Economical Catalyst Research Articles

Efficient degradation of levofloxacin using peroxymonosulfate activated by a novel magnetic catalyst derived from waste walnut shell biomass

Developing an economical and efficient catalyst derived from biochar and metal-organic frameworks (MOFs) for the activation of peroxymonosulfate (PMS) to degrade pollutants holds promise for practical applications. Herein, a simple in-situ synthesis method was designed to generate zeolitic imidazole framework with Co-based (ZIF-67) on the surface of waste walnut shell biomass, and novel derived magnetic catalysts (BC@CobC, Biochar@Co base Carbon) were obtained by high-temperature carbonization. This structure could avoid the drawbacks of structural collapse and particle agglomeration of MOF derivatives, while the presence of biochar could accelerate electron transfer and improve the activation performance. For the degradation of levofloxacin, the removal rate in the 0.5-BC@CobC/PMS system reached 89.88 % in 15 min with a mineralization of 60.43 % when the dosage of catalyst was 0.01 g L−1. Capture experiments and EPR tests showed that SO4−•, •OH, •O2− and 1O2 were jointly participated in the levofloxacin degradation process. Meanwhile, the BC@CobC/PMS system was minimally affected by the pH, co-existing inorganic anions, and natural active substances. It is worth noting that the BC@CobC/PMS system also had excellent removal effect on other typical organic pollutants, and the removal rate could reach 100 %. Cycling experiments showed that BC@CobC maintained high catalytic activity after multiple recycling. The degradation pathway of levofloxacin was also analyzed. Compared to the existing reports, the catalyst is economically superior, with much improved pollutant removal, and boasts a lower catalyst usage. This work will provide a viable idea in terms of reusing biomass waste and activating PMS for wastewater treatment.

Synthesis of polymetallic oxide nanoarrays as efficient hydrogen evolution reaction electrocatalyst for alkaline seawater and urea splitting

Nowadays, with the depletion of traditional fossil resources, hydrogen energy comes into our eyes as a renewable and sustainable energy source. Electrocatalytic water splitting has been widely studied as an environmentally friendly method to produce hydrogen rapidly and large-scale. Since 96.5 % of the world’s abundant water resources are seawater, exploring an economical and efficient catalyst for seawater splitting is an attractive method to realize industrial hydrogen production. In this paper, polymetallic oxide Mn-MoWNi catalyst was in situ synthesized on nickel foam using one-step hydrothermal approach and composite strategy. The catalyst has excellent hydrogen evolution reaction (HER) performance in seawater and urea solution containing 1 M KOH. In 1 M KOH alkaline seawater solution, Mn-MoWNi only requires overpotential of 261 mV to drive the current density of 100 mA cm−2. When the current density of 100 mA cm−2 was reached in the alkaline solution of 1 M KOH + 0.5 M Urea, the overpotential of Mn-MoWNi catalyst was only 206 mV. After 15 h stability measurement in 1 M KOH alkaline seawater solution, the surface morphology of Mn-MoWNi was changed and corroded, indicating that its stability needs to be improved. Density functional theory calculations show that in Mn-MoWNi catalysts, MoO3 promotes the hydrogen adsorption ability of the material, while MnO2 promotes the electrical conductivity of the electrode, and both of them work synergistically with WO3 and NiWO4 to jointly improve the activity of the catalyst.

Greenly synthesized zinc oxide nanoparticles: An efficient, cost-effective catalyst for dehydrogenation of formic acid and with improved antioxidant and phyto-toxic properties

Formic acid (FA) dehydrogenation is of particular industrial interest as a source of alternative fuels such as H2. However, the development of economical, highly efficient, and selective catalysts for this reaction is a challenging task. Most highly selective catalysts for the conversion of formic acid (FA)/sodium formate (SF) system into hydrogen are based on precious noble metals. Rendering their large-scale utilization more cumbersome and expensive. Therefore, it is of utmost importance to explore a facile and cost-effective strategy for the fabrication of a simple structured solid nano-catalyst with outstanding performance and selectivity for H2 generation without CO evolution from the FA/SF system. In the current study, a phenolic-enriched extract of wild olive leaves was employed for the synthesis of ZnO nanoparticles (ZnO@WOLE-NPs). TEM analysis revealed that the size of ZnO@WOLE nanoparticles was about33 nm. Zeta potential evaluation (38.39 ± 1.32 mV) demonstrated the significant stability of the nanoparticles. XRD analysis provided insights into the formation of hexagonal wurtzite phase ZnO nanoparticles. The reaction conditions were optimized. These resulting ZnO@WOLE-NPs showed extraordinarily high catalytic performance and about 80 % selectivity for H2 generation from the FA/SF system at 50 °C. A turn over frequency and activation energy values for dehydrogenation of FA were noted as 1519 h−1 and 32.1 kJ mol−1, respectively. The kinetics and thermodynamics of FA dehydrogenation were also determined. Furthermore, ZnO@WOLE-NPs exhibited potent antioxidant activity against hydroxyl, DPPH, superoxide, and peroxide radicals. Moreover, the synthesized nanoparticles demonstrated the highest seed germination of Okra seed at a concentration of 1.25 µg mL−1. Whereas, the highest shoot length and root length were observed at the concentration of 1 µg mL−1.

One-pot assembly of sulfated lignin/Zr coordination polymer for efficient alcoholysis of furfuryl alcohol to methyl levulinate

Biomass-derived alkyl levulinates are considered to be ideal fuel additives, and the construction of green and economic catalysts for the production of alkyl levulinates was still a challenging goal. In this work, a facile method for the synthesis of sulfated lignin/Zr coordination polymer (Zr-LSNa@SX) was developed through the coordination of sodium lignosulfonate with Zr ions by hydrothermal procedure. The catalytic performance of prepared Zr-LSNa@SX for the direct conversion of furfuryl alcohol (FA) to methyl levulinate (ML) was studied and a 73.1 % yield of ML was achieved at 180 °C in 180 min. The as-prepared sulfated lignin/Zr coordination polymer was characterized using SEM, FT-IR, and Py-FTIR techniques, and it was determined that the Brønsted acid sites of the catalyst played a crucial role in the conversion of FA to ML in methanol. This work provided a facile method for constructing the green and economical bio-based solid acid catalyst which will greatly extend the application of bio-based materials in the acid-catalyzed reaction.

Hydrogen production from chemical hydrogen storage materials over copper‐based catalysts

AbstractHydrogen, as a clean and efficient energy source, is one of the important energy carriers in the future. However, the safe storage and delivery of hydrogen is still a bottleneck in its practical applications. Chemical hydrides (such as NaBH4, NH3BH3, N2H4·H2O, N2H4BH3, and HCOOH) are considered as potential chemical hydrogen storage materials that can achieve rapid on‐site hydrogen production. At present, the most critical issue for them is to develop economic catalysts to achieve efficient hydrogen production from chemical hydrides. Copper (Cu) is considered as a promising catalyst that is one of the most reactive metals among the first‐row transition metals and economically cheap. In this review, we outline the recent advancements of Cu‐based catalysts in catalyzing hydrogen production from chemical hydrides. Moreover, the synthesis methods, characterization techniques, and hydrogen production catalytic activity of Cu‐based catalysts were also introduced. Finally, a brief conclusion and outlook are given for the application of Cu‐based catalysts in the dehydrogenation of chemical hydrides. We hope that this review will stimulate interest in the promising research area of Cu‐based catalysts for the dehydrogenation of chemical hydrides.

Synthesis of surficial-modified green biochar catalyst generated by biogas residue biochar and potential application for catalytic ozonation degradation of ciprofloxacin

This study synthesized novel, green, and easily recoverable surface-modified economical catalysts via hydrothermal treatment (HT) successfully, utilizing biogas residue biochar (BRB), a food waste product from anaerobic fermentation, pyrolyzed at 500 °C for 50 min. Using autoclaves, a total of six solutions were prepared, each having 1 g fine-grinded BRB, surficial modified by adding glycerol (GL) (10 or 20 mL) and SDI water (70 or 60 mL), and heated in an oven at 240 °C, 180 °C, and 120 °C for 24 h. Afterward, the catalysts showed the potential for degradation of widely used emerging pollutants like ciprofloxacin. Taking advantage of catalytic surface modification, the catalytic ozonation degradation was more effective than that of a single ozonation. However, under similar conditions, catalyst amount 0.20 g, ozone dose 15 mg L−1, and ciprofloxacin 80 mg L−1, the performance of the 10 mL GL-180 °C catalyst was excellent. It showed a 92.45%–94.41% optimum removal rate in the 8–10 min interval. After five continuous cycles, the 10 mL GL-180 °C catalyst exhibited excellent stability and reusability. XPS, FT-IR, BET, XRD, and SEM before and after the reaction confirmed the successful synthesis and degradation mechanism. A possible degradation pathway was unrevealed based on a liquid chromatography-mass spectrometer (LC-MS) and scavenger test, proving the significant roles of superoxide radicals (O2•-), hydroxyl radicals (•OH), and singlet oxygen (1O2). Further, Electron paramagnetic resonance (EPR) analysis confirmed the presence of active oxygen species. Subsequently, 10 mL GL-180 °C showed promising degradation for the actual water environment, such as groundwater (73.55%) and river water (64.74%). This work provides a valuable economic strategy to convert biogas residue biochar into a low-cost catalyst for organic pollutant decomposition.

Synergistic Catalysis of SO42-/TiO2-CNT for the CO2 Desorption Process with Low Energy Consumption.

To address the issue of high energy consumption associated with monoethanolamine (MEA) regeneration in the CO2 capture process, solid acid catalysts have been widely investigated due to their performance in accelerating carbamate decomposition. The recently discovered carbon nanotube (CNT) catalyst presents efficient catalytic activity for bicarbonate decomposition. In this paper, bifunctional catalysts SO42-/TiO2-CNT (STC) were prepared, which could simultaneously catalyze carbamate and bicarbonate decomposition, and outstanding catalytic performance has been exhibited. STC significantly increased the CO2 desorption amount by 82.3% and decreased the relative heat duty by 46% compared to the MEA-CO2 solution without catalysts. The excellent stability of STC was confirmed by 15 cyclic absorption-desorption experiments, showing good practical feasibility for decreasing energy consumption in an industrial CO2 capture process. Furthermore, associated with the results of experimental characterization and theoretical calculations, the synergistic catalysis of STC catalysts via proton and charge transfer was proposed. This work demonstrated the potential of STC catalysts in improving the efficiency of amine regeneration processes and reducing energy consumption, contributing to the design of more effective and economical catalysts for carbon capture.

Niacin based MOF as efficient nano-catalyst in the synthesis of some new benzothiazoles and benzimidazoles as anti-Alzheimer (AChE inhibitors)

Metal-organic frameworks (MOFs) presented as an efficient, economic, sustainable and green stable catalyst. Co/Niacin-MOF in nano shape was prepared by hydrothermal method and illustrated by IR, SEM and XRD. The prepared Co/Niacin-MOF used in the synthesis of some new benzothiazoles and benzimidazoles (3a-3f, 4a-4f). The prepared benzo heterocyclic compounds were checked as acetylcholine esterase inhibitors (AChE inhibitors) and the data obtained from in vitro and molecular docking explained that there two promised values for compounds 4-(benzo[d]thiazol-2-yl)phenyl benzoate (3e) and 4-(1H-benzo[d]imidazol-2-yl)phenyl 4-methylbenzenesulfonate (4f) compared with Donepezil as a reference Alzheimer drug.

Decoding the digital leap: Exploring the role of global value chains in driving country-level digitalization

This study employs a dynamic bootstrap corrected fixed effects model to investigate the impact of Global Value Chain (GVC) participation and its components (forward and backward participation) on digitalization across 47 economies from 2001 to 2018. The findings indicate that GVC participation significantly enhances digitalization in countries with lower economic growth by facilitating access to advanced technologies and global networks, thereby accelerating their digitalization efforts. Conversely, in countries with higher economic growth, the effects of GVC participation on digitalization appear negligible, suggesting that these economies may already possess robust digital infrastructures. Notably, backward participation hinders digitalization in lower-growth countries, whereas it positively impacts higher-growth countries. Forward participation, however, distinctly benefits digitalization in lower-growth economies but does not show significant effects in more advanced ones. These nuanced outcomes underline the importance of tailoring policy interventions to the specific economic context of a country. Policymakers are recommended to support GVC integration in developing economies as a strategic approach to boost digitalization, while in more developed economies, policies should focus on enhancing existing digital capabilities and innovation ecosystems. This study's insights advocate for nuanced, context-specific policies to leverage GVC participation as a digital transformation and economic development catalyst.

Fe3O4@SiO2@CSH+VO3− as a novel recyclable heterogeneous catalyst with core–shell structure for oxidation of sulfides

Iron nanoparticles, with low toxicity and many active sites, are among the materials that not only reduce waste along with green chemistry but also increase the separation power and recover the catalyst from the reaction environment. In this study, first, the surface of iron nanoparticles was silanized, and in the next step, the complex of chitosan HCl.VO3 was placed on the surface of Fe3O4 (Fe3O4@SiO2@CSH+VO3−). This nanocatalyst is a novel, recoverable, and potent nanocatalyst with high selectivity for the oxidation of sulfides to sulfoxides. Various physicochemical techniques such as IR, XRD, TGA, SEM, EDX, mapping, TEM, and VSM were used to affirm the well synthesis of the catalyst. Oxidation of sulfides in the presence of hydrogen peroxide as a green oxidant and in ethanol was catalyzed by the Fe3O4@SiO2@CSH+VO3−. All sulfoxides were achieved with high efficiency and in a short time. The notable privileges of this method include facile and economic catalyst synthesis, proper catalyst durability, great performance, simple catalyst isolation, good recovery capability, at least up to 5 times without an index drop in catalytic power.

Enhanced oxygen evolution reaction of electrodeposited Functionally-Graded Ni-Cu-Fe coating

This study aimed to use a functionally graded (FG) Ni-Cu-Fe coating as an electrocatalyst for oxygen evolution reaction (OER) applications. The coating was applied on a mild carbon steel substrate by an electrodeposition technique, with the current density being progressively increased from 0.5 A/dm2 to 5 A/dm2 at a steady rate of 0.2 (A/dm2)/min during the coating operation. Using this specific method, the Ni content of the FG Ni-Cu-Fe coating changed along the cross-section when increasing the current density, 17 % more than the constant current coating. This technique also affected the surface morphology of the FG Ni-Cu-‌Fe coating and changed it from cauliflower to micro/nanocones when the current density was linearly increased, enhancing active sites significantly and thereby improving electrocatalytic activity. The coating's electrocatalytic behavior was studied by electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), and cyclic voltammetry (CV). results showed that the FG Ni-Cu-Fe coating had the smallest overpotential (134 mV) at the current density of 10 mA.cm−2. Also, it had the smallest Tafel slope (24.3 mV.dec− 1) and smallest resistance (598 Ω.cm2) compared to all of the other coatings. The FG Ni-Cu-‌‌Fe coating had higher OER performance because of high Ni content, micro/nanocones morphology with many active sites, and FG nature. The FG Ni-Cu-Fe coating is finally concluded to be a promising and economical catalyst with high OER activity.

HPW-Catalyzed environmentally benign approach to imidazo[1,2-a]pyridines.

The imidazo[1,2-a]pyridine moiety is present in drugs with several biological activities. The most direct way of obtaining this nucleus is the Groebke-Blackburn-Bienaymé three-component reaction (GBB-3CR) between aminopyridines, aldehydes, and isocyanides under both Lewis and Brønsted acid catalysis. However, several catalysts for this reaction have major drawbacks such as being expensive, extremely dangerous, strong oxidizing, and even explosive. In this scenario, heteropolyacids emerge as greener and safer alternatives due to their very strong Brønsted acidity. In particular, phosphotungstic acid (HPW) is an economical and green attractive catalyst for being cheap, non-toxic, and is known for its chemical and thermal stability. Herein, we report a straightforward approach to the GBB-3CR using HPW as catalyst in ethanol under microwave (μw) heating. This convenient environmentally benign methodology is broad in scope, provides the heterobicyclic products in high yields (up to 99%), with a low catalyst loading (2 mol %) in only 30 minutes, and allows the successful use of aliphatic aldehydes, substrates not so frequently explored with most usual catalysts for this reaction. Furthermore, the aforementioned advantages make this methodology very attractive and superior to the existing ones.

Religious Pilgrimages in South Africa: A Catalyst for Sustainable Tourism and Local Economic Development

Sustainable tourism and local economic development as a mechanism for religious pilgrimages in KwaZulu-Natal (KZN). This is particularly pertinent for religious pilgrimages in KZN province which boosts historical landmarks and pilgrimage destinations. Pilgrimage tourism and several other forms of tourism related to it have significant affinities to the tenets of sustainable development. The purpose of this paper is to examine the complications that could arise from religious pilgrimages' potential as a form of travel that, once implemented, would be beneficial for sustainable tourism and local economic development (LED). This paper further intends to assess the pilgrimage destinations to be viewed as a mechanism for local economic development. A quantitative research design was employed, as the nature of this research necessitates the use of numerical data and descriptive statistics to draw conclusions. A standardised questionnaire was used to collect data from 410 respondents selected using a convenience sampling technique from different pilgrimage destinations in KZN, South Africa. Descriptive, bivariate, and multivariate analyses were conducted using IBM’s SPSS version 28 software. The pilgrims and local communities’ perceptions of socio-economic contribution indicate that the availability of tourism facilities might be perceived as a socio-economic contributor to pilgrimage destinations. The findings further reveal that African religious pilgrimages can be sustainable and be a local economic development catalyst in KwaZulu-Natal. The study recommends that the South African National Christian Forum (SANCF), in collaboration with the South African government (national and provincial), develop an operational plan to provide business education, entrepreneurial skills, and relevant support to local communities surrounding religious pilgrimages or religious destinations, to empower them to contribute to the development of the local economy. This will assist to reduce South Africa's high unemployment rate, particularly in less developed regions.

Discrimination against Women in the Workplace

Although China has made great progress in women's equality, the awareness of gender equality continues to improve, Chinese contemporary environment has given women more job hunting and employment opportunities, but women still suffer from a lot of gender discrimination in job hunting and employment, resulting in female employment is seriously hindered the low employment rate. The influence of gender stereotypes and the unique physiological characteristics of women are the main reasons that make women suffer discrimination in job hunting and employment. The study highlights the persistent gender pay gap as the main discrimination women face in the job market. Women are often paid less than men, despite having the same educational background and qualifications. This pay inequality reflects a deep-seated gender bias against women. Biased hiring also contributes to discrimination against women in the workplace. Addressing these issues requires implementing policies that promote gender equality in employment, encouraging employers to adopt diversity and inclusion initiatives, and valuing women's rights. Educational programs and campaigns to promote a more inclusive work environment. By fostering a culture of gender equality, we can fully tap the potential of the female labor force, thereby improving social productivity and promoting economic growth. Discrimination against women in the workplace is a complex issue that requires concerted and multifaceted efforts from all sectors of society. By addressing the root causes of discrimination and taking positive measures to achieve fair employment in the workplace, we will provide an economic catalyst for the sustainable development of society.

Degradation of atrazine by N-doped graphitic carbon encapsulated Nickel-iron alloy via heterogeneous activation of peroxymonosulfate

Heterogeneous magnetic catalysts for peroxymonosulfate (PMS) activation that are used to degrade pollutants have attracted growing attention, and bimetallic alloy catalysts have excellent catalytic performance. In this study, nitrogen-doped graphite carbon encapsulated NiFe (NiFe@NC) alloy catalysts were synthesized using nickel-iron Prussian blue analog precursors to remove atrazine (ATZ) via the activation of PMS. The effects of various operating parameters (NiFe@NC dosage, PMS concentration, initial solution pH, and reaction temperature), and the effects of co-existing components were investigated. The synergistic catalysis of Ni and Fe gives NiFe@NC good catalytic properties. The NiFe@NC/PMS system achieved 100% removal of 10 mg L−1 ATZ was achieved in 30 min with an initial pH of 5.9; the TOF was 4.33 min−1, and the system exhibited resistance to interference from many co-existing substances. The graphite-carbon core-shell structure of NiFe@NC slowed down the leaching rate of metal ions and had good stability. Redox cycles in the system were achieved by facilitating the interaction between the transition metal and HSO5-, ensuring the continuous generation of reactive oxygen species. Ecotoxicity assessment showed that the toxicity level was significantly reduced after treatment. The total treatment cost of treating 1 m3 wastewater was lower than that of Fenton sludge catalyst. A continuous flow reactor was constructed to achieve continuous degradation of ATZ for long periods. This study expanded the application of PMS advanced oxidation technology by synthesizing an economical and recyclable magnetic catalyst and provided new insights for the removal of refractory organic matter.

The interface mechanism of ball-milled natural pyrite activating persulfate to degrade monochlorobenzene in soil: Intrinsic synergism of S and Fe species

Ball-milled natural pyrite has been proven to be an efficient and economical catalyst for persulfate (PDS) activation; however, the synergistic interface mechanism between S and Fe species transformation remains a large challenge. Herein, ball-milled pyrite was used in the degradation of monochlorobenzene (MCB) from soil, and the surface characteristics and identification of the S and Fe species in the ball-milled natural pyrite during the Fenton-like reaction were reported. The pyrite/PDS system was found to eliminate 93.8 % of the 95.6 mg/kg MCB in the soil. Ball milling changed the fundamental pathway of reactive species (RS) generation, and the FeIV contribution increased to 33.0 % for MCB degradation. Compared with heterogeneous activation, homogeneous activation induced by dissolved Fe(II) played an important role. Self-oxidation induced by sulfur vacancy sites (SVs) also occurred during MCB degradation (30.8 %). An exploration of the mechanism of the interfacial reaction at the microscopic level revealed that ball milling promoted the formation of SVs and increased the reducibility of S(-II) on pyrite, thus accelerating Fe(III) reduction and Fe(II) dissolution, limiting the generation of an Fe(III) passivation layer at the pyrite–water interface and promoting RS generation for MCB degradation. These findings provide new insights into the interface mechanism for PDS activation in a ball-milled pyrite/PDS system.

Enhancing Bio-Ethanol conversion to renewable H2 via Ethanol Steam Reforming over a highly porous “one-pot” nickel and molybdenum carbide-based catalyst

The pursuit of an economical, active, and stable catalyst for Bio-Ethanol Steam Reforming (ESR) to facilitate renewable H2 production continues. Especially considering that traditional-noble-metal-based catalysts, are too expensive for large scale applications. In this paper, a sol-gel Ni–Mo2C–Al2O3 catalyst was employed for the first time in the ESR reaction. Synthesized by an innovative “one-pot” sol-gel method, this highly porous catalyst (670 m2. gcat−1) promises to deliver, in a single material, the nickel's ability on cleaving C–C bonds with the known catalytic stability of Mo2C in reforming reactions. Catalytic stability and activity were tested over a wide range of temperatures (450 °C-700 °C) and at a high Gas-Hourly-Space-Velocity (GHSV), 200,000 mmol h−1. gcat−1. The high temperature tests (T > 650 °C) exhibited elevated stability (over 12 h) and activity (ethanol conversion and H2-Production-Rate of 100 % and 1700 mmol h−1. gcat−1, respectively). Besides, TPO-O2 and TEM micrographs have shown the presence of both graphitic and aromatic coke on tests E and H spent catalysts, 2.08 mgcarbon. gcat− 1h−1 and 541 mgcarbon. gcat− 1h−1, respectively. Nevertheless, given its more graphitic nature and lower formation rate, H2 yield, and conversion remained constant throughout the entirety of the high-temperature tests, confirming that the coke did not block the catalytic sites.

N-Decorated Main-Group MgAl2O4 Spinel: Unlocking Exceptional Oxygen Reduction Activity for Zn-Air Batteries.

The development of economical and efficient oxygen reduction reaction (ORR) catalysts is crucial to accelerate the widespread application rhythm of aqueous rechargeable zinc-air batteries (ZABs). Here, a strategy is reported that the modification of the binding energy for reaction intermediates by the axial N-group converts the inactive spinel MgAl2O4 into the active motif of MgAl2O4-N. It is found that the introduction of N species can effectively optimize the electronic configuration of MgAl2O4, thereby significantly reducing the adsorption strength of *OH and boosting the reaction process. This main-group MgAl2O4-N catalyst exhibits a high ORR activity in a broad pH range from acidic and alkaline environments. The aqueous ZABs assembled with MgAl2O4-N shows a peak power density of 158.5mWcm-2, the long-term cyclability over 2000h and the high stability in the temperature range from -10 to 50°C, outperforming the commercial Pt/C in terms of activity and stability. This work not only serves as a significant candidate for the robust ORR electrocatalysts of aqueous ZABs, but also paves a new route for the effective reutilization of waste Mg alloys.

Triaminoguanidine-based ionic hydrazone gels for catalyzed formylation of amines with carbon dioxide

The development of efficient, economic and heterogeneous catalysts to effectively reduce carbon dioxide into value-added products keeps an effective solution to build a sustainable society. Herein we report ionic porous organic polymer gels via hydrazone condensation reaction using triaminoguanidine cationic units and 1,3,5-benzenetricarbaldehyde as precursors under mild conditions. Ionic hydrazone gel (TB-OH) is obtained through ion exchange. The resulting TB-OH gel is catalytically active due to the synergistic effects of hierarchically porous structure, triaminoguanidine cationic activation centers and hydroxide anions. TB-OH is used as an efficient metal-free, halogen-free heterogeneous catalyst that achieves the formylation of various amines with CO2 to give formamides under ambient conditions. The gel catalyst is stable in the catalysis, is easy to separate, and can be reused for at least 5 cycles. TB-OH thus shows potential application in the catalytic conversion of CO2 because of its low cost, easy acquisition, excellent catalytic performance and easy recycling characteristics.

Significance of Epitaxial Growth of PtO2 on Rutile TiO2 for Pt/TiO2 Catalysts.

TiO2-supported Pt species have been widely applied in numerous critical reactions involving photo-, thermo-, and electrochemical-catalysis for decades. Manipulation of the state of the Pt species in Pt/TiO2 catalysts is crucial for fine-tuning their catalytic performance. Here, we report an interesting discovery showing the epitaxial growth of PtO2 atomic layers on rutile TiO2, potentially allowing control of the states of active Pt species in Pt/TiO2 catalysts. The presence of PtO2 atomic layers could modulate the geometric configuration and electronic state of the Pt species under reduction conditions, resulting in a spread of the particle shape and obtaining a Pt/PtO2/TiO2 structure with more positive valence of Pt species. As a result, such a catalyst exhibits exceptional electrocatalytic activity and stability toward hydrogen evolution reaction, while also promoting the thermocatalytic CO oxidation, surpassing the performance of the Pt/TiO2 catalyst with no epitaxial structure. This novel epitaxial growth of the PtO2 structure on rutile TiO2 in Pt/TiO2 catalysts shows its potential in the rational design of highly active and economical catalysts toward diverse catalytic reactions.