Catalysis by ultrathin
LaBO₃ (B=Co, Fe) perovskite films

@article{Maqbool_2024b,

title = {Highly Stable Self-Cleaning Paints Based on Waste-Valorized PNC-Doped TiO_{2} Nanoparticles},

author = {Qaisar Maqbool and Orlando Favoni and Thomas Wicht and Niusha Lasemi and Simona Sabbatini and Michael Stöger-Pollach and Maria Letizia Ruello and Francesca Tittarelli and Günther Rupprechter},

url = {https://doi.org/10.1021/acscatal.3c06203},

year  = {2024},

date = {2024-03-15},

journal = {ACS Catalysis},

volume = {14},

issue = {7},

pages = {4820–4834},

abstract = {Adding photocatalytically active TiO_{2} nanoparticles (NPs) to polymeric paints is a feasible route toward self-cleaning coatings. While paint modification by TiO_{2}-NPs may improve photoactivity, it may also cause polymer degradation and release of toxic volatile organic compounds. To counterbalance adverse effects, a synthesis method for nonmetal (P, N, and C)-doped TiO_{2}-NPs is introduced, based purely on waste valorization. PNC-doped TiO_{2}-NP characterization by vibrational and photoelectron spectroscopy, electron microscopy, diffraction, and thermal analysis suggests that TiO_{2}-NPs were modified with phosphate (P═O), imine species (R═N-R), and carbon, which also hindered the anatase/rutile phase transformation, even upon 700 °C calcination. When added to water-based paints, PNC-doped TiO_{2}-NPs achieved 96% removal of surface-adsorbed pollutants under natural sunlight or UV, paralleled by stability of the paint formulation, as confirmed by micro-Fourier transform infrared (FTIR) surface analysis. The origin of the photoinduced self-cleaning properties was rationalized by three-dimensional (3D) and synchronous photoluminescence spectroscopy, indicating that the dopants led to 7.3 times stronger inhibition of photoinduced e^{–}/h^{+} recombination when compared to a benchmark P25 photocatalyst.},

keywords = {P08},

pubstate = {published},

tppubtype = {article}

}

@article{Sidorowicz_2024a,

title = {Microalgae-derived Co_{3}O_{4} nanomaterials for catalytic CO oxidation},

author = {Agnieszka Sidorowicz and Nevzat Yigit and Thomas Wicht and Michael Stöger-Pollach and Alessandro Concas and Roberto Orrù and Giacomo Cao and Günther Rupprechter},

url = {https://doi.org/10.1039/D4RA00343H},

year  = {2024},

date = {2024-02-05},

urldate = {2024-02-05},

journal = {RSC Advances},

volume = {14},

pages = {4575-4586},

abstract = {Efficient carbon monoxide oxidation is important to reduce its impacts on both human health and the environment. Following a sustainable synthesis route toward new catalysts, nanosized Co_{3}O_{4} was synthesized based on extracts of microalgae: Spirulina platensis, Chlorella vulgaris, and Haematococcus pluvialis. Using the metabolites in the extract and applying different calcination temperatures (450, 650, 800 °C) led to Co_{3}O_{4} catalysts with distinctly different properties. The obtained Co_{3}O_{4} nanomaterials exhibited octahedral, nanosheet, and spherical morphologies with structural defects and surface segregation of phosphorous and potassium, originating from the extracts. The presence of P and K in the oxide nanostructures significantly improved their catalytic CO oxidation activity. When normalized by the specific surface area, the microalgae-derived catalysts exceeded a commercial benchmark catalyst. In situ studies revealed differences in oxygen mobility and carbonate formation during the reaction. The obtained insights may facilitate the development of new synthesis strategies for manufacturing highly active Co_{3}O_{4} nanocatalysts.},

keywords = {P08},

pubstate = {published},

tppubtype = {article}

}

@article{Chanka_2024a,

title = {Potassium Permanganate-Impregnated Amorphous Silica–Alumina Derived from Sugar Cane Bagasse Ash as an Ethylene Scavenger for Extending Shelf Life of Mango Fruits},

author = {Napassorn Chanka and Waleeporn Donphai and Metta Chareonpanich and Kajornsak Faungnawakij and Günther Rupprechter and Anusorn Seubsai},

url = {https://doi.org/10.1021/acsomega.3c08119},

year  = {2024},

date = {2024-02-02},

journal = {ACS Omega},

volume = {9},

issue = {6},

pages = {6749–6760},

abstract = {Ethylene, a plant hormone, is a gas that plays a crucial role in fruit ripening and senescence. In this work, a novel ethylene scavenger was prepared from amorphous silica–alumina derived from sugar cane bagasse ash (SC-ASA) and used to prolong the shelf life of mango fruits during storage. KMnO_{4} at 2, 4, or 6 wt %/w was loaded on SC-ASA using an impregnation method. The results showed that 4% w/w KMnO_{4} loaded on SC-ASA (4KM/SC-ASA) was superior for ethylene removal at an initial ethylene concentration of 400 μL L^{–1} for 120 min under ambient conditions (25–27 °C and 70–75% relative humidity), resulting in 100% ethylene removal. The kinetic study of ethylene removal showed that the adsorption data were best fitted with a pseudo-first-order kinetic model. The effects of 4KM/SC-ASA as sachets on the quality changes of the mango fruits were investigated, with the results showing that mango fruits packed in cardboard boxes with 4KM/SC-ASA had significantly delayed ripening, low levels of ethylene production, respiration, and weight loss, high fruit firmness, low total soluble solids, and high acidity compared to those of the control treatment. These findings should contribute to developing an ethylene scavenger to extend the shelf life of fruits, reduce the waste of the sugar and ethanol industries, and make it a valuable material.},

keywords = {P08},

pubstate = {published},

tppubtype = {article}

}

@article{Raab2023b,

title = {Lanthanum modulated reaction pacemakers on a single catalytic nanoparticle},

author = {Maximilian Raab and Johannes Zeininger and Yuri Suchorski and Alexander Genest and Carla Weigl and Günther Rupprechter},

doi = {10.1038/s41467-023-43026-3},

year  = {2023},

date = {2023-11-08},

urldate = {2023-11-08},

journal = {Nature Communications},

volume = {14},

number = {7186},

abstract = {Promoters are important in catalysis, but the atomistic details of their function and particularly their role in reaction instabilities such as kinetic phase transitions and oscillations are often unknown. Employing hydrogen oxidation as probe reaction, a Rh nanotip for mimicking a single Rh nanoparticle and field electron microscopy for in situ monitoring, we demonstrate a La-mediated local catalytic effect. The oscillatory mode of the reaction provides a tool for studying the interplay between different types of reaction pacemakers, i.e., specific local surface atomic configurations that initiate kinetic transitions. The presence of La shifts the bistable reaction states, changes the oscillation pattern and deactivates one of two pacemaker types for the La-free surface. The observed effects originate from the La-enhanced oxygen activation on the catalyst. The experimental observations are corroborated by micro-kinetic model simulations comprising a system of 25 coupled oscillators.},

keywords = {P08},

pubstate = {published},

tppubtype = {article}

}

@article{Phichairatanaphong2023,

title = {Highly Efficient Conversion of Greenhouse Gases Using a Quadruple Mixed Oxide-Supported Nickel Catalyst in Reforming Process},

author = {Orrakanya Phichairatanaphong and Nevzat Yigit and Günther Rupprechter and Metta Chareonpanich and Waleeporn Donphai},

doi = {10.1021/acs.iecr.3c02030},

year  = {2023},

date = {2023-10-02},

urldate = {2023-10-02},

journal = {Industrial & Engineering Chemistry Research},

volume = {62},

issue = {40},

pages = {16254--16267},

abstract = {The greenhouse gas reduction as well as the utilization of more renewable and clean energy via a dry reforming reaction is of interest. The impact of a CeMgZnAl oxide quad-blend-supported Ni catalyst on performance and anticoking during dry reforming reactions at 700 °C was studied. A high Ce–Mg/Zn ratio, as seen in the CeMg_{0.5}ZnAl-supported nickel catalyst, enhances lattice oxygen, and the presence of strong basic sites, along with the creation of the carbonate intermediate species, is accompanied by the production of gaseous CO through a gasification reaction between the carbon species and Ni-CO_{ads-lin} site. The phenomena caused the outstanding performance of the Ni/CeMg_{0.5}ZnAl catalyst─CH_{4} (84%), CO_{2} (83%) conversions, and the H_{2}/CO (0.80) ratio; moreover, its activity was also stable throughout 30 h.},

keywords = {P08},

pubstate = {published},

tppubtype = {article}

}

@article{Tangpakonsab2023,

title = {Kinetic and Computational Studies of CO Oxidation and PROX on Cu/CeO_{2} Nanospheres},

author = {Parinya Tangpakonsab and Alexander Genest and Jingxia Yang and Ali Meral and Bingjie Zou and Nevzat Yigit and Sabine Schwarz and Günther Rupprechter},

doi = {10.1007/s11244-023-01848-x},

year  = {2023},

date = {2023-07-31},

urldate = {2023-07-31},

journal = {Topics in Catalysis},

volume = {66},

pages = {1129--1142},

publisher = {Springer Science and Business Media LLC},

abstract = {As supported CuO is well-known for low temperature activity, CuO/CeO_{2} nanosphere catalysts were synthesized and tested for CO oxidation and preferential oxidation of CO (PROX) in excess H_{2}. For the first reaction, ignition was observed at 95 °C, whereas selective PROX occurred in a temperature window from 50 to 100 °C. The catalytic performance was independent of the initial oxidation state of the catalyst (CuO vs. Cu^{0}), suggesting that the same active phase is formed under reaction conditions. Density functional modeling was applied to elucidate the intermediate steps of CO oxidation, as well as those of the comparably less feasible H_{2} transformation. In the simulations, various Cu and vacancy sites were probed as reactive centers enabling specific pathways.},

keywords = {P08},

pubstate = {published},

tppubtype = {article}

}

@article{Asencios2023,

title = {Partial Oxidation of Bio-methane over Nickel Supported on MgO–ZrO_{2} Solid Solutions},

author = {Yvan J. O. Asencios and Nevzat Yigit and Thomas Wicht and Michael Stöger-Pollach and Alessandra F. Lucrédio and Francielle C. F. Marcos and Elisabete M. Assaf and Günther Rupprechter},

doi = {10.1007/s11244-023-01822-7},

year  = {2023},

date = {2023-05-24},

urldate = {2023-05-24},

journal = {Topics in Catalysis},

volume = {66},

pages = {1539--1552},

publisher = {Springer Science and Business Media LLC},

abstract = {Syngas can be produced from biomethane via Partial Oxidation of Methane (POM), being an attractive route since it is ecofriendly and sustainable. In this work, catalysts of Ni supported on MgO–ZrO_{2} solid solutions, prepared by a one-step polymerization method, were characterized by HRTEM/EDX, XRD, XPS, H_{2}-TPR, and in situ XRD. All catalysts, including Ni/ZrO_{2} and Ni/MgO as reference, were tested for POM (CH_{4}:O_{2} molar ratio 2, 750 ºC, 1 atm). NiO/MgO/ZrO_{2} contained two solid-solutions, MgO–ZrO2 and NiO-MgO, as revealed by XRD and XPS. Ni (30 wt%) supported on MgO–ZrO_{2} solid solution exhibited high methane conversion and hydrogen selectivity. However, depending on the MgO amount (0, 4, 20, 40, 100 molar percent) major differences in NiO reducibility, growth of Ni^{0} crystallite size during H_{2} reduction and POM, and in carbon deposition rates were observed. Interestingly, catalysts with lower MgO content achieved the highest CH_{4} conversion (~ 95%), high selectivity to H_{2} (1.7) and CO (0.8), and low carbon deposition rates (0.024 g_{carbon} g_{cat}^{−1} h^{−1}) with Ni_{4}MgZr (4 mol% MgO) turning out to be the best catalyst. In situ XRD during POM indicated metallic Ni nanoparticles (average crystallite size of 31 nm), supported by MgO–ZrO_{2} solid solution, with small amounts of NiO–MgO being present as well. The presence of MgO also influenced the morphology of the carbon deposits, leading to filaments instead of amorphous carbon. A combustion-reforming mechanism is suggested and using a MgO–ZrO_{2} solid solution support strongly improves catalytic performance, which is attributed to effective O_{2}, CO_{2} and H_{2}O activation at the Ni/MgO–ZrO_{2} interface.},

keywords = {P08},

pubstate = {published},

tppubtype = {article}

}

@article{doi:10.1021/acscatal.3c00060,

title = {Imaging Interface and Particle Size Effects by In Situ Correlative Microscopy of a Catalytic Reaction},

author = {Philipp Winkler and Maximilian Raab and Johannes Zeininger and Lea M. Rois and Yuri Suchorski and Michael Stöger-Pollach and Matteo Amati and Rahul Parmar and Luca Gregoratti and Günther Rupprechter},

doi = {10.1021/acscatal.3c00060},

year  = {2023},

date = {2023-05-23},

urldate = {2023-01-01},

journal = {ACS Catalysis},

volume = {13},

number = {11},

pages = {7650--7660},

abstract = {The catalytic behavior of Rh particles supported by three different materials (Rh, Au, and ZrO_{2_{) in H_{2_{ oxidation has been studied in situ by correlative photoemission electron microscopy (PEEM) and scanning photoemission electron microscopy (SPEM). Kinetic transitions between the inactive and active steady states were monitored, and self-sustaining oscillations on supported Rh particles were observed. Catalytic performance differed depending on the support and Rh particle size. Oscillations varied from particle size-independent (Rh/Rh) via size-dependent (Rh/ZrO_{2_{) to fully inhibited (Rh/Au). For Rh/Au, the formation of a surface alloy induced such effects, whereas for Rh/ZrO_{2_{, the formation of substoichiometric Zr oxides on the Rh surface, enhanced oxygen bonding, Rh-oxidation, and hydrogen spillover onto the ZrO_{2_{ support were held responsible. The experimental observations were complemented by micro-kinetic simulations, based on variations of hydrogen adsorption and oxygen binding. The results demonstrate how correlative in situ surface microscopy enables linking of the local structure, composition, and catalytic performance.},

keywords = {P08},

pubstate = {published},

tppubtype = {article}

}

@article{Pramhaas2023,

title = {Polarization-Dependent Sum-Frequency-Generation Spectroscopy for In Situ Tracking of Nanoparticle Morphology},

author = {Verena Pramhaas and Holger Unterhalt and Hans-Joachim Freund and Günther Rupprechter},

doi = {10.1002/anie.202300230},

year  = {2023},

date = {2023-03-08},

journal = {Angewandte Chemie - International Edition},

volume = {62},

number = {19},

publisher = {Wiley},

abstract = {The surface structure of oxide-supported metal nanoparticles can be determined via characteristic vibrations of adsorbed probe molecules such as CO. Usually, spectroscopic studies focus on peak position and intensity, which are related to binding geometries and number of adsorption sites, respectively. Employing two differently prepared model catalysts, it is demonstrated that polarization-dependent sum-frequency-generation (SFG) spectroscopy reveals the average surface structure and shape of the nanoparticles. SFG results for different particle sizes and morphologies are compared to direct real-space structure analysis by TEM and STM. The described feature of SFG could be used to monitor particle restructuring in situ and may be a valuable tool for operando catalysis.},

keywords = {P08},

pubstate = {published},

tppubtype = {article}

}

@article{Raab2023,

title = {Emergence of chaos in a compartmentalized catalytic reaction nanosystem},

author = {Maximilian Raab and Johannes Zeininger and Yuri Suchorski and Keita Tokuda and Günther Rupprechter},

doi = {10.1038/s41467-023-36434-y},

year  = {2023},

date = {2023-02-10},

urldate = {2023-02-01},

journal = {Nature Communications},

volume = {14},

pages = {736--745},

publisher = {Springer Science and Business Media LLC},

abstract = {In compartmentalized systems, chemical reactions may proceed in differing ways even in adjacent compartments. In compartmentalized nanosystems, the reaction behaviour may deviate from that observed on the macro- or mesoscale. In situ studies of processes in such nanosystems meet severe experimental challenges, often leaving the field to theoretical simulations. Here, a rhodium nanocrystal surface consisting of different nm-sized nanofacets is used as a model of a compartmentalized reaction nanosystem. Using field emission microscopy, different reaction modes are observed, including a transition to spatio-temporal chaos. The transitions between different modes are caused by variations of the hydrogen pressure modifying the strength of diffusive coupling between individual nanofacets. Microkinetic simulations, performed for a network of 52 coupled oscillators, reveal the origins of the different reaction modes. Since diffusive coupling is characteristic for many living and non-living compartmentalized systems, the current findings may be relevant for a wide class of reaction systems.},

keywords = {P08},

pubstate = {published},

tppubtype = {article}

}