Synthesis And Catalytic Property Of Ru Based Catalysts For Hydrogen Evolution

Ammonia borane(AB) and sodium borohydride(SB) are recognized as promising hydrogen storage materials because of their high capacity of hydrogen. Hydrogen evolution from the hydrolysis of these compounds catalyzed by Ru based catalysts has attracted considerable attention because of their high catalytic activity and stability.Considerable interest has been focused on the two-dimensional graphene-like titanium carbide(Ti3C2X2) and graphic carbon nitride(g-C3N4) because of their unique chemical and physical properties. In this work, Ti3C2X2 and g-C3N4 supported Ru based catalysts were prepared and applied for the catalytic hydrolysis of ammonia borane and sodium borohydride.Ru/Ti3C2X2 nanocomposite was prepared for the hydrolysis of SB through reducing RuCl3 aqueous solution using SB as reducing agent. The as-prepared nanocomposite was characterized by SEM, TEM, XRD, XPS and FT-IR. The catalytic property of Ru/Ti3C2X2 was studied for the hydrolysis of SB at room temperature. It was found that Ru/Ti3C2X2 exhibited excellent catalytic activity toward the hydrolysis of SB with a hydrogen generation rate of 59.04 L H2(gRu·min)-1 and an activation energy of 22.1 kJ/mol. The as-prepared catalyst is quite stable and can be recycled for at least five runs.RuCo nanoparticles(NPs) were in-situ synthesized and immobilized on the surface of graphene like titanium carbide(Ti3C2X2). Characterization results indicate that the RuCo nanoparticles are well dispersed on Ti3C2X2 surface. The catalytic property of RuCo/Ti3C2X2 for hydrogen generation from the hydrolysis of AB at room temperature was investigated. Ru1Co9/Ti3C2X2 showed the highest turnover frequency of 896 mol H2(molRu·min)-1 because of the synergetic effect between Ru and Co nanoparticles. The activation energy is estimated to be 31.1 kJ/mol. The catalyst can be easily separated from the reaction system by using a magnet and recycled at least four times.Graphitic carbon nitride prepared by the thermal decomposition of urea was used catalyst support for the in situ immobilization of Ru NPs(Ru/g-C3N4). The morphologies of Ru NPs on the surface of g-C3N4 were verified by TEM. Results show that the in situ generated Ru NPs are well dispersed on the surface of g-C3N4 with a mean particle size of 2.8 nm. The catalytic property of Ru/g-C3N4 was investigated in the hydrolysis of AB in an aqueous solution under mild conditions. The catalytic performance for AB hydrolysis indicates that 3.28wt% Ru/g-C3N4 exhibits excellent catalytic activity with a high turnover frequency number of 313.0 mol H2(mol Ru·min)-1at room temperature.