Photocatalytic Reforming for Hydrogen Evolution: A Review

Abstract

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.

Effect of the Microstructure of the Semiconductor Support on the Photocatalytic Performance of the Pt-PtOx/TiO2 Catalyst System

“…This rendered direct comparison of the catalytic properties of the bare TiO 2 materials impossible in this study. Otherwise, our hydrogen production results are of the same order as those in other works [ 13 , 57 , 58 , 59 ]. As can be seen from Figure 2 , the P25-based samples gave a higher H 2 production rate than the sol–gel-based samples, irrespectively if the Pt co-catalyst was formed by hydrogen reduction or calcination.…”

“…Since hydrogen is regarded as an important secondary energy source for the future [ 3 , 4 , 5 ]; photocatalytic implementation of hydrogen production would give an opportunity to transform solar energy into chemical energy for storage [ 6 ]. Large numbers of publications have indicated that photoinduced reforming of alcohols such as methanol, glycerol and more, over semiconducting oxides in the presence of water, could be an efficient way of hydrogen generation [ 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. Even if the conversion of the methanol in the photoinduced reforming reaction (1) is rather low compared to other methanol-reforming systems, reaction (1) is widely studied and used as a model reaction to compare photocatalysts [ 14 , 15 ].…”

Recent Developments of TiO2-Based Photocatalysis in the Hydrogen Evolution and Photodegradation: A Review

“…In general, there are two types of sacrificial reagents: organic and inorganic based electron donors. Among organic electron donors, the most effective are water–alcohol mixtures, in particular, methanol > ethanol > ethylene glycol > glycerol [ 53 , 54 , 55 , 56 , 57 , 58 , 59 ]. However, an increase in the concentration of the sacrificial agent does not always lead to an increase in the yield of hydrogen.…”

Photocatalytic hydrogen evolution from biomass conversion

“…Effective photochemical biomass-to-hydrogen processes relying on solar energy inputs could valorize biomass feedstocks currently viewed as waste products, such as pulp generated during paper processing. Moreover, the possibility that this photochemical approach could also enable the production of low molecular weight aromatic products from the biomass stream concomitant with H 2 production could offer another economic advantage [ 2 ]. The targeted and currently unused biomass sources, such as raw lignocellulosic biomass, do present difficulties such as limited solubility and chemical inertness [ 63 ].…”

“…The oxidation of H 2 coupled to the reduction of O 2 in a fuel cell produces water as the only product, a more environmentally friendly process than fossil fuel combustion, which produces harmful greenhouse gas emissions in the form of CO 2 . Moreover, hydrogen is also attractive as an alternative energy source because of its high energy density (e.g., 141.8 ⨯ 10 6 kJ/kg), which is greater than that of most fuels (e.g., 44 ⨯ 10 6 kJ/kg for gasoline) at room temperature [ 2 ]. The most prevalent production method for H 2 is steam reforming of methane feedstocks, producing nearly half of the hydrogen gas in the world [ 3 ].…”