Novel defect-transit dual Z-scheme heterojunction: Sulfur-doped carbon nitride nanotubes loaded with bismuth oxide and bismuth sulfide for efficient photocatalytic amine oxidation.

The rational design of Z-scheme heterojunction hybrid photocatalysts is considered a promising way to achieve high photocatalytic activity. In this study, a dual Z-scheme heterojunction with bismuth sulfide (Bi2S3) nanorods and bismuth oxide (Bi2O3) nanoparticles anchored Sulfur-doped carbon nitride (S-CN) nanotubes (Bi2S3/S-CN/Bi2O3) is designed and fabricated through the ordinal metal ion adsorption, pyrolysis, and sulfidation processes using supramolecular rods as precursor. Compared with pristine Bi2S3, Bi2O3, and CN, the dual Z-scheme tube-shaped Bi2S3/S-CN/Bi2O3 catalyst exhibited a significantly improved photocatalytic activity in amine oxidation. The optimized Bi2S3/S-CN/Bi2O3 nanostructure exhibits a 97.6 % benzylamine conversion and 99.4 % imine selectivity within 4 h under simulated solar light irradiation. The excellent activity of Bi2S3/S-CN/Bi2O3 nanotubes can be attributed to the characteristic hollow defect band structure and efficient charge separation and transfer achieved by the dual Z-scheme charge transfer mechanism, which was systematically studied using electron spin resonance spectroscopy, Kelvin probe force microscope, and other techniques. The optimized dual Z-scheme heterojunction hybrid photocatalyst maintains the high oxidizing ability of Bi2S3 and Bi2O3 and the excellent reducing ability of CN, thereby significantly enhancing the photocatalytic activity. This research provides a facile and feasible synthesis strategy for designing dual Z-scheme heterojunctions with defect band structure to improve the photocatalytic activity.

Engineering of Ultra-Thin Layer of MIL-125(Ti) Nanosheet\Zn-Tetracarboxy-Phthalocyanine S-Scheme Heterojunction as Photocatalytic CO2 Reduction Catalyst.

Metal-organic frameworks (MOFs) with ultrathin 2D structure have attracted remarkable attention in photocatalytic application owing to the accessibility of abundant active sites on the surface. But high charge recombination results in poor photocatalytic activity. Herein, the synthesis of ultrathin MIL-125(Ti) nanosheets is reported with a thickness of 1.3 nm through a simple chemical reaction route of precursor solution aging and subsequent solvothermal process for photocatalytic CO2 production. The maximal CO evolution rate achieves 200.8 µmol g-1 h-1, which is prominently higher than that (78.6 µmol g-1 h-1) of the bulk MIL-125(Ti) counterpart. Furthermore, the structurally stable Zn (II) tetracarboxy phthalocyanine (ZnTcPc) molecules assembly on ultrathin MIL-125(Ti) nanosheet (NS) to form MIL-125(Ti) NS\ZnTcPc S-scheme heterojunction through the strong interaction between the Ti3+ in MIL-125(Ti) and the COOH in ZnTcPc. The introduction of ZnTcPc greatly extends light absorption range and increases charge separation rate. The experimental and density functional theory calculation results validate that the MIL-125(Ti) NS\ZnTcPc S-scheme heterojunction can favor CO2 adsorption and effectively depress the formation energy of the intermediates, achieving a high CO evolution rate of 450.8 µmol g-1 h-1. This work provides a strategy of engineering 2D MOF-based heterostructure systems for photocatalytic application.

Enhanced charge transfer and photocatalytic carbon dioxide reduction of copper sulphide@cerium dioxide p-n heterojunction hollow cubes.

Hollow structure hybrids have gained considerable attention for their ability to reduce CO2 owing to their rich active sites, high gas adsorption ability, and excellent light utilization capacity. Herein, a template-engaged strategy was provided to fabricate copper sulphide@cerium dioxide (CuS@CeO2) p-n heterojunction hollow cube photocatalysts using Cu2O cubes as a sacrificial template. The sequential steps of loading of CeO2 nanolayer, sulfidation, and etching reaction facilitate the formation of CuS@CeO2 p-n heterojunction hollow cubes. Compared with the single CuS, CeO2, and their physical mixture, the CuS@CeO2 p-n heterojunction hollow cube photocatalyst expresses a higher performance toward photocatalytic CO2 reduction under solid-gas reaction conditions due to the faster separation of photogenerated charges. The further enhanced performance of CuS@CeO2 p-n heterojunction hollow cubes was achieved by decorating pt nanoparticles due to the fact that Pt nanoparticles had a high electron affinity and CO2 adsorption capacity, and the highest CO and CH4 yields of the optimized hybrid reached 195.8 µmol g-1 h-1 and 19.96 µmol g-1 h-1, respectively. This work might provide a strategy for designing and synthesizing efficient hollow heterostructured photocatalysts for solar energy conversion and utilization.

Task-Oriented Robot Cognitive Manipulation Planning Using Affordance Segmentation and Logic Reasoning.

The purpose of task-oriented robot cognitive manipulation planning is to enable robots to select appropriate actions to manipulate appropriate parts of an object according to different tasks, so as to complete the human-like task execution. This ability is crucial for robots to understand how to manipulate and grasp objects under given tasks. This article proposes a task-oriented robot cognitive manipulation planning method using affordance segmentation and logic reasoning, which can provide robots with semantic reasoning skills about the most appropriate parts of the object to be manipulated and oriented by tasks. Object affordance can be obtained by constructing a convolutional neural network based on the attention mechanism. In view of the diversity of service tasks and objects in service environments, object/task ontologies are constructed to realize the management of objects and tasks, and the object-task affordances are established through causal probability logic. On this basis, the Dempster-Shafer theory is used to design a robot cognitive manipulation planning framework, which can reason manipulation regions' configuration for the intended task. The experimental results demonstrate that our proposed method can effectively improve the cognitive manipulation ability of robots and make robots preform various tasks more intelligently.

Hierarchical S-scheme titanium dioxide@cobalt-nickel based metal-organic framework nanotube photocatalyst for selective carbon dioxide photoreduction to methane.

Efficient photocatalysts are of great importance for the photochemical conversion of CO2 into fuels. Herein, S-scheme titanium dioxide@cobalt-nickel based metal-organic framework (TiO2@CoNi-MOF) heterojunction photocatalysts with high surface area and porosity are designed and fabricated by a multi-step controllable strategy. The photocatalytic activity of the composites can be optimized by adjusting the loading content of CoNi-MOF in TiO2@CoNi-MOF and molar ratios of Co2+ and Ni2+ in CoNi-MOF. The optimized hybrid photocatalyst showed a much higher CO2 photoreduction activity than the control single-component samples (TiO2 and CoNi-MOF) with a high CH4 yield (41.65 µmol g-1 h-1) and selectivity (93.2%). The accelerated charge carrier separation induced by the S-scheme heterojunction significantly promoted the photocatalytic performance of TiO2@CoNi-MOF NTs. Meanwhile, the introduction of bimetallic CoNi-MOF nanosheets significantly resulted in the increase of active sites, CO2 adsorbability, visible-light utilization, and CH4 selectivity. Moreover, the S-scheme photoinduced charge transfer model of the TiO2@CoNi-MOF NTs photocatalyst was confirmed by photoluminescence spectroscopy, free radical trapping tests, and work function calculated from Kelvin probe. The work aims to design and fabricate heterojunction photocatalysts with high efficiency for solar fuel production.

Robot gaining robust pouring skills through fusing vision and audio.

In the pouring task of service robots, the robust and accurate estimate of liquid height is a crucial step. However, neither vision nor audio alone can achieve better liquid height estimation. We instead propose a visual-audio information fusion network to enable robots with good pouring skills. Visual and audio information are used as information sources. Firstly, visual features are extracted by residual network based on attention model. Secondly, the Fourier characteristic matrix of audio information is obtained by fast Fourier transform, and then the audio feature is extracted by long-short term memory. Thirdly, visual features and audio features are fused by fully connected network to output the liquid height and state of the cup. Finally, a sinusoidal and transient fusion control method is proposed, which takes the liquid height and cup state as inputs, outputs the angle of the gripper, and provides an implementation method for the pouring task. Experiments are carried out to evaluate the performance of multimodal information fusion method and verify the effectiveness of the algorithm for pouring tasks of service robots.

Multi-channel charge transfer of hierarchical TiO2 nanosheets encapsulated MIL-125(Ti) hollow nanodisks sensitized by ZnSe for efficient CO2 photoreduction.

Metal-organic frameworks-based hybrids with desirable components, structures, and properties have been proven to be promising functional materials for photocatalysis and energy conversion applications. Herein, we proposed and prepared ZnSe sensitized hierarchical TiO2 nanosheets encapsulated MIL-125(Ti) hollow nanodisks with sandwich-like structure (MIL-125(Ti)@TiO2\ZnSe HNDs) through a successive solvothermal and selenylation reaction route using the as-prepared MIL-125(Ti) nanodisks as precursor. In the ternary MIL-125(Ti)@TiO2\ZnSe HNDs hybrid, TiO2 nanosheets were transformed from MIL-125(Ti) and in situ grown on both sides of the MIL-125(Ti) shell, forming sandwich-like hollow nanodisks, and the ratio of MIL-125(Ti)/TiO2 can be tuned by changing the solvothermal time. The ternary hybrids possess the advantages of enhanced incident light utilization and abundant accessible active sites originating from bimodal pore-size distribution and hollow sandwich-like heterostructure, which can effectively promote CO2 photoreduction reaction. Especially, the formed multi-channel charge transfer routes in the ternary heterojunctions contribute to the charge transfer/separation and extend the lifespan of charge-separated state, thus boosting CO2 photoreduction performance. The CO (513.1 µmol g-1h-1) and CH4 (45.1 µmol g-1h-1) evolution rates over the optimized ternary hybrid were greatly enhanced compared with the single-component and binary hybrid photocatalysts.

Sandwich-Structured Hybrid of NiCo Nanoparticles-Embedded Carbon Nanotubes Grafted on C3N4 Nanosheets for Efficient Photodehydrogenative Coupling Reactions.

Exploring cheap and efficient hybrid catalysts offers exciting opportunities for enhancing the performance of photocatalysts in the green organic synthesis field. Herein, a facile and effective approach is designed for the synthesis of a sandwich-structured hybrid in which NiCo bimetallic nanoparticles are embedded in the tip of nitrogen-doped carbon nanotubes (N-CNTs) grafted on both sides of a nitrogen deficient C3N4 (Nv-C3N4) nanosheet for photodehydrogenative coupling reactions. Such a brand-new type of sandwich-structured hybrid comprises Nv-C3N4 nanosheets and surrounding N-CNTs embedded with NiCo nanoparticles at their tips. Remarkably, the resultant hybrid exhibits integrated functionalities, abundant active sites, enhanced visible light absorption, and excellent interfacial charge transfer ability. As a result, the optimized NiCo@N-CNTs@Nv-C3N4 photocatalyst shows significantly improved photodehydrogenative coupling performance of amines to imines compared to the control single-metal-based catalysts (Ni@N-CNTs@Nv-C3N4 and Co@N-CNTs@Nv-C3N4). The mechanistic investigation through experimental and computational study demonstrates that, compared with single-metal-based hybrids, the NiCo bimetallic hybrid exhibits stronger amine adsorption and weaker photogenerated hydrogen atom adsorption, thus promoting the dehydrogenative activation of primary amines and fast generation of imines. This work presents a promising insight for designing and preparing efficient photocatalysts to trigger organic synthesis in high yields.

Hierarchical CuS@ZnIn2S4 Hollow Double-Shelled p-n Heterojunction Octahedra Decorated with Fullerene C60 for Remarkable Selectivity and Activity of CO2 Photoreduction into CH4.

In this work, a hollow double-shelled architecture, based on n-type ZnIn2S4 nanosheet-coated p-type CuS hollow octahedra (CuS@ZnIn2S4 HDSOs), is designed and fabricated as a p-n heterojunction photocatalyst for selective CO2 photoreduction into CH4. The resulting hybrids provide rich active sites and effective charge migration/separation to drive CO2 photoreduction, and meanwhile, CO detachment is delayed to increase the possibility of eight-electron reactions for CH4 production. As expected, the optimized CuS@ZnIn2S4 HDSOs manifest a CH4 yield of 28.0 µmol g-1 h-1 and a boosted CH4 selectivity up to 94.5%. The decorated C60 both possesses high electron affinity and improves catalyst stability and CO2 adsorption ability. Thus, the C60-decorated CuS@ZnIn2S4 HDSOs exhibit the highest CH4 evolution rate of 43.6 µmol g-1 h-1 and 96.5% selectivity. This work provides a rational strategy for designing and fabricating efficient heteroarchitectures for CO2 photoreduction.

Efficient charge transfer in cadmium sulfide quantum dot-decorated hierarchical zinc sulfide-coated tin disulfide cages for carbon dioxide photoreduction.

Constructing hybrid photocatalysts with advanced structures and controllable compositions is a promising way to improve CO2 photoreduction performance. In this work, SnS2 nanosheets are grown on ZnS polyhedron cages to fabricate hierarchical ZnS@SnS2 double-shelled heterostructured cages. This design integrates ZnS cages and SnS2 nanosheets into a stable heterostructured hybrid catalyst with a hierarchical double-shelled cage-like architecture, possessing abundant active sites, quick charge separation/migration, and high CO2 adsorption capacity. Benefiting from these advantages, the optimized hierarchical ZnS@SnS2 heterostructured cages exhibit significant gas-phase CO2 photoreduction activity with a CO generation rate of 95.38 µmol g-1h-1 and 72.4% CO selectivity, which are greatly improved in comparison with those of pure ZnS cages and nanosheet-assembled SnS2 particles. Furthermore, charge carrier separation efficiency and visible light harvesting ability are further improved by constructing a ZnS@SnS2/CdS type-I/type-II complex heterostructured system through surface decoration of CdS quantum dots. The optimized ZnS@SnS2/CdS hybrid exhibits a CO generation rate of 155.57 µmol g-1h-1 and an excellent selectivity of 80.4%. This work is conducive to the design and manufacture of advanced hybrids for solar energy utilization and photocatalytic reactions.

Fabrication of size-controlled hierarchical ZnS@ZnIn2S4 heterostructured cages for enhanced gas-phase CO2 photoreduction.

Designing and constructing advanced heterojunction architectures are desirable for boosting CO2 photoreduction performance of semiconductor photocatalysts. Herein, we have prepared hierarchical ZnS@ZnIn2S4 core-shell cages with controlled particle sizes using sequential synthesis of Zeolitic imidazolate (ZIF-8) polyhedrons, ZnS cages, and ZnIn2S4 nanosheets on the ZnS polyhedron cages. ZIF-8 polyhedrons are firstly synthesized by a liquid-phase approach. The subsequent sulfidation of the ZIF-8 polyhedrons results in the formation of ZnS polyhedron cages, which act as substrates for fabricating ZnS@ZnIn2S4 core-shell cages by growing ZnIn2S4 nanosheets. The size of ZnS cages can be tuned to optimize CO2 photoreduction performance of hierarchical ZnS@ZnIn2S4 core-shell cages. The synergy of the unique hierarchical core-shell cage-like structure and heterojunction composition endows the hybrid catalyst high incident light utilization, abundant active sites, and effective separation of photoexcited charge carriers. Benefiting from these advantages, the optimized hierarchical ZnS@ZnIn2S4 core-shell cages exhibit enhanced performance for CO2 photoreduction with the CO yield of 87.43 µmol h-1g-1 and 84.3% selectivity, which are much superior to those of single ZnIn2S4 or ZnS. Upon Au decoration, the CO2 photoreduction performance of ZnS@ZnIn2S4 core-shell cages is further enhanced because of the Schottky junctions and surface plasmon resonance effect.

Hierarchical Co0.85 Se-CdSe/MoSe2 /CdSe Sandwich-Like Heterostructured Cages for Efficient Photocatalytic CO2 Reduction.

Fabricating efficient photocatalysts with rapid charge carrier separation and high visible light harvesting is an advisable strategy to improve CO2 reduction performance. Herein, hierarchical Co0.85 Se-CdSe/MoSe2 /CdSe cages with sandwich-like heterostructure are prepared to act as efficient photocatalysts for CO2 reduction. In this study, the structure and composition of the final products can be regulated through the cation-exchange reaction in the presence of ascorbic acid. In the Co0.85 Se-CdSe/MoSe2 /CdSe cages, MoSe2 nanosheets function as a bridge to integrate Co0.85 Se-CdSe and CdSe on both sides of the MoSe2 nanosheet shell into a sandwich-like heterostructured catalyst system, which possesses multiple positive merits for photocatalysis, including accelerated transport and separation of photogenerated carriers, improved visible light utilization, and increased catalytic active sites. Thus, the optimized Co0.85 Se-CdSe/MoSe2 /CdSe cages exhibit remarkable visible-light photocatalytic performance and outstanding stability for CO2 reduction with a high CO average yield of 15.04 µmol g-1 h-1 and 90.14% selectivity, which are much higher than those of other control samples including single-component catalysts and binary hybrid catalysts. This study provides a promising way for the design and fabrication of high-efficiency photocatalysts.

Improved charge separation and carbon dioxide photoreduction performance of surface oxygen vacancy-enriched zinc ferrite@titanium dioxide hollow nanospheres with spatially separated cocatalysts.

Here, we describe the fabrication of surface oxygen vacancy-enriched ZnFe2O4@TiO2 double-shell hollow heterostructure nanospheres (ZnFe2O4@H-TiO2-x) coupled with spatially separated CoOx and Au-Cu bimetallic cocatalysts. The ZnFe2O4@TiO2 heterojunction and spatially separated dual cocatalysts can significantly promote the separation of photoinduced charge carriers. Combined with the unique hollow double-shell heterostructure characteristics and improved surface state properties, the hybrid nanospheres can efficiently adsorb and activate CO2 molecules. These advantages cause the optimized catalyst to exhibit remarkably higher gas-phase photocatalytic CO2 reduction activity than the control CoOx/ZnFe2O4/Au-Cu and ZnFe2O4@H-TiO2-x double-shell hollow nanospheres loaded with a single cocatalyst. Meanwhile, the Au-Cu bimetal effect boosts the CO2 conversion rate and CH4 selectivity. The optimized hybrid catalyst with a Au/Cu ratio of 1:1 provides a CH4 yield of 21.39 µmol g-1 h-1 with 93.8% selectivity. This work provides a rational photocatalyst design to improve CO2 conversion and CH4 selectivity.

Synergetic enhancement of surface reactions and charge separation over holey C3N4/TiO2 2D heterojunctions.

Efficient charge separation and rapid interfacial reaction kinetics are crucial factors that determine the efficiency of photocatalytic hydrogen evolution. Herein, a fascinating 2D heterojunction photocatalyst with superior photocatalytic hydrogen evolution performance - holey C3N4 nanosheets nested with TiO2 nanocrystals (denoted as HCN/TiO2) - is designed and fabricated via an in situ exfoliation and conversion strategy. The HCN/TiO2 is found to exhibit an ultrathin 2D heteroarchitecture with intimate interfacial contact, highly porous structures and ultrasmall TiO2 nanocrystals, leading to drastically improved charge carrier separation, maximized active sites and the promotion of mass transport for photocatalysis. Consequently, the HCN/TiO2 delivers an impressive hydrogen production rate of 282.3 µmol h-1 per 10 mg under AM 1.5 illumination and an apparent quantum efficiency of 13.4% at a wavelength of 420 nm due to the synergetic enhancement of surface reactions and charge separation. The present work provides a promising strategy for developing high-performance 2D heterojunctions for clean energy applications.

In situ intercalation and exploitation of Co3O4 nanoparticles grown on carbon nitride nanosheets for highly efficient degradation of methylene blue.

The low surface area, poor electrical conductivity, and rapid electron-hole recombination in bulk C3N4 limit its photocatalytic activity, which makes it challenging to improve the performance of bulk C3N4. Herein, an effective strategy is proposed to fabricate Co3O4/C3N4 heterojunctions (Co3O4 nanoparticles grown on C3N4 nanosheets), where bulk C3N4 is exfoliated to thin nanosheets. The bulk C3N4 precursor was synthesized with the hydrothermal treatment of melamine solution, and Co2+ ions were then inserted into the interlayer of the precursor through a vacuum-assisted intercalation process. Subsequently, the precursor was exfoliated to C3N4 nanosheets, and 15 nm Co3O4 nanoparticles were simultaneously formed using in situ thermal polycondensation. The Brunauer-Emmett-Teller (BET) specific surface area of the prepared heterojunction was 21 times higher than that of bulk C3N4, and thus more active sites were exposed on the surface of the heterostructure. Co3O4 nanoparticles contained oxygen vacancies, and the type-II transfer mechanism between these nanoparticles and C3N4 could be used to effectively separate photogenic carriers and improve the electron mobility. As expected, the heterostructure exhibited an excellent photocatalyzed degradation rate of 99.5% for methylene blue within 30 min (10 mg catalyst, wavelength >420 nm) under visible light irradiation, which was nearly three times higher than that of bulk C3N4. Electron paramagnetic resonance (EPR) analysis indicated that ˙O2- was the main reactive oxidizing species during the degradation process.

Achieving cadmium selenide-decorated zinc ferrite@titanium dioxide hollow core/shell nanospheres with improved light trapping and charge generation for photocatalytic hydrogen generation.

We report the rational design and fabrication of magnetically separable zinc ferrite@titanium dioxide (ZnFe2O4@TiO2) hollow core/shell nanospheres as photocatalysts for efficient H2 evolution by loading the TiO2 shell layer on the prepared ZnFe2O4 hollow nanospheres using the kinetics-controlled coating method. Meanwhile, the incident light absorption, photogenerated charge transfer and separation and photocatalytic hydrogen evolution activity were remarkably improved by well anchoring cadmium selenide (CdSe) quantum dots on the ZnFe2O4@TiO2 hollow core/shell nanospheres. This unique design integrates the structural and functional merits of the ZnFe2O4, TiO2, and CdSe quantum dots into porous hollow nanospheres with the double-shell heterostructure. This design significantly accelerates the separation and transport of photogenerated charge carriers, enhances the light absorption, and offers more active sites for the photocatalytic H2 evolution reaction. Benefitting from the unique structural and component merits, the optimized magnetically separable ZnFe2O4@TiO2/CdSe hollow core/shell nanospheres exhibit excellent photocatalytic hydrogen evolution performance with a high H2 generation rate (266.0 µmol h-1·g-1) and high stability.

Surface-oxygen vacancy defect-promoted electron-hole separation of defective tungsten trioxide ultrathin nanosheets and their enhanced solar-driven photocatalytic performance.

Defective WO3 ultrathin surface-engineered nanosheets are fabricated by a solvothermal and low-temperature surface hydrogenation reduction strategy. The obtained defective WO3 ultrathin nanosheets with thicknesses of ∼4 nm possess a relatively large surface area of ∼25 m2 g-1. After surface engineering, the bandgap is narrowed to ∼2.48 eV due to the presence of surface oxygen vacancies, which further enhance the visible light absorption. The defective WO3 ultrathin nanosheets exhibit excellent solar-driven photocatalytic degradation performance for the complete degradation of the highly-toxic metribuzin herbicide (∼100%). The first-order rate constant (k) of the defective WO3 ultrathin nanosheets is ∼3 times higher than that of the pristine one. This can be ascribed to the formation of suitable surface-oxygen vacancy defects that promote the separation of photogenerated electron-hole pairs, and the two-dimensional ultrathin structure facilitating the surface engineering as well as furnishing a large number of surface active sites. Moreover, the defective WO3 ultrathin nanosheets exhibit high stability because the photocatalytic activity remains almost unchanged after 10 cycles, making them favorable for practical applications. This work offers new insights into the fabrication of other high-performance ultrathin nanosheet oxide photocatalysts for environmental applications.

Controlled synthesis and exceptional photoelectrocatalytic properties of Bi2S3/MoS2/Bi2MoO6 ternary hetero-structured porous film.

In this work, Bi2S3/MoS2/Bi2MoO6 hetero-structured porous films were fabricated via a facile anion exchange process using the as-prepared Bi2MoO6 nanoflake array film as substrate material. The formation of Bi2S3/MoS2/Bi2MoO6 ternary hetero-structured porous film is both thermodynamically controllable and reaction time dependent. Systematic experiments were done to investigate the products at each reaction stage and disclose the relationships between the composite components and reaction temperature and time. The study showed that the energy barrier need to be overpassed when MoS2 and Bi2S3 were simultaneously produced. The optimized Bi2S3/MoS2/Bi2MoO6 photoelectrode exhibited significantly higher photoelectrocatalytic efficiency than Bi2MoO6, binary Bi2S3/Bi2MoO6 and Bi2S3/MoS2 photoelectrodes. The remarkable degradation efficiency of the Bi2S3/MoS2/Bi2MoO6 photoelectrode comes from the synergy of high quality assembly and heterostructure interfaces between the three components. The optimized film assembly and stepwise band alignment in the ternary heterostructure composite contribute to visible light utilization, transport and separation of charge carriers, mass transport, and accessibility of active sites. The generated active species such as superoxide anions (O2-) and holes were detected to promote the decomposition of organic pollutants. The reasonable photoeletrocatalytic degradation mechanism was also proposed.

Hierarchical SnS2/CuInS2 Nanosheet Heterostructure Films Decorated with C60 for Remarkable Photoelectrochemical Water Splitting.

Rational architectural design and catalyst components are beneficial to improve the photoelectrochemical (PEC) performance. Herein, hierarchical SnS2/CuInS2 nanosheet heterostructure porous films were fabricated and decorated with C60 to form photocathodes for PEC water reduction. Large-size CuInS2 nanosheet films were first grown on transparent conducting glass to form substrate films. Then, small-size SnS2 nanosheets were epitaxially grown on both sides of the CuInS2 nanosheets to form uniform hierarchical porous laminar films. The addition of C60 on the surface of the SnS2/CuInS2 porous nanosheets effectively increased visible light absorption of the composite photocathode. Photoluminescence spectroscopy and impedance spectroscopy analyses indicated that the formation of a SnS2/CuInS2 heterojunction and decoration of C60 significantly increased the photocurrent density by promoting the electron-hole separation and decreasing the resistance to the transport of charge carriers. The hierarchical SnS2/CuInS2 nanosheet heterostructure porous films containing multiscale nanosheets and pore configurations can enlarge the surface area and enhance visible light utilization. These beneficial factors make the optimized C60-decorated SnS2/CuInS2 photocathode exhibit much higher photocathodic current (4.51 mA cm-2 at applied potential -0.45 V vs reversible hydrogen electrode ) and stability than the individual CuInS2 (2.58 mA cm-2) and SnS2 (1.92 mA cm-2) nanosheet film photocathodes. This study not only reveals the promise of C60-decorated hierarchical SnS2/CuInS2 nanosheet heterostructure porous film photocathodes for efficient solar energy harvesting and conversion but also provides rational guidelines in designing high-efficiency photoelectrodes from earth-abundant and low-cost materials allowing widely practical applications.

Molecule Self-Assembly Synthesis of Porous Few-Layer Carbon Nitride for Highly Efficient Photoredox Catalysis.

Polymeric carbon nitride (C3N4) has emerged as the most promising candidate for metal-free photocatalysts but is plagued by low activity due to the poor quantum efficiency and low specific surface area. Exfoliation of bulk crystals into ultrathin nanosheets has proven to be an effective and widely used strategy for enabling high photocatalytic performances; however, this process is complicated, time-consuming, and costly. Here, we report a simple bottom-up method to synthesize porous few-layer C3N4, which involves molecule self-assembly into layered precursors, alcohol molecules intercalation, and subsequent thermal-induced exfoliation and polycondensation. The as-prepared few-layer C3N4 expose more active sites and greatly enhance the separation of charge carriers, thus exhibiting a 26-fold higher hydrogen evolution activity than bulk counterpart. Furthermore, we find that both the high activity and selectivity for the oxidative coupling of amines to imines can be obtained under visible light that surpass those of other metal-free photocatalysts so far.