8 research outputs found

    Hybrid Quantum Neural Network Model with Catalyst Experimental Validation: Application for the Dry Reforming of Methane

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    Machine learning (ML), which has been increasingly applied to complex problems such as catalyst development, encounters challenges in data collection and structuring. Quantum neural networks (QNNs) outperform classical ML models, such as artificial neural networks (ANNs), in prediction accuracy, even with limited data. However, QNNs have limited available qubits. To address this issue, we introduce a hybrid QNN model, combining a parametrized quantum circuit with an ANN structure. We used the catalyst data sets of the dry reforming of methane reaction from the literature and in-house experimental results to compare the hybrid QNN and the ANN models. The hybrid QNN exhibited superior prediction accuracy and a faster convergence rate, achieving an R2 of 0.942 at 2478 epochs, whereas the ANN achieved an R2 of 0.935 at 3175 epochs. For the 224 in-house experimental data points previously unreported in the literature, the hybrid QNN exhibited an enhanced generalization performance. It showed a mean absolute error (MAE) of 13.42, compared with an MAE of 27.40 for the ANN under similar training conditions. This study highlights the potential of the hybrid QNN as a powerful tool for solving complex problems in catalysis and chemistry, demonstrating its advantages over classical ML models

    Synthesis gas conversion over Rh-based catalysts promoted by Fe and Mn

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    FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICORh/SiO2 catalysts promoted with Fe and Mn are selective for synthesis gas conversion to oxygenates and light hydrocarbons at 523 K and 580 psi. Selective anchoring of Fe and Mn species on Rh nanoparticles was achieved by controlled surface reactions and w7745504563FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO2015/20477-12015/23900-2309373/2014-

    Plasmon-enhanced Photoelectrochemical Water Splitting with Size-controllable Au Nanodot Arrays

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    Size-controllable Au nanodot arrays (50, 63, and 83 nm dot size) with a narrow size distribution (+/- 5%) were prepared by a direct contact printing method on an indium tin oxide (ITO) substrate. Titania was added to the Au nanodots using TiO2 sols of 2-3 nm in size. This created a precisely controlled Au nanodot with 110 nm of TiO2 overcoats. Using these precisely controlled nanodot arrays, the effects of Au nanodot size and TiO2 overcoats were investigated for photoelectrochemical water splitting using a three-electrode system with a fiber-optic visible light source. From UV-vis measurement, the localized surface plasmon resonance (LSPR) peak energy (ELSPR) increased and the LSPR line width (G) decreased with decreasing Au nanodot size. The generated plasmonic enhancement for the photoelectrochemical water splitting reaction increased with decreasing Au particle size. The measured plasmonic enhancement for light on/off experiments was 25 times for the 50 nm Au size and 10 times for the 83 nm Au nanodot size. The activity of each catalyst increased by a factor of 6 when TiO2 was added to the Au nanodots for all the samples. The activity of the catalyst was proportional to the quality factor (defined as Q = E-LSPR/Gamma) of the plasmonic metal nanostructure. The enhanced water splitting performance with the decreased Au nanodot size is probably due to more generated charge carriers (electron/hole pair) by local field enhancement as the quality factor increases.116457sciescopu

    Plasmon-Enhanced Photoelectrochemical Water Splitting with Size-Controllable Gold Nanodot Arrays

    No full text
    Size-controllable Au nanodot arrays (50, 63, and 83 nm dot size) with a narrow size distribution (±5%) were prepared by a direct contact printing method on an indium tin oxide (ITO) substrate. Titania was added to the Au nanodots using TiO<sub>2</sub> sols of 2–3 nm in size. This created a precisely controlled Au nanodot with 110 nm of TiO<sub>2</sub> overcoats. Using these precisely controlled nanodot arrays, the effects of Au nanodot size and TiO<sub>2</sub> overcoats were investigated for photoelectrochemical water splitting using a three-electrode system with a fiber-optic visible light source. From UV–vis measurement, the localized surface plasmon resonance (LSPR) peak energy (<i>E</i><sub>LSPR</sub>) increased and the LSPR line width (Γ) decreased with decreasing Au nanodot size. The generated plasmonic enhancement for the photoelectrochemical water splitting reaction increased with decreasing Au particle size. The measured plasmonic enhancement for light on/off experiments was 25 times for the 50 nm Au size and 10 times for the 83 nm Au nanodot size. The activity of each catalyst increased by a factor of 6 when TiO<sub>2</sub> was added to the Au nanodots for all the samples. The activity of the catalyst was proportional to the quality factor (defined as <i>Q</i> = <i>E</i><sub>LSPR</sub>/Γ) of the plasmonic metal nanostructure. The enhanced water splitting performance with the decreased Au nanodot size is probably due to more generated charge carriers (electron/hole pair) by local field enhancement as the quality factor increases

    Synthesis Gas Conversion over Rh-Based Catalysts Promoted by Fe and Mn

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    Rh/SiO<sub>2</sub> catalysts promoted with Fe and Mn are selective for synthesis gas conversion to oxygenates and light hydrocarbons at 523 K and 580 psi. Selective anchoring of Fe and Mn species on Rh nanoparticles was achieved by controlled surface reactions and was evidenced by ultraviolet–visible absorption spectroscopy, scanning transmission electron microscopy, and inductively coupled plasma absorption emission spectroscopy. The interaction between Rh and Fe promotes the selective production of ethanol through hydrogenation of acetaldehyde and enhances the selectivity toward C<sub>2</sub> oxygenates, which include ethanol and acetaldehyde. The interaction between Rh and Mn increases the overall reaction rate and the selectivity toward C<sub>2+</sub> hydrocarbons. The combination of Fe and Mn on Rh/SiO<sub>2</sub> results in trimetallic Rh-Fe-Mn catalysts that surpass the performance of their bimetallic counterparts. The highest selectivities toward ethanol (36.9%) and C<sub>2</sub> oxygenates (39.6%) were achieved over the Rh-Fe-Mn ternary system with a molar ratio of 1:0.15:0.10, as opposed to the selectivities obtained over Rh/SiO<sub>2</sub>, which were 3.5% and 20.4%, respectively. The production of value-added oxygenates and C<sub>2+</sub> hydrocarbons over this trimetallic catalyst accounted for 55% of the total products. X-ray photoelectron spectroscopy measurements suggest that significant fractions of the Fe and Mn species exist as metallic iron and manganese oxides on the Rh surface upon reduction. These findings are rationalized by density functional theory (DFT) calculations, which reveal that the exact state of metals on the surfaces is condition-dependent, with Mn present as Mn­(I) and Mn­(II) oxide on the Rh (211) step edges and Fe present as Fe­(I) oxide on the step edge and metallic subsurface iron on both Rh steps and terraces. CO Fourier transform infrared spectroscopy and DFT calculations suggest that the binding of CO to Rh (211) step edges modified by Fe and/or manganese oxide is altered in comparison to CO adsorption on a clean Rh (211) surface. These results suggest that Mn<sub>2</sub>O<sub><i>x</i></sub> species and Fe and Fe<sub>2</sub>O modify bonding at Rh step edges and shift reaction selectivity away from CH<sub>4</sub>

    Role of the Cu-ZrO<sub>2</sub> Interfacial Sites for Conversion of Ethanol to Ethyl Acetate and Synthesis of Methanol from CO<sub>2</sub> and H<sub>2</sub>

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    Well-defined Cu catalysts containing different amounts of zirconia were synthesized by controlled surface reactions (CSRs) and atomic layer deposition methods and studied for the selective conversion of ethanol to ethyl acetate and for methanol synthesis. Selective deposition of ZrO<sub>2</sub> on undercoordinated Cu sites or near Cu nanoparticles via the CSR method was evidenced by UV–vis absorption spectroscopy, scanning transmission electron microscopy, and inductively coupled plasma absorption emission spectroscopy. The concentrations of Cu and Cu-ZrO<sub>2</sub> interfacial sites were quantified using a combination of subambient CO Fourier transform infrared spectroscopy and reactive N<sub>2</sub>O chemisorption measurements. The oxidation states of the Cu and ZrO<sub>2</sub> species for these catalysts were determined using X-ray absorption near edge structure measurements, showing that these species were present primarily as Cu<sup>0</sup> and Zr<sup>4+</sup>, respectively. It was found that the formation of Cu-ZrO<sub>2</sub> interfacial sites increased the turnover frequency by an order of magnitude in both the conversion of ethanol to ethyl acetate and the synthesis of methanol from CO<sub>2</sub> and H<sub>2</sub>
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