Exploration Of Composite Catalyst Based On Biomass Carbon Materials For Hydrogen Evolution Reaction

Due to its good conductivity, acid and alkaline endurance, high specific surface area, abundant pore structure and inexpensive cost, porous carbon materials have been well applied in various fields. Among these porous carbon materials, as a unique kind, ordered mesoporous carbon materials not only possess the intrinsic properties of porous carbon materials, but also have the characteristics ordered pore structure and so on, so they attract the recent research attention. As the promotion and development of the recyclable economy, it is of significant importance to synthesis functional carbon materials from biomass resources, which is cheap and reproducible. Although progress has been achieved in converting biomass resources into carbon materials by hydrothermal carbonization, there still remain many challenges:?1? usually direct biomass hydrothermal require high reaction temperature, which increase the synthesis cost and demand much higher standard of the equipment; ?2? normally only micro-sized and interconnected carbon spheres or random bulk materials can be obtained via direct hydrothermal, which seriously constrain the future prospect; ?3? the understanding of biomass hydrothermal carbonization is still rudimentary, while a series of complicated reactions involved in the reaction process makes it difficult to realize the controllable synthesize of target materials.Considering the problem that it is difficult to synthesize functional carbon materials of specific structure from biomass and its derivatives through soft-template hydrothermal method, the first part of the thesis successfully synthesizes ordered mesoporous carbon materials by using xylose as the carbon precursors, as this soft-template hydrothermal method coordinates the hydrothermal process. This thesis develops a simple method by introducing sulfuric acid into the biomass soft-template hydrothermal carbonization process. It lowers the hydrothermal temperature ??30?? required for biomass precursors, promotes the rate of hydrothermal carbonization; also, it enhanced the aggregation of micelles, solidifies the micelles structure under high temperature and it provides electrostatic interaction besides the hydrogen bond though interaction between different charges as well, which further enhances the interaction between micelles and biomass carbon precursors and finally strengthens the stability of the self-assembly structure. Though this acid induced self-assembly process of biomass carbon precursors and soft-template, ordered mesoporous carbon materials with hexagonal symmetry are obtained. This kind of ordered mesoporous carbon materials is of high specific surface area(532 cm²g^-1) and large mesopore size?3.6 nm?. This method is not only for the first time that S⁰H⁺X^-I⁺synthesis mechanism is successfully applied to synthesize ordered mesoporous carbon materials from biomass and its derivatives, but also it shows universality for other pentose precursors. It is a promising synthesis method for ordered mesoporous carbon materials in the future. Subsequently, in order to promote the development of inexpensive electrocatalysts to replace the use of Pt based catalysts in the hydrogen evolution reaction, we developed acid induced self-assembly method synthesize ordered mesoporous carbon materials from biomass as the catalysts support for loading metal Ru for hydrogen evolution reaction. The as-synthesized electrocatalysts Ru/ai-OMC exhibit well catalytic activity, rapid reaction rate and excellent stability for hydrogen evolution reaction. After deep insight into the superiority of the material, we find that the select of support significantly influence the performance of the hydrogen evolution reaction. Due to rich surface functional groups, ordered pore structure and large pore size of ai-OMC, these characteristics, on the one hand is good for the dispersion of Ru nanoparticles inhibiting the aggregation; on the other hand, boost the mass transfer of reaction molecule to the reaction active sites and the dissociation of hydrogen molecule from the catalysts surface. Thus the design of appropriate catalysts support can substantially improve the performance of hydrogen evolution reaction, which provides new solution to the development of hydrogen evolution reaction catalysts.Afterwards, in the second part, in order to solve the problem that the catalytic activity of Ru still falls behind that of the Pt-based electrocatalyst, we focus on how to develop less Pt mass loading, more active and more stable Pt-based elcetrocatalyst. By introducing another earth-abundant metal element Ni into the Pt, we synthesize PtNi alloy with the morphology of octahedral through solvent co-reduction. Through the HER test in 0.5M H₂SO₄ solution, we find that the introduced inexpensive metal could effectively reduce the mass loading of Pt, and do no harm to the HER activity and stability. In addition, the proportion of the earth-abundant metal in the alloy could significantly affect the HER activity. The alloying method could turn intrinsic slow reaction facet into highly active reaction surface, and the introduction of inexpensive metal element could improve the rate of Tafel reaction. This method to control the component of the catalytic active site can boost the HER activity substantially, and this offer new method for future HER catalyst design.