Preparation Of Boron Nitride Nanosheet-based Nanocomposites And Its Catalytic Performance For Hydrogen Production By Hydrogenation Of Ammonia Borane

Hydrogen is considered to be the most promising“zero-carbon”clean energy source.The release of hydrogen from reservoirs is a key challenge in the research of hydrogen storage materials.Ammonia borane（NH₃BH₃,AB）is considered to be a potential solid hydrogen storage material with a high hydrogen content（19.6 wt%）,and its aqueous solution can be rapidly hydrolyzed to release high purity hydrogen in the presence of a suitable catalyst.At present,it has been proved that the composite system formed by two non-noble metals has a relatively excellent activity in the hydrogen production experiment of ammonia borane,but it is still difficult to further improve the catalytic activity and stability.The catalytic activity largely depends on the size of the metal nanoparticles（NPs）.The smaller the particle size,the stronger the catalytic performance.Compared with large particles,nano-sized metal particles tend to form agglomerates,leading to the loss of catalytic activity,so enhancing their stability is the key.Boron nitride nanosheets（BNNSs）are a new type of two-dimensional material with a large specific surface area,which can provide the flexible and smooth surface required for the adhesion of metal nanoparticles and prevent their agglomeration.Theoretical calculations show that the N-pz-Metal-dz²anti-bond hybrid formed by the bonding of transition metals to the surface of BNNSs can enhance the stability of the metal on the surface of BNNSs.Nano-boron nitride can also shorten the induction time and reduce the hydrogen release temperature in the AB hydrolysis reaction in the ammonia borane hydrolysis reaction.Based on the above characteristics,BNNSs can be used as excellent catalyst carrier materials.In this paper,boron nitride nanosheets were prepared by polyvinylpyrrolidone（PVP）-assisted ion intercalation method,and the peeling mechanism of this method was explored.Various methods were used to characterize the morphology and structure of BNNSs.The effects of the addition ratio of K⁺-Li⁺,the amount of intercalating ions,and the centrifugation rate on the stripping effect of boron nitride were investigated.The yield of nanosheets can reach 37%.CuCo/BNNSs nano-catalysts with different metal ratios were prepared by simple co-reduction method using boron nitride nanosheets prepared by stripping as carriers.Fourier transform infrared spectroscopy（FT-IR）,X-ray diffraction（XRD）,laser Raman,X-ray photoelectron spectroscopy（XPS）,scanning electron microscopy（SEM）,high-resolution transmission electron microscopy（HRTEM）,and inductively coupled plasma spectrometer（ICP-AES）are used to characterize its structure and morphology.The prepared catalyst was used in the catalytic hydrogen production experiment of the solid hydrogen storage material ammonia borane hydrolysis,and the catalytic performance and cycle stability of the catalyst were evaluated by the hydrogen production rate.In addition,the addition of acids and bases to the reaction solution can greatly increase the AB hydrolysis rate,explore the optimal p H value of AB hydrolysis for hydrogen production,and analyze the mechanism of AB hydrolysis hydrogen production under alkaline conditions.On the basis of CuCo/BNNSs nanocomposite catalyst,amorphous CuCo Mo/BNNSs nanocomposite catalyst was successfully prepared by doping a small amount of Mo.Its structure and morphology were characterized by FT-IR,XRD,XPS,SEM,HRTEM,and ICP-AES.Ammonia borane water was used to explain the hydrogen reaction to evaluate the catalytic activity and recycling performance of the composite.The effects of the amount of catalyst and the concentration of ammonia borane on the activity of ammonia borane water to explain the hydrogen reaction were investigated.