scholarly journals Time-Resolved Spectroscopic Investigation of Charge Trapping in Carbon Nitrides Photocatalysts for Hydrogen Generation

2017 ◽  
Vol 139 (14) ◽  
pp. 5216-5224 ◽  
Author(s):  
Robert Godin ◽  
Yiou Wang ◽  
Martijn A. Zwijnenburg ◽  
Junwang Tang ◽  
James R. Durrant
Keyword(s):  
Spectroscopic Investigation ◽  
Hydrogen Generation ◽  
Charge Trapping ◽  
Time Resolved ◽  
Carbon Nitrides

scholarly journals Highly Ordered Nitrogen-Rich Mesoporous Carbon Nitrides and Their Superior Performance for Sensing and Photocatalytic Hydrogen Generation

2017 ◽  
Vol 129 (29) ◽  
pp. 8601-8605 ◽  
Author(s):  
Gurudas P. Mane ◽  
Siddulu N. Talapaneni ◽  
Kripal S. Lakhi ◽  
Hamid Ilbeygi ◽  
Ugo Ravon ◽  
...  
Keyword(s):  
Mesoporous Carbon ◽  
Hydrogen Generation ◽  
Superior Performance ◽  
Photocatalytic Hydrogen Generation ◽  
Carbon Nitrides

Multimodal spectroscopic investigation of the conformation and local environment of biomolecules at an electrified interface

2020 ◽  
Vol 8 (31) ◽  
pp. 7024-7030
Author(s):  
Sasha A. Moonitz ◽  
Noah Shepard ◽  
Rodrigo Noriega
Keyword(s):  
Spectroscopic Investigation ◽  
Local Environment ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Mid Infrared ◽  
Electrochemically Active ◽  
Electrified Interface

A combination of mid-infrared plasmons and time-resolved fluorescence are used to probe biomolecules at a buried electrochemically active interface.

A Rapid Microwave-Assisted Thermolysis Route to Highly Crystalline Carbon Nitrides for Efficient Hydrogen Generation

2016 ◽  
Vol 128 (47) ◽  
pp. 14913-14917 ◽  
Author(s):  
Yufei Guo ◽  
Jing Li ◽  
Yupeng Yuan ◽  
Lu Li ◽  
Mingyi Zhang ◽  
...  
Keyword(s):  
Hydrogen Generation ◽  
Microwave Assisted ◽  
Carbon Nitrides

scholarly journals [FeFe] Hydrogenase based Prototype Photosensitizer-Catalyst Dyad for Hydrogen Generation under Visible Light

2021 ◽  
Author(s):  
Philipp Buday ◽  
Chizuru Kasahara ◽  
Elisabeth Hofmeister ◽  
Daniel Kowalczyk ◽  
Michael K. Farh ◽  
...  
Keyword(s):  
Visible Light ◽  
Precious Metal ◽  
Hydrogen Generation ◽  
Theoretical Calculations ◽  
Electrochemical Techniques ◽  
Time Resolved ◽  
Metal Free ◽  
Pi Conjugated ◽  
Visible Light Driven ◽  
Light Absorbers

Inspired by the active center of the natural [FeFe] hydrogenases, we designed a compact and precious metal-free photosensitizer-catalyst dyad (PS-CAT) for photocatalytic hydrogen evolution under visible light irradiation. PS-CAT represents a prototype dyad comprising pi-conjugated oligothiophenes as light absorbers. PS-CAT and its interaction with the sacrificial donor 1,3-dimethyl-2-phenylbenzimidazoline were studied by steady-state and time-resolved spectroscopy coupled with electrochemical techniques and visible light-driven photocatalytic investigations. Operando EPR spectroscopy revealed the formation of an active [Fe(I)Fe(0)] species – in accordance with theoretical calculations – presumably driving photocatalysis effectively (TON ≈ 210).

Time-Resolved Switching Studies in a-Si:H and Related Films

2003 ◽  
Vol 762 ◽  
Author(s):  
P. Stradins ◽  
W. B. Jackson ◽  
H. M. Branz ◽  
J. Hu ◽  
C.L. Perkins ◽  
...  
Keyword(s):  
Local Heating ◽  
Charge Trapping ◽  
Atomic Diffusion ◽  
Latency Time ◽  
Time Resolved ◽  
Wide Bandgap Material ◽  
Precursor Phase ◽  
Two Phases ◽  
Pulse Polarity ◽  
Ag Contact

AbstractSwitching in a-Si:H and a-Si:HNx layers is investigated by pulse current transient and Auger scanning microspectroscopy measurements. Switching in a-Si:H with Ag and Cr contacts exhibits 2 different regimes depending on the voltage pulse polarity. With a positive top Ag contact, switching occurs in nanoseconds after a certain latency time, which depends on voltage exponentially. For a negative Ag contact, there is no latency time provided the voltage exceeds a certain critical value. This might be related to interface effects on contact properties or field-assisted metal diffusion. Scanning Auger element micromaps reveal metallic filaments in the switched films. They contain both Ag and Cr throughout the film thickness. Two phases of the filament formation are suggested – a precursor phase and a post-switching phase characterized by local heating and atomic diffusion. Soft and hard switching are observed in a-Si:HNx films simultaneously and their rates depend strongly on the contact material and applied voltage. Soft switching might be related to the charge trapping in this wide bandgap material.

Effective Quenching and Excited-State Relaxation of a Cu(I) Photosensitizer Addressed by Time-Resolved Spectroscopy and TDDFT Calculations

2018 ◽  
Author(s):  
Aleksej Friedrich ◽  
Olga S. Bokareva ◽  
Shu-Ping Luo ◽  
Henrik Junge ◽  
Matthias Beller ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Copper Complex ◽  
Hydrogen Generation ◽  
Iron Catalyst ◽  
Time Resolved ◽  
Solar Hydrogen ◽  
Time Resolved Spectroscopy ◽  
Oxidative Pathway ◽  
The Individual ◽  
Mlct State

<p>Homogenous photocatalytic systems based on copper photosensitizers are promising candidates for noble metal free approaches in solar hydrogen generation. To improve their performance a detailed understanding of the individual steps is needed. Here, we study the interaction of a heteroleptic copper (I) photosensitizer with an iron catalyst by time-resolved spectroscopy and ab-initio calculations. The catalyst leads to rather efficient quenching of the <sup>3</sup>MLCT state of the copper complex, with a bimolecular rate being about three times smaller than the collision rate. Using control experiments with methyl viologen an appearing absorption band is assigned to the oxidized copper complex demonstrating that electron transfer from the sensitizer to the iron catalyst occurs and the system reacts along an oxidative pathway. However, only about 30% of the quenching events result in an electron transfer while the other 70% experience deactivation indicating that the photocatalytic performance could be improved by optimizing the intermolecular interaction.</p><p><br></p>

Effective Quenching and Excited-State Relaxation of a Cu(I) Photosensitizer Addressed by Time-Resolved Spectroscopy and TDDFT Calculations

2018 ◽  
Author(s):  
Aleksej Friedrich ◽  
Olga S. Bokareva ◽  
Shu-Ping Luo ◽  
Henrik Junge ◽  
Matthias Beller ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Copper Complex ◽  
Hydrogen Generation ◽  
Iron Catalyst ◽  
Time Resolved ◽  
Solar Hydrogen ◽  
Time Resolved Spectroscopy ◽  
Oxidative Pathway ◽  
The Individual ◽  
Mlct State

<p>Homogenous photocatalytic systems based on copper photosensitizers are promising candidates for noble metal free approaches in solar hydrogen generation. To improve their performance a detailed understanding of the individual steps is needed. Here, we study the interaction of a heteroleptic copper (I) photosensitizer with an iron catalyst by time-resolved spectroscopy and ab-initio calculations. The catalyst leads to rather efficient quenching of the <sup>3</sup>MLCT state of the copper complex, with a bimolecular rate being about three times smaller than the collision rate. Using control experiments with methyl viologen an appearing absorption band is assigned to the oxidized copper complex demonstrating that electron transfer from the sensitizer to the iron catalyst occurs and the system reacts along an oxidative pathway. However, only about 60% of the quenching events result in an electron transfer while the other 40% experience deactivation indicating that the photocatalytic performance could be improved by optimizing the intermolecular interaction.</p>

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