Article
Chemistry, Multidisciplinary
Matthias Peeters, Jonathan Decaens, Alois Fuerstner
Summary: Chiral [BiRh]-paddlewheel complexes empowered by London dispersion enable the generation of (trifluoromethyl)furfurylidene metal complexes from a bench-stable triftosylhydrazone precursor. These complexes undergo asymmetric [2+1] cycloadditions, providing optically active trifluoromethylated cyclopropane or -cyclopropene derivatives, which are important building blocks for medicinal chemistry and difficult to obtain in optically active form.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Review
Chemistry, Inorganic & Nuclear
Han Peng, Vincent Ritleng, Christophe Michon
Summary: This article reviews the development of supported Noyori-Ikariya catalysts based on ruthenium, rhodium, and iridium for asymmetric transfer hydrogenation and related tandem reactions over the past 7 years. It highlights and discusses the synthesis, reactivity, and recycling of these catalysts.
COORDINATION CHEMISTRY REVIEWS
(2023)
Article
Chemistry, Applied
Danyu Wang, Zhe Li, Tian-Yi Luo, Michael B. Schmithorst, Sunghwan Park, Wenqian Xu, Yurun Miao, Kaivalya Gawande, Chaoyun Tang, Brandon C. Bukowski, Bradley F. Chmelka, Howard Fairbrother, Efrosini Kokkoli, Michael Tsapatsis
Summary: Adenosine triphosphate (ATP) and other nucleotides can be irreversibly bound to the metal-organic framework (MOF) MIL-101(Cr). Analysis suggests that ATP is bound to MIL-101(Cr) through the terminal phosphate group with Cr(III) of the framework. The MOF-supported nucleotides can function as stable and reusable enantioselective heterogeneous catalysts in the presence of Cu(II) ions.
MICROPOROUS AND MESOPOROUS MATERIALS
(2023)
Article
Chemistry, Physical
Zhitong Zhao, Chengyi Wang, Qipeng Chen, Yu Wang, Rui Xiao, Chunxia Tan, Guohua Liu
Summary: By developing a supported dual catalysts system, the conflicts between oxidative and reductive catalysts were overcome, resulting in an efficient one-pot redox deracemization of secondary alcohols. This process demonstrated enhanced yields and enantioselectivities compared to unsupported dual catalysts systems.
Article
Chemistry, Applied
Irma Garcia-Monzon, Jorge Borges-Gonzalez, Tomas Martin
Summary: The heterogenization of homogeneous catalysts onto a solid support is a crucial step towards sustainable chemistry. In this study, we developed a series of polymer-supported tetrahydropyran-based hybrid dipeptides as active catalysts for the enantioselective Michael addition of aldehydes to beta-nitrostyrenes. The optimal anchor position and orientation between the catalyst and solid support, as well as the linker length, were carefully designed to enhance the catalytic efficiency. These supported catalysts exhibited high yields and enantiomeric excesses, and detailed deactivation studies provided important insights for prolonging their useful life.
ADVANCED SYNTHESIS & CATALYSIS
(2022)
Article
Chemistry, Multidisciplinary
Wei Xiao, Zihao Wang, Jinxiang Yang, Meishuang Qiu, Yan Peng, Xiaorong Xiong, Yizhuo Lu, Tianyou Chen, Zushun Xu
Summary: Colloidal polystyrene-supported cooperative imidazolidinone/thiourea catalysts were developed for efficient aldol reaction and substrate-selective Knoevenagel condensation in water, with the synergistic effect of hydrophobic interaction and hydrogen bonding between the substrates and catalysts playing a crucial role. These catalysts show great potential for efficient and selective catalysis in other reactions.
NEW JOURNAL OF CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Nobuya Tsuji, Pavel Sidorov, Chendan Zhu, Yuuya Nagata, Timur Gimadiev, Alexandre Varnek, Benjamin List
Summary: Catalyst optimization processes often rely on qualitative assumptions of chemists based on screening data, while machine learning models using molecular properties or calculated 3D structures are time-consuming and costly. This study proposes a machine learning model based on fragment descriptors, which are fine-tuned for asymmetric catalysis and result in robust and efficient virtual screening. Through theoretical design and experimental validation, new catalysts with higher selectivities in a challenging synthesis were developed using only moderately selective training data.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Yuki Saito, Shu Kobayashi
Summary: The application of heterogeneous catalysts in continuous-flow enantioselective hydroacylation reactions was studied. Catalysts were prepared by mixing supports and rhodium complexes, and showed excellent activity and enantioselectivity. Under optimized conditions, the catalysts exhibited high turnover numbers and could be applied to various substrates. Furthermore, sequential-flow reactions with other heterogeneous catalysts were demonstrated for the synthesis of biologically active molecules and functional materials.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Biochemistry & Molecular Biology
Zita Szabo, Sophia Ben Ahmed, Zoltan Nagy, Attila Paczal, Andras Kotschy
Summary: The formation of polysubstituted cyclopropane derivatives in the gold(I)-catalyzed reaction of olefins and propargylic esters is of significant interest due to its potential usefulness in generating diversity. We tested a series of chiral gold(I)-carbene complexes as catalysts and achieved high enantioselectivity in the test reaction. However, the cis:trans selectivity of the transformation was independent of the catalyst. Although the reactions proceeded smoothly, the observed enantioselectivity varied greatly and a structure-property relationship could not be established.
Article
Chemistry, Physical
Jacopo De Bellis, Michael Felderhoff, Ferdi Schuth
Summary: In this study, it was demonstrated that mixing multiple metal sources through ball milling can result in supported alloyed nanoparticles, expanding the method's application to the synthesis of supported bimetallic catalysts. The prepared Au-Pd and Au-Cu nanoparticles supported on MgO or YSZ were characterized using powder X-ray diffraction and electron microscopy, and their catalytic performance in CO oxidation was investigated to understand the impact of the synthetic method on the final catalyst materials.
CHEMISTRY OF MATERIALS
(2021)
Article
Chemistry, Multidisciplinary
A. Prekob, L. Vanyorek, Z. Fejes
Summary: The study found that the BCNT support exhibited higher selectivity towards benzhydrol during the hydrogenation of benzophenone, possibly due to the presence of covalently bonded nitrogen atoms that can inhibit over-hydrogenation processes.
MATERIALS TODAY CHEMISTRY
(2021)
Article
Chemistry, Physical
Junwen Wang, Jun Li, Yan Wang, Sisi He, Hengzhi You, Fen -Er Chen
Summary: In this study, a polymer-supported chiral heterogeneous copper catalyst was reported, which demonstrated high reactivity and enantioselectivity in asymmetric conjugate addition reactions.
Review
Chemistry, Multidisciplinary
Qiming Sun, Ning Wang, Jihong Yu
Summary: Zeolite-supported metal catalysts have shown superior activity and thermal stability in catalytic reactions, being widely applied in hydrogenation, dehydrogenation, oxidation, and other reactions, with promising prospects for future advancements.
ADVANCED MATERIALS
(2021)
Article
Chemistry, Physical
Cornelius V. Gaertner, Christoph Schneider
Summary: Chiral diphosphane Pd-aqua complexes have been used as efficient cooperative Bronsted acid-base catalysts in asymmetric transformations for the past 25 years. By deprotonating beta-dicarbonyl compounds, they readily form reactive chiral Pd enolates, while a Bronsted acid released from the catalyst activates the electrophile. After a period of dormancy, new developments in the enantioselective synthesis of heterocycles and other useful compounds have recently emerged, utilizing the unique properties of chiral Pd-aqua complexes.
Review
Chemistry, Physical
Jia Yu, Yida Yang, Yuliang Li, Changyan Cao, Weiguo Song
Summary: Supported metal catalysts using GDY as a promising catalyst support have shown rapid progress in thermocatalytic reactions, benefiting from the electronic interaction between the support and active components.
Article
Polymer Science
Matteo Calosi, Elisa Guazzelli, Simona Braccini, Marco Lessi, Fabio Bellina, Giancarlo Galli, Elisa Martinelli
Summary: Water-soluble amphiphilic copolymers composed of TEGMA or PEGMA and FA were synthesized and their self-assembling, thermoresponsive behavior, and drug encapsulation and release properties were studied. The results showed that the copolymers exhibited different behaviors in drug incorporation and release depending on their structure. In addition, the copolymers at high concentrations may have toxic effects on cells.
Article
Energy & Fuels
Jianxing Xia, Marco Cavazzini, Cansu Igci, Cristina Momblona, Simonetta Orlandi, Bin Ding, Yi Zhang, Hiroyuki Kanda, Nadja Klipfel, Sher Bahadar Khan, Abdullah Mohamed Asiri, Paul Joseph Dyson, Gianluca Pozzi, Mohammad Khaja Nazeeruddin
Summary: This study developed novel Ullazine derivatives bearing thiophene units to enhance the efficiency of perovskite solar cells. The new materials not only improved conductivity, but also retained 90% of the efficiency, demonstrating superior stability on the new materials.
Article
Chemistry, Applied
Elisabetta Rosadoni, Fabio Bellina, Marco Lessi, Cosimo Micheletti, Francesco Ventura, Andrea Pucci
Summary: This article describes the synthesis of three compounds modified with typical electron-donating and electron-withdrawing groups and their evaluation as fluorescent dyes for solar concentrators. These compounds showed good fluorescence properties and device efficiencies in poly(methyl methacrylate) films.
Article
Chemistry, Multidisciplinary
Oliver G. Willis, Filippo Petri, Gennaro Pescitelli, Andrea Pucci, Enrico Cavalli, Alessandro Mandoli, Francesco Zinna, Lorenzo Di Bari
Summary: Novel chiral Er complexes based on (i)PrPyBox show strong near-infrared circularly polarized luminescence, which has potential applications in fields such as optical communications and bioimaging.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Physical
Nadja Klipfel, Jianxing Xia, Pavel Culik, Simonetta Orlandi, Marco Cavazzini, Naoyuki Shibayama, Hiroyuki Kanda, Cansu Igci, Wei Li, Yi-Bing Cheng, Vygintas Jankauskas, Kristijonas Genevicius, Abdullah M. Asiri, Cristina Momblona, Kasparas Rakstys, Gianluca Pozzi, Mohammad Khaja Nazeeruddin
Summary: Finding new hole-transporting materials to replace spiro-OMe-TAD remains challenging. In this study, newly synthesized metal phthalocyanines functionalized with alkoxyl chains were evaluated as HTMs in perovskite solar cells. The nature of the alkoxyl chains and coordinated metal species were found to affect the functional properties of the new materials. ZnPc with four n-butoxy side chains demonstrated the highest power conversion efficiency.
MATERIALS TODAY ENERGY
(2022)
Article
Chemistry, Multidisciplinary
Jianxing Xia, Yi Zhang, Marco Cavazzini, Simonetta Orlandi, Bin Ding, Hiroyuki Kanda, Nadja Klipfel, Xiao-Xin Gao, Qurat Ul Ain, Vygintas Jankauskas, Kasparas Rakstys, Ruiyuan Hu, Zeliang Qiu, Abdullah M. Asiri, Hobeom Kim, Paul J. Dyson, Gianluca Pozzi, Mohammad Khaja Nazeeruddin
Summary: Hole-transporting materials based on the 10H, 10 'H-9,9' -spirobi[acridine] core were synthesized and their electronic properties were explored. The presence of specific structural elements in these materials resulted in improved hole mobility and higher work function, leading to enhanced performance of perovskite solar cells.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Physical
David Possetto, Ilir Pecnikaj, Gabriela Marzari, Simonetta Orlandi, Silvia Sereno, Marco Cavazzini, Gianluca Pozzi, Fernando Fungo
Summary: This study demonstrates the relationship between the monomer molecular structure and the capability of tuning the morphology of electrodeposited gas bubbles template polymer thin films. By adjusting electrochemical parameters, the nanostructural properties of the soft-templated films can be fine-tuned, resulting in superhydrophobic surfaces.
Article
Chemistry, Physical
Zilong Zhang, Wenbo Li, Simonetta Orlandi, Marco Cavazzini, Abdullah M. Asiri, Mohammad Khaja Nazeeruddin, Gianluca Pozzi, Michael Saliba, Peng Gao
Summary: In this study, three spiro-[cyclopenta[1,2-b:5,4-b ']dithiophene-4,9 '-fluorene] (SDTF) derivatives decorated with triphenylamine were designed and synthesized. The impact of the linkage position of triphenylamine groups on the thermal, optoelectronic, and charge-transport properties of these molecules was investigated through a combination of experimental and theoretical methods. The results showed that one of the SDTF derivatives exhibited suitable energy alignment, good hole injection/transportability, and high theoretical hole mobility, making it a promising candidate for efficient perovskite solar cells.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Agronomy
Immacolata Iovinella, Beniamino Caputo, Pietro Cobre, Mattia Manica, Alessandro Mandoli, Francesca Romana Dani
Summary: The researchers synthesized derivatives of citronellal with lower volatility and weaker odor, which showed a longer-lasting mosquito repellent effect. In field trials, these derivatives performed comparably to synthetic repellents such as DEET and Icaridin.
PEST MANAGEMENT SCIENCE
(2022)
Article
Agriculture, Multidisciplinary
Immacolata Iovinella, Alessandro Mandoli, Cristina Luceri, Mario D'Ambrosio, Beniamino Caputo, Pietro Cobre, Francesca Romana Dani
Summary: The use of skin repellents is important for personal protection against disease-carrying mosquitoes. In this study, cyclic hydroxyacetals were tested as potential repellents and found to be as effective as DEET and Icaridin, with some compounds performing even better. These compounds also showed lower toxicity compared to DEET, suggesting their potential as safe mosquito repellents.
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
(2023)
Article
Biochemistry & Molecular Biology
Elisabetta Rosadoni, Federico Banchini, Sara Bellini, Marco Lessi, Luca Pasquinelli, Fabio Bellina
Summary: This paper reports an unprecedented selective C-5 arylation method using anisole as an environmentally friendly reaction solvent, and highlights the beneficial role of benzoic acid as an additive.
Article
Chemistry, Multidisciplinary
Oliver G. Willis, Filippo Petri, Davide F. De Rosa, Alessandro Mandoli, Robert Pal, Francesco Zinna, Lorenzo Di Bari
Summary: In this study, chiral lanthanide complexes with extended pi conjugation were synthesized for efficient circularly polarized luminescence via two-photon excitation. The conjugated backbone was extended through the pyridine 4-position with a phenylacetylene unit, increasing the two-photon absorption cross section. This work represents a significant advancement in the development of chiral systems with enhanced nonlinear optical properties, and has potential applications in imaging, sensing, and photodynamic therapy.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Physical
Zilong Zhang, Wenbo Li, Simonetta Orlandi, Marco Cavazzini, Abdullah M. Asiri, Mohammad Khaja Nazeeruddin, Gianluca Pozzi, Michael Saliba, Peng Gao
Summary: Spiro-type molecules have been investigated as hole-transporting materials in perovskite solar cells. In this study, three spiro-[cyclopenta[1,2-b:5,4-b ']dithiophene-4,9 '-fluorene] derivatives decorated with triphenylamine were designed and synthesized. The thermal and optoelectronic properties, single-crystal structures, and charge-transport properties were extensively studied to understand the impact of the triphenylamine linkage position. The results showed that one of the derivatives, SDTF-2, exhibited suitable energy alignment, good hole injection/transportability, and high theoretical hole mobility, making it a promising candidate for efficient perovskite solar cells with a high power conversion efficiency of 19.3%. First-principle calculations also revealed the strong interactions between SDTF-2 and the perovskite surface, facilitating fast hole extraction.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Chemistry, Multidisciplinary
Delia Blasi, Silvio Quici, Simonetta Orlandi, Pierluigi Mercandelli, Andrey Sokolov, Eugeny Alexandrov, Lucia Carlucci
Summary: A new nanometric length beta-diketone ligand (HL) combined with silver(I) has been used to assemble two-dimensional coordination networks (CNs) with the highest level of interpenetration reported so far. The degree of interpenetration in the CNs is determined by the conformational steric hindrance of the ligand and the nature of the counterions. The unique topologies and interesting emissive properties of the CNs make them significant in the field of coordination chemistry.
Article
Horticulture
Luana Beatriz dos Santos Nascimento, Antonella Gori, Ilaria Degano, Alessandro Mandoli, Francesco Ferrini, Cecilia Brunetti
Summary: The study compared the efficiency of fermentation extraction with ultrasound-assisted extraction on the yield of antioxidant polyphenols from elderberry fruits and pomegranate fruit-peels. Results showed that ultrasound-assisted extraction was more suitable for extracting polyphenols from both fruits and exhibited higher antioxidant capacities.
Article
Chemistry, Applied
Qingyuan Zheng, Jack H. Williams, Scott Elgersma, Mick D. Mantle, Andrew J. Sederman, G. Leendert Bezemer, Constant M. Guedon, Lynn F. Gladden
Summary: In this study, a pilot-scale fixed-bed reactor compatible with NMR/MRI was developed for Fischer-Tropsch synthesis. Multiple magnetic resonance techniques were applied to quantitatively characterize different product species within catalyst pellets, providing valuable information for catalyst and reactor optimization.
Article
Chemistry, Applied
Lisa Ramisch, Sebastian Pfaff, Sabrina M. Gericke, Edvin Lundgren, Johan Zetterberg
Summary: We present a combination of optical operando techniques that allow simultaneous measurement of adsorbed species on catalyst surfaces, monitoring of surface oxide formation, and imaging of the gas phase above the catalyst surface. The experimental setup was validated by studying CO oxidation on Pd(100) at different pressures, revealing the effects of pressure on the heterogeneous catalytic reaction.
Article
Chemistry, Applied
Marta Paniagua, Gabriel Morales, Juan A. Melero, Daniel Garcia-Salgado
Summary: The influence of common impurities in levulinic acid on the catalytic performance of different acid catalysts for bio-jet fuel production was studied. It was found that furfural had the greatest detrimental effect on catalyst performance, while propyl-sulfonic acid-modified SBA-15 and sulfonic acid resin Amberlyst-70 showed good regeneration ability.
Article
Chemistry, Applied
Jesus Tapiador, Pedro Leo, Guillermo Calleja, Gisela Orcajo
Summary: This study presents a new MOF material, Zn-URJC-13, with acid and basic sites, permanent porosity, and high affinity to CO2 molecules. The Zn-URJC-13 catalyst exhibits efficient performance in CO2 cycloaddition reactions and can be reused multiple times.
Article
Chemistry, Applied
Dan Zhao, Vita A. Kondratenko, Dmitry E. Doronkin, Shanlei Han, Jan-Dierk Grunwaldt, Uwe Rodemerck, David Linke, Evgenii V. Kondratenko
Summary: This study demonstrates the potential of cheap and commercially available Zr or Ti-based supports and ZnO to serve as active and selective catalysts for propane dehydrogenation (PDH). The catalytically active species formed in situ under PDH conditions consist of isolated ZnOx. ZnOx on the surface of LaZrOx shows the highest rate of propene formation.
Article
Chemistry, Applied
Hanbyeol Kim, Jung Rae Kim, Young-Kwon Park, Jeong-Myeong Ha, Jungho Jae
Summary: In this study, metal phosphates were used as catalysts for biomass conversion to produce sustainable aromatics through DielsAlder cycloaddition reactions. The effects of synthesis method, activation method, and P/Ti molar ratio on the structure and acid properties of titanium phosphate catalysts were systematically studied. The mesoporous titanium phosphate catalyst synthesized by hydrothermal method at 180℃ for 12 h followed by ethanol refluxing at 60℃ for 24 h at a molar P/Ti ratio of 1 showed the highest surface area and acid site density.
Article
Chemistry, Applied
Yasin Khani, Sumin Pyo, Kwang-Eun Jeong, Chul-Ung Kim, Moonis Ali Khan, Byong-Hun Jeon, Kun-Yi Andrew Lin, Siyoung Q. Choi, Young-Kwon Park
Summary: A protonated form of Zeolite Socony Mobil-5 (H-ZSM-5) catalyst was synthesized through a hydrothermal method using different sources of silica. The effect of loading the catalyst with yttrium, samarium, and gadolinium on the acidic properties was investigated. Among the metal-loaded catalysts, the Sm/LHZ catalyst showed the best performance in the methanol to propylene conversion due to its high amount of weak and intermediate acid sites, while the Gd-LHZ catalyst increased the selectivity towards ethane and propane.
Article
Chemistry, Applied
Michael Franc, Ivana Cisarova, Jan Vesely
Summary: The present study investigates an enantioselective cyclization of enals with imidazolone derivatives catalyzed by a combination of achiral Pd(0) complex and chiral secondary amine. Corresponding spirocyclic imidazolones were produced in high yields with moderate diastereoselectivity and excellent enantioselectivity. The developed co-operative catalytic methodology provides a highly substituted spirocyclic scaffold with four stereogenic centers under mild conditions.
Article
Chemistry, Applied
Mauro Alvarez, Jennifer Cueto, David P. Serrano, Pablo Marin, Salvador Ordonez
Summary: This study focuses on improving the formulation and preparation methods of catalysts for the production of dimethyl carbonate. By using suitable catalyst preparation methods and copper salt precursors, the researchers successfully produced catalysts with optimal performance for dimethyl carbonate formation.
Article
Chemistry, Applied
Claudia J. Keijzer, Luc C. J. Smulders, Dennie Wezendonk, Jan Willem de Rijk, Petra E. de Jongh
Summary: This study investigates the catalytic behavior of alpha-alumina supported silver catalysts in the presence of chloride. It is found that the particle size of silver can affect the selectivity of the catalyst, but different strategies lead to different results. In this size range, the selectivity of ethylene oxide is correlated to the Ag : Al2O3 surface ratio.
Article
Chemistry, Applied
Takeshi Aihara, Wataru Aoki, Michikazu Hara, Keigo Kamata
Summary: The development of acid-base bifunctional catalysts is important for promoting specific chemical transformations. In this study, Ti-based perovskite oxides were synthesized and used as catalysts for two C-C bond-forming reactions (cyanosilylation and Knoevenagel condensation). The highly pure SrTiO3 nanoparticles with a high specific surface area exhibited the highest catalytic performance, and could be easily recovered and reused.
Article
Chemistry, Applied
Olga Gorlova, Petra Pribylova, Eliska Vyskocilova, Katerina Peroutkova, Jan Kohout, Iva Paterova
Summary: This study investigates the Baeyer-Villiger oxidation of beta-cyclocitral using tin-modified mixed oxides as catalysts. The optimal reaction conditions and the effects of various factors on the reaction course and selectivity were determined. The results show that tin-modified mixed oxides exhibit high activity and selectivity in the oxidation reaction.
Article
Chemistry, Applied
M. I. Avila, M. M. Alonso-Doncel, L. Briones, G. Gomez-Pozuelo, J. M. Escola, D. P. Serrano, A. Peral, J. A. Botas
Summary: The catalytic fast pyrolysis of lignin using ion-exchanged zeolite catalysts showed significant improvements in bio-oil quality and the production of aromatic hydrocarbons and oxygenated compounds.
Article
Chemistry, Applied
Enrico Catizzone, Giorgia Ferrarelli, Paolo Bruno, Girolamo Giordano, Massimo Migliori
Summary: The acid-catalysed alcohol conversion reaction is a promising route for de-fossilization strategies. Research on pure alcohol conversion and simultaneous dehydration of mixed alcohols have shown different product compositions, with the type and distribution of acid sites affecting the reaction mechanism.
Article
Chemistry, Applied
Alireza Ranjbari, Juho Kim, Jihee Yu, Jiyun Kim, Mireu Park, Nayoung Kim, Kristof Demeestere, Philippe M. Heynderickx
Summary: This study investigated a novel kinetic model for the adsorption and photocatalytic degradation of methyl orange using commercial ZnO and reduced ZnO photocatalysts. The results provided new insights into the interaction of catalysts with molecules of different charges and compared with a previous study on methylene blue. The presence of oxygen vacancies in ZnO and their effects on adsorption and photocatalytic degradation were analyzed, and the photocatalytic degradation rate of reduced ZnO was found to increase significantly.