http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Marques Mota, Filipe,Choi, Chi Hun,Boppella, Ramireddy,Lee, Ji-Eun,Kim, Dong Ha The Royal Society of Chemistry 2019 Journal of Materials Chemistry A Vol.7 No.2
<P>In the development of water splitting technologies, the design of hybrid architectures incorporating multiple phases which provide active centers with precise functionalities is a promising strategy. Herein, we report the design of Ni- and Ru-based electrocatalysts within a wide Ni/Ru ratio range, prepared through a one-step heat treatment of ultra-thin ruthenate nanosheets and NiCl2·6H2O and NaH2PO2·H2O precursors. At 250 °C under an argon flow, a pristine Ru electrode was shown to undergo preferential ruthenate-to-metallic Ru phase transformation, revealing preferable hydrogen evolution reaction (HER) fingerprints. At low Ni/Ru ratios, the interaction between the Ni<SUP>2+</SUP> ions and the negatively charged ruthenate favored the <I>in situ</I> growth of highly dispersed surface Ni-based moieties below 5 nm in diameter. XPS measurements confirmed, however, that these narrow moieties were swiftly oxidized to NiO, whereas larger Ni-based agglomerates at higher Ni/Ru ratios were less prone to oxidation. This size-dependent propensity of Ni2P moieties toward oxidation, reported here for the first time, agrees with the surface oxidation of Ni2P nanoparticles (50-100 nm) to a limited extent. At Ni/Ru = 0.36, the incorporated NiO favored a synergistically superior oxygen evolution reaction (OER) performance and an optimal 1.7-fold activity enhancement at limiting current densities. An antagonistic effect in the HER performance of these hybrid materials was, nonetheless, simultaneously observed and ascribed to the blockage of the active Ru surface. While the performance of these nano-architectures remains a modest addition to the current state-of-the-art of water splitting platforms in alkaline electrolyte media, our results primarily reveal representative bottlenecks in the integration of multiple phases during synthesis steps and the effects of arising between integrated components on the catalytic behavior of resulting hybrids.</P>
( Filipe Marques Mota ),변혜령,김동하 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1
Rechargeable Li-air cells operating under CO<sub>2</sub> or O<sub>2</sub>/CO<sub>2</sub> offer alternative mechanistic pathways with analogously high theoretical energy density. The Li-O<sub>2</sub>/CO<sub>2</sub> cell in tetraglyme electrolyte suffers from recharge potentials at ~4.5 V required for the decomposition of the main discharge product, Li<sub>2</sub>CO<sub>3</sub>. In this work we assess the promise of incorporating a Br<sub>3</sub><sup>-</sup>/Br<sub>2</sub> redox promoter. Hindered overcharges (~0.5 V) driven by electrochemically-generated Br<sub>2</sub> are revealed to be a function of the LiBr concentration and the insulating Li<sub>2</sub>CO<sub>3</sub> structure. Coupled electrochemical and spectroscopic analyses at progressive states-of-charge are proposed as a seminal methodology to dissect the underlying complexity of involved redox shuttling steps and evaluate the appropriateness of redox mediators beyond an overcharge decrease.
( Filipe Marques Mota ),변혜령,김동하 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1
Reflecting the languished research state of Li-O<sub>2</sub>, alternative devices operating under CO<sub>2</sub> or O<sub>2</sub>/CO<sub>2</sub> with analogously high theoretical energy density have gained recent attraction. Here, we assess the effect of CO<sub>2</sub> within a 5 to 100% range in Li-O<sub>2</sub>/CO<sub>2</sub>. In the LiTFSI/tetraglyme electrolyte, the reaction mechanism is swiftly shifted toward the formation of Li<sub>2</sub>CO<sub>3</sub> even at 5% CO<sub>2</sub>. Conspicuous product and intermediate species identification and quantification are presented. Tuning the CO<sub>2</sub> content is shown to offer superior cyclability, deterred byproduct formation with enhanced electrolyte stability, and extended discharge capacity (1.5-fold), correlated with an induced stabilization of metastable CO<sub>4</sub><sup>-</sup>/C<sub>2</sub>O<sub>6</sub><sup>2-</sup> intermediates in tetraglyme. These findings highlight the promise of a shift in the underlying mechanism of Li-air cells upon CO<sub>2</sub> incorporation on conventional O<sub>2</sub>-based devices.
( Filipe Marques Mota ),변혜령,김동하 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-
While replacing O<sub>2</sub> with air reflects a critical step towards the practical application of Li-air batteries, the present CO<sub>2</sub> alters the O<sub>2</sub> chemistry. In the tetraglyme-electrolyte, minor CO<sub>2</sub> reflected a swift shift towards the formation of Li<sub>2</sub>CO<sub>3</sub>, requiring impracticable recharge potentials (4.5 V). In our recent study, we revealed that a Br<sub>3</sub> <sup>-</sup>/Br<sub>2</sub> redox mediator could successfully suppress the overcharge potential. Hindered overcharges (~0.5 V) driven by electrochemically-generated Br<sub>2</sub> were found to be a function of the LiBr concentration and the insulating Li<sub>2</sub>CO<sub>3</sub> structure. Coupled electrochemical and spectroscopic analyses shed light on the involved redox shuttling steps and unveiled the prominent presence of soluble Br<sub>2</sub>···Br<sub>3</sub> <sup>-</sup> loosely-bound anionic complexes at progressive states-of-charge.
( Filipe Marques Mota ),( Ramireddy Boppella ),( Keiji Tanaka ),김동하 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-
To harvest low energy photons, we investigated a 3D composite photoanode integrating visible-responsive plasmonic Au nanoparticles and NIR-responsive upconversion nanocrystals (UCN) into 3D TiO<sub>2</sub> inverse-opals (Au/UCN/TiO<sub>2</sub>) with extended solar energy utilization in the UV-vis-NIR range for photoelectrochemical (PEC) water splitting platforms. The NIR-responsive properties of NaYF<sub>4</sub>:Yb<sup>3+</sup> UCN nanocrystals doped with Er<sup>3+</sup> or Tm<sup>3+</sup> ions, and the effect of an alternating sequential introduction of UCN and Au were also investigated. Our Au/Er-UCN/TiO<sub>2</sub> hybrid revealed a 10-fold photocurrent density enhancement under UV-vis-NIR against the pristine TiO<sub>2</sub>.
Assessing the Promise of CO<sub>2</sub>-driven Li-air Batteries
( Filipe Marques Mota ),( Hye Ryung Byon ),김동하 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0
In recent years, an increasing number of perspectives have reflected the languished state of the Li-O<sub>2</sub> research field, and the need for a focus on exploratory works toward the development of energy storage devices with analogously high theoretical energy density. The incorporation of CO<sub>2</sub> up to 50% in Li-air cells in a TEGDME-based electrolyte was shown to result in a 1.9-fold increase in capacity. More interestingly, results also highlighted an analogous cyclability up to at least 30% of incorporated CO<sub>2</sub> upon comparison with conventional Li-O<sub>2</sub> cells (~400-500 h). The incorporation of CO<sub>2</sub> favors a preferable mechanistic pathway toward CO<sub>4</sub> - species with complete absence of Li<sub>2</sub>O<sub>2</sub> formation, and increased electrolyte stability suggested by OEMS results and detailed product characterization. These O<sub>2</sub>-assisted Li-CO<sub>2</sub> cells are presumed advantageous energy storage devices that may find its way to compete in an economical and environmental level with current Li-ion cells.
( Filipe Marques Mota ),김동하 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0
Tuning the bifunctional water splitting fingerprints toward H<sub>2</sub> and O<sub>2</sub> evolution through the design of architectures incorporating multiple functionalities is of increasing attention. Here, Ni- and Ru-based electrocatalysts with increasing Ni/Ru content ratios were designed through a one-step heat treatment at 250°C of ruthenate nanosheets, and NiCl<sub>2</sub>6H<sub>2</sub>O and NaH<sub>2</sub>PO<sub>2</sub>H<sub>2</sub>O precursors, under argon flow. XPS measurements confirmed that incorporated narrow Ni-based moieties on the surface of the ruthenium substrate were swiftly oxidized to NiO, whereas larger Ni-based agglomerates at higher Ni/Ru ratios were less prone to oxidation. This size-dependent propensity of Ni<sub>2</sub>P to oxidation was here reported for the first time and shown to directly determine the OER performance of the resulting hybrids. Our results reflect the difficulty in the integration of multiple phases during the synthesis procedure and its effect on resulting catalytic behaviors.
( Filipe Marques Mota ),( Dang Nguyen ),이지은,( Huiyan Piao ),( Jin-ho Choy ),황윤정,김동하 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
The electroreduction of CO<sub>2</sub> has emerged as a rational answer to uprising CO<sub>2</sub> emissions and a strategy to incorporate renewable electricity into the global energy supply. In particular, CO<sub>2</sub>RR to CO has been highlighted in the industrial conversion of syngas (H<sub>2</sub> and CO) to fuels through subsequent technologies. Here we report for the first time a strategy to tune the H<sub>2</sub> to CO ratio by facile composition control of the components of a rationally designed binary nanostructure. By adjusting the loading of Au nanoparticles immobilized on ultra-thin titanate nanosheets in a 0 to 93 wt.% range, the CO Faradaic efficiency balanced by exclusive H<sub>2</sub> formation could be effectively varied in a 3 to 80% range. A variation of the electronic properties of these nanostructures, corroborated by XPS characterization, was proposed to dictate the stabilization of formed reaction intermediates and subsequent product selectivity.