Pub Date : 2022-08-04DOI: 10.3389/fctls.2022.890842
Reshalaiti Hailili, D. Bahnemann, J. Schneider
The presence of pollutants, e.g., pharmaceutical residues and industrial pollutants causes serious risks and irreversible damage to public health and ecological balance. Semiconductor-based photocatalysis is an attractive way to treat polluted water. Rational design and nanostructuring of semiconductors with visible light absorption and prominent surfaces could strengthen surface-interface reactions, resulting in improved photocatalytic degradation. Herein, layered structured perovskites Bi4Ti3O12 (BTO) were synthesized by an ionic liquid [1-butyl-3-methylimidazolium iodide (Bmim)I] assisted approach. The precise tuning of synthetic conditions allowed formations of various microstructures, including spherical nanoparticles, nanoplates and nanorods, respectively. The optical analyses demonstrated that samples were typically visible light absorbents with narrow band gap energies (2.96–2.73 eV), and displayed pronounced degradation for pharmaceutical residues under visible light illumination. The factors responsible for the high efficiency of BTO photocatalysts were discussed in terms of unique structure, optical alignment, dipole induced carrier separation and formation of active radicals. Among studied samples, the nanorod shaped BTO showed 1.31 and 1.46 times higher apparent rate constants for tetracycline and ibuprofen degradation than its counterparts (spherical nanoparticles and nanoplates), respectively. The better performance of nanorods was ascribed to their higher visible light harvesting ability. Importantly, BTO nanorods exhibited nonselective degradation activity for diverse pollutants of pharmaceutical residues and industrial contaminants. This work demonstrates the unique strategy of microstructure regulation and a wide range of applications of layered perovskites for environmental remediation.
{"title":"Ionic liquid-mediated microstructure regulations of layered perovskite for enhanced visible light photocatalytic activity","authors":"Reshalaiti Hailili, D. Bahnemann, J. Schneider","doi":"10.3389/fctls.2022.890842","DOIUrl":"https://doi.org/10.3389/fctls.2022.890842","url":null,"abstract":"The presence of pollutants, e.g., pharmaceutical residues and industrial pollutants causes serious risks and irreversible damage to public health and ecological balance. Semiconductor-based photocatalysis is an attractive way to treat polluted water. Rational design and nanostructuring of semiconductors with visible light absorption and prominent surfaces could strengthen surface-interface reactions, resulting in improved photocatalytic degradation. Herein, layered structured perovskites Bi4Ti3O12 (BTO) were synthesized by an ionic liquid [1-butyl-3-methylimidazolium iodide (Bmim)I] assisted approach. The precise tuning of synthetic conditions allowed formations of various microstructures, including spherical nanoparticles, nanoplates and nanorods, respectively. The optical analyses demonstrated that samples were typically visible light absorbents with narrow band gap energies (2.96–2.73 eV), and displayed pronounced degradation for pharmaceutical residues under visible light illumination. The factors responsible for the high efficiency of BTO photocatalysts were discussed in terms of unique structure, optical alignment, dipole induced carrier separation and formation of active radicals. Among studied samples, the nanorod shaped BTO showed 1.31 and 1.46 times higher apparent rate constants for tetracycline and ibuprofen degradation than its counterparts (spherical nanoparticles and nanoplates), respectively. The better performance of nanorods was ascribed to their higher visible light harvesting ability. Importantly, BTO nanorods exhibited nonselective degradation activity for diverse pollutants of pharmaceutical residues and industrial contaminants. This work demonstrates the unique strategy of microstructure regulation and a wide range of applications of layered perovskites for environmental remediation.","PeriodicalId":73071,"journal":{"name":"Frontiers in catalysis","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48107458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-19DOI: 10.3389/fctls.2022.935174
Wenda Hu, Nicholas R. Jaegers, Austin D. Winkelman, Shiva Murali, K. Mueller, Yong Wang, J. Hu
Nuclear magnetic resonance (NMR) is a non-destructive and atom-specific specific tool that has become a burgeoning analytic method for understanding the detailed molecular interactions in catalysis and energy storage materials. However, the observation of diverse chemical shifts arising from complex molecular interactions makes the interpretation of NMR spectroscopy increasingly challenging, in particular for a novel system without standards for comparison. Density functional theory-NMR (DFT-NMR) is an indispensable tool to mitigate these challenges and provide detailed 3D molecular structures that relate materials and reaction intermediate structures, and information about chemical interactions, dynamics, and reaction mechanisms. This review provides a fundamental background in DFT-NMR relating to theory development, critical parameters for calculating NMR properties, computational accuracy, and the current capabilities. A variety of practical examples from the fields of catalysis and energy storage, including CO2 capture, are summarized to illustrate the capabilities of DFT-NMR application to date. Last but not least, cautionary notes on the application of these strategies are presented for researchers modeling their own systems.
{"title":"Modelling complex molecular interactions in catalytic materials for energy storage and conversion in nuclear magnetic resonance","authors":"Wenda Hu, Nicholas R. Jaegers, Austin D. Winkelman, Shiva Murali, K. Mueller, Yong Wang, J. Hu","doi":"10.3389/fctls.2022.935174","DOIUrl":"https://doi.org/10.3389/fctls.2022.935174","url":null,"abstract":"Nuclear magnetic resonance (NMR) is a non-destructive and atom-specific specific tool that has become a burgeoning analytic method for understanding the detailed molecular interactions in catalysis and energy storage materials. However, the observation of diverse chemical shifts arising from complex molecular interactions makes the interpretation of NMR spectroscopy increasingly challenging, in particular for a novel system without standards for comparison. Density functional theory-NMR (DFT-NMR) is an indispensable tool to mitigate these challenges and provide detailed 3D molecular structures that relate materials and reaction intermediate structures, and information about chemical interactions, dynamics, and reaction mechanisms. This review provides a fundamental background in DFT-NMR relating to theory development, critical parameters for calculating NMR properties, computational accuracy, and the current capabilities. A variety of practical examples from the fields of catalysis and energy storage, including CO2 capture, are summarized to illustrate the capabilities of DFT-NMR application to date. Last but not least, cautionary notes on the application of these strategies are presented for researchers modeling their own systems.","PeriodicalId":73071,"journal":{"name":"Frontiers in catalysis","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41393446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-30DOI: 10.3389/fctls.2022.926316
Eva Puchľová, T. Hilberath, Kvetoslava Vranková, F. Hollmann
Non-enantioselective alcohol dehydrogenases (ADHs) are rarely found in the biocatalysis portfolio. Generally, highly enantioselective ADHs are sought for. Using such ADHs for the oxidation of racemic alcohols generally results in a kinetic resolution of the starting material, which is unfavourable if the ketone represents the product of interest. In the current contribution we report the ADH from Sphingobium yanoikuyae (SyADH) as non-enantioselective ADH for the complete oxidation or rac-heptan-2-ol (representing further 2-alkanols).
{"title":"Towards Biocatalytic Oxidation of Secondary Alcohols to Carbonyl Products of Relevance for Flavors and Fragrances","authors":"Eva Puchľová, T. Hilberath, Kvetoslava Vranková, F. Hollmann","doi":"10.3389/fctls.2022.926316","DOIUrl":"https://doi.org/10.3389/fctls.2022.926316","url":null,"abstract":"Non-enantioselective alcohol dehydrogenases (ADHs) are rarely found in the biocatalysis portfolio. Generally, highly enantioselective ADHs are sought for. Using such ADHs for the oxidation of racemic alcohols generally results in a kinetic resolution of the starting material, which is unfavourable if the ketone represents the product of interest. In the current contribution we report the ADH from Sphingobium yanoikuyae (SyADH) as non-enantioselective ADH for the complete oxidation or rac-heptan-2-ol (representing further 2-alkanols).","PeriodicalId":73071,"journal":{"name":"Frontiers in catalysis","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48197641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-17DOI: 10.3389/fctls.2022.906694
M. Ramírez, Shiny Joseph Srinivasan, Sarah E. Cleary, Peter M. T. Todd, H. Reeve, K. Vincent
Hydrogenase-mediated reduction of flavin mononucleotide by H2 is exploited to enable cleaner application of nitroreductase enzymes for reduction of aromatic nitro functional groups. This turns the overall reaction into a biocatalytic hydrogenation. Use of flavin-containing nitroreductases in industrial biotechnology typically relies upon NADH or NADPH as reductant, together with glucose dehydrogenase and glucose as a regeneration system for the reduced nicotinamide cofactor, with 3 equivalents of the carbon-intensive glucose required for a single 6-electron nitro to amine conversion. We show here that reduced flavin mononucleotide is an alternative reductant for nitroreductases, and by combining this with H2-driven recycling of reduced flavin, we avoid glucose, thereby enabling atom-efficient biocatalytic nitro reductions. We compare this biocatalytic system, via green chemistry metrics, to existing strategies for biocatalytic nitro-group reductions, particularly with respect to replacing glucose with H2 gas. We take steps towards demonstrating industrial viability: we report an overexpression system for E. coli hydrogenase 1, giving a 12-fold improvement in enzyme yield; we show a reaction in which the hydrogenase exhibits > 26,000 enzyme turnovers; and we demonstrate reasonable solvent tolerance of the hydrogenase and flavin reduction system which would enable reaction intensification.
{"title":"H2-Driven Reduction of Flavin by Hydrogenase Enables Cleaner Operation of Nitroreductases for Nitro-Group to Amine Reductions","authors":"M. Ramírez, Shiny Joseph Srinivasan, Sarah E. Cleary, Peter M. T. Todd, H. Reeve, K. Vincent","doi":"10.3389/fctls.2022.906694","DOIUrl":"https://doi.org/10.3389/fctls.2022.906694","url":null,"abstract":"Hydrogenase-mediated reduction of flavin mononucleotide by H2 is exploited to enable cleaner application of nitroreductase enzymes for reduction of aromatic nitro functional groups. This turns the overall reaction into a biocatalytic hydrogenation. Use of flavin-containing nitroreductases in industrial biotechnology typically relies upon NADH or NADPH as reductant, together with glucose dehydrogenase and glucose as a regeneration system for the reduced nicotinamide cofactor, with 3 equivalents of the carbon-intensive glucose required for a single 6-electron nitro to amine conversion. We show here that reduced flavin mononucleotide is an alternative reductant for nitroreductases, and by combining this with H2-driven recycling of reduced flavin, we avoid glucose, thereby enabling atom-efficient biocatalytic nitro reductions. We compare this biocatalytic system, via green chemistry metrics, to existing strategies for biocatalytic nitro-group reductions, particularly with respect to replacing glucose with H2 gas. We take steps towards demonstrating industrial viability: we report an overexpression system for E. coli hydrogenase 1, giving a 12-fold improvement in enzyme yield; we show a reaction in which the hydrogenase exhibits > 26,000 enzyme turnovers; and we demonstrate reasonable solvent tolerance of the hydrogenase and flavin reduction system which would enable reaction intensification.","PeriodicalId":73071,"journal":{"name":"Frontiers in catalysis","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48738404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-08DOI: 10.3389/fctls.2022.914670
Manoj Kumar Kumawat, Samuel Lalthazuala Rokhum
Biodiesel, as an alternative fuel for petroleum-based fuel, has recently acquired significant attention. The current study focused on using biowaste to produce catalysts for low-cost biodiesel manufacturing. Orange peels (OP) were used to make carbon-based solid acid catalysts with sulfonic acid group (–SO3H) density of 1.96 mmol g−1 via a “one-pot” carbonization-sulfonation treatment. Under the optimized reaction conditions (15:1 MeOH to oleic acid molar ratio, 7 wt.% catalyst loading w.r.t oleic acid, 80°C reaction temperature, 60 min reaction time), 96.51 ± 0.4% conversion of oleic acid to methyl oleate (a biodiesel component) was obtained. The catalyst displayed high recyclability and stability on repeated reuse, with a negligible decrease in biodiesel conversion up to 5 catalytic cycles.
{"title":"Biodiesel Production From Oleic Acid Using Biomass-Derived Sulfonated Orange Peel Catalyst","authors":"Manoj Kumar Kumawat, Samuel Lalthazuala Rokhum","doi":"10.3389/fctls.2022.914670","DOIUrl":"https://doi.org/10.3389/fctls.2022.914670","url":null,"abstract":"Biodiesel, as an alternative fuel for petroleum-based fuel, has recently acquired significant attention. The current study focused on using biowaste to produce catalysts for low-cost biodiesel manufacturing. Orange peels (OP) were used to make carbon-based solid acid catalysts with sulfonic acid group (–SO3H) density of 1.96 mmol g−1 via a “one-pot” carbonization-sulfonation treatment. Under the optimized reaction conditions (15:1 MeOH to oleic acid molar ratio, 7 wt.% catalyst loading w.r.t oleic acid, 80°C reaction temperature, 60 min reaction time), 96.51 ± 0.4% conversion of oleic acid to methyl oleate (a biodiesel component) was obtained. The catalyst displayed high recyclability and stability on repeated reuse, with a negligible decrease in biodiesel conversion up to 5 catalytic cycles.","PeriodicalId":73071,"journal":{"name":"Frontiers in catalysis","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46165737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-23DOI: 10.3389/fctls.2022.861364
Fabian Morteo-Flores, A. Roldan
Understanding the mechanisms of guaiacol’s catalytic hydrodeoxygenation (HDO) is essential to remove the oxygen excess in bio-oils. The present work systematically examines guaiacol’s HDO mechanisms to form benzene on six transition metal (TM) catalysts using density functional theory calculations. The results suggested a preferable Caryl−O bond scission on Ni (111) and Co (0001), whereas on Fe (110), the Caryl–OH bond scission is the most likely pathway. The C−O scission on Pd (111) and Pt (111) is not energetically feasible due to their high activation barriers and endothermic behaviour. Fe (110) also demonstrated its high oxophilic character by challenging the desorption of oxygenated products. A detailed analysis concludes that Co (0001) and Ni (111) are the most favourable in breaking phenolic compounds’ C−O type bonds. Brønsted-Evans-Polanyi (BEP) and transition state scaling (TSS) models were implemented on the catalytic results to derive trends and accelerate the catalyst design and innovation. TSS demonstrated a reliable trend in defining dissociation and association reaction energies. The phenyl ring-oxo-group and the metal-molecule distances complement the catalysts’ oxophilicity as selectivity descriptors in the HDO process.
{"title":"Mechanisms and Trends of Guaiacol Hydrodeoxygenation on Transition Metal Catalysts","authors":"Fabian Morteo-Flores, A. Roldan","doi":"10.3389/fctls.2022.861364","DOIUrl":"https://doi.org/10.3389/fctls.2022.861364","url":null,"abstract":"Understanding the mechanisms of guaiacol’s catalytic hydrodeoxygenation (HDO) is essential to remove the oxygen excess in bio-oils. The present work systematically examines guaiacol’s HDO mechanisms to form benzene on six transition metal (TM) catalysts using density functional theory calculations. The results suggested a preferable Caryl−O bond scission on Ni (111) and Co (0001), whereas on Fe (110), the Caryl–OH bond scission is the most likely pathway. The C−O scission on Pd (111) and Pt (111) is not energetically feasible due to their high activation barriers and endothermic behaviour. Fe (110) also demonstrated its high oxophilic character by challenging the desorption of oxygenated products. A detailed analysis concludes that Co (0001) and Ni (111) are the most favourable in breaking phenolic compounds’ C−O type bonds. Brønsted-Evans-Polanyi (BEP) and transition state scaling (TSS) models were implemented on the catalytic results to derive trends and accelerate the catalyst design and innovation. TSS demonstrated a reliable trend in defining dissociation and association reaction energies. The phenyl ring-oxo-group and the metal-molecule distances complement the catalysts’ oxophilicity as selectivity descriptors in the HDO process.","PeriodicalId":73071,"journal":{"name":"Frontiers in catalysis","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43524856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-23DOI: 10.3389/fctls.2022.882992
T. Hilberath, Anouska van Troost, M. Alcalde, F. Hollmann
The use of water-miscible organic co-solvents in biocatalysis is a simple procedure for obtaining higher enzymatic activities toward hydrophobic substrates. However, effects on activity and stability have to be carefully evaluated, also with regard to the type and concentration of the respective co-solvent. In this contribution, we investigated and evaluated the effect of some common water-miscible co-solvents on the biocatalytic performance of the recombinant unspecific peroxygenase rAaeUPO from Agrocybe aegerita. rAaeUPO showed promising activities in the presence of high concentrations of the best co-solvent acetonitrile, which enabled to use higher substrate concentrations (≥100 mM). Employing high acetonitrile concentrations for UPO-mediated oxidation of ethylbenzene to (R)-1-phenylethanol was demonstrated under preparative scale conditions and led to product accumulation rates of 31 mM h−1.
在生物催化中使用与水混溶的有机助溶剂是获得对疏水性底物的更高酶活性的简单程序。然而，必须仔细评估对活性和稳定性的影响，也要考虑各自助溶剂的类型和浓度。在这篇文章中，我们研究并评估了一些常见的水混溶性共溶剂对Agrocybe aegerita重组非特异性过氧酶rAaeUPO生物催化性能的影响。rAaeUPO在高浓度的最佳共溶剂乙腈存在下显示出有希望的活性，这使得能够使用更高的底物浓度（≥100mM）。在制备规模条件下，证明了使用高乙腈浓度进行UPO介导的乙苯氧化为（R）-1-苯基乙醇，并导致产物积累率为31 mM h−1。
{"title":"Assessing Peroxygenase-Mediated Oxidations in the Presence of High Concentrations of Water-Miscible Co-Solvents","authors":"T. Hilberath, Anouska van Troost, M. Alcalde, F. Hollmann","doi":"10.3389/fctls.2022.882992","DOIUrl":"https://doi.org/10.3389/fctls.2022.882992","url":null,"abstract":"The use of water-miscible organic co-solvents in biocatalysis is a simple procedure for obtaining higher enzymatic activities toward hydrophobic substrates. However, effects on activity and stability have to be carefully evaluated, also with regard to the type and concentration of the respective co-solvent. In this contribution, we investigated and evaluated the effect of some common water-miscible co-solvents on the biocatalytic performance of the recombinant unspecific peroxygenase rAaeUPO from Agrocybe aegerita. rAaeUPO showed promising activities in the presence of high concentrations of the best co-solvent acetonitrile, which enabled to use higher substrate concentrations (≥100 mM). Employing high acetonitrile concentrations for UPO-mediated oxidation of ethylbenzene to (R)-1-phenylethanol was demonstrated under preparative scale conditions and led to product accumulation rates of 31 mM h−1.","PeriodicalId":73071,"journal":{"name":"Frontiers in catalysis","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46860145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-17DOI: 10.3389/fctls.2022.883161
J. Woodley
The use of highly selective enzymes to catalyze value-added reactions outside the cell is commonly termed biocatalysis. In this brief perspective, some of the future opportunities for the application of biocatalysis are discussed. First, there are opportunities using multi-enzyme cascades where entirely new synthetic routes can be created independent of cellular constraints. Here the target is mostly high-priced products, such as pharmaceuticals. Secondly, there also exist opportunities for biocatalysis in the synthesis of low-priced products where the high productivities achievable make them eminently suited for drop-in solutions. Both options provide a wealth of interesting research and development possibilities, which are also discussed.
{"title":"New Horizons for Biocatalytic Science","authors":"J. Woodley","doi":"10.3389/fctls.2022.883161","DOIUrl":"https://doi.org/10.3389/fctls.2022.883161","url":null,"abstract":"The use of highly selective enzymes to catalyze value-added reactions outside the cell is commonly termed biocatalysis. In this brief perspective, some of the future opportunities for the application of biocatalysis are discussed. First, there are opportunities using multi-enzyme cascades where entirely new synthetic routes can be created independent of cellular constraints. Here the target is mostly high-priced products, such as pharmaceuticals. Secondly, there also exist opportunities for biocatalysis in the synthesis of low-priced products where the high productivities achievable make them eminently suited for drop-in solutions. Both options provide a wealth of interesting research and development possibilities, which are also discussed.","PeriodicalId":73071,"journal":{"name":"Frontiers in catalysis","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44707163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-10DOI: 10.3389/fctls.2022.892183
F. Zaccaria, Gabriel Menendez Rodriguez, L. Rocchigiani, A. Macchioni
Molecular hydrogen (H2) is considered an ideal energy vector and a clean fuel, due to its zero-carbon combustion. Nevertheless, despite hydrogen is the most and one of the most abundant elements in the universe and in earth crust, respectively, it is always combined with other elements in our planet and never appears in its elemental state. This means that H2 must be produced through, almost always, endergonic processes, whose sustainability depend not only on the starting material but also on the source of energy necessary for these processes to occur. Colors have been assigned to identify the level of sustainability of H2 production with the green one indicating H2 produced from water using a renewable source of energy, preferably sunlight. Redox water splitting (WS) into H2 (hydrogen evolution reaction, HER) and O2 (oxygen evolution reaction, OER) is, nevertheless, an extremely difficult process not only from the thermodynamic but also from the kinetic point of view. Relevant kinetic barriers are present in both sides of the redox process, especially in OER. For this reason, performing WS in an efficient manner requires the development of active and robust catalysts capable of offering alternative reaction pathways to WS, lowering down the unfavorable kinetic barriers and thus maximizing the energy conversion efficiency. Inspiration for developing efficient catalysts for HER and OER has traditionally derived from Nature, who, over the course of many billions of years, according to the evolutionary theory, has assembled two molecular catalytic pools, namely oxygen evolving complex and ferredoxin/ferredoxin NADP+ reductase, which offer viable kinetic pathways to both OER and reduction of NADP+ (the “biological form” of H2). In reality, after several attempts of mimicking natural catalysts, the efforts of the researchers have been addressed to different molecular systems, which exhibit best performances, unfortunately often based on noble-metal atoms, especially for OER. In this contribution we review the journey of the development of molecular catalysts for both HER and the OER, highlighting selected systems, which have brought us to the current level of knowledge.
{"title":"Molecular Catalysis in “Green” Hydrogen Production","authors":"F. Zaccaria, Gabriel Menendez Rodriguez, L. Rocchigiani, A. Macchioni","doi":"10.3389/fctls.2022.892183","DOIUrl":"https://doi.org/10.3389/fctls.2022.892183","url":null,"abstract":"Molecular hydrogen (H2) is considered an ideal energy vector and a clean fuel, due to its zero-carbon combustion. Nevertheless, despite hydrogen is the most and one of the most abundant elements in the universe and in earth crust, respectively, it is always combined with other elements in our planet and never appears in its elemental state. This means that H2 must be produced through, almost always, endergonic processes, whose sustainability depend not only on the starting material but also on the source of energy necessary for these processes to occur. Colors have been assigned to identify the level of sustainability of H2 production with the green one indicating H2 produced from water using a renewable source of energy, preferably sunlight. Redox water splitting (WS) into H2 (hydrogen evolution reaction, HER) and O2 (oxygen evolution reaction, OER) is, nevertheless, an extremely difficult process not only from the thermodynamic but also from the kinetic point of view. Relevant kinetic barriers are present in both sides of the redox process, especially in OER. For this reason, performing WS in an efficient manner requires the development of active and robust catalysts capable of offering alternative reaction pathways to WS, lowering down the unfavorable kinetic barriers and thus maximizing the energy conversion efficiency. Inspiration for developing efficient catalysts for HER and OER has traditionally derived from Nature, who, over the course of many billions of years, according to the evolutionary theory, has assembled two molecular catalytic pools, namely oxygen evolving complex and ferredoxin/ferredoxin NADP+ reductase, which offer viable kinetic pathways to both OER and reduction of NADP+ (the “biological form” of H2). In reality, after several attempts of mimicking natural catalysts, the efforts of the researchers have been addressed to different molecular systems, which exhibit best performances, unfortunately often based on noble-metal atoms, especially for OER. In this contribution we review the journey of the development of molecular catalysts for both HER and the OER, highlighting selected systems, which have brought us to the current level of knowledge.","PeriodicalId":73071,"journal":{"name":"Frontiers in catalysis","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44138140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-10DOI: 10.3389/fctls.2022.906668
P. Hagedoorn
Isothermal titration calorimetry (ITC) is a popular chemical analysis technique that can be used to measure macromolecular interactions and chemical and physical processes. ITC involves the measurement of heat flow to and from a measurement cell after each injection during a titration experiment. ITC has been useful to measure the thermodynamics of macromolecular interactions such as protein-ligand or protein-protein binding affinity and also chemical processes such as enzyme catalyzed reactions. The use of ITC in biocatalysis has a number of advantages as ITC enables the measurement of enzyme kinetic parameters in a direct manner and, in principle, can be used for most enzymes and substrates. ITC approaches have been developed to measure reversible and irreversible enzyme inhibition, the effects of molecular crowding on enzyme activity, the activity of immobilized enzymes and the conversion of complex polymeric substrates. A disadvantage is that in order to obtain accurate kinetic parameters special care has to be taken in proper experimental design and data interpretation, which unfortunately is not always the case in reported studies. Furthermore, special caution is necessary when ITC experiments are performed that include solvents, reducing agents and may have side reactions. An important bottleneck in the use of calorimetry to measure enzyme activity is the relatively low throughput, which may be solved in the future by sensitive chip based microfluidic enzyme calorimetric devices.
{"title":"Isothermal Titration Calorimetry in Biocatalysis","authors":"P. Hagedoorn","doi":"10.3389/fctls.2022.906668","DOIUrl":"https://doi.org/10.3389/fctls.2022.906668","url":null,"abstract":"Isothermal titration calorimetry (ITC) is a popular chemical analysis technique that can be used to measure macromolecular interactions and chemical and physical processes. ITC involves the measurement of heat flow to and from a measurement cell after each injection during a titration experiment. ITC has been useful to measure the thermodynamics of macromolecular interactions such as protein-ligand or protein-protein binding affinity and also chemical processes such as enzyme catalyzed reactions. The use of ITC in biocatalysis has a number of advantages as ITC enables the measurement of enzyme kinetic parameters in a direct manner and, in principle, can be used for most enzymes and substrates. ITC approaches have been developed to measure reversible and irreversible enzyme inhibition, the effects of molecular crowding on enzyme activity, the activity of immobilized enzymes and the conversion of complex polymeric substrates. A disadvantage is that in order to obtain accurate kinetic parameters special care has to be taken in proper experimental design and data interpretation, which unfortunately is not always the case in reported studies. Furthermore, special caution is necessary when ITC experiments are performed that include solvents, reducing agents and may have side reactions. An important bottleneck in the use of calorimetry to measure enzyme activity is the relatively low throughput, which may be solved in the future by sensitive chip based microfluidic enzyme calorimetric devices.","PeriodicalId":73071,"journal":{"name":"Frontiers in catalysis","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42146261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：