jan 2023
TL;DR: In this article , the electronic Ru-Al2O3 interaction was tailored by controlling the sizes of supported Ru nanoparticles to regulate the profiles of energy barriers for selective hydrogenolysis of diphenyl ether (DPE), modeling compound of lignin.
Abstract: Aromatics are desirable products from the depolymerization/valorization of lignin; however, it is still challenging to achieve selective hydrogenolysis of the C–O bond with the preservation of aromatic rings. In this work, the electronic Ru-Al2O3 interaction was tailored by controlling the sizes of supported Ru nanoparticles to regulate the profiles of energy barriers for selective hydrogenolysis of diphenyl ether (DPE, modeling compound of lignin). Complementary characterizations and kinetic studies demonstrate that a stronger electronic metal–support interaction (EMSI) occurs between smaller Ru nanoparticles and Al2O3, leading to a more electron-deficient Ru domain. This tailored electronic structure dramatically increases the barrier of an undesired secondary reaction (i.e., ring hydrogenation), outstripping that of DPE hydrogenolysis for the production of aromatics. In addition, although the latter barrier also increases over smaller and more electron-deficient Ru, the much more abundant active site compensates for the increased barrier and enhanced the apparent reactivity. The catalyst bearing the smallest Ru particle displays the highest activity and selectivity under the tested conditions. This work provides an approach to control selectivity in hydrotreatment by regulating the energy barriers along the reaction pathway.
TL;DR: In this article , a doped alkenyl-type carbon ligand on Pd-Fe catalyst is demonstrated to donate electrons to Pd, creating an electron-rich environment that elongates the distance and weakens the electronic interaction between Pd and unsaturated C of the reactants/products to control the hydrogenation chemistry.
Abstract: Noble metals have been extensively employed in a variety of hydrotreating catalyst systems for their featured functionality of hydrogen activation but may also bring side reactions such as undesired deep hydrogenation. It is crucial to develop a viable approach to selectively inhibit side reactions while preserving beneficial functionalities. Herein, we present modifying Pd with alkenyl-type ligands that forms homogeneous-like Pd-alkene metallacycle structure on the heterogeneous Pd catalyst to achieve the selective hydrogenolysis and hydrogenation. Particularly, a doped alkenyl-type carbon ligand on Pd-Fe catalyst is demonstrated to donate electrons to Pd, creating an electron-rich environment that elongates the distance and weakens the electronic interaction between Pd and unsaturated C of the reactants/products to control the hydrogenation chemistry. Moreover, high H2 activation capability is maintained over Pd and the activated H is transferred to Fe to facilitate C-O bond cleavage or directly participate in the reaction on Pd. The modified Pd-Fe catalyst displays comparable C-O bond cleavage rate but much higher selectivity (>90%) than the bare Pd-Fe (<50%) in hydrotreating of diphenyl ether (DPE, modelling the strongest C-O linkage in lignin) and enhanced ethene selectivity (>90%) in acetylene hydrogenation. This work sheds light on the controlled synthesis of selective hydrotreating catalysts via mimicking homogeneous analogues.