Anchoring Bi2S3 quantum dots on flower-like TiO2 nanostructures to boost photoredox coupling of H2 evolution and oxidative organic transformation.

The rational integration of semiconductor quantum dots (QDs) with anatase TiO2 nanostructures is a promising strategy to develop efficient photocatalysts. Herein, Bi2S3QD/TiO2 photocatalyst was constructed by controllably depositing Bi2S3 QDs on flower-like TiO2 nanostructures and used for the photocatalytic redox-coupling reaction of H2 evolution and oxidative transformation of benzyl alcohol. The abundant amino groups in TiO2 nanostructures served as the anchoring sites for uniform growth of Bi2S3 QDs. The anchoring of Bi2S3 QDs onto TiO2 nanostructures not only enhanced the photoabsorption ability and the photogenerated charge separation efficiency but also afforded powerful photogenerated charge carriers and abundant active sites for the photocatalytic reaction. As a result, the Bi2S3QD/TiO2 photocatalyst exhibited a favorable performance in the redox-coupling reaction, providing the high production rates of H2 up to 4.75 mmol·gcat-1·h-1 and benzaldehyde up to 6.12 mmol·gcat-1·h-1, respectively, as well as an excellent stability in the long-term photocatalytic reaction. Meanwhile, a trace amount of water in the reaction system could act as a promoter to accelerate the photocatalytic redox-coupling reaction. The photocatalytic mechanism following S-scheme heterojunction was proposed according to the systematic characterizations and experimental results. This work offers some insight into the rational construction of efficient and cost-effective photocatalysts for the conversion of solar to chemical energy.

A susceptible coordination hybrid based terbium sensibilization coupled ESIPT effects for pattern discrimination of analogues.

Multianalyte detection and analogue discrimination are extremely valuable frontier areas for their wide applications in environmental, medical, clinical and industrial analyses. Nowadays, researchers rack their brains on how to develop excellent multianalyte chemosensors that have presented huge challenges in designing high-efficient fluorescent sensing materials and constructing high-throughput detection methods. In this paper, we propose a novel strategy to utilize the dual-emission fluorescent detection platform as a lab-on-a-molecule, arising from the disalicylaldehyde-coordinated hybrid H2Qj3/Tb based terbium sensibilization coupled excited-state intramolecular proton transfer effects. Using the statistical analysis (PCA and HCA) for sensing signals of three fluorescence channels (431, 543 and 583 nm), we demonstrate this elaborate chemosensor with multianalyte detection of three species (solvents, anions and cations) and pattern discrimination of analogues. As a result, the H2Qj3/Tb shows great lab-on-a-molecule characters for each set of species, resulting in the easier identification of many critical analytes (e.g., H2O, NO2- and Fe3+) and discrimination of analogues. In addition, it is also proven to be able to provide reliable content determination for an analyte, especially the NO2- (LOD = 0.37 µM), and discrimination for mixed analogues. A combination of easy-to-implement preparation procedure and data analysis technique makes this work promising for not only designing similar lanthanide-based materials but also realizing more high-efficient multianalyte sensing systems towards various potential applications.

Rational fabrication of cadmium-sulfide/graphitic-carbon-nitride/hematite photocatalyst with type II and Z-scheme tandem heterojunctions to promote photocatalytic carbon dioxide reduction.

Artificial photosynthesis has become one of the most attractive strategies for lowering atmospheric carbon dioxide (CO2) level and achieving the carbon balance; whereas, the fast electron-hole recombination and sluggish charge transfer in photocatalysts are themain stumbling blocks to the applications. Constructing semiconductor nano-heterostructures provides a promising strategy to accelerate the separation and transfer of photoinduced charge carriers for promoting the multielectron CO2 reduction reaction. Herein, a CdS/g-C3N4/α-Fe2O3 three-component photocatalyst consisting of type II and Z-scheme tandem heterojunctions is skillfully fabricated via the solvothermal synthesis followed with photoinduced deposition. The CdS/g-C3N4/α-Fe2O3 tandem-heterojunction photocatalyst exhibits superior performance toward the conversion of CO2 to fuels (CO and CH4), compared with the single- and binary-component systems, owing to the favorable energy-level alignment, accelerated charge separation, facilitated water dissociation and sufficient reactive-hydrogen provision. The total consumed electron number of CdS/g-C3N4/α-Fe2O3 catalyst for CO2 reduction is about 10.5 times that of pure g-C3N4. The photocatalytic mechanism is elucidated according to detailed characterizations and in-situ spectroscopy analyses. This work sheds light on the rational construction of heterojunction photocatalysts to promote the conversion of CO2 to solar fuels, without using any sacrifice reagent or noble-metal cocatalysts.

Synthesis of Fe3O4@CdS@CQDs ternary core-shell heterostructures as a magnetically recoverable photocatalyst for selective alcohol oxidation coupled with H2O2 production.

Photocatalytic aerobic oxidation of aromatic alcohols to corresponding aldehydes coupled with producing hydrogen peroxide (H2O2) represents one of the most efficient strategies for converting solar energy into chemical energy. In this work, a magnetically recoverable photocatalyst of Fe3O4@CdS@CQDs ternary core-shell heterostructures is elaborately fabricated through the hydrothermal growth of CdS on Fe3O4 nanospheres with in-situ incorporation of carbon quantum dots (CQDs) and used for selective alcohol oxidation coupled with H2O2 production. The Fe3O4@CdS@CQDs photocatalyst possess distinct advantages of full solar spectral absorption, efficient charge separation, and high stability. The Fe3O4-nanosphere cores not only endow photocatalyst with the characteristics of magnetic recovery but also form Fe3O4@CdS Z-scheme heterojunction to prevent CdS from photocorrosion. The in-situ modified CQDs act as charge mediators to accelerate the photogenerated electron-hole separation and afford active sites to facilitate H2O2 production. As a result, the Fe3O4@CdS@CQDs photocatalyst exhibits excellent performance in selectively converting benzyl alcohol to benzaldehyde accompanied with H2O2 production. The generation rates of benzaldehyde and H2O2 reach up to 57.22 and 27.06 mmol·gCdS-1·h-1, respectively. This work highlights a rational construction of magnetic heterostructure photocatalyst and its application in the photo-redox coupling reactions.

Engineering Catalytic Interfaces in Cuδ+/CeO2-TiO2 Photocatalysts for Synergistically Boosting CO2 Reduction to Ethylene.

Photocatalytic CO2 conversion into a high-value-added C2 product is a highly challenging task because of insufficient electron deliverability and sluggish C-C coupling kinetics. Engineering catalytic interfaces in photocatalysts provides a promising approach to manipulate photoinduced charge carriers and create multiple catalytic sites for boosting the generation of C2 product from CO2 reduction. Herein, a Cuδ+/CeO2-TiO2 photocatalyst that contains atomically dispersed Cuδ+ sites anchored on the CeO2-TiO2 heterostructures consisting of highly dispersed CeO2 nanoparticles on porous TiO2 is designedly constructed by the pyrolytic transformation of a Cu2+-Ce3+/MIL-125-NH2 precursor. In the designed photocatalyst, TiO2 acts as a light-harvesting material for generating electron-hole pairs that are efficiently separated by CeO2-TiO2 interfaces, and the Cu-Ce dual active sites synergistically facilitate the generation and dimerization of *CO intermediates, thus lowering the energy barrier of C-C coupling. As a consequence, the Cuδ+/CeO2-TiO2 photocatalyst exhibits a production rate of 4.51 µmol-1·gcat-1·h-1 and 73.9% selectivity in terms of electron utilization for CO2 to C2H4 conversion under simulated sunlight, with H2O as hydrogen source and hole scavenger. The photocatalytic mechanism is revealed by operando spectroscopic methods as well as theoretical calculations. This study displays the rational construction of heterogeneous photocatalysts for boosting CO2 conversion and emphasizes the synergistic effect of multiple active sites in enhancing the selectivity of C2 product.

Cadmium-sulfide/gold/graphitic-carbon-nitride sandwich heterojunction photocatalyst with regulated electron transfer for boosting carbon-dioxide reduction to hydrocarbon.

Developing the heterogeneous photocatalysts with high performance for carbon dioxide (CO2) conversion to solar fuels is remarkably significant for reducing the atmospheric CO2 level and achieving the target of carbon neutrality through the artificial photosynthesis strategies. However, it remains a great challenge for most of the photocatalysts to achieve the CO2-to-hydrocarbon conversion via a multi-proton coupled multi-electron reduction process. In this work, the cadmium-sulfide/gold/graphitic-carbon-nitride (CdS/Au/g-C3N4) heterojunction photocatalyst with sandwich nanostructures is designedly constructed by a selective two-step photodeposition process. The better separation of photogenerated electrons and holes in CdS/Au/g-C3N4 heterojunction creates the higher density of surface photogenerated electron, dynamically accelerating the multi-electron reduction of CO2. Moreover, the selective photodeposition of CdS on Au/g-C3N4 affords sufficient electron-enriched Sδ- active sites which are more beneficial to the provision of H adatoms. These advantages jointly improve the photocatalytic CO2 conversion to methane (CH4) via a multi-proton coupled multi-electron reduction process. The CH4 yield rate on CdS/Au/g-C3N4 photocatalyst is about twice that of CdS/g-C3N4, while g-C3N4 and Au/g-C3N4 only produce CO. The total electron utilization for CO2 reduction on CdS/Au/g-C3N4 photocatalyst is 6.9 times that of g-C3N4. Furthermore, the CdS/Au/g-C3N4 photocatalyst exhibits high stability in consecutive cycles of CO2 reduction reaction. The photocatalytic mechanism is proposed on the basis of in situ spectrographic analyses together with other detailed characterizations.

Synthesis of Ni modified Au@CdS core-shell nanostructures for enhancing photocatalytic coproduction of hydrogen and benzaldehyde under visible light.

The development of visible light responsive photocatalysts for simultaneous production of hydrogen (H2) fuel and value-added chemicals is greatly promising to solve the energy and environmental issues by improving the utilization efficiency of solar energy. Herein, the three-component Ni/(Au@CdS) core-shell nanostructures were constructed by the hydrothermal synthesis followed with photodeposition. The intimate integration of plasmonic Au nanospheres and visible-light responsive CdS shells modified with Ni cocatalyst facilitated the generation and separation of electron-hole pairs as well as reduced the overpotential of hydrogen evolution. The Ni/(Au@CdS) photocatalyst exhibited excellent performance toward the selective transformation of benzyl alcohol under anaerobic conditions, and the yields of H2 and benzaldehyde reached up to 3882 and 4242 µmol·g-1·h-1, respectively. The apparent quantum efficiency (AQE) was determined to be 4.09% under the irradiation of 420 nm. The systematic studies have verified the synergy of plasmonic effect and metal cocatalyst on enhancing the photocatalysis. This work highlights the desirable design and potential application of plasmonic photocatalysts for solar-driven coproduction of H2 fuel and high-value chemicals.

Modulating oxygen vacancies on bismuth-molybdate hierarchical hollow microspheres for photocatalytic selective alcohol oxidation with hydrogen peroxide production.

Photocatalytic selective oxidation of alcohols into high value-added carbonyl compounds accompanied by producing hydrogen peroxide (H2O2) is undoubtedly a more efficient solar energy conversion strategy with high atom economy. Herein, we have developed an efficient photocatalyst of bismuth-molybdate (Bi2MoO6) hierarchical hollow microspheres with tunable surface oxygen vacancies (OVs) for promoting the photocatalytic selective alcohol oxidation with H2O2 production. The effect of surface OVs on the photocatalytic efficiency is studied systematically by comparing the performance of different photocatalysts. The benzaldehyde and H2O2 production rates over the OV-rich Bi2MoO6 photocatalyst reach up to 1310 and 67.2 µmol g-1 h-1, respectively, which are 2.3 and 4.0 times those generated from the OV-poor Bi2MoO6 hollow microspheres. The roles of various active radicals in the photocatalytic reaction are probed by a series of controlled experiments and in situ ESR measurements, revealing that both superoxide radical (•O2-) and carbon-centered radical are the key active intermediates. The introduction of surface OVs on Bi2MoO6 hollow microspheres accelerates the separation and transfer of photo-generated charge carriers as well as enhances the adsorption and activation of reactant molecules, thereby greatly promoting the photocatalytic selective oxidation of alcohols along with H2O2 production. This work not only demonstrates a facile strategy for the preparation of high-efficiency photocatalysts by simultaneous modulations of morphology and surface defects, but also offers insight into developing the dual-functional photocatalytic reactions for the full utilizations of photoinduced electrons and holes.

Imine bond transformation of a dynamic Sm(III) macrocycle-based chemosensor: The indirect approach for detecting cyanuric chloride.

Herein, we report our strategy to develop the efficient chemosensor and real-time monitoring technique for cyanuric chloride (TCT) detection. A luminescent macrocyclic mononuclear Sm(III) complex Sm-2k bearing with two dynamic imine bonds has been constructed via the template synthesis between dialdehyde H2Qk and matched diamine 1,2-bis(2-aminoethoxy)ethane. Sensing experiments reveal that complex Sm-2k exhibits the turn-off fluorescent and colorimetric response for TCT in CH3OH. It is especially encouraging that this optical sensing process is not only rapid within 60 s but also high-efficient in the presence of TCT analogues as well as sensitive with the low limit of detection (LOD, 1.74 µM) and wide linear sensing range. Mechanism studies demonstrate that TCT sensing is mainly based on the imine bond transformation of probe Sm-2k, which is due to the increased acidity induced by TCT. Meanwhile, a smartphone-based analytical method was developed to make complex Sm-2k accessible for the real-time TCT detection by RGB value outputs. It is believed that this work can shed some constructive lights on design of chemosensors and convenient detection technique for highly reactive analytes.

Hybrid nanostructures for electrochemical potassium storage.

The wide availability and low cost of potassium resources have made electrochemical potassium storage a promising energy storage solution for sustainable decarbonisation. Research activities have been rapidly increasing in the last few years to investigate various potassium batteries such as K-ion batteries (KIBs), K-S batteries and K-Se batteries. The electrode materials of these battery technologies are being extensively studied to examine their suitability and performance, and the utilisation of hybrid nanostructures has undoubtedly contributed to the advancement of the performance. This review presents a timely summary of utilising hybrid nanostructures as battery electrodes to address the issues currently existing in potassium batteries via taking advantage of the compositional and structural diversity of hybrid nanostructures. The complex challenges in KIBs and K-S and K-Se batteries are outlined and the role of hybrid nanostructures is discussed in detail regarding the characteristics of intercalation, conversion and alloying reactions that take place to electrochemically store K in hybrid nanostructures, highlighting their multifunctionality in addressing the challenges. Finally, outlooks are given to stimulate new ideas and insights into the future development of hybrid nanostructures for electrochemical potassium storage.

Synergistic Pd Single Atoms, Clusters, and Oxygen Vacancies on TiO2 for Photocatalytic Hydrogen Evolution Coupled with Selective Organic Oxidation.

Developing efficient photocatalysts for synchronously producing H2 and high value-added chemicals holds great promise to enhance solar energy conversion. Herein, a facile strategy of simultaneously engineering Pd cocatalyst and oxygen vacancies (VO s) on TiO2 to promote H2 production coupled with selective oxidation of benzylamine is demonstrated. The optimized PdSA+C /TiO2 -VO photocatalyst containing Pd single atoms (SAs), clusters (C), and VO s exhibits much superior performance to those of TiO2 -VO and PdSA /TiO2 -VO counterparts. The production rates of H2 and N-benzylidenebenzylamine over PdSA+C /TiO2 -VO are 52.7 and 1.5 times those over TiO2 -VO , respectively. Both experimental and theoretical studies have elucidated the synergistic effect of Pd SAs, clusters, and VO s on TiO2 in boosting the photocatalytic reaction. The presence of Pd SAs facilitates the generation and stabilization of abundant VO s by the formation of PdOTi3+ atomic interface, while Pd clusters promote the photogenerated charge separation and afford the optimum active sites for H2 evolution. Surface VO s of TiO2 guarantee the efficient adsorption and dissociation/activation of reactant molecules. This study reveals the effect of active-site engineering on the photocatalysis and is expected to shed substantial light on future structure design and modulation of semiconductor photocatalysts.

Anchoring Positively Charged Pd Single Atoms in Ordered Porous Ceria to Boost Catalytic Activity and Stability in Suzuki Coupling Reactions.

Single-atom (SA) catalysis bridging homogeneous and heterogeneous catalysis offers new opportunities for organic synthesis, but developing SA catalysts with high activity and stability is still a great challenge. Herein, a heterogeneous catalyst of Pd SAs anchored in 3D ordered macroporous ceria (Pd-SAs/3DOM-CeO2 ) is developed through a facile template-assisted pyrolysis method. The high specific surface area of 3DOM CeO2 facilitates the heavily anchoring of Pd SAs, while the introduction of Pd atoms induces the generation of surface oxygen vacancies and prevents the grain growth of CeO2 support. The Pd-SAs/3DOM-CeO2 catalyst exhibits excellent activity toward Suzuki coupling reactions for a broad scope of substrates under ambient conditions, and the Pd SAs can be stabilized in CeO2 in long-term catalytic cycles without leaching or aggregating. Theoretical calculations indicate that the CeO2 supported Pd SAs can remarkably reduce the energy barriers of both transmetalation and reductive elimination steps for Suzuki coupling reactions. The strong metal-support interaction contributes to modulating the electronic state and maintaining the stability of Pd SA sites. This work demonstrates an effective strategy to design and synthesize stable single-atom catalysts as well as sheds new light on the origin for enhanced catalysis based on the strong metal-support interactions.

An N-linked disalicylaldehyde together with its caesium ion and dichloromethane sensing performances: 'dual key & lock' LMCT-enhanced fluorescence strategy.

The development of inexpensive, selective and rapid-response chemosensors for detecting Cs+ in waste water is highly desirable in the nuclear power industry. Here we demonstrate an efficient Cs+ optical sensor based on the N-linked disalicylaldehyde H2Qj with excited state intramolecular proton transfer (ESIPT), and it will transform into the ligand-to-metal charge transfer (LMCT) process in the presence of Cs+, resulting in dramatically enhanced fluorescence together with a distinct change of color from light-green to green-yellow. Simultaneously, it is found that CH2Cl2 can serve as the quencher of LMCT-enhanced fluorescence, thus enabling selective CH2Cl2 detection in a turn-off fluorescence approach. Further detailed studies reveal that both Cs+ and CH2Cl2 sensing processes are rapid within 60 seconds. The corresponding limit of detection (LOD) values for sensing Cs+ and CH2Cl2 are as low as 0.37 mM and 0.37%. Moreover, it was also verified that Cs+ sensing is applicable in the range of pH = 7-11 and the reversibility of sensor H2Qj can be easily achieved by modulating pH values, and H2Qj is also assessed for its Cs+ sensing performces in real water samples. This H2Qj-Cs sensing system must provide a valuable reference for further Cs+ sensors.

Synthesis of EDTA-bridged CdS/g-C3N4 heterostructure photocatalyst with enhanced performance for photoredox reactions.

Photocatalytic reactions represent a kind of green and sustainable chemical processes for organic transformations, but the efficiency is limited by the severe recombination and/or inadequate redox potentials of photoinduced charge carriers in photocatalysts. To address these issues, herein, the CdS-EDTA/g-C3N4 heterostructures were designed according to Z-scheme photocatalytic mechanism and synthesized by the hydrothermal growth of CdS on g-C3N4 nanoflakes with assistance of EDTA chelating agent. EDTA played multiple roles in the formation of CdS-EDTA/g-C3N4 heterostructure photocatalysts, such as controlling the morphology of CdS nanostructures, linking CdS and g-C3N4 together, and boosting the charge transfer between two semiconductors. The optimized CdS-EDTA/g-C3N4(10%) photocatalyst exhibited much higher activities toward the selective reduction of nitrophenol and the selective oxidation of benzyl alcohol, than those of CdS/g-C3N4 heterostructures without EDTA. The enhanced photocatalysis of CdS-EDTA/g-C3N4 can be ascribed to the efficient separation and suitable photoredox potentials of photoexcited charge carriers in the EDTA-bridged Z-scheme system. This work provides the inspiration for exploring inexpensive organic electron mediators for constructing all-solid-state Z-scheme photocatalysts and demonstrates the enhanced performance of Z-scheme photocatalysts for photoredox reactions of organic transformations.

Optimal synthesis of a direct Z-scheme photocatalyst with ultrathin W18O49 nanowires on g-C3N4 nanosheets for solar-driven oxidation reactions.

Constructing Z-scheme photocatalysts is an effective approach to enhance the conversion efficiency of solar to chemical energy. Herein, W18O49/g-C3N4 heterostructures have been synthesized by growing W18O49 ultrathin nanowires on g-C3N4 nanosheets via a convenient solvothermal process. Various characterizations were performed on the materials to understand the structure-performance relationship. The photocatalytic properties of the W18O49/g-C3N4 heterostructures were evaluated by the two oxidation reactions, phenol degradation and oxidative NC coupling of benzylamines, under a simulated sunlight (360 ≤  λ  ≤ 780 nm). With tuning the W18O49/g-C3N4 mass ratio, the optimal photocatalyst of W18O49(30)/g-C3N4 containing 30 wt% W18O49 nanowires exhibited the highest activity in both the photocatalytic reactions. The generations and contributions of the active species in the photocatalytic reactions were identified by electron spin resonance (ESR) spectra and active-species-eliminating experiments. Accordingly, the photocatalytic mechanism of W18O49/g-C3N4 heterostructures has been expounded based on the direct Z-scheme electron transfer between the two semiconductors as well as the synergistic actions of active sites on W18O49 nanowires and g-C3N4 nanosheets. This work demonstrates a rational paradigm to construct 1D/2D semiconductor heterostructures and provides further insights into Z-scheme photocatalytic mechanism for boosting solar-driven pollutant degradation and organic transformation.

Synthesis of BiVO4 nanoflakes decorated with AuPd nanoparticles as selective oxidation photocatalysts.

The ultrathin BiVO4 nanoflakes decorated with Pd and AuPd nanoparticles (NPs) were respectively synthesized and optimized for the enhanced photocatalysis towards selective oxidation of aromatic alcohols. The monometallic Pd(x)-BiVO4 samples presented hump-like variation in the photocatalytic activity with increasing Pd amount (x) from 0 to 2.0 wt%. Subsequently, coupling Au with Pd on BiVO4 nanoflakes resulted in a further improvement in the photocatalysis, with retaining the high selectivity (>99%) for aldehyde production. By tuning metal loading, the typical Au(0.5)Pd(0.5)-BiVO4 photocatalyst exhibited the highest benzaldehyde yield of 887.7 µmol·g-1·h-1, which was 6.0 times that of bare BiVO4 nanoflakes and 1.35 times that of Pd(1.0)-BiVO4 photocatalyst. A series of characterizations and DFT calculations confirmed the enhanced light harvesting and charge separation of the Au(0.5)Pd(0.5)-BiVO4 material, owing to the strong electronic couplings in AuPd NPs and its remarkable influence on the band structure of BiVO4. The photocatalytic mechanism studies indicated that the selective oxidation of aromatic alcohols was achieved by the cooperation of photogenerated holes and O2- radical, and this process was promoted by the interfacial synergism between AuPd NPs and BiVO4 nanoflakes. This work demonstrates a systematic study on optimizing photocatalysts to improve their performance in light-driven organic transformations as well as highlights the synergistic effect of metal-metal coupling and metal-semiconductor interface on photocatalysis.

Facile surface modification of textiles with photocatalytic carbon nitride nanosheets and the excellent performance for self-cleaning and degradation of gaseous formaldehyde.

Great advances in photocatalysis have been made by developing various efficient photocatalysts, but investigation on practical applications of photocatalysis is relatively backward. Herein we report a facile surface modification approach to functionalize textiles with excellent ability for photocatalytic self-cleaning and degradation of indoor volatile organic pollutants. Graphitic carbon nitride nanosheets (CNNS) in colloidal suspension were directly sprayed onto the surface of cellulose fibers in textiles, and the powerful hydrogen bonding action between surface hydroxyl groups of cellulose and plentiful hydroxyl and amino groups of exfoliated CNNS from alkali-treating realizes high stability of CNNS modified textiles. Due to ultrathin 2D thickness and high visible light transparency, the modification of CNNS would not affect the hand feeling of textiles and shield their original colors. The obtained textiles show superior photocatalytic self-cleaning performance to remove stains from various colored pollutants under solar light irradiation, including industrial organic dyes and juices. Meanwhile, gaseous formaldehyde also can be efficiently decomposed using Xe lamp or commercial LED lamp as light sources. This work realizes photocatalytic performance of textiles using a simple spraying method, and it has great potential application in textile self-cleaning, not only for surface stains but also for volatile organic compounds from textile release.

Tuning Ion Complexing To Rapidly Prepare Hollow Ag-Pt Nanowires with High Activity toward the Methanol Oxidization Reaction.

Hollow Pt-based nanowires (NWs) have important applications in catalysis. Their preparation often involves a two-step process in which M (M=Ag, Pd, Co, Ni) NWs are prepared and subsequently subjected to galvanic reaction in solution containing a Pt precursor. It is challenging to achieve a simple one-step preparation, because the redox potential of PtIV /Pt or PtII /Pt to Pt is high, and therefore, Pt atoms always form first. This work demonstrates that an appropriate pH can decrease the redox potential of PtIV /Pt and allows the one-step preparation of high-quality hollow Pt-Ag NWs rapidly (10 min). Moreover, it is easy to realize large-scale preparation with this method. The NW composition can be adjusted readily to optimize their performance in the electrocatalytic methanol oxidization reaction (MOR). Compared with commercial Pt/C, NWs with appropriate Ag/Pt ratios exhibit high stability, activity, and CO tolerance ability.

NiO/Ni/TiO2 nanocables with Schottky/p-n heterojunctions and the improved photocatalytic performance in water splitting under visible light.

Construction of Schottky junction or p-n heterojunction is admitted as an effective way for improving the separation of photo-induced carriers through its built-in electric field. In this work, fabrication of cooperative Schottky and p-n (SPN) heterojunction has been realized by intercalating metal Ni into a NiO/TiO2p-n junction, forming a NiO/Ni/TiO2 Sandwich-like heterojunction. The special heterostructure was confirmed by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and the high-resolution transmission electron microscopic (HRTEM), Brunauer Emmett Teller (BET). After a serial of contrast experiments with solo Schottky or p-n junction, it was found that the electron-hole separation in this NiO/Ni/TiO2 SPN heterojunction was enhanced through charge transfer channel, and it was also in accordance with their related optical and photoelectrical properties characterizations, such as photoluminescence (PL) spectrum and UV-Vis diffused reflectance spectra. In the following photocatalytic water splitting process under visible light, the hydrogen generation rate of NiO/Ni/TiO2 reached up to 4653 µmol h-1 g-1, which was 10.2, 6.7 and 2.3 times of those of TiO2 (457 µmol h-1 g-1), Ni/TiO2 (691 µmol h-1 g-1) with a Schottky junction and NiO/TiO2 (2059 µmol h-1 g-1) with a p-n junction, respectively. This SPN heterojunction with excellent photo-induced electron-hole separation ability opens a new window to exploring photocatalyst for water splitting.

Understanding size-dependent properties of BiOCl nanosheets and exploring more catalysis.

Investigating the dependence of the catalysis on the size and structure of materials is of great significance for exploiting catalysts with characteristics of high activity, low cost, and new property. Non-precious metal catalysts bear high hope to meet the increasing demands of industrial applications in a cost-effective and environmentally friendly way. In this work, we take size-controlled BiOCl nanosheets as examples, which are synthesized via a hydrothermal method by changing the reaction conditions. The BiOCl nanosheets were characterized in details to understand their size-property relationships, and were found to exhibit a series of thickness-dependent physicochemical properties, including specific surface area, light absorption, and the separation efficiency of photo-generated charge carriers. Moreover, this work demonstrates the first example that BiOCl nanostructures have very high catalytic activity for the reduction of nitrophenols by sodium borohydride, without any light irradiation. The high catalytic activity of BiOCl nanosheets was proved to be due to the metallic Bi0 clusters that were produced by surface Bi (III) reduction. The catalytic activity increased greatly with a decrease in the average thickness from 106.42nm of BiOCl(H2O) to 3.47nm of ultrathin BiOCl, because the increased specific surface area provided more active sites for catalytic reactions. As a result, this work provides evidences for the size-property relationships of nanostructured catalysts as well as some inspirations for exploiting novel heterogeneous catalysis of BiOCl nanomaterials.