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

Abstract

Graphite-oxide/TiO 2 (GO/TiO 2 ) composite materials were prepared by heterocoagulation method from Brodie's graphiteoxide (GO) in order to test them as catalysts in the methanol photocatalytic reforming reaction in liquid phase. The preparation of the composite itself resulted in only little changes in the structure of GO as it was indicated by attenuated total reflection infrared (ATR-IR) and 13 C magic-angle spinning nuclear magnetic resonance ( 13 C MAS NMR) spectroscopic measurements. However, during the photocatalytic reaction, all of the GO/TiO 2 samples darkened strongly indicating structural changes of GO. X-ray photoelectron spectroscopy along with NMR confirmed the loss of oxygen functionalities and emergence of graphitic species in the samples recovered from the photocatalytic reaction. Model experiments were designed to identify the key factors determining the activity of the GO/TiO 2 derived photocatalysts. It was found that the emergence of a pronounced coupling between TiO 2 and the graphite-like carbonaceous material is the most important contribution to get active and stable photocatalysts.

Photocatalytic Reforming for Hydrogen Evolution: A Review

“…Graphene oxide (GO) has been widely applied to improve the photocatalytic activity [50][51][52][53]. Majrik et al prepared GO modified TiO 2 by a hetero-coagulation method and evaluated its photocatalytic activity of methanol reforming [54]. It was found that with 2% of GO in the composite (GO-TiO 2 ), the photocatalytic production rate of H 2 was more than 5 times higher than pure TiO 2 .…”

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

“…These included doping with various non-metals [2,6,10,14], modifying with noble metals [15,16,17], sensitizing with dyes [18,19], synthesizing TiO 2 with various morphologies [11,20], and coupling TiO 2 with other semiconductors [21,22,23]. A promising direction is the use of different forms of carbon, e.g., carbon nanotubes [2,24,25,26], graphite oxide [27], activated carbon [7], graphene [28], and graphene oxide [1]. Carbon materials have the potential of improving the photocatalytic activity of TiO 2 by (1) narrowing the band gap of the semiconductor, (2) decreasing the recombination rate of photogenerated charge carriers, (3) providing more active reaction/adsorption centers in greater amounts and higher surface area, (4) acting as a photosensitizer for the photocatalytic reactions, and (5) prolonging the lifespan of charge carriers [27,29,30].…”

“…A promising direction is the use of different forms of carbon, e.g., carbon nanotubes [2,24,25,26], graphite oxide [27], activated carbon [7], graphene [28], and graphene oxide [1]. Carbon materials have the potential of improving the photocatalytic activity of TiO 2 by (1) narrowing the band gap of the semiconductor, (2) decreasing the recombination rate of photogenerated charge carriers, (3) providing more active reaction/adsorption centers in greater amounts and higher surface area, (4) acting as a photosensitizer for the photocatalytic reactions, and (5) prolonging the lifespan of charge carriers [27,29,30]. There are numerous examples described in the literature where most of these advantageous effects were observed when amorphous (that is, not crystalline) carbon was used [31,32,33].…”

Enhancement of photocatalytic activity of titanium dioxide-based photocatalysts

“…In the topic of composites it is worth highlighting that a promising direction is to make composites using different forms of carbon, e.g. carbon nanotubes [94,[176][177][178], graphite oxide [179], activated carbon [180], graphene [181] and graphene oxide [95].…”

“…Following the oxygen rich modification of anatase, rutile and even amorphous phase was investigated based on the following points. Carbon materials have the potential of improving the photocatalytic activity of TiO2 by (i) narrowing the band gap of the semiconductor; (ii) decreasing the recombination rate of photogenerated charge carriers; (iii) providing more active reaction/adsorption centers in greater amounts and higher surface area; (iv) acting as a photosensitizer for the photocatalytic reactions; (v) prolonging the lifespan of charge carriers [36,179,219]. There are numerous examples described in the literature where most of these advantageous effects were observed even when amorphous (i.e.…”