Yusen Liao

Microwave-assisted heating synthesis: a general and rapid strategy for large-scale production of highly crystalline g-C3N4 with enhanced photocatalytic H2 production

The metal-free photocatalyst, g-C3N4, is very attractive for solar hydrogen production. Presently, g-C3N4 is mainly fabricated by the conversion of nitrogen-rich precursors at high temperature (400–600 °C) for a long reaction time (several hours to days). Herein we report a rapid synthetic strategy named “microwave (MW)-assisted heating synthesis”, which allows the highly crystalline g-C3N4 photocatalyst to be fabricated in minutes. The obtained g-C3N4 displays enhanced photocatalytic H2 production. In addition, the described synthetic strategy is a general approach that can also be applicable to other nitrogen-rich organic precursors, such as melamine, cyanamide, and thiourea. Importantly, the present process enables scale-up production of g-C3N4 for several grams in minutes.

Efficient CO2 Capture and Photoreduction by Amine‐Functionalized TiO2

Amine-functionalization of TiO2 nanoparticles, through a solvothermal approach, substantially increases the affinity of CO2 on TiO2 surfaces through chemisorption. This chemisorption allows for more effective activation of CO2 and charge transfer from excited TiO2 , and significantly enhances the photocatalytic rate of CO2 reduction into methane and CO.

Temperature-controlled morphology evolution of graphitic carbon nitride nanostructures and their photocatalytic activities under visible light

A series of g-C3N4 photocatalysts were synthesized by changing the temperature through air-assisted thermal polymerization and etching. The detailed characterization and analysis clearly revealed that the texture, surface structure, optical properties, and band structure of g-C3N4 depend on the preparation conditions such as atmosphere and temperature. The morphology of samples obtained at different temperatures undergoes sequential evolution from bulk to nanosheet with multilayer, nanosheet with few layer, moderately rolled nanosheet, tailored nanotube, nanoflakelet and even nanoparticles. Accordingly, the BET surface area increased dramatically from 4.5 m2 g−1 of bulk g-C3N4 to 210.1 m2 g−1 of modified sample obtained at 540 °C. The different textural and structural properties resulted in the different optical and electronic features. The exfoliated and tailored samples obtained by this method presented better photocatalytic performance as compared with bulk g-C3N4. Factors affecting the photocatalytic activity of g-C3N4 were discussed in details on the basis of the textural and structural characterization as well as the photocatalytic activity results. We found that the surface area, surface defects, and light absorption have great impacts on the photocatalytic activities of g-C3N4.

Controllable Galvanic Synthesis of Triangular Ag–Pd Alloy Nanoframes for Efficient Electrocatalytic Methanol Oxidation

Triangular Ag-Pd alloy nanoframes were successfully synthesized through galvanic replacement by using Ag nanoprisms as sacrificial templates. The ridge thickness of the Ag-Pd alloy nanoframes could be readily tuned by adjusting the amount of the Pd source during the reaction. These obtained triangular Ag-Pd alloy nanoframes exhibit superior electrocatalytic activity for the methanol oxidation reaction as compared with the commercial Pd/C catalyst due to the alloyed Ag-Pd composition as well as the hollow-framed structures. This work would be highly impactful in the rational design of future bimetallic alloy nanostructures with high catalytic activity for fuel cell systems.

Surfactant-Free Synthesis of Plasmonic Tungsten Oxide Nanowires with Visible-Light-Enhanced Hydrogen Generation from Ammonia Borane

WO3-x nanowires were successfully synthesized through a simple surfactant-free solvothermal method. These nanowires exhibit strong plasmonic absorption in the visible and near-infrared region owing to the abundant oxygen vacancies. The plasmon excitation of these WO3-x nanowires provide five times enhancement on the hydrogen generation from ammonia borane.

Amine-Functionalized ZnO Nanosheets for Efficient CO2 Capture and Photoreduction

Amine-functionalized ZnO nanosheets were prepared through a one-step hydrothermal method by using monoethanolamine, which has a hydroxyl group, for covalent attachment on ZnO and a primary amine group to supply the amine-functionalization. We demonstrate that the terminal amine groups on ZnO surfaces substantially increase the capability of CO2 capture via chemisorption, resulting in effective CO2 activation. As a result, the photogenerated electrons from excited ZnO can more readily reduce the surface-activated CO2, which thereby enhances the activity for photocatalytic CO2 reduction.

Dye-sensitized Pt@TiO2 core–shell nanostructures for the efficient photocatalytic generation of hydrogen

Summary Pt@TiO2 core–shell nanostructures were prepared through a hydrothermal method. The dye-sensitization of these Pt@TiO2 core–shell structures allows for a high photocatalytic activity for the generation of hydrogen from proton reduction under visible-light irradiation. When the dyes and TiO2 were co-excited through the combination of two irradiation beams with different wavelengths, a synergic effect was observed, which led to a greatly enhanced H2 generation yield. This is attributed to the rational spatial distribution of the three components (dye, TiO2, Pt), and the vectored transport of photogenerated electrons from the dye to the Pt particles via the TiO2 particle bridge.