Graphite Oxide-TiO2 Nanocomposite Type Photocatalyst for Methanol Photocatalytic Reforming Reaction

Photocatalytic hydrogen evolution from biomass conversion

Biomass has incredible potential as an alternative to fossil fuels for energy production that is sustainable for the future of humanity. Hydrogen evolution from photocatalytic biomass conversion not only produces valuable carbon-free energy in the form of molecular hydrogen but also provides an avenue of production for industrially relevant biomass products. This photocatalytic conversion can be realized with efficient, sustainable reaction materials (biomass) and inexhaustible sunlight as the only energy inputs. Reported herein is a general strategy and mechanism for photocatalytic hydrogen evolution from biomass and biomass-derived substrates (including ethanol, glycerol, formic acid, glucose, and polysaccharides). Recent advancements in the synthesis and fundamental physical/mechanistic studies of novel photocatalysts for hydrogen evolution from biomass conversion are summarized. Also summarized are recent advancements in hydrogen evolution efficiency regarding biomass and biomass-derived substrates. Special emphasis is given to methods that utilize unprocessed biomass as a substrate or synthetic photocatalyst material, as the development of such will incur greater benefits towards a sustainable route for the evolution of hydrogen and production of chemical feedstocks.

Photocatalytic Reforming for Hydrogen Evolution: A Review

Hydrogen is considered to be an ideal energy carrier to achieve low-carbon economy and sustainable energy supply. Production of hydrogen by catalytic reforming of organic compounds is one of the most important commercial processes. With the rapid development of photocatalysis in recent years, the applications of photocatalysis have been extended to the area of reforming hydrogen evolution. This research area has attracted extensive attention and exhibited potential for wide application in practice. Photocatalytic reforming for hydrogen evolution is a sustainable process to convert the solar energy stored in hydrogen into chemical energy. This review comprehensively summarized the reported works in relevant areas, categorized by the reforming precursor (organic compound) such as methanol, ethanol and biomass. Mechanisms and characteristics for each category were deeply discussed. In addition, recommendations for future work were suggested.

Utilization of Carbon Nanospheres in Photocatalyst Production: From Composites to Highly Active Hollow Structures

Titanium dioxide–carbon sphere (TiO₂–CS) composites were constructed via using prefabricated carbon spheres as templates. By the removal of template from the TiO₂–CS, TiO₂ hollow structures (HS) were synthesized. The CS templates were prepared by the hydrothermal treatment of ordinary table sugar (sucrose). TiO₂–HSs were obtained by removing CSs with calcination. Our own sensitized TiO₂ was used for coating the CSs. The structure of the CSs, TiO₂–CS composites, and TiO₂–HSs were characterized by scanning electron microscopy (SEM), infrared spectroscopy (IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and diffuse reflectance spectroscopy (DRS). The effect of various synthesis parameters (purification method of CSs, precursor quantity, and applied furnace) on the morphology was investigated. The photocatalytic activity was investigated by phenol model pollutant degradation under visible light irradiation (λ > 400 nm). It was established that the composite samples possess lower crystallinity and photocatalytic activity compared to TiO₂ hollow structures. Based on XPS measurements, the carbon content on the surface of the TiO₂–HS exerts an adverse effect on the photocatalytic performance. The synthesis parameters were optimized and the TiO₂–HS specimen having the best absolute and surface normalized photocatalytic efficiency was identified. The superior properties were explained in terms of its unique morphology and surface properties. The stability of this TiO₂–HS was investigated via XRD and SEM measurements after three consecutive phenol degradation tests, and it was found to be highly stable as it entirely retained its crystal phase composition, morphology and photocatalytic activity.

Preparation and Characterization of Nanocrystalline TiO2 on Microsericite for High-Efficiency Photo-Energy Conversion of Methanol to Hydrogen

TiO2 and TiO2/sericite photocatalysts were successfully synthesized via the sol-gel method by adding a varying amount of acetic acid. The effect of acetic acid on TiO2 and TiO2/sericite photocatalysts was studied. The crystallite size, surface morphology, chemical composition, specific surface area, surficial functional groups, and light absorbance of the prepared photocatalysts were revealed by the analysis of X-ray diffraction (XRD), scanning electron microscope-energy dispersive spectrometry (SEM-EDS), nitrogen adsorption-desorption isotherms by using BET theory (Brunauer–Emmett–Teller), Fourier-transform infrared spectroscopy (FTIR), and UV-Vis absorption spectrometry. Photo-energy conversion of methanol to hydrogen was also conducted over the prepared photocatalysts. The best hydrogen production was achieved by using the TiO2/sericite photocatalyst to give a hydrogen production rate of 1424 μmol/g·h in 6 h of UV-light irradiation.