Photocatalytic generation of hydrogen from cellulose

Abstract: Uncontrolled emission of greenhouse gases caused by consumption of fossil fuels has led to the urgent need to develop low-emitting energy technologies such as those exploiting renewable energies. In this context, hydrogen (H2) represents an opportunity to enhance the development of such technologies, in light of the possibility to use it as an energy storage for non-programmable renewables, and for its potential to decarbonize key emitting sectors such as transport sector. This study is therefore focused on photocatalytic generation of H2 using cellulose as sacrificial agent, with the aim of valorizing renewable resources like solar energy and the chemical energy contained in an abundant biopolymer. The types of cellulose which are most suitable for this application were determined, and the influence on the rate of H2 production of parameters like pH of the reaction medium, and concentrations of cellulose and photocatalyst was clarified. It was found that an acidic pH, a relatively high concentration of photocatalyst and a relatively low concentration of cellulose constitute the most advantageous configuration to maximize the performances. An estimation of the conversion efficiency from light energy to H2 energy is provided, and the performances allowed by cellulose are compared to those allowed by more commonly used sacrificial agents. Finally, attempts to synthesize advanced photocatalysts with the aim of increasing the efficiency are reported.