8 research outputs found
Hybrid Quantum Neural Network Model with Catalyst Experimental Validation: Application for the Dry Reforming of Methane
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
FAPESP - FUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICORh/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 - FUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICOFAPESP - FUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICO2015/20477-12015/23900-2309373/2014-
Plasmon-enhanced Photoelectrochemical Water Splitting with Size-controllable Au Nanodot Arrays
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
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 2â3 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 UVâvis measurement, the localized surface plasmon resonance (LSPR) peak energy (<i>E</i><sub>LSPR</sub>) increased and the LSPR line width (Î) 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>/Î) 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
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 ultravioletâvisible 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 MnÂ(I) and
MnÂ(II) oxide on the Rh (211) step edges and Fe present as FeÂ(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>
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 UVâvis
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>