Molecular self-assembly is the spontaneous association of molecules under equilibrium conditions into stable, structurally well-defined aggregates joined by noncovalent bonds. Molecular self-assembly is ubiquitous in biological systems and underlies the formation of a wide variety of complex biological structures. Understanding self-assembly and the associated noncovalent interactions that connect complementary interacting molecular surfaces in biological aggregates is a central concern in structural biochemistry. Self-assembly is also emerging as a new strategy in chemical synthesis, with the potential of generating nonbiological structures with dimensions of 1 to 10(2) nanometers (with molecular weights of 10(4) to 10(10) daltons). Structures in the upper part of this range of sizes are presently inaccessible through chemical synthesis, and the ability to prepare them would open a route to structures comparable in size (and perhaps complementary in function) to those that can be prepared by microlithography and other techniques of microfabrication.

Molecular self-assembly and nanochemistry: A chemical strategy for the synthesis of nanostructures

Selective catalytic reduction with NH3 (NH3-SCR) is the most efficient technology to reduce the emission of nitrogen oxides (NOx) from coal-fired industries, diesel engines, etc. Although V2O5-WO3(MoO3)/TiO2 and CHA structured zeolite catalysts have been utilized in commercial applications, the increasing requirements for broad working temperature window, strong SO2/alkali/heavy metal-resistance, and high hydrothermal stability have stimulated the development of new-type NH3-SCR catalysts. This review summarizes the latest SCR reaction mechanisms and emerging poison-resistant mechanisms in the beginning and subsequently gives a comprehensive overview of newly developed SCR catalysts, including metal oxide catalysts ranging from VOx, MnOx, CeO2, and Fe2O3 to CuO based catalysts; acidic compound catalysts containing vanadate, phosphate and sulfate catalysts; ion exchanged zeolite catalysts such as Fe, Cu, Mn, etc. exchanged zeolite catalysts; monolith catalysts including extruded, washcoated, and metal-mesh/foam-based monolith catalysts. The challenges and opportunities for each type of catalysts are proposed while the effective strategies are summarized for enhancing the acidity/redox circle and poison-resistance through modification, creating novel nanostructures, exposing specific crystalline planes, constructing protective/sacrificial sites, etc. Some suggestions are given about future research directions that efforts should be made in. Hopefully, this review can bridge the gap between newly developed catalysts and practical requirements to realize their commercial applications in the near future.

Selective Catalytic Reduction of NOx with NH3 by Using Novel Catalysts: State of the Art and Future Prospects.

Defect engineering in photocatalytic materials

CO2 methanation over heterogeneous catalysts: recent progress and future prospects

The use of hydrogen as a fuel, when generated from water using semiconductor photocatalysts and driven by sunlight, is a sustainable alternative to fossil fuels. Polymeric photocatalysts are based on Earth-abundant elements and have the advantage over their inorganic counterparts in that their electronic properties are easily tuneable through molecular engineering. Polymeric photocatalysts have developed rapidly over the past decade, resulting in the discovery of many active materials. However, our understanding of the key properties underlying their photoinitiated redox processes has not kept pace, and this impedes further progress to generate cost-competitive technologies. Here, we discuss state-of-the-art polymeric photocatalysts and our microscopic understanding of their activities. We conclude with a discussion of five outstanding challenges in this field: non-standardized reporting of activities, limited photochemical stability, insufficient knowledge of reaction mechanisms, balancing charge carrier lifetimes with catalysis timescales and the use of unsustainable sacrificial reagents. Solar-driven photocatalytic water splitting provides a clean pathway for production of hydrogen fuel. This Review examines both amorphous and crystalline polymeric materials for water splitting, exploring polymer design strategies, theoretical understanding and challenges for the field.

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Current understanding and challenges of solar-driven hydrogen generation using polymeric photocatalysts

The preferred exposure of (040) crystal facet of BiVO 4 is conductive to optimizing its photocatalytic performance. And the great separation of photoinduced electron-hole pairs is also a critical factor for semiconductor photocatalyst. Herein we designed a hierarchical g-C 3 N 4 @Ag/BiVO 4 (040) hybrid photocatalyst, in which Ag was photodeposited on the (040) facets of BiVO 4 and subsequently g-C 3 N 4 was covered on the surface of Ag/BiVO 4 (040). The physical and chemical properties of the synthetic samples were analyzed by several characterization techniques. SEM spectrum clearly reveals the morphology and structure of g-C 3 N 4 @Ag/BiVO 4 (040), suggesting the existence of the hierarchical composite photocatalyst. The visible light absorption wavelength of the composite is increased due to the surface plasmon resonance (SPR) effect of metal Ag nanoparticles, displayed in UV–vis spectrum. The photogenerated electron-hole pairs are also greatly enhanced through the Z-scheme g-C 3 N 4 @Ag/BiVO 4 (040) system with the Ag nanoparticles as the electron mediator. The above synergistic effects of the hybrid photocatalyst result in higher photocatalytic oxidation performance not only for water splitting but also for NO oxidation in gas phase compared with pure BiVO 4 .

Hierarchical Z-scheme photocatalyst of g-C3N4@Ag/BiVO4 (040) with enhanced visible-light-induced photocatalytic oxidation performance

A modified Cr/Ce x Zr 1− x O 2 with the rigid benzene-muti-carboxylate ligands are prepared and studied on the oxidation of NO. These catalysts were investigated in detail by means of X-ray diffraction (XRD), High resolution transmission electron microscope (HR-TEM), Brunauer–Emmett–Teller (BET) surface area analysis, Ultra violet–visible diffuse reflectance spectroscopy (UV–vis DRS), X-ray photoelectron spectroscopy (XPS), NO(O 2 ) Temperature-programmed desorption (NO(O 2 )-TPD) and in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The results demonstrated that the catalysts prepared with cinnamic acid as precipitant showed a higher surface area, a lower band gap and a stronger ability to adsorb reactant gas. Otherwise, the ligands such as terephthalic acid and trimesic acid were unfavorable for the synthesis of Ce x Zr 1− x O 2 due to the long distance between the carboxyl groups. Furthermore, the π–π conjugated effect of the cinnamic acid balanced the charge in the precursor of the catalysts prepared with cinnamic acid, thus leading to their band gaps lower than that of other catalysts after calcinations. The catalytic performance over the catalysts prepared with cinnamic acid exhibited the highest NO conversion, and the preparation with one-pot method was simpler. Moreover, the catalyst prepared with one-pot method showed well ability to resist the poison effect of H 2 O and SO 2 , which was due to the large surface area. Finally, while combined the XPS analysis, in-situ DRIFTS demonstrated that the adsorbed NO interacted with the adsorbed O 2 to generate NO 2 , and the adsorption and activation O 2 was the key factor.

Focus on the modified CexZr1−xO2 with the rigid benzene-muti-carboxylate ligands and its catalysis in oxidation of NO

High performance of NO oxidation over Ce-Co-Ti catalyst: The interaction between Ce and Co

In this study, graphene-decorated 3D flower-like BiVO4 photocatalyst coupling with highly reactive (040) facets was synthesized by a facile alkaline solvothermal route. With the addition of graphene oxide (GO), the size of the subunits composing the 3D flower-like dramatically decreases, while the size of the flower is almost unchanged. Fascinatingly, the introduction of GO in the synthesis medium facilitates the preferential crystal growth of the 3D BiVO4 photocatalyst along its (040) facets. The as-prepared 3D BiVO4/graphene composites with the exposed (040) facets exhibits the enhanced activity in the visible-light photocatalytic oxidation (PCO) of NO (∼400 ppm), wherein the BiVO4/graphene (2.4 wt%) composite displays the highest photoactivity of PCO of NO. The improved photocatalytic performance was found to be associated with the synergetic effects of the exposed photogenerated electron-rich (040) facets of BiVO4 and the enhanced electronic conductivity caused by the graphene, and more significantly, the interaction between BiVO4 and graphene sheets which reduces the recombination of photoinduced charge carriers. The present study points out that the role of graphene is not only a capping agent to design the highly reactive (040) facets, but also a catalyst promoter for the photocatalytic performance, resulting in an enhanced photoactivity.

Graphene-decorated 3D BiVO4 superstructure: Highly reactive (040) facets formation and enhanced visible-light-induced photocatalytic oxidation of NO in gas phase

Wei Cai

Papers

Hierarchical Z-scheme photocatalyst of g-C3N4@Ag/BiVO4 (040) with enhanced visible-light-induced photocatalytic oxidation performance

Focus on the modified CexZr1−xO2 with the rigid benzene-muti-carboxylate ligands and its catalysis in oxidation of NO

High performance of NO oxidation over Ce-Co-Ti catalyst: The interaction between Ce and Co

Graphene-decorated 3D BiVO4 superstructure: Highly reactive (040) facets formation and enhanced visible-light-induced photocatalytic oxidation of NO in gas phase

The characterization of CrCe-doped on TiO2-pillared clay nanocomposites for NO oxidation and the promotion effect of CeOx