Hydrogen Generation for 500 hours by Photoelectrolysis of Water using GaN

2012 ◽  
Vol 1446 ◽  
Author(s):  
W. Ohara ◽  
D. Uchida ◽  
T. Hayashi ◽  
M. Deura ◽  
K. Ohkawa
Keyword(s):  
Conversion Efficiency ◽  
Electric Charge ◽  
Hydrogen Generation ◽  
Incident Light ◽  
Hydrogen Gas ◽  
Light Energy ◽  
Chemical Energy ◽  
Incident Photon

ABSTRACTWe confirmed that GaN photocatalyst with NiO cocatalyst (GaN-NiO) continuously produced hydrogen from water for 500 hours without any extra bias. The GaN-NiO photocatalyst was hardly etched and 184-mL hydrogen gas was produced from the electric charge of 1612 coulombs, the Faradic efficiency of which was 89.2%. The conversion efficiency from incident light energy to hydrogen chemical energy was 0.98% in average for 500 h. The incident photon-to-current conversion efficiency (IPCE) was 50% at 300 nm and 35% at 350 nm after the experiment, which was much higher than those of other semiconductor-based photocatalysts.

scholarly journals Research of Hydrogen Preparation with Catalytic Steam-Carbon Reaction Driven by Photo-Thermochemistry Process

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
Xiaoqing Zhang ◽  
Bingqing Xu ◽  
Yan Xu ◽  
Shuyong Shang ◽  
Yongxiang Yin
Keyword(s):  
Solar Energy ◽  
Conversion Efficiency ◽  
Catalytic Reaction ◽  
Hydrogen Generation ◽  
Reaction System ◽  
Chemical Energy ◽  
Xenon Lamp ◽  
Rate Of Reaction ◽  
Catalyst Content ◽  
Content Range

An experiment of hydrogen preparation from steam-carbon reaction catalyzed by K2CO3was carried out at 700°C, which was driven by the solar reaction system simulated with Xenon lamp. It can be found that the rate of reaction with catalyst is 10 times more than that without catalyst. However, for the catalytic reaction, there is no obvious change for the rate of hydrogen generation with catalyst content range from 10% to 20%. Besides, the conversion efficiency of solar energy to chemical energy is more than 13.1% over that by photovoltaic-electrolysis route. An analysis to the mechanism of catalytic steam-carbon reaction with K2CO3is given, and an explanation to the nonbalanced [H2]/[CO + 2CO2] is presented, which is a phenomenon usually observed in experiment.

scholarly journals Thickness-dependent photoelectrochemical properties of a semitransparent Co3O4 photocathode

2018 ◽  
Vol 9 ◽  
pp. 2432-2442 ◽  
Author(s):  
Malkeshkumar Patel ◽  
Joondong Kim
Keyword(s):  
Water Splitting ◽  
Water Oxidation ◽  
Hydrogen Generation ◽  
Hydrogen Gas ◽  
Generation Rate ◽  
Alkaline Electrolyte ◽  
Stoichiometric Ratio ◽  
Gas Generation ◽  
Pec Cells ◽  
Gas Generation Rate

Co3O4 has been widely studied as a catalyst when coupled with a photoactive material during hydrogen production using water splitting. Here, we demonstrate a photoactive spinel Co3O4 electrode grown by the Kirkendall diffusion thermal oxidation of Co nanoparticles. The thickness-dependent structural, physical, optical, and electrical properties of Co3O4 samples are comprehensively studied. Our analysis shows that two bandgaps of 1.5 eV and 2.1 eV coexist with p-type conductivity in porous and semitransparent Co3O4 samples, which exhibit light-induced photocurrent in photoelectrochemical cells (PEC) containing the alkaline electrolyte. The thickness-dependent properties of Co3O4 related to its use as a working electrode in PEC cells are extensively studied and show potential for the application in water oxidation and reduction processes. To demonstrate the stability, an alkaline cell was composed for the water splitting system by using two Co3O4 photoelectrodes. The oxygen gas generation rate was obtained to be 7.17 mL·h−1 cm−1. Meanwhile, hydrogen gas generation rate was almost twice of 14.35 mL·h−1·cm−1 indicating the stoichiometric ratio of 1:2. We propose that a semitransparent Co3O4 photoactive electrode is a prospective candidate for use in PEC cells via heterojunctions for hydrogen generation.

scholarly journals Nanostructures GaAs Solar Cells

2020 ◽  
Author(s):  
Mohammad Nur E Alam ◽  
Narottam Das
Keyword(s):  
Power Generation ◽  
Solar Cells ◽  
Conversion Efficiency ◽  
Human Mobility ◽  
Incident Light ◽  
Front Surface ◽  
Pv Systems ◽  
Energy Demands ◽  
Power Generation Technology ◽  
Pv Power Generation

At present, the world is now passing a very far different time than normal situation due to the COVID-19 pandemic crisis. The global life-style and human civilization is currently progressing with down-stream that affecting almost every sectors necessary for human civilizations except the current environmental situation. To control the COVID-19 spreading, most of the countries are following lockdown process that reduces human mobility, thus reducing the CO2 emission to the environment. Though the COVID-19 pandemic is a blessing for the present environment, however, the post-COVID world will face a massive thrust of energy and only conventional energy resources may not be enough to mitigate the energy demands. Solar power generation technology mainly the photovoltaic (PV) systems and their advancement can be the leading possibilities to minimize the gap between the power demand and generation. It is now time to think how we can improve the PV power generation in future and the post-COVID world. In this encyclopaedia communication, we report on Nano-technological approach to improve the conversion efficiency of GaAs solar cells. We have designed and optimized several types of nano-structured assemblies that can be implemented to reduce the front surface incident light reflection losses thus can assist to improve the conversion efficiency of GaAs solar cells.

scholarly journals Magnesium Hydride-Mediated Sustainable Hydrogen Supply Prolongs the Vase Life of Cut Carnation Flowers via Hydrogen Sulfide

2020 ◽  
Vol 11 ◽  
Author(s):  
Longna Li ◽  
Yuhao Liu ◽  
Shu Wang ◽  
Jianxin Zou ◽  
Wenjiang Ding ◽  
...  
Keyword(s):  
Hydrogen Sulfide ◽  
Hydrogen Generation ◽  
Magnesium Hydride ◽  
Hydrogen Gas ◽  
Vase Life ◽  
Buffer Solution ◽  
Citrate Buffer ◽  
Sodium Hydrosulfide ◽  
Practical Applications ◽  
Citrate Buffer Solution

Magnesium hydride (MgH2) is a promising solid-state hydrogen source with high storage capacity (7.6 wt%). Although it is recently established that MgH2 has potential applications in medicine because it sustainably supplies hydrogen gas (H2), the biological functions of MgH2 in plants have not been observed yet. Also, the slow reaction kinetics restricts its practical applications. In this report, MgH2 (98% purity; 0.5–25 μm size) was firstly used as a hydrogen generation source for postharvest preservation of flowers. Compared with the direct hydrolysis of MgH2 in water, the efficiency of hydrogen production from MgH2 hydrolysis could be greatly improved when the citrate buffer solution is introduced. These results were further confirmed in the flower vase experiment by showing higher efficiency in increasing the production and the residence time of H2 in solution, compared with hydrogen-rich water. Mimicking the response of hydrogen-rich water and sodium hydrosulfide (a hydrogen sulfide donor), subsequent experiments discovered that MgH2-citrate buffer solution not only stimulated hydrogen sulfide (H2S) synthesis but also significantly prolonged the vase life of cut carnation flowers. Meanwhile, redox homeostasis was reestablished, and the increased transcripts of representative senescence-associated genes, including DcbGal and DcGST1, were partly abolished. By contrast, the discussed responses were obviously blocked by the inhibition of endogenous H2S with hypotaurine, an H2S scavenger. These results clearly revealed that MgH2-supplying H2 could prolong the vase life of cut carnation flowers via H2S signaling, and our results, therefore, open a new window for the possible application of hydrogen-releasing materials in agriculture.

Peptide-mediated porphyrin based hierarchical complexes for light-to-chemical conversion

Nanoscale ◽  
2020 ◽  
Vol 12 (28) ◽  
pp. 15201-15208 ◽  
Author(s):  
Yang Xiu ◽  
Xiao Zhang ◽  
Yifan Feng ◽  
Rupu Wei ◽  
Sidi Wang ◽  
...  
Keyword(s):  
Chemical Conversion ◽  
Light Energy ◽  
Chemical Energy

We constructed hierarchical complexes via the peptide-regulated assembly of porphyrin and Pt for converting light energy into chemical energy and storing it as NADH.

scholarly journals Structural Effects on the Incident Photon-to-Current Conversion Efficiency of Zn Porphyrin Dyes on the Low-Index Planes of TiO2

ACS Omega ◽  
2017 ◽  
Vol 2 (1) ◽  
pp. 128-135 ◽  
Author(s):  
Ryo Ide ◽  
Yamato Fujimori ◽  
Yukihiro Tsuji ◽  
Tomohiro Higashino ◽  
Hiroshi Imahori ◽  
...  
Keyword(s):  
Conversion Efficiency ◽  
Structural Effects ◽  
Incident Photon
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