scholarly journals Enhanced hydrogen generation by reverse spillover effects over bicomponent catalysts

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Zhe Gao ◽  
Guofu Wang ◽  
Tingyu Lei ◽  
Zhengxing Lv ◽  
Mi Xiong ◽  
...  

AbstractThe contribution of the reverse spillover effect to hydrogen generation reactions is still controversial. Herein, the promotion functions for reverse spillover in the ammonia borane hydrolysis reaction are proven by constructing a spatially separated NiO/Al2O3/Pt bicomponent catalyst via atomic layer deposition and performing in situ quick X-ray absorption near-edge structure (XANES) characterization. For the NiO/Al2O3/Pt catalyst, NiO and Pt nanoparticles are attached to the outer and inner surfaces of Al2O3 nanotubes, respectively. In situ XANES results reveal that for ammonia borane hydrolysis, the H species generated at NiO sites spill across the support to the Pt sites reversely. The reverse spillover effects account for enhanced H2 generation rates for NiO/Al2O3/Pt. For the CoOx/Al2O3/Pt and NiO/TiO2/Pt catalysts, reverse spillover effects are also confirmed. We believe that an in-depth understanding of the reverse effects will be helpful to clarify the catalytic mechanisms and provide a guide for designing highly efficient catalysts for hydrogen generation reactions.

2017 ◽  
Vol 7 (2) ◽  
pp. 322-329 ◽  
Author(s):  
Jiankang Zhang ◽  
Chaoqiu Chen ◽  
Shuai Chen ◽  
Qingmin Hu ◽  
Zhe Gao ◽  
...  

Highly active Pt nanoparticles deposited on CNTs were synthesized by atomic layer deposition used for hydrogen generation from AB hydrolysis.


2016 ◽  
Vol 6 (7) ◽  
pp. 2112-2119 ◽  
Author(s):  
Jiankang Zhang ◽  
Chaoqiu Chen ◽  
Wenjun Yan ◽  
Feifei Duan ◽  
Bin Zhang ◽  
...  

Highly efficient Ni nanoparticles deposited on CNTs were synthesized by atomic layer deposition used for hydrogen generation from AB hydrolysis.


2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Mi Xiong ◽  
Zhe Gao ◽  
Peng Zhao ◽  
Guofu Wang ◽  
Wenjun Yan ◽  
...  

Abstract In situ tuning of the electronic structure of active sites is a long-standing challenge. Herein, we propose a strategy by controlling the hydrogen spillover distance to in situ tune the electronic structure. The strategy is demonstrated to be feasible with the assistance of CoOx/Al2O3/Pt catalysts prepared by atomic layer deposition in which CoOx and Pt nanoparticles are separated by hollow Al2O3 nanotubes. The strength of hydrogen spillover from Pt to CoOx can be precisely tailored by varying the Al2O3 thickness. Using CoOx/Al2O3 catalyzed styrene epoxidation as an example, the CoOx/Al2O3/Pt with 7 nm Al2O3 layer exhibits greatly enhanced selectivity (from 74.3% to 94.8%) when H2 is added. The enhanced selectivity is attributed to the introduction of controllable hydrogen spillover, resulting in the reduction of CoOx during the reaction. Our method is also effective for the epoxidation of styrene derivatives. We anticipate this method is a general strategy for other reactions.


Nanoscale ◽  
2020 ◽  
Vol 12 (21) ◽  
pp. 11684-11693
Author(s):  
Eduardo Solano ◽  
Jolien Dendooven ◽  
Ji-Yu Feng ◽  
Philipp Brüner ◽  
Matthias M. Minjauw ◽  
...  

Supported Pt nanoparticle stabilization via Atomic Layer Deposition overcoating with Al2O3 has been proved to prevent particle coarsening during thermal annealing for widely spaced nanoparticles while ensuring surface accessibility for applications.


2020 ◽  
Vol 22 (43) ◽  
pp. 24917-24933 ◽  
Author(s):  
Jolien Dendooven ◽  
Michiel Van Daele ◽  
Eduardo Solano ◽  
Ranjith K. Ramachandran ◽  
Matthias M. Minjauw ◽  
...  

The nucleation rate and diffusion-driven growth of Pt nanoparticles are revealed with in situ X-ray fluorescence and scattering measurements during ALD: the particle morphology at a certain Pt loading is similar for high and low precursor exposures.


2017 ◽  
Author(s):  
Younghee Lee ◽  
Daniela M. Piper ◽  
Andrew S. Cavanagh ◽  
Matthias J. Young ◽  
Se-Hee Lee ◽  
...  

<div>Atomic layer deposition (ALD) of LiF and lithium ion conducting (AlF<sub>3</sub>)(LiF)<sub>x</sub> alloys was developed using trimethylaluminum, lithium hexamethyldisilazide (LiHMDS) and hydrogen fluoride derived from HF-pyridine solution. ALD of LiF was studied using in situ quartz crystal microbalance (QCM) and in situ quadrupole mass spectrometer (QMS) at reaction temperatures between 125°C and 250°C. A mass gain per cycle of 12 ng/(cm<sup>2</sup> cycle) was obtained from QCM measurements at 150°C and decreased at higher temperatures. QMS detected FSi(CH<sub>3</sub>)<sub>3</sub> as a reaction byproduct instead of HMDS at 150°C. LiF ALD showed self-limiting behavior. Ex situ measurements using X-ray reflectivity (XRR) and spectroscopic ellipsometry (SE) showed a growth rate of 0.5-0.6 Å/cycle, in good agreement with the in situ QCM measurements.</div><div>ALD of lithium ion conducting (AlF3)(LiF)x alloys was also demonstrated using in situ QCM and in situ QMS at reaction temperatures at 150°C A mass gain per sequence of 22 ng/(cm<sup>2</sup> cycle) was obtained from QCM measurements at 150°C. Ex situ measurements using XRR and SE showed a linear growth rate of 0.9 Å/sequence, in good agreement with the in situ QCM measurements. Stoichiometry between AlF<sub>3</sub> and LiF by QCM experiment was calculated to 1:2.8. XPS showed LiF film consist of lithium and fluorine. XPS also showed (AlF<sub>3</sub>)(LiF)x alloy consists of aluminum, lithium and fluorine. Carbon, oxygen, and nitrogen impurities were both below the detection limit of XPS. Grazing incidence X-ray diffraction (GIXRD) observed that LiF and (AlF<sub>3</sub>)(LiF)<sub>x</sub> alloy film have crystalline structures. Inductively coupled plasma mass spectrometry (ICP-MS) and ionic chromatography revealed atomic ratio of Li:F=1:1.1 and Al:Li:F=1:2.7: 5.4 for (AlF<sub>3</sub>)(LiF)<sub>x</sub> alloy film. These atomic ratios were consistent with the calculation from QCM experiments. Finally, lithium ion conductivity (AlF<sub>3</sub>)(LiF)<sub>x</sub> alloy film was measured as σ = 7.5 × 10<sup>-6</sup> S/cm.</div>


2021 ◽  
Author(s):  
Marwa Atwa ◽  
Xiaoan Li ◽  
Zhaoxuan Wang ◽  
Samuel Dull ◽  
Shicheng Xu ◽  
...  

A self-supported, binder-free and scalable nanoporous carbon scaffold serves as an excellent host for the efficient and uniform atomic layer deposition of Pt nanoparticles, showing exemplary performance as a cathode catalyst layer in a PEM fuel cell.


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