Metalloporphyrin immobilized CeO2: in situ generation of active sites and synergistic promotion of photocatalytic water oxidation

2021 ◽  
Author(s):  
Jiao Meng ◽  
Yue Zhao ◽  
Haining Li ◽  
Ruiping Chen ◽  
Xun Sun ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Active Sites ◽  
Oxygen Vacancies ◽  
Electron Coupling ◽  
Catalytically Active ◽  
In Situ Generation ◽  
The Creation

CoTCPP transfer photoexcited electrons to CeO2 by d–f electron coupling. The in situ generation of catalytically active sites: reduction on CeO2 accompanied with the creation of oxygen vacancies and oxidation on CoTCPP that transforms into CoOOH.

Ultrathin NiCo2O4 nanosheets with dual-metal active sites for enhanced solar water splitting of a BiVO4 photoanode

2019 ◽  
Vol 7 (39) ◽  
pp. 22274-22278 ◽  
Author(s):  
Chenchen Feng ◽  
Qi Zhou ◽  
Bin Zheng ◽  
Xiang Cheng ◽  
Yajun Zhang ◽  
...  
Keyword(s):  
Water Splitting ◽  
Water Oxidation ◽  
Active Sites ◽  
Oxygen Vacancies ◽  
Solar Water ◽  
Solar Water Splitting ◽  
Highly Efficient ◽  
Dual Metal ◽  
Nico2o4 Nanosheets ◽  
First Time

Spinel-structured NiCo2O4 nanosheets with dual-metal active sites, an ultrathin structure, and abundant oxygen vacancies were decorated for the first time on a BiVO4 photoanode for highly efficient PEC water oxidation.

scholarly journals Co@CoO: a Unique Catalyst for Hydrogenolysis of Biomass-derived 5-Hydroxymethylfurfural to 2,5-Dimethylfuran

2021 ◽  
Author(s):  
Shuang Xiang ◽  
Lin Dong ◽  
Zhiqiang Wang ◽  
Xue Han ◽  
Luke Daemen ◽  
...  
Keyword(s):  
Active Sites ◽  
Oxygen Vacancies ◽  
Computational Modelling ◽  
Renewable Biomass ◽  
Structured Catalyst ◽  
Excellent Activity ◽  
Catalytically Active ◽  
Fuels And Chemicals ◽  
Lignin Model ◽  
First Time

The development of precious-metal-free catalysts to promote the sustainable production of fuels and chemicals from biomass remains an important and challenging target. Here, we report the efficient hydrogenolysis of biomass-derived 5-hydroxymethylfurfural to 2,5-dimethylfuran over a unique core-shell structured catalyst Co@CoO that affords the highest productivity among all catalysts reported to date. Surprisingly, we found that the catalytically active sites reside on the shell of CoO with oxygen vacancies rather than the metallic Co. The combination of various spectroscopic experiments and computational modelling reveals that the CoO shell incorporating oxygen vacancies drives the heterolytic and homolytic cleavage of dihydrogen to yield active Hδ- species, resulting in the exceptional catalytic activity. Co@CoO also exhibits excellent activity toward the direct hydrodeoxygenation of lignin model compounds. This study unlocks, for the first time, the potential of metal-oxide catalysts for the production of renewable biomass-derived fuels.

scholarly journals Evolution of anatase surface active sites probed by in situ sum-frequency phonon spectroscopy

2016 ◽  
Vol 2 (9) ◽  
pp. e1601162 ◽  
Author(s):  
Yue Cao ◽  
Shiyou Chen ◽  
Yadong Li ◽  
Yi Gao ◽  
Deheng Yang ◽  
...  
Keyword(s):  
Active Sites ◽  
Oxygen Vacancies ◽  
Surface Reactivity ◽  
Ambient Conditions ◽  
Sum Frequency ◽  
Surface Active ◽  
Surface Phonon Mode ◽  
Titanium Dioxides ◽  
Associated Species

Surface active sites of crystals often govern their relevant surface chemistry, yet to monitor them in situ in real atmosphere remains a challenge. Using surface-specific sum-frequency spectroscopy, we identified the surface phonon mode associated with the active sites of undercoordinated titanium ions and conjoint oxygen vacancies, and used it to monitor them on anatase (TiO2) (101) under ambient conditions. In conjunction with theory, we determined related surface structure around the active sites and tracked the evolution of oxygen vacancies under ultraviolet irradiation. We further found that unlike in vacuum, the surface oxygen vacancies, which dominate the surface reactivity, are strongly regulated by ambient gas molecules, including methanol and water, as well as weakly associated species, such as nitrogen and hydrogen. The result revealed a rich interplay between prevailing ambient species and surface reactivity, which can be omnipresent in environmental and catalytic applications of titanium dioxides.

scholarly journals MOF-Mediated Synthesis of Supported Fe-doped Pd Nanoparticles under Mild Conditions for Magnetically Recoverable Catalysis

2020 ◽  
Author(s):  
Guillermo Minguez Espallargas ◽  
Mohanad D. Darawsheh ◽  
Dr. Mónica Giménez Marqués ◽  
Marcelo E. Domine ◽  
Pascual Oña-Burgos ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Active Sites ◽  
Pd Nanoparticles ◽  
Reusable Catalyst ◽  
Synthetic Approach ◽  
Promising Alternative ◽  
Mild Conditions ◽  
Catalytic Materials ◽  
In Situ Generation

MOF-driven synthesis is considered as a promising alternative for the development of new catalytic materials with well-designed active sites. This synthetic approach is used here to gradually transform a new bimetallic MOF, composed of Pd and Fe as metal components, via the in situ generation of aniline under mild conditions. This methodology results in a compositionally homogeneous nanocomposite formed by Fedoped Pd nanoparticles and these, in turn, supported on an iron oxide-doped carbon. The nanocomposite has been fully characterized by several techniques such as IR, Raman, TEM, XPS, XAS, among others. The performance of this nanocomposite as an heterogeneous catalyst for hydrogenation of nitroarenes and nitrobenzene coupling with benzaldehyde has been evaluated, proving it to be an efficient and reusable catalyst.

scholarly journals Origin of Enhanced Water Oxidation Activity in an Iridium Single Atom Catalyst

2021 ◽  
Author(s):  
Xueli Zheng ◽  
Jing Tang ◽  
Alessandro Gallo ◽  
Jose Antonio Garrido Torres ◽  
Xiaoyun Yu ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Active Sites ◽  
High Performance ◽  
Operating Conditions ◽  
Utilization Efficiency ◽  
Oxidation Catalyst ◽  
Single Atom ◽  
Photochemical Reduction ◽  
Oxidation Activity

<p>The efficiency of the synthesis of renewable fuels and feedstocks from electrical sources is limited at present by the sluggish water oxidation reaction. Single atom catalysts (SACs) with a controllable coordination environment and exceptional atom utilization efficiency open new paradigms towards designing high performance water oxidation catalysts. Here, using<i> operando</i> X-ray absorption spectroscopy measurements with calculations of spectra and electrochemical activity, we demonstrate that the origin of water oxidation activity of IrNiFe SACs is the presence of highly oxidized Ir single atom (Ir<sup>5.3+</sup>)<sup> </sup>in the NiFe oxyhydroxide under operating conditions. We show that the optimal water oxidation catalyst could be achieved by systematically increasing the oxidation state and modulating the coordination environments of the Ir active sites anchored atop the NiFe oxyhydroxide layers. Based on the proposed mechanism, we have successfully anchored Ir single-atom sites on NiFe oxyhydroxides (Ir<sub>0.1</sub>/Ni<sub>9</sub>Fe SAC) via a unique<i> in situ</i> cryogenic photochemical reduction (<i>in situ</i> Cryo-PCR) method which delivers an overpotential of 183 millivolts at 10 milliamperes per square centimeter and retains its performance following 20 hours of operation in 1 M KOH electrolyte, outperforming the reported catalysts and the commercial IrO<sub>2</sub> catalysts. These findings open the avenue towards atomic-level understanding of oxygen evolution of catalytic centers under <i>in operando</i> condition.</p>

scholarly journals In-situ spectroscopic observation of dynamic-coupling oxygen on atomically dispersed iridium electrocatalyst for acidic water oxidation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Hui Su ◽  
Wanlin Zhou ◽  
Wu Zhou ◽  
Yuanli Li ◽  
Lirong Zheng ◽  
...  
Keyword(s):  
Working Conditions ◽  
Water Oxidation ◽  
Active Sites ◽  
Proton Exchange Membrane ◽  
Large Mass ◽  
Spectroscopic Observation ◽  
Proton Exchange ◽  
Dynamic Coupling ◽  
Active Centre

AbstractUncovering the dynamics of active sites in the working conditions is crucial to realizing increased activity, enhanced stability and reduced cost of oxygen evolution reaction (OER) electrocatalysts in proton exchange membrane electrolytes. Herein, we identify at the atomic level potential-driven dynamic-coupling oxygen on atomically dispersed hetero-nitrogen-configured Ir sites (AD-HN-Ir) in the OER working conditions to successfully provide the atomically dispersed Ir electrocatalyst with ultrahigh electrochemical acidic OER activity. Using in-situ synchrotron radiation infrared and X-ray absorption spectroscopies, we directly observe that one oxygen atom is formed at the Ir active site with an O-hetero-Ir-N4 structure as a more electrophilic active centre in the experiment, which effectively promotes the generation of key *OOH intermediates under working potentials; this process is favourable for the dissociation of H2O over Ir active sites and resistance to over-oxidation and dissolution of the active sites. The optimal AD-HN-Ir electrocatalyst delivers a large mass activity of 2860 A gmetal−1 and a large turnover frequency of 5110 h−1 at a low overpotential of 216 mV (10 mA cm−2), 480–510 times larger than those of the commercial IrO2. More importantly, the AD-HN-Ir electrocatalyst shows no evident deactivation after continuous 100 h OER operation in an acidic medium.

Boosting the efficiency of water oxidation via surface states on hematite photoanodes by incorporating Bi3+ ions

2020 ◽  
Vol 4 (8) ◽  
pp. 4207-4218
Author(s):  
Abdul Zeeshan Khan ◽  
Tarek A. Kandiel ◽  
Safwat Abdel-Azeim ◽  
Khalid Alhooshani
Keyword(s):  
Crystal Structure ◽  
Water Oxidation ◽  
Oxidation Kinetics ◽  
Oxygen Vacancies ◽  
Surface States ◽  
The Creation ◽  
Photoelectrochemical Water Oxidation

The incorporation of Bi3+ ions into the hematite crystal structure induces the creation of oxygen vacancies and boosts the photoelectrochemical water oxidation kinetics.

Sign in / Sign up

Export Citation Format

Share Document