The conversion and storage of solar energy to chemical energy
via
artificial photosynthesis holds significant potential for optimizing the energy situation and mitigating the global warming effect. ...Photocatalytic water splitting utilizing particulate semiconductors offers great potential for the production of renewable hydrogen, while this cross-road among biology, chemistry, and physics features a topic with fascinating interdisciplinary challenges. Progress in photocatalytic water splitting has been achieved in recent years, ranging from fundamental scientific research to pioneering scalable practical applications. In this review, we focus mainly on the recent advancements in terms of the development of new light-absorption materials, insights and strategies for photogenerated charge separation, and studies towards surface catalytic reactions and mechanisms. In particular, we emphasize several efficient charge separation strategies such as surface-phase junction, spatial charge separation between facets, and polarity-induced charge separation, and also discuss their unique properties including ferroelectric and photo-Dember effects on spatial charge separation. By integrating time- and space-resolved characterization techniques, critical issues in photocatalytic water splitting including photoinduced charge generation, separation and transfer, and catalytic reactions are analyzed and reviewed. In addition, photocatalysts with state-of-art efficiencies in the laboratory stage and pioneering scalable solar water splitting systems for hydrogen production using particulate photocatalysts are presented. Finally, some perspectives and outlooks on the future development of photocatalytic water splitting using particulate photocatalysts are proposed.
Recent advances in particulate photocatalytic water splitting are reviewed and the pioneering works in scalable H
2
evolution
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photocatalytic OWS are presented.
Dear Editor, The class 2/type Ⅱ clustered regularly interspaced short palindromic repeat （CRISPR）/Cas9 system has been used successfully for simultaneous modification of multiple loci in plants. Two ...general strategies have been applied to coexpress multiple single guide RNAs （sgRNAs） to achieve multiplex gene editing in plant cells.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Summary
Base editing is a novel genome editing strategy that enables irreversible base conversion at target loci without the need for double stranded break induction or homology‐directed repair. ...Here, we developed new adenine and cytosine base editors with engineered SpCas9 and SaCas9 variants that substantially expand the targetable sites in the rice genome. These new base editors can edit endogenous genes in the rice genome with various efficiencies. Moreover, we show that adenine and cytosine base editing can be simultaneously executed in rice. The new base editors described here will be useful in rice functional genomics research and will advance precision molecular breeding in crops.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
As wide range of light absorption and suitable redox potentials are prerequisites for photocatalytic water splitting, exploring new semiconductor‐based materials with proper band structures for water ...splitting still calls for longstanding efforts. In this work, a series of photocatalysts, bismuth tantalum oxyhalide, Bi4TaO8X (X = Cl, Br), with valence band and conduction band positions at ≈−0.70 and ≈1.80 eV versus the reversible hydrogen electrode (RHE), respectively, are found to be capable for both water oxidation and reduction under visible light irradiation. Using flux synthetic methods, Bi4TaO8X (X = Cl, Br) with microplatelet morphology can be successfully prepared. The photocatalyst based on these materials shows an apparent quantum efficiency as high as 20% at 420 nm for water oxidation. In addition, a Z‐scheme system coupling Bi4TaO8Br with Ru/SrTiO3:Rh is successfully achieved for overall water splitting with a stoichiometric ratio of H2 and O2 evolutions. This work demonstrates a new series of semiconductors Bi4TaO8X (X = Cl, Br) with the promising application in the field of solar energy utilization.
A series of photocatalysts, bismuth tantalum oxyhalides, Bi4TaO8X (X = Cl, Br), with the energy band gaps of around 2.5 eV, are explored and found to be capable of both water oxidation and reduction under visible light irradiation. Notably, an apparent quantum efficiency as high as 20% (at 420 nm) for water oxidation is achieved.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Surface modulation via injection or extraction of charge carriers in microelectric devices has been used to tune the energy band alignment for desired electrical and optical properties, yet not well ...recognized in photocatalysis field. Here, taking semiconductor bismuth tantalum oxyhalides (Bi4TaO8X) as examples, chemically inactive molybdenum oxide (MoO3) with a large work function is introduced to qualitatively tune the properties of interfacial charges, achieving an evidently enhanced upward band bending and intensive built‐in electric field. Such a simple charge modulation exhibits a remarkable improvement in photocatalytic water oxidation, reaching an apparent quantum efficiency of 25% at the input wavelength of 420 nm. The validity and generality of surface charge modulating strategy are further demonstrated using other semiconductors (e.g., C3N4) and decorators (e.g., V2O5). The findings not only provide a promising strategy for rationally manipulating the interfacial built‐in electric field in photocatalysis but also pave the way to learn from microelectronic technologies to construct artificial photosynthesis systems for solar energy conversion.
Molybdenum oxide (MoO3) is introduced as a surface modification on Bi4TaO8X (X = Cl, Br) to tune the interfacial charges, achieving an enhanced upward band bending as well as an intensive built‐in electric field. Such charge modulation results in an evident improvement in photocatalytic water oxidation under visible light irradiation, reaching an apparent quantum efficiency of 25% at 420 nm.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The photocatalytic conversion of carbon dioxide to fuels presents great promise for storing renewable energy and alleviating global warming. Herein, using the visible-light-responsive semiconductor ...bismuth tantalum oxyhalogen (Bi4TaO8X, X = Cl, Br) with suitable band structures, we realize the photocatalytic reduction of CO2 to selectively produce CO under visible light without introducing any sacrificial reagents. An isotope-labeling experiment clearly demonstrated that the produced CO originated from CO2 and, additionally, continuous water oxidation for O2 evolution was also detected during photocatalytic CO2 reduction. Further introducing crystal morphology modulation to prepare well-defined nanocrystals enables great enhancement of the photogenerated charge separation performance compared to that of irregular nanoparticles. Moreover, surface modification of the silver nanoparticles deployed as the CO2 reduction cocatalyst evidently facilitates the generation of intermediate species to promote the surface catalytic reaction. This work not only presents a potential semiconductor candidate for photocatalytic CO2 reduction, but it also provides a feasible strategy for designing artificial photosynthetic systems via combining morphology tailoring and suitable cocatalysts.
Spatial charge separation has already been realized between different facets of a single crystal. However, how the photogenerated charges distribute on one facet of a single crystal is still unknown. ...In this work, we found that the distribution of photogenerated charges on a SrTiO3 nanocube varies with the light intensity. Photogenerated holes tend to transfer to the edges and corners of the crystal under weak illumination, indicating that a spatial charge separation takes place on the same facet of the SrTiO3 nanocube. Based on this effect, oxidation and reduction cocatalysts can be respectively photodeposited on the edges and central areas of one facet. The separated dual-cocatalysts lead to a remarkable enhancement in photocatalytic overall water splitting. These findings reveal that the spatial charge separation can happen even on the same facet.
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IJS, KILJ, NUK, PNG, UL, UM
Solar-driven water splitting by photocatalysts is potentially a promising solution for global-scale production of nonfossil fuels and environmental problems, yet deep understanding toward the ...intrinsic active sites and activity of photocatalysts under real photocatalytic conditions is still insufficient. Here, taking bismuth tantalum oxyhalogen (Bi4TaO8X) as an example, we unraveled a commonly overlooked phenomenon of photoinduced surface activation, in which the intrinsic active sites generated and dominated the enhanced photocatalytic activity under reaction conditions. We demonstrated that a thin layer of amorphous tantalum oxides species was in situ generated on the surface of the Bi4TaO8X photocatalyst at the initial stage of the photocatalytic reaction, and such amorphous species were proven to be the active sites which can significantly facilitate the photocatalytic water-splitting reactions. The investigation focusing on photoinduced surface activation of photocatalysts under the reaction conditions not only unravels the reactive states of semiconductor photocatalysts but also sheds light on the understanding of photocatalytic mechanisms.
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IJS, KILJ, NUK, PNG, UL, UM
Abstract So-called Z-scheme systems permit overall water splitting using narrow-bandgap photocatalysts. To boost the performance of such systems, it is necessary to enhance the intrinsic activities ...of the hydrogen evolution photocatalyst and oxygen evolution photocatalyst, promote electron transfer from the oxygen evolution photocatalyst to the hydrogen evolution photocatalyst, and suppress back reactions. The present work develop a high-performance oxysulfide photocatalyst, Sm 2 Ti 2 O 5 S 2 , as an hydrogen evolution photocatalyst for use in a Z-scheme overall water splitting system in combination with BiVO 4 as the oxygen evolution photocatalyst and reduced graphene oxide as the solid-state electron mediator. After surface modifications of the photocatalysts to promote charge separation and redox reactions, this system is able to split water into hydrogen and oxygen for more than 100 hours with a solar-to-hydrogen energy conversion efficiency of 0.22%. In contrast to many existing photocatalytic systems, the water splitting activity of the present system is only minimally reduced by increasing the background pressure to 90 kPa. These results suggest characteristics suitable for applications under practical operating conditions.
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