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Herein, we report the in situ single-step hydrothermal synthesis of hierarchical 2D SnS@ZnIn2S4 nano-heterostructures and the examination of their photocatalytic activity towards hydrogen generation from H2S and water under sunlight. The photoactive sulfides rationally integrate via strong electrostatic interactions between ZnIn2S4 and SnS with two-dimensional ultrathin subunits, i.e. nanopetals. The morphological study of nano-heterostructures revealed that the hierarchical marigold flower-like structure is self-assembled via the nanopetals of ZnIn2S4 with few layers of SnS nanopetals. Surprisingly, it also showed that the SnS nanopetals with a thickness of ∼25 nm couple in situ with the nanopetals of ZnIn2S4 with a thickness of ∼25 nm to form a marigold flower–like assembly with intimate contact. Considering the unique band gap (2.0–2.4 eV) of this SnS@ZnIn2S4, photocatalytic hydrogen generation from water and H2S was performed under sunlight. SnS@ZnIn2S4 exhibits enhanced hydrogen evolution, i.e. 650 μmol h−1 g−1 from water and 6429 μmol h−1 g−1 from H2S, which is much higher compared to that of pure ZnIn2S4 and SnS. More significantly, the enhancement in hydrogen generation is 1.6–2 times more for H2S splitting and 6 times more for water splitting. SnS@ZnIn2S4 forms type I band alignment, which accelerates charge separation during the surface reaction. Additionally, this has been provoked by the nanostructuring of the materials. Due to the nano-heterostructure with hierarchical morphology, the surface defects increased which ultimately suppresses the recombination of the electron–hole pair. The above-mentioned facts demonstrate a significant improvement in the interface electron transfer kinetics due to such a unique 2D nano-heterostructure semiconductor which is responsible for a higher photocatalytic activity.

Covalent organic frameworks (COFs) have emerged as a promising light-harvesting module for artificial photosynthesis and photovoltaics. For efficient generation of free charge carriers, the donor–acceptor (D-A) conjugation has been adopted for two-dimensional (2D) COFs recently. In the 2D D-A COFs, photoexcitation would generate a polaron pair, which is a precursor to free charge carriers and has lower binding energy than an exciton. Although the character of the primary excitation species is a key factor in determining optoelectronic properties of a material, excited-state dynamics leading to the creation of a polaron pair have not been investigated yet. Here, we investigate the dynamics of photogenerated charge carriers in 2D D-A COFs by combining femtosecond optical spectroscopy and non-adiabatic molecular dynamics simulation. From this investigation, we elucidate that the polaron pair is formed through ultrafast intra-layer hole transfer coupled with coherent vibrations of the 2D lattice, suggesting a mechanism of phonon-assisted charge transfer., The donor–acceptor (D-A) conjugation has been adopted for two-dimensional (2D) covalent organic frameworks (COFs) for efficient generation of free charge carriers. Here, the authors investigate the dynamics of photogenerated charge carriers in 2D D-A COFs by combining femtosecond optical spectroscopy and non-adiabatic molecular dynamics simulation.

The selective production of fine chemicals using inexpensive solar light continues to be a challenge. As a means to achieve this we report herein the synthesis and development of a perylene-based solar-light-driven photocatalyst (PDA–DAA) obtained by the covalent bonding of perylene tetracarboxylic dianhydride (PDA) with a 2,6-diamino-anthraquinone (DAA) molecule. The photocatalyst/biocatalyst coupled system developed using PDA–DAA as a photocatalyst functions in a highly efficient manner, leading to high NADH regeneration (80.12%), followed by its consumption in exclusive production of l-glutamate (94.16%) from α-ketoglutarate. The present research highlights the development and application of the PDA–DAA photocatalyst for direct formation of l-glutamate under solar light.

Our growing energy demands must be met by a sustainable supply with reduced carbon intensity. One of the most exciting prospects to realize this goal is the photocatalyst-biocatalyst integrated artificial photosynthesis system which affords solar fuel/chemicals in high selectivity from CO2. Graphene based photocatalysts are highly suitable for the system, but their industrial scale use requires immobilization for improved separation and recovery of the photocatalyst. Therefore for practical purposes, design and fabrication of film type graphene photocatalyst with higher solar energy conversion efficiency is an absolute necessity. As a means to achieve this, we report herein the successful development of a new type of flexible graphene film photocatalyst that leads to >225% rise in visible light harvesting efficiency of the resultant photocatalyst-biocatalyst integrated artificial photosynthesis system for highly selective solar fuel production from CO2 compared to conventional spin coated graphene film photocatalyst. It is an important step towards the design of a new pool of graphene film based photocatalysts for artificial photosynthesis of solar fuels from CO2.

In situ synthesis of the orthorhombic Bi2S3 nanowires decorated with hexagonal CdS nanoparticles (nano-heterostructure) has been demonstrated by a facile solvothermal method. The tiny 5–7 nm CdS spherical nanoparticles are decorated on the surfaces of 30–40 nm Bi2S3 nanowires, successfully. Structural, morphological and optical studies clearly show the existence of CdS on the nanowires. A possible sequential deposition growth mechanism is proposed on the basis of experimental results to reveal the formation of the nano heterostructure. The heterostructures have been used as a photocatalyst for hydrogen production as well as degradation of methylene blue under solar light. The maximum hydrogen evolution i.e. 4560 and 2340 μmol h−1 0.5 g was obtained from H2S splitting and glycerol degradation for Bi2S3 NWs decorated with CdS nanoparticles (nano-heterostructure) which is higher than that of the Bi2S3 NWs (3000 and 1170 μmol h−1 0.5 g, respectively). The enhanced photocatalytical hydrogen evolution efficiency of the heterostructures is mainly attributed to its nanostructure. In the nano heterostructure, the CdS nanoparticles control the charge carrier transition, recombination, and separation, while the Bi2S3 nanowire serves as a support for the CdS nanoparticles. The photogenerated electron's migration is faster than the holes from the inside of a CdS nanoparticle to its surface or to the phase interface, resulting in a relatively higher hole density inside the CdS nanoparticle leaving electron density at surface of the Bi2S3 NWs. This influences the photocatalytic activity under solar light. Such nano-heterostructures may have potential in other photocatalytic reactions.

Conductive metal–organic frameworks are an emerging class of three-dimensional architectures with degrees of modularity, synthetic flexibility and structural predictability that are unprecedented in other porous materials. However, engendering long-range charge delocalization and establishing synthetic strategies that are broadly applicable to the diverse range of structures encountered for this class of materials remain challenging. Here, we report the synthesis of K x Fe2(BDP)3 (0 ≤ x ≤ 2; BDP2− = 1,4-benzenedipyrazolate), which exhibits full charge delocalization within the parent framework and charge mobilities comparable to technologically relevant polymers and ceramics. Through a battery of spectroscopic methods, computational techniques and single-microcrystal field-effect transistor measurements, we demonstrate that fractional reduction of Fe2(BDP)3 results in a metal–organic framework that displays a nearly 10,000-fold enhancement in conductivity along a single crystallographic axis. The attainment of such properties in a K x Fe2(BDP)3 field-effect transistor represents the realization of a general synthetic strategy for the creation of new porous conductor-based devices. A conducting metal–organic framework with charge delocalization by reductive potassium insertion is demonstrated. Integration into a field-effect transistor shows similar mobilities to semiconductors, with a mobility estimated to be at least 0.84 cm2 V–1 s–1.

Natural photosynthesis is the primary route that supplies energy required for the endurance of all living things. The initial step in this process is the absorption of solar light by an organic-inorganic molecular organization called a light harvesting complex. This complicated natural solar energy conversion platform has inspired scientists to create artificial counter parts. As a means to achieve this, a self-assembled light harvesting carbon nitride/cobalt tetra-phenyl-porphyrin (CN/Co(III)TPP) material as a highly selective solar light active photocatalyst has been developed. The system exhibited excellent NADH regeneration (87.87%) and L-glutamate (94.30%) production under visible light irradiation. The current research endeavor highlights the development and application of a self-assembled CN/Co(III)TPP photocatalyst for the selective production of L-glutamate from α-ketoglutarate.

Herein, for the first time, CuAlGaO 4 is demonstrated as an efficient visible-light-active (band-gap of 1.87 eV, λ ≥ 420 nm) photocatalyst for solar H 2 production. The CuAlGaO 4 prepared by solid-state method is capable of producing 3214 μmol of H 2 per hour from H 2 S photodecomposition under visible-light irradiation with quantum yield of 10.8% at 550 nm. Loading with 1 wt.% NiO enhances the rate of H 2 generation of the photocatalyst to 3616 μmolh −1 with quantum yield of 12.7% at 550 nm. The CuAlGaO 4 exhibits a spinel structure with particle size varying from a few nanometers to a few micrometers. The regenerated catalysts validate the stability and the reusability.

The present communication is the report of our research work on synthesis of new delafossite oxides containing Ga/Ga and In p-block elements, and their visible light driven catalytic activity in solar H 2 production from H 2 S decomposition. CuGaO 2 and its indium doped analogue CuGa 1− x In x O 2 ( x = 0.065) delafossite oxides without/with NiO and RuO 2 co-catalysts loading in nanostructures were prepared by solid state reaction method. These materials possess hexagonal rhombohedral structure (XRD); morphologically CuGaO 2 has irregularly-shaped plate like particles while all others have ordered hexagonal rod-like arrangements (FESEM). Co-catalyst deposits of few nm sizes are observable as white spots/patches on the surface of naked oxide catalysts. Acquiring p-type conductivity from the mixed valence of Cu (+1 and +2) and oxygen deficiency, these catalysts strongly absorb visible light (Eg = 1.85 eV) in a wide wavelength range. They decompose H 2 S in aqueous 0.5 M KOH solution under visible light ( λ ⩾ 420 nm) irradiation and generate H 2 to the tune of 4300 μmol/h, giving rise to a high quantum efficiency of 13.6% at 550 nm. The exceedingly higher rate of H 2 production appears to result from a combined contribution of chemical nature (p-block elements Ga and In), p-type conductivity and an efficient e − –h + separation.

Tantalum-containing metal oxides, well known for their efficiency in water splitting and H 2 production, have never been used in visible light driven photodecomposition of H 2 S and H 2 production. The present work is an attempt in this direction and investigates their efficiency. A mixed metal oxide, ZnFe 2 Ta 2 O 9 , with the inclusion of Fe 2 O 3 to impart color, was prepared by the conventional ceramic route in single- and double-calcinations (represented as ZnFe 2 Ta 2 O 9 -SC and ZnFe 2 Ta 2 O 9 -DC respectively). The XRD characterization shows that both have identical patterns and reveals tetragonal structure to a major extent and a minor contribution of orthorhombic crystalline system. The UV-visible diffuse reflection spectra demonstrate the intense, coherent and wide absorption of visible light by both the catalysts, with absorption edge at 650 nm, giving rise to a band gap of 1.9 eV. Between the two catalysts, however, ZnFe 2 Ta 2 O 9 -DC has greater absorption in almost the entire wavelength region, which accounts for its strong brown coloration than ZnFe 2 Ta 2 O 9 -SC when viewed by the naked eye. In photocatalysis, both catalysts decompose H 2 S under visible light irradiation (λ ≥ 420 nm) and produce solar H 2 at a much higher rate than previously reported catalysts. Nevertheless, ZnFe 2 Ta 2 O 9 -DC distinguishes itself from ZnFe 2 Ta 2 O 9 -SC by exhibiting a higher efficiency because of its greater light absorption. Altogether, the tantalum-containing mixed metal oxide proves its efficient catalytic role in H 2 S decomposition and H 2 production process also.

We have calculated electronic structure of InTaO4 using first-principle method, in order to investigate the relationship between its electronic structures and visible light absorption. We have calculated densities of states (DOS) for various states of InTaO4, such as pristine, oxygen vacancy, Ni-doped, and A-doped (A = C, N, and S) states. We have found that oxygen vacancy can induce the gap states and Ni-doping can narrow the band gap by generating additional states on the top of the valence band as well as on the top of the gap states. For A-doped states, it was found that N-doping and S-doping could narrow the pristine band gap inducing the additional states above the pristine valence band, while C-doping can generate the gap states in the middle of the pristine band gap. To cite this article: H. Chang et al., C. R. Chimie 9 (2006).

Formation of octahedral shaped PbSe quantum dots at higher synthesis temperature is being reported in this paper. The synthesis includes the reaction between lead oleate and trioctylphosphine selenide under inert gas conditions to produce PbSe. TEM, SEM, XRD and EDS were used to characterize the samples. The SEM exhibited the formation of spherical shaped nanocrystals at temperature below 140 and octahedral shaped nanoparticles at higher temperatures. Moreover, the TEM also showed the well resolved (111) lattice fringes proving that the nanocrystals were crystalline in nature. Synthesis of highly pure PbSe nanocrystals was another interesting aspect of this research.

A novel metal-oxide photocatalyst, ZnBiVO4, was investigated for the photodecomposition of hydrogen sulfide. ZnBiVO4 was prepared using the solid-state method, as well as a solution route for the first time. Oxides of zinc, bismuth, and vanadium were used for the solid-state method, whereas the respective metal salts were used as precursors for the solution route synthesis. The microstructure of the newly prepared ZnBiVO4 was examined using XRD and FESEM. Tetragonal and monoclinic crystallite systems were observed in this ternary oxide system. Nanocrystalline ZnBiVO4 was obtained through the solution route. The catalyst was also characterized using UV–visible diffuse reflectance spectroscopy to evaluate its band gap. Photodecomposition of H2S using this catalyst was observed for the first time. The influence of preparation methods on the photocatalytic activity of ZnBiVO4 was examined and it was observed that the ZnBiVO4 prepared by the solution route led to a higher photocatalytic activity during H2S decomposition. It is noteworthy that the hydrogen evolution was enhanced by 100% using ZnBiVO4 prepared by the solution route as compared with the ZnBiVO4 prepared by the solid-state method.Key words: photocatalyst, ZnBiVO4, hydrogen sulfide, metal oxide, photodecomposition.

Highly dispersed nanometer-sized α-Fe2O3 (hematite) and γ-Fe2O3 (maghemite) iron oxide particles were synthesized by the combustion method. Ferric nitrate was used as a precursor. X-ray diffractometer study revealed the phase purity of α- and γ-Fe2O3. Both the products were characterized using field emission scanning electron microscope and transmission electron microscope for particle size and morphology. Necked structure particle morphology was observed for the first time in both the iron oxides. The particle size was observed in the range of 25–55 nm. Photodecomposition of H2S for hydrogen generation was performed using α- and γ-Fe2O3. Good photocatalytic activity was obtained using α- and γ-Fe2O3 as photocatalysts under visible light irradiation.

Acetidines react with carbodiimides in the presence of bis(benzonitrile)palladium dischloride to form tetrahydrophyrimidin-2-imines in 64-97% yields. The reaction is both regio- and stereospecific, the cycloaddition occurring with retention of configuration of the carbon centers bearing the substitutent groups. 2 figs.

1,1′-Bis(diphenylphosphino)ferrocene (BPPF) reacts with a 5–10 molar excess of Fe(CO)5 to give three new iron complexes (η2-BPPF)Fe(CO)3 (1), (η1-BPPF)Fe(CO)4 (2), and (μ,η1-BPPF)Fe2(CO)8 (3) with the product distribution depending upon reaction conditions. The structure of 1 has been determined. Crystals are monoclinic, space group P21/c, with a 9.708(1), b 16.195(2), c 19.869(5) A, β 95.75(2)°, V 3108(1) A3, Z = 4, and Dcalc 1.49 g cm−3. The geometry around the central iron is a distorted trigonal bipyramid, with the two phosphorus atoms occupying axial and equatorial positions. All these compounds can catalyze efficiently the reaction of propargyl alcohol with secondary amines in the presence of CO2 to provide corresponding carbamate esters. The yields of some carbamates are among the highest (∼ 65%) ever reported in the literature.