TY - JOUR A1 - Lai, Feili A1 - Feng, Jianrui A1 - Heil, Tobias A1 - Tian, Zhihong A1 - Schmidt, Johannes A1 - Wang, Gui-Chang A1 - Oschatz, Martin T1 - Partially delocalized charge in Fe-doped NiCo2S4 nanosheet-mesoporous carbon-composites for high-voltage supercapacitors JF - Journal of materials chemistry : A, Materials for energy and sustainability N2 - Unraveling the effect of transition-metal doping on the energy storage properties of bimetallic sulfides remains a grand challenge. Herein, we construct bimetallic sulfide nanosheets and hence deliberately introduce transition-metal doping domains on their surface. The resulting materials show not only an enhanced density of states near the Fermi level but also partially delocalized charge as shown by density functional theory (DFT) calculations. Fe-doped NiCo2S4 nanosheets wrapped on N,S-doped ordered mesoporous carbon (Fe-NiCo2S4@N,S-CMK-3) are prepared, which show an enhanced specific capacitance of 197.8 F g(-1) in ionic liquid-based supercapacitors at a scan rate of 2 mV s(-1). This is significantly higher as compared to the capacitance of 155.2 and 135.9 F g(-1) of non-iron-doped NiCo2S4@N,S-CMK and Fe-NiCo2S4@CMK-3 electrodes, respectively. This result arises from the enhanced ionic liquid polarization effect and transportation ability from the Fe-NiCo2S4 surface and N,S-CMK-3 structure. Furthermore, the importance of matching multi-dimensional structures and ionic liquid ion sizes in the fabrication of asymmetric supercapacitors (ASCs) is demonstrated. As a result, the ASC device exhibits a high energy density of 107.5 W h kg(-1) at a power density of 100 W kg(-1) in a working-voltage window of 4 V when using Fe-NiCo2S4@N,S-CMK-3 and N,S-CMK-3 as positive and negative electrodes, respectively. This work puts forward a new direction to design supercapacitor composite electrodes for efficient ionic liquid coupling. Y1 - 2019 U6 - https://doi.org/10.1039/c9ta06250e SN - 2050-7488 SN - 2050-7496 VL - 7 IS - 33 SP - 19342 EP - 19347 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Qin, Qing A1 - Zhao, Yun A1 - Schmallegger, Max A1 - Heil, Tobias A1 - Schmidt, Johannes A1 - Walczak, Ralf A1 - Gescheidt-Demner, Georg A1 - Jiao, Haijun A1 - Oschatz, Martin T1 - Enhanced Electrocatalytic N-2 Reduction via Partial Anion Substitution in Titanium Oxide-Carbon Composites JF - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition N2 - The electrochemical conversion of N-2 at ambient conditions using renewably generated electricity is an attractive approach for sustainable ammonia (NH3) production. Considering the chemical inertness of N-2, rational design of efficient and stable catalysts is required. Therefore, in this work, it is demonstrated that a C-doped TiO2/C (C-TixOy/C) material derived from the metal-organic framework (MOF) MIL-125(Ti) can achieve a high Faradaic efficiency (FE) of 17.8 %, which even surpasses most of the established noble metal-based catalysts. On the basis of the experimental results and theoretical calculations, the remarkable properties of the catalysts can be attributed to the doping of carbon atoms into oxygen vacancies (OVs) and the formation of Ti-C bonds in C-TixOy. This binding motive is found to be energetically more favorable for N-2 activation compared to the non-substituted OVs in TiO2. This work elucidates that electrochemical N-2 reduction reaction (NRR) performance can be largely improved by creating catalytically active centers through rational substitution of anions into metal oxides. KW - ammonia synthesis KW - anion substitution KW - MOF-derived catalysts KW - N-2 fixation KW - non-noble metal catalysts Y1 - 2019 U6 - https://doi.org/10.1002/anie.201906056 SN - 1433-7851 SN - 1521-3773 VL - 58 IS - 37 SP - 13101 EP - 13106 PB - Wiley-VCH CY - Weinheim ER - TY - GEN A1 - Ilic, Ivan K. A1 - Tsouka, Alexandra A1 - Perovic, Milena A1 - Hwang, Jinyeon A1 - Heil, Tobias A1 - Löffler, Felix A1 - Oschatz, Martin A1 - Antonietti, Markus A1 - Liedel, Clemens T1 - Sustainable cathodes for Lithium-ion energy storage devices based on tannic acid-toward ecofriendly energy storage T2 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - The use of organic materials with reversible redox activity holds enormous potential for next-generation Li-ion energy storage devices. Yet, most candidates are not truly sustainable, i.e., not derived from renewable feedstock or made in benign reactions. Here an attempt is reported to resolve this issue by synthesizing an organic cathode material from tannic acid and microporous carbon derived from biomass. All constituents, including the redox-active material and conductive carbon additive, are made from renewable resources. Using a simple, sustainable fabrication method, a hybrid material is formed. The low cost and ecofriendly material shows outstanding performance with a capacity of 108 mAh g(-1) at 0.1 A g(-1) and low capacity fading, retaining approximately 80% of the maximum capacity after 90 cycles. With approximately 3.4 V versus Li+/Li, the cells also feature one of the highest reversible redox potentials reported for biomolecular cathodes. Finally, the quinone-catecholate redox mechanism responsible for the high capacity of tannic acid is confirmed by electrochemical characterization of a model compound similar to tannic acid but without catecholic groups. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1366 KW - biomass KW - electrochemistry KW - energy storage KW - redox chemistry KW - sustainability KW - tannic acid Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-570560 SN - 1866-8372 IS - 1 ER - TY - JOUR A1 - Ilic, Ivan K. A1 - Tsouka, Alexandra A1 - Perovic, Milena A1 - Hwang, Jinyeon A1 - Heil, Tobias A1 - Löffler, Felix A1 - Oschatz, Martin A1 - Antonietti, Markus A1 - Liedel, Clemens T1 - Sustainable cathodes for Lithium-ion energy storage devices based on tannic acid-toward ecofriendly energy storage JF - Advanced sustainable systems N2 - The use of organic materials with reversible redox activity holds enormous potential for next-generation Li-ion energy storage devices. Yet, most candidates are not truly sustainable, i.e., not derived from renewable feedstock or made in benign reactions. Here an attempt is reported to resolve this issue by synthesizing an organic cathode material from tannic acid and microporous carbon derived from biomass. All constituents, including the redox-active material and conductive carbon additive, are made from renewable resources. Using a simple, sustainable fabrication method, a hybrid material is formed. The low cost and ecofriendly material shows outstanding performance with a capacity of 108 mAh g(-1) at 0.1 A g(-1) and low capacity fading, retaining approximately 80% of the maximum capacity after 90 cycles. With approximately 3.4 V versus Li+/Li, the cells also feature one of the highest reversible redox potentials reported for biomolecular cathodes. Finally, the quinone-catecholate redox mechanism responsible for the high capacity of tannic acid is confirmed by electrochemical characterization of a model compound similar to tannic acid but without catecholic groups. KW - biomass KW - electrochemistry KW - energy storage KW - redox chemistry KW - sustainability KW - tannic acid Y1 - 2020 U6 - https://doi.org/10.1002/adsu.202000206 SN - 2366-7486 VL - 5 IS - 1 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Kossmann, Janina A1 - Sanchez-Manjavacas, Maria Luz Ortiz A1 - Brandt, Jessica A1 - Heil, Tobias A1 - López-Salas, Nieves A1 - Albero, Josep T1 - Mn(ii) sub-nanometric site stabilization in noble, N-doped carbonaceous materials for electrochemical CO2 reduction JF - Chemical communications : ChemComm / The Royal Society of Chemistry N2 - The preparation of stable and efficient electrocatalysts comprising abundant and non-critical row-materials is of paramount importance for their industrial implementation. Herein, we present a simple synthetic route to prepare Mn(ii) sub-nanometric active sites over a highly N-doped noble carbonaceous support. This support not only promotes a strong stabilization of the Mn(ii) sites, improving its stability against oxidation, but also provides a convenient coordination environment in the Mn(ii) sites able to produce CO, HCOOH and CH3COOH from electrochemical CO2 reduction. Y1 - 2022 U6 - https://doi.org/10.1039/d2cc00585a SN - 1359-7345 SN - 1364-548X VL - 58 IS - 31 SP - 4841 EP - 4844 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Lepre, Enrico A1 - Heske, Julian A1 - Nowakowski, Michal A1 - Scoppola, Ernesto A1 - Zizak, Ivo A1 - Heil, Tobias A1 - Kühne, Thomas D. A1 - Antonietti, Markus A1 - Lopez-Salas, Nieves A1 - Albero, Josep T1 - Ni-based electrocatalysts for unconventional CO2 reduction reaction to formic acid JF - Nano energy N2 - Electrochemical reduction stands as an alternative to revalorize CO2. Among the different alternatives, Ni single atoms supported on carbonaceous materials are an appealing catalytic solution due to the low cost and versatility of the support and the optimal usage of Ni and its predicted selectivity and efficiency (ca. 100% towards CO). Herein, we have used noble carbonaceous support derived from cytosine to load Ni subnanometric sites. The large heteroatom content of the support allows the stabilization of up to 11 wt% of Ni without the formation of nanoparticles through a simple impregnation plus calcination approach, where nickel promotes the stabilization of C3NOx frameworks and the oxidative support promotes a high oxidation state of nickel. EXAFS analysis points at nickel single atoms or subnanometric clusters coordinated by oxygen in the material surface. Unlike the wellknown N-coordinated Ni single sites selectivity towards CO2 reduction, O-coordinated-Ni single sites (ca. 7 wt% of Ni) reduced CO2 to CO, but subnanometric clusters (11 wt% of Ni) foster the unprecedented formation of HCOOH with 27% Faradaic efficiency at - 1.4 V. Larger Ni amounts ended up on the formation of NiO nanoparticles and almost 100% selectivity towards hydrogen evolution. KW - CO 2 reduction reaction KW - Noble carbon KW - Ni-O4 electrocatalysts KW - Formic acid Y1 - 2022 U6 - https://doi.org/10.1016/j.nanoen.2022.107191 SN - 2211-2855 SN - 2211-3282 VL - 97 PB - Elsevier CY - Amsterdam ER -