Hydrogen Generation via Sodium Borohydride Hydrolysis Using the Graphene Supported Platinum-Ruthenium-Cobalt Catalysts Prepared nu Microwave-Assisted Synthesis

Sodium borohydride is of interest as a source for a hydrogen generation during its catalytic hydrolysis. Various catalysts have been developed for this purpose. In the present study the graphene supported platinum-ruthenium-cobalt catalysts (denoted as PtRuCo/GR) with the different Pt:Ru:Co molar ratios, prepared by means of microwave-assisted synthesis, were used as catalysts towards hydrogen generation via sodium borohydride hydrolysis. The morphology and composition of catalysts were examined using Field Emission Scanning Electron Microscopy and Inductively Coupled Plasma Optical Emission Spectroscopy. Catalytic activity of PtRuCo/GR with the different Pt:Ru:Co molar ratios was determined by measuring the amount of hydrogen generated directly from aqueous alkaline solutions of sodium borohydride and compared with that of Co/GR. The data on hydrogen generation volume with respect to time at different concentrations of sodium borohydride and different temperatures have been presented.

It has been determined that the PtRuCo/GR catalysts were synthesized with the Pt:Ru:Co molar ratios equal to 1:2:2, 1:1.7:5.6 and 3.5:1:23. The EDX spectra confirm the presence of Pt, Co and Ru nanoparticles in the investigated PtCoRu/GR catalysts.

It was found that the temperature and composition of catalysts have exceptional influence on the rate of hydrogen generation from alkaline sodium borohydride solutions. Significantly greater hydrogen generation rate is obtained at the synthesized PtRuCo/GR catalysts as compared with that at Co/GR. Highest rates of hydrogen generation were obtained at 60 ^oC and are 207.5, 82.8 and 53.1 L min^-1 g_Mtotal^-1 for the PtRuCo/GR catalysts with the Pt:Ru:Co molar ratios equal to 1:2:2, 1:1.7:5.6 and 3.5:1:23, respectively. The activation energy (E_a), determined from the kinetic data, is 45.6, 55.9 and 50.2 kJ mol^-1 for PtRuCo/GR with the above mentioned Pt:Ru:Co molar ratios, indicating a high catalytic activity of the synthesized catalysts towards hydrolysis of sodium borohydride.