Study of Catalysts for Water Photosonolysis to Increase the Hydrogen Production

This paper deals with an experimental investigation on water catalyzed photosonolysis for hydrogen production. This study was focused to identify the optima catalysts for photosonolysis at 1.0 pressure conditions. The identified catalysts are solid solutions of oxides based on Lanthanum, Indium and Gallium. They need a sacrificial agent to make the water sample able to absorb the sunlight visible components: it was requested that the sacrificial agent is a more oxidable substance with respect to the water oxygen. Thus, ethanol was chosen as sacrificial agent. Water splitting is obtained by the superposition of photolysis and sonolysis phenomena (photosonolysis) which are induced by the combined action of sunlight, catalysts and ultrasounds. An experimental device was built to investigate such phenomena; experimental tests were carried out for different concentrations and molar compositions of the identified oxides. Results show that hydrogen production obtained by the superposition of photolysis and sonolysis is higher than the algebraic sum of hydrogen produced singularly by sonolysis and photolysis. Thus, a synergy between sonolysis and photolysis is shown: the two phenomena help each other for hydrogen production. At last, results allowed to determinate the optimum catalyst and its solution concentration for hydrogen production.