Preparation And Performance Study Of Hydrogen Generation Supported Catalysts For Sodium Borohydride Methanolysis

The use of hydrogen energy reduces human dependence on the increasingly depleted fossil fuels and reduces the environmental pollution caused by fossil fuel use.The conventional limited storage forms of hydrogen increase the cost of hydrogen energy and seriously hinder the wide application of hydrogen energy.Therefore,it is a hot.topic for people to study on-site produce portable hydrogen through simple chemical reactions by using a chemical with high hydrogen storage density.Portable NaBH₄-4CH₃OH fuel cell has been widely studied for sodium borohydride has high gravimetric hydrogen density（10.8 wt.%）,high stability in alkaline solution,non-flammability,and low requirement for storage environment.The key problem of developing NaBH₄-4CH₃OH fuel cell is to prepare a catalyst that is efficient,high stability,and easily separated.In this paper,Ru-Co/CNTs、Ru/Ni foam、Co-Mo-P/CNTs-Ni foam catalysts were prepared and used to catalyze hydrogen generation from NaBH4 methanolysis.The main contents are as follows:（1）Ru-Co bimetallic nanoparticles catalysts were deposited on the CNTs carriers by the microwave assisted heating electroless plating method.The influence of the diameters of carbon nanotubes carriers on the catalytic performance of the Ru-Co/CNTs catalysts was studied,and when the carbon nanotube diameter with 10～20 nm as the catalyst carrier,the maximum rate of hydrogen generation from NaBH4 methanolysis catalyzed by the Ru-Co/CNTs was determined to reach 21.19 L·min^-1·g^-1,and the activation energy was 34.35 kJ·mol^-1.（2）Ru nanoparticles catalysts were prepared on the Ni foam substrates by electroplated method,and the preparation conditions of the catalysts were optimized from the concentration of complexing agent,current density,temperature and electroplating time.The maximum rate of hydrogen generation from NaBH4 methanolysis catalyzed by the optimized Ru/Ni foam catalyst was 1.93 L·min^-1·g^-1,and the activation energy was 41.1 kJ·mol^-1.After 8 cycles,the morphology of Ru/Ni foam catalyst has hardly changed,which indicates that Ru nanoparticles can be firmly loaded on Ni foam substrates by electroplating method.（3）The chemical vapor deposition method was used to prepare dandelion-like CNTs-Ni foam composite carrier,and then the electroless plating method was used to deposit Co-Mo-P nanoparticles on the CNTs of the CNTs-Ni foam.Among them,the diameter of carbon nanotubes is about 70 nm,and the particle size of Co-Mo-P alloy nanoparticles is about 80 nm.The dandelion-like Co-Mo-P/CNTs-Ni foam catalysts complete retained the tubular structure of carbon nanotubes and the gaps between carbon nanotubes,which increased specific surface area of the catalyst and flow space of reactant.The dandelion-like Co-Mo-P/CNTs-Ni foam catalysts reached a maximum hydrogen production rate of 2.64 L·min^-1·g^-1,and the activation energy was 47.27 kJ·mol^-1.