Perovskite-A wonder catalyst for solar hydrogen production

Hydrogen generation via artificial photosynthesis paves a promising way to remit the ever-increasing energy crisis and deteriorative environmental issues.Among ...     

Transition metal phosphides: A wonder catalyst for electrocatalytic hydrogen production

Hydrogen evolution from water electrolysis has become an important reaction for the green energy revolution. Traditional precious metals and their compounds are excellent catalysts for producing hydrogen; however, their high cost limits their large-scale practical application. Therefore, the development of affordable electrocatalysts to replace these precious metals is important. Transition metal phosphides(TMPs) have shown remarkable performance for hydrogen evolution and garnered considerable ...     

Transition metal dichalcogenide thin films for solar hydrogen production

In the last three decades, transition metal dichalcogenides (TMDs) have been extensively studied for electronic, photonic, and energy applications. Different efforts are directed to find a holy grail of efficient and economically feasible materials that could be simple in production and available on a large scale. The interest in TMDs (MoS₂, WS₂, MoSe₂, WSe₂) stems from their suitable electronic structure for efficient solar light absorption and simple exfoliation technique of 2D crystallites due to the van der Waals bonding of these materials. This led to various designs and combinations of 2D single layers that could form heterojunctions and multijunctions for efficient light absorption, charge carrier generation/separation, and its transfer in optoelectronic and energy harvesting devices. Herein, TMD thin films are reviewed as photoelectrodes for solar hydrogen evolution and compared to that of other more developed materials.     

Noble metal ionic sites for catalytic hydrogen combustion: spectroscopic insights

A catalytic hydrogen combustion reaction was carried out over noble metal catalysts substituted in ZrO(2) and TiO(2) in ionic form. The catalysts were synthesized by the solution combustion technique. The compounds showed high activity and CO tolerance for the reaction. The activity of Pd and Pt ion substituted TiO(2) was comparable and was higher than Pd and Pt ion substituted ZrO(2). The mechanisms of the reaction over the two supports were proposed by making use of the X-ray photoelectron spectroscopy and FT infrared spectroscopic observations. The reaction over ZrO(2) supported catalysts was proposed to take place by the utilization of the surface hydroxyl groups while the reaction over TiO(2) supported catalysts was hypothesized to be a hybrid mechanism utilizing surface hydroxyl groups and the lattice oxygen.     

Pt deposited TiO2 catalyst fabricated by thermal decomposition of titanium complex for solar hydrogen production

C, N codoped TiO₂ catalyst has been synthesized by thermal decomposition of a novel water-soluble titanium complex. The structure, morphology, and optical properties of the synthesized TiO₂ catalyst were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and UV–vis diffuse reflectance spectroscopy. The photocatalytic activity of the Pt deposited TiO₂ catalysts synthesized at different temperatures was evaluated by means of hydrogen evolution reaction under both UV–vis and visible light irradiation. The investigation results reveal that the photocatalytic H₂ evolution rate strongly depended on the crystalline grain size as well as specific surface area of the synthesized catalyst. Our studies successfully demonstrate a simple method for the synthesis of visible-light responsive Pt deposited TiO₂ catalyst for solar hydrogen production.     

High-temperature hydrogen production by solar thermochemical reactors,metal interfaces,and nanofluid cooling

Journal of Thermal Analysis and Calorimetry - Solar thermochemical reactors have been considered in recent studies because of converting the solar energy to a fuel, which is called solar fuel. In...     

含金金属纳米颗粒用于液相化学氢化物催化制氢

液相化学氢化物以化学键的形式储存氢能,被认为是一类很有前景的化学储氢材料。液相化学氢化物的大规模应用很大程度上依赖于高效催化系统的开发。含金金属纳米颗粒在用于液相化学氢化物催化制氢中表现出优异的催化性能。本文综述了金纳米颗粒和含金异金属纳米颗粒用于液相氢化物催化制氢的最新研究进展。     

Highly active iridium catalyst for hydrogen production from formic acid

Formic acid(FA) dehydrogenation has attracted a lot of attentions since it is a convenient method for H_2 production. In this work, we designed a self-supporting fuel cell system, in which H_2 from FA is supplied into the fuel cell, and the exhaust heat from the fuel cell supported the FA dehydrogenation. In order to realize the system, we synthesized a highly active and selective homogeneous catalyst Ir Cp*Cl_2 bpym for FA dehydrogenation. The turnover frequency(TOF) of the catalyst for FA dehydrogenation is as high as7150 h~(-1)at 50°C, and is up to 144,000 h~(-1)at 90°C. The catalyst also shows excellent catalytic stability for FA dehydrogenation after several cycles of test. The conversion ratio of FA can achieve 93.2%, and no carbon monoxide is detected in the evolved gas. Therefore, the evolved gas could be applied in the proton exchange membrane fuel cell(PEMFC) directly. This is a potential technology for hydrogen storage and generation. The power density of the PEMFC driven by the evolved gas could approximate to that using pure hydrogen.     

Organic photochemistry V: photochemistry of substituted Schiff''s bases—search for luminescent dyes for solar collectors

The pH dependence of the absorption and fluorescence spectra of Schiff's bases derived from 2-amino-4-phenylthiazole and aniline with substitued 2-hydroxybenzaldehydes was investigated. The pK_a values of the Schiff's bases associated with the ground state equilibria were determined spectrophotometrically. The excited state pK_a values were also estimated. Their Stokes shifts were also calculated.     

Cobalt thiolate complexes catalyst in noble-metal-free system for photocatalytic hydrogen production

Thiolate complexes Co(bpy)(pyS)₂ (M) were synthesized, the effect of reaction conditions (such as pH values, solvents, electron donor, photosensitizers, catalyst, and concentrations) on catalytic performance of catalyst M was studied and the optimum reaction conditions were selected. The results of catalytic performance imply that complexes M showed good catalytic activity when concentration of catalyst M was 2.5 μM, concentration of fluorescein was 2.0 mM, pH value was 11.6, electron donor was triethylamine (5%), and the solvent was EtOH/H₂O (1: 1 V/V). The catalysis system presented the best performance and hydrogen production reached 369.2 μmol h^–1 after reacting for 15 h; the life of catalyst M was 41 h investigated under the optimum conditions.     

The preparation of hydrogen by the catalytic pyrolysis of ethanol on a nickel catalyst

High efficiency of a nickel catalyst on the SiO₂ support in low-temperature ethanol conversion as a method for the preparation of hydrogen was demonstrated. One mole of the alcohol was found to yield one mole of hydrogen. The catalyst studied did not stimulate the methanation and shift reactions.     

Electrochemical catalytic reforming of oxygenated-organic compounds: a highly efficient method for production of hydrogen from bio-oil

A novel approach to produce hydrogen from bio-oil was obtained with high carbon conversion (>90%) and hydrogen yield (>90%) at T<500 degrees C by using the electrochemical catalytic reforming of oxygenated-organic compounds over 18%NiO/Al(2)O(3) reforming catalyst; thermal electrons play important promoting roles in the decomposition and reforming of the oxygenated-organic compounds in the bio-oil.     

Plasmonic metal/semiconductor hybrid nanomaterials for solar to chemical energy conversion

Plasmonic nanomaterials are sources of light,heat and electrons at nanometer scale.Given the outstand-ing performance in harvesting and converting solar energy ...     

Semiconductor,molecular and hybrid systems for photoelectrochemical solar fuel production

The paper shortly reviews the basic direct approaches applied in searching for viable solutions to solar fuel production. These are generally distinguished in molecular and semiconductor(non-molecular)systems, however, hybrid strategies, proposed recently, have also been included. The most promising efforts are considered, highlighting key aspects and emerging critical issues. Special attention is paid to aspects such as electrode architecture, device design, and main differences in the scientific vision and challenges to directly produce solar fuels. This overview could be useful to orientate the readers in the wide panorama of research activities concerning water splitting, natural and artificial photosynthesis, and solar fuel production through the identification of common aspects, specialties and potentialities of the many initiatives and approaches that are developing worldwide in this field with the final aim to meet world energy demand.     

Theoretical studies of the mechanism of catalytic hydrogen production by a cobaloxime

Our theoretical studies of the standard reduction potentials of the molecular complex [Co(II)(dmgBF(2))(2)](0) (dmgBF(2) = difluoro-boryldimethylglyoximate) in acetonitrile solution shed light on its electrocatalytic mechanism for hydrogen production. Three such mechanisms have been proposed, all proceeding through the formation of Co(III)H. Our results indicate that the mechanism involving a Co(II)H intermediate is the most likely.     

The use of plasmas in catalysis: catalyst preparation and hydrogen production

Plasma technologies are introduced in the field of hydrogen production related to fuel cells. Two ways are described: Plasma synthesis of catalysts and membranes for the production and purification of hydrogen and, direct production of hydrogen based on atmospheric plasma-assisted methane steam reforming.     

Electrodeposition: Synthesis of advanced transition metal-based catalyst for hydrogen production via electrolysis of water

Developing lower-cost and higher-effective catalyst to support hydrogen (H2) production by electrochemical water-splitting has been recognized as a preferred st...     

Photochemical hydrogen production with molecular devices comprising a zinc porphyrin and a cobaloxime catalyst

Two new noble-metal-free molecular devices,[{Co(dmgH) 2 Cl}{Zn(PyTPP)}](1,dmgH = dimethyloxime,PyTPP = 5-(4pyridyl)-10,15,20-triphenylporphyrin) and [{Co(dmgH) 2 Cl}{Zn(apPyTPP)}](2,apPyTPP = 5-[4-(isonicotinamidyl)phenyl]10,15,20-triphenylporphyrin),for light-driven hydrogen generation were prepared and spectroscopically characterized.The zinc porphyrin photosensitizer and the Co III-based catalyst unit are linked by axial coordination of a pyridyl group in the periphery of zinc-porphyrin to the cobalt centre of catalyst with different lengths of bridges.The apparent fluorescence quenching and lifetime decays of 1 and 2 were observed in comparison with their reference chromophores,Zn(PyTPP)(3) and Zn(apPyTPP)(4),suggesting a possibility for an intramolecular electron transfer from the singlet excited state of zinc porphyrin unit to the cobalt centre in the molecular devices.Photochemical H2-evolving studies show that complexes 1 and 2 are efficient molecular photocatalysts for visible light-driven H2 generation from water with triethylamine as a sacrificial electron donor in THF/H2 O,with turnover numbers up to 46 and 35 for 1 and 2,respectively.In contrast to these molecular devices,the multicomponent catalyst of zinc porphyrin and [Co(dmgH) 2 PyCl] did not show any fluorescence quenching and as a consequence,no H2 gas was detected by GC analysis in the presence of triethylamine with irradiation of visible light.The plausible mechanism for the photochemical H2 generation with these molecular devices is discussed.     

Homogeneous catalytic system for photoinduced hydrogen production utilizing iridium and rhodium complexes

An efficient homogeneous catalytic system for the visible-light-induced production of hydrogen from water utilizing cyclometalated iridium(III) and tris-2,2'-bipyridyl rhodium(III) complexes is described. Synthetic modification of the photosensitizer Ir(C--N) 2(N--N) (+) and water reduction catalyst Rh(N--N) 3 (3+) creates a family of catalysts with diverse photophysical and electrochemical properties. Parallel screening of the various catalyst combinations and photoreaction conditions allows the rapid development of an optimized photocatalytic system that achieves over 5000 turnovers with quantum yields ( (1)/ 2 H 2 per photon absorbed) greater than 34%. Photophysical and electrochemical characterization of the optimized system reveals that the reductive quenching pathway provides the necessary driving force for the formation of [Rh(N--N) 2] (0), the active catalytic species for the reduction of water to produce hydrogen. Tests for system poisoning with mercury or CS 2 provide strong evidence that the system is a true homogeneous system for photocatalytic hydrogen production.