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M. Li
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8 records found
1
Journal article
(2026)
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Shuo Zhang, Ming Li, He Tian, J. Ruud van Ommen, Luuk C. Rietveld, Sebastiaan G.J. Heijman
Catalytic ceramic membranes are regarded as a promising technology for removal of organic micropollutants (OMPs). However, excessive catalyst loading will decrease membrane flux and increase deposition costs, thus hindering practical application. In this work, ceramic ultrafiltration membranes were modified by atomic layer deposition to achieve a low loading of palladium (Pd) for OMP degradation. The Pd deposited on the membrane surface and within the pores was used to activate peroxymonosulfate (PMS) to induce reactive species (RS) for the degradation of four OMPs (benzotriazole, diclofenac, sotalol, and trimethoprim). The Pd-deposited membranes exhibited an almost complete degradation of the four OMPs at a high flux of 100 L/(m2 h). Notably, Pd confined within membrane nanopores induced a pronounced nano-confinement effect, enhancing degradation kinetics by up to three orders of magnitude compared to surface-deposited Pd, revealing a distinct catalytic mechanism governed by confined reaction environments. Varying RS can be generated from PMS activation by Pd-modified alumina membranes, but the dominant RS pathways were found to depend on the type of OMPs, providing new mechanistic insight into PMS activation in heterogeneous catalytic membrane systems. A high degradation efficacy was achieved at a pH of 7, while the PMS dosage (20–80 μM), anion (1 mM Cl¯, SO42¯, HCO3¯, or ClO¯), and natural substances in river water had a minor impact on the OMPs' degradation. However, considerably high salinity, e.g., as present in brine water, exhibited a negative impact on the degradation of certain OMPs. This study demonstrates that a robust and effective strategy for OMPs' degradation can be achieved by ceramic membranes with a low loading of catalysts, which shows strong potential for cost-effective and scalable application in water treatment.
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Catalytic ceramic membranes are regarded as a promising technology for removal of organic micropollutants (OMPs). However, excessive catalyst loading will decrease membrane flux and increase deposition costs, thus hindering practical application. In this work, ceramic ultrafiltration membranes were modified by atomic layer deposition to achieve a low loading of palladium (Pd) for OMP degradation. The Pd deposited on the membrane surface and within the pores was used to activate peroxymonosulfate (PMS) to induce reactive species (RS) for the degradation of four OMPs (benzotriazole, diclofenac, sotalol, and trimethoprim). The Pd-deposited membranes exhibited an almost complete degradation of the four OMPs at a high flux of 100 L/(m2 h). Notably, Pd confined within membrane nanopores induced a pronounced nano-confinement effect, enhancing degradation kinetics by up to three orders of magnitude compared to surface-deposited Pd, revealing a distinct catalytic mechanism governed by confined reaction environments. Varying RS can be generated from PMS activation by Pd-modified alumina membranes, but the dominant RS pathways were found to depend on the type of OMPs, providing new mechanistic insight into PMS activation in heterogeneous catalytic membrane systems. A high degradation efficacy was achieved at a pH of 7, while the PMS dosage (20–80 μM), anion (1 mM Cl¯, SO42¯, HCO3¯, or ClO¯), and natural substances in river water had a minor impact on the OMPs' degradation. However, considerably high salinity, e.g., as present in brine water, exhibited a negative impact on the degradation of certain OMPs. This study demonstrates that a robust and effective strategy for OMPs' degradation can be achieved by ceramic membranes with a low loading of catalysts, which shows strong potential for cost-effective and scalable application in water treatment.
Journal article
(2026)
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Shilong Fu, Bowen Sha, Asvin Sajeev, Ming Li, Thijs J.H. Vlugt, Othonas A. Moultos, Wiebren de Jong, Ruud Kortlever
Electrochemical CO2 reduction to CO offers a sustainable route for converting CO2 into value-added chemicals and fuels. However, CO2 streams derived from industrial sources often contain SO2 impurities that severely poison conventional metal-based catalysts. Here, we report a nitrogen-doped carbon catalyst that exhibits pronounced tolerance and stability for CO2-to-CO conversion in the presence of SO2 (100–10,000 ppm). The catalyst maintains over 90% Faradaic efficiency toward CO during 8 h of electrolysis at −1.0 V vs RHE with 100 ppm of SO2, whereas Ag foil electrodes undergo rapid deactivation. Density functional theory calculations combined with surface analyses indicate that weak SO2 adsorption and the absence of stable sulfur accumulation on nitrogen-doped carbon strengthen its resistance to impurity-induced deactivation, in contrast to Ag catalysts that form Ag2S. Gas-fed tests in a membrane electrode assembly (MEA) electrolyzer further confirm that nitrogen-doped carbon sustains high CO selectivity at elevated current densities, while Ag nanoparticles suffer irreversible sulfur poisoning. These results demonstrate that nitrogen-doped carbon is intrinsically resistant to SO2-induced deactivation and highlight its potential as a robust catalyst for CO2 electroreduction under impurity-containing conditions.
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Electrochemical CO2 reduction to CO offers a sustainable route for converting CO2 into value-added chemicals and fuels. However, CO2 streams derived from industrial sources often contain SO2 impurities that severely poison conventional metal-based catalysts. Here, we report a nitrogen-doped carbon catalyst that exhibits pronounced tolerance and stability for CO2-to-CO conversion in the presence of SO2 (100–10,000 ppm). The catalyst maintains over 90% Faradaic efficiency toward CO during 8 h of electrolysis at −1.0 V vs RHE with 100 ppm of SO2, whereas Ag foil electrodes undergo rapid deactivation. Density functional theory calculations combined with surface analyses indicate that weak SO2 adsorption and the absence of stable sulfur accumulation on nitrogen-doped carbon strengthen its resistance to impurity-induced deactivation, in contrast to Ag catalysts that form Ag2S. Gas-fed tests in a membrane electrode assembly (MEA) electrolyzer further confirm that nitrogen-doped carbon sustains high CO selectivity at elevated current densities, while Ag nanoparticles suffer irreversible sulfur poisoning. These results demonstrate that nitrogen-doped carbon is intrinsically resistant to SO2-induced deactivation and highlight its potential as a robust catalyst for CO2 electroreduction under impurity-containing conditions.
The severe effects of climate change, along with the rising global energy demand, have driven extensive research efforts into the development of sustainable technologies for energy generation, conversion, storage, distribution, and CO2 removal from various industrial sectors. Electrocatalysis is expected to play a pivotal role in achieving these goals, as it can utilize intermitent renewable energy sources such as wind, geothermal, hydropower and solar energy, together with CO2 directly captured from the air or from flue gas, and H2O, to store energy into chemical building blocks. Meanwhile, the catalyst is indispensable in these electrochemical conversions, as it enables the reduction of the reaction energy barrier, thereby lowering the electrochemical overpotential required to initiate reactions. Moreover, it facilitates the direction of reactions along specific pathways without itself being consumed in the process, thereby enhancing reaction rates and improving the efficiency. This thesis focuses on the electrocatalysts used for CO2 reduction and water spling, and uses atomic layer deposition (ALD) and molecular layer deposition (MLD) to precisely control the catalyst structure and protect the catalysts from degradation and poisoning...
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The severe effects of climate change, along with the rising global energy demand, have driven extensive research efforts into the development of sustainable technologies for energy generation, conversion, storage, distribution, and CO2 removal from various industrial sectors. Electrocatalysis is expected to play a pivotal role in achieving these goals, as it can utilize intermitent renewable energy sources such as wind, geothermal, hydropower and solar energy, together with CO2 directly captured from the air or from flue gas, and H2O, to store energy into chemical building blocks. Meanwhile, the catalyst is indispensable in these electrochemical conversions, as it enables the reduction of the reaction energy barrier, thereby lowering the electrochemical overpotential required to initiate reactions. Moreover, it facilitates the direction of reactions along specific pathways without itself being consumed in the process, thereby enhancing reaction rates and improving the efficiency. This thesis focuses on the electrocatalysts used for CO2 reduction and water spling, and uses atomic layer deposition (ALD) and molecular layer deposition (MLD) to precisely control the catalyst structure and protect the catalysts from degradation and poisoning...
Electrochemical CO2 reduction presents an opportunity to transform waste flue gas with water and renewable electricity into chemicals or fuels. However, the energy-intensive nature of purification of flue gas underscores the appeal of directly utilizing the flue gas streams containing impurities. In this study, we investigate the impact of SO2 impurities on CO2 electroreduction in two electrochemical cell geometries: an H-cell and a membrane electrode assembly (MEA) cell. We observe distinctly different behavior of the Ag on carbon black (Ag/CB) catalyst under SO2 impurities in the H-cell compared to the MEA cell, where SO2 impurities exhibit a more pronounced effect on Ag/CB catalysts in the H-cell than in the MEA cell. This difference is attributed to the higher solubility of SO2 in the electrolyte compared to CO2, resulting in an accumulation effect and causing differences in the SO2 concentration near the electrode between the H-cell and the MEA system. By depositing a very thin SiO2 coating on the outermost surface of the Ag/CB catalyst using atomic layer deposition (ALD), the impact of SO2 on the catalyst's selectivity is diminished. This is attributed to the permeability difference between CO2 and SO2 through the SiO2 coatings and results in a local SO2 concentration difference between samples with and without SiO2 coatings.
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Electrochemical CO2 reduction presents an opportunity to transform waste flue gas with water and renewable electricity into chemicals or fuels. However, the energy-intensive nature of purification of flue gas underscores the appeal of directly utilizing the flue gas streams containing impurities. In this study, we investigate the impact of SO2 impurities on CO2 electroreduction in two electrochemical cell geometries: an H-cell and a membrane electrode assembly (MEA) cell. We observe distinctly different behavior of the Ag on carbon black (Ag/CB) catalyst under SO2 impurities in the H-cell compared to the MEA cell, where SO2 impurities exhibit a more pronounced effect on Ag/CB catalysts in the H-cell than in the MEA cell. This difference is attributed to the higher solubility of SO2 in the electrolyte compared to CO2, resulting in an accumulation effect and causing differences in the SO2 concentration near the electrode between the H-cell and the MEA system. By depositing a very thin SiO2 coating on the outermost surface of the Ag/CB catalyst using atomic layer deposition (ALD), the impact of SO2 on the catalyst's selectivity is diminished. This is attributed to the permeability difference between CO2 and SO2 through the SiO2 coatings and results in a local SO2 concentration difference between samples with and without SiO2 coatings.
Journal article
(2025)
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Shilong Fu, Boaz Izelaar, Ming Li, Qi An, Min Li, Wiebren de Jong, Ruud Kortlever
Carbon-supported nickel and nitrogen co-doped (Ni-N-C) catalysts have been extensively studied as selective and active catalysts for CO2 electroreduction to CO. Most studies have focused on adjusting the coordination structure of Ni-Nx active sites, while the impact of the carbon supports has often been overlooked. In this study, a series of Ni-N-C catalysts on different carbon supports, including carbon black (CB), multi-walled carbon nanotubes (CNT), and activated nitrogen-doped biochar (ANBC), were synthesized using a ligand-mediated method. The effect of the carbon support on the electrocatalytic performance for CO2 reduction was investigated at both low current densities, in a H-cell, and high current densities, in a MEA electrolyzer. All of the prepared Ni-N-C catalysts show good faradaic efficiencies (FE) toward CO production (up to ∼90 %), however, the onset potentials and partial current densities for CO production vary greatly. The textural properties of the carbon support and the distribution of Ni-Nx active sites on the carbon support are demonstrated as the main factors behind the performance differences. In particular, hierarchical porous structures with a large specific surface area are helpful to facilitate mass transport and improve the dispersion of active sites, which allows for a better CO2 reduction performance of Ni-N-ANBC compared to Ni-N-CB and Ni-N-CNT. This study demonstrates the importance of the carbon support for Ni-N-C catalysts and provides new insights into the design of efficient Ni-N-C catalysts for the CO2RR.
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Carbon-supported nickel and nitrogen co-doped (Ni-N-C) catalysts have been extensively studied as selective and active catalysts for CO2 electroreduction to CO. Most studies have focused on adjusting the coordination structure of Ni-Nx active sites, while the impact of the carbon supports has often been overlooked. In this study, a series of Ni-N-C catalysts on different carbon supports, including carbon black (CB), multi-walled carbon nanotubes (CNT), and activated nitrogen-doped biochar (ANBC), were synthesized using a ligand-mediated method. The effect of the carbon support on the electrocatalytic performance for CO2 reduction was investigated at both low current densities, in a H-cell, and high current densities, in a MEA electrolyzer. All of the prepared Ni-N-C catalysts show good faradaic efficiencies (FE) toward CO production (up to ∼90 %), however, the onset potentials and partial current densities for CO production vary greatly. The textural properties of the carbon support and the distribution of Ni-Nx active sites on the carbon support are demonstrated as the main factors behind the performance differences. In particular, hierarchical porous structures with a large specific surface area are helpful to facilitate mass transport and improve the dispersion of active sites, which allows for a better CO2 reduction performance of Ni-N-ANBC compared to Ni-N-CB and Ni-N-CNT. This study demonstrates the importance of the carbon support for Ni-N-C catalysts and provides new insights into the design of efficient Ni-N-C catalysts for the CO2RR.
Extending the lifetime of electrocatalytic materials is a major challenge in electrocatalysis. Here, we employ atomic layer deposition (ALD) to coat the surface of carbon black supported platinum nanoparticles (Pt/CB) with an ultra-thin layer of silicon dioxide (SiO2) to prevent deactivation of the catalyst during H2 evolution. Our results show that after an accelerated durability test (ADT) the current density at −0.2 V vs. reversible hydrogen electrode (RHE) of the unprotected Pt/CB catalyst was reduced by 34%. By contrast, after coating the Pt/CB catalyst with 2 SiO2 ALD cycles, the current density at the same potential was reduced by 7% after the ADT procedure, whereas when the Pt/CB sample was coated with 5 SiO2 ALD cycles, the current density was reduced by only 2% after the ADT. Characterization of the Pt particles after electrochemical testing shows that the average particle size of the uncoated Pt/CB catalyst increases by roughly 16% after the ADT, whereas it only increases by 3% for the Pt/CB catalyst coated with 5 cycles of SiO2 ALD. In addition, the coating also strongly reduces the detachment of Pt nanoparticles, as shown by a strong decrease in the Pt concentration in the electrolyte after the ADT. However, 20 cycles of SiO2 ALD coating results in an over-thick coating that has an inhibitory effect on the catalytic activity. In summary, we demonstrate that only a few cycles of SiO2 ALD can strongly improve the stability of Pt catalyst for the hydrogen evolution reaction.
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Extending the lifetime of electrocatalytic materials is a major challenge in electrocatalysis. Here, we employ atomic layer deposition (ALD) to coat the surface of carbon black supported platinum nanoparticles (Pt/CB) with an ultra-thin layer of silicon dioxide (SiO2) to prevent deactivation of the catalyst during H2 evolution. Our results show that after an accelerated durability test (ADT) the current density at −0.2 V vs. reversible hydrogen electrode (RHE) of the unprotected Pt/CB catalyst was reduced by 34%. By contrast, after coating the Pt/CB catalyst with 2 SiO2 ALD cycles, the current density at the same potential was reduced by 7% after the ADT procedure, whereas when the Pt/CB sample was coated with 5 SiO2 ALD cycles, the current density was reduced by only 2% after the ADT. Characterization of the Pt particles after electrochemical testing shows that the average particle size of the uncoated Pt/CB catalyst increases by roughly 16% after the ADT, whereas it only increases by 3% for the Pt/CB catalyst coated with 5 cycles of SiO2 ALD. In addition, the coating also strongly reduces the detachment of Pt nanoparticles, as shown by a strong decrease in the Pt concentration in the electrolyte after the ADT. However, 20 cycles of SiO2 ALD coating results in an over-thick coating that has an inhibitory effect on the catalytic activity. In summary, we demonstrate that only a few cycles of SiO2 ALD can strongly improve the stability of Pt catalyst for the hydrogen evolution reaction.
N-doped carbon materials can be efficient and cost-effective catalysts for the electrochemical CO2 reduction reaction (CO2RR). Activators are often used in the synthesis process to increase the specific surface area and porosity of these carbon materials. However, owing to the diversity of activators and the differences in physicochemical properties that these activators induce, the influence of activators used for the synthesis of N-doped carbon catalysts on their electrochemical performance is unclear. In this study, a series of bagasse-derived N-doped carbon catalysts is prepared with the assistance of different activators to understand the correlation between activators, physicochemical properties, and electrocatalytic performance for the CO2RR. The properties of N-doped carbon catalysts, such as N-doping content, microstructure, and degree of graphitization, are found to be highly dependent on the type of activator applied in the synthesis procedure. Moreover, the overall CO2RR performance of the synthesized electrocatalysts is not determined only by the N-doping level and the configuration of the N-dopant, but rather by the overall surface chemistry, where the porosity and the degree of graphitization are jointly responsible for significant differences in CO2RR performance.
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N-doped carbon materials can be efficient and cost-effective catalysts for the electrochemical CO2 reduction reaction (CO2RR). Activators are often used in the synthesis process to increase the specific surface area and porosity of these carbon materials. However, owing to the diversity of activators and the differences in physicochemical properties that these activators induce, the influence of activators used for the synthesis of N-doped carbon catalysts on their electrochemical performance is unclear. In this study, a series of bagasse-derived N-doped carbon catalysts is prepared with the assistance of different activators to understand the correlation between activators, physicochemical properties, and electrocatalytic performance for the CO2RR. The properties of N-doped carbon catalysts, such as N-doping content, microstructure, and degree of graphitization, are found to be highly dependent on the type of activator applied in the synthesis procedure. Moreover, the overall CO2RR performance of the synthesized electrocatalysts is not determined only by the N-doping level and the configuration of the N-dopant, but rather by the overall surface chemistry, where the porosity and the degree of graphitization are jointly responsible for significant differences in CO2RR performance.
Journal article
(2022)
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Ming Li, Shilong Fu, Saeed Saedy, Aparna Rajendrakumar, Frans D. Tichelaar, Ruud Kortlever, J. Ruud van Ommen
Preparing supported nanoparticles with a well-defined structure, uniform particle size, and composition using conventional catalyst synthesis methods, such as impregnation, precipitation, and deposition-precipitation is challenging. Furthermore, these liquid phase methods require significant solvent consumption, which has sustainable issues and requires complex purification processes, usually leaving impurities on the catalyst, affecting its selectivity and activity. In this work, we employed atomic layer deposition (ALD, a vapor phase synthesis method) to synthesize electrocatalysts with well-controlled core-shell and alloy structures for CO2 reduction to formic acid. With this approach, the structural control of the catalysts is down to the atomic scale, and the effect of core-shell and alloy structure on Pt−Pd bimetallic catalysts has been investigated. It is shown that the Pt−Pd alloy catalyst displays a 46 % faradaic efficiency toward formic acid, outperforming Pt@Pd and Pd@Pt core-shell structures that show faradaic efficiencies of 22 % and 11 %, respectively. Moreover, both core-shell bimetallic catalysts (Pd@Pt and Pt@Pd) are not stable under electroreduction conditions. These catalysts restructure to more thermodynamically stable structures, such as segregated clusters or alloy particles, during the electrochemical reduction reaction, altering the catalytic selectivity.
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Preparing supported nanoparticles with a well-defined structure, uniform particle size, and composition using conventional catalyst synthesis methods, such as impregnation, precipitation, and deposition-precipitation is challenging. Furthermore, these liquid phase methods require significant solvent consumption, which has sustainable issues and requires complex purification processes, usually leaving impurities on the catalyst, affecting its selectivity and activity. In this work, we employed atomic layer deposition (ALD, a vapor phase synthesis method) to synthesize electrocatalysts with well-controlled core-shell and alloy structures for CO2 reduction to formic acid. With this approach, the structural control of the catalysts is down to the atomic scale, and the effect of core-shell and alloy structure on Pt−Pd bimetallic catalysts has been investigated. It is shown that the Pt−Pd alloy catalyst displays a 46 % faradaic efficiency toward formic acid, outperforming Pt@Pd and Pd@Pt core-shell structures that show faradaic efficiencies of 22 % and 11 %, respectively. Moreover, both core-shell bimetallic catalysts (Pd@Pt and Pt@Pd) are not stable under electroreduction conditions. These catalysts restructure to more thermodynamically stable structures, such as segregated clusters or alloy particles, during the electrochemical reduction reaction, altering the catalytic selectivity.