Supported Co-M-B （M=Fe、Mo） For Hydrogen Production From Sodium Borohydride Hydrolysis

Hydrogen energy has been selected as a potential energy carrier due to the massive adoption of traditional fossil energy and the impending energy shortage.Hydrogen production from fossil fuels will cause serious pollution.Hydrogen production from catalytic hydrolysis of sodium borohydride（Na BH₄）has been widely concerned.Although noble metal catalysts have shown good catalytic activity and stability,their large-scale use is limited by limited resources and high cost.Therefore,the development of non-precious metal catalysts became the primary task.In this paper,two kinds of supported catalysts（Co-Fe-B/Cu foam,g-C₃N₄/Co-M-B/Ni foam（M=Fe,Mo））were prepared.For the first kind,Cu foam is employed to be the single carrier.For the other kind,Ni foam and g-C₃N₄ are used as the double carrier,where g-C₃N₄is introduced to be light absorption materials to further improve the catalytic activity of non-noble metals.The catalysts were characterized by XRD,XPS,SEM,TEM,EDX and ICP-MS,and the catalytic hydrolysis performance of Na BH₄ was investigated.The main research contents and results are as follows:1.Co-Fe-B/Cu foam catalyst was synthesized by chemical deposition method.The results show that hydrogen production rate（HGR）significantly increases with the increase of p H from 11.0 to 12.0,but HGR decreases with the increase of p H from12.0 to 12.5.It can be inferred that the optimal p H value is 12.0.The as-prepared Co-Fe-B/Cu foam material（p H=12.0）has the smallest particle size.The HGR of catalytic hydrolysis of Na BH₄ is 10690.3 m L·min^-1·g^-1_cat.,and the activation energy（E_a）value is 55.6 k J·mol^-1.The outstanding catalytic performance of Co-Fe-B/Cu foam catalyst（p H=12.0）may be due to the unique spherical and hollow structure.In addition,the synergistic effect of Co,Fe and Co₃B is another reason..2.g-C₃N₄/Co-M-B/Ni foam composite catalyst was prepared by chemical deposition method.Through process optimization,the following conclusions are obtained:When the reducing agent concentration is 0.9 mol·L^-1,the particle size of g-C₃N₄/Co-M-B/Ni foam is smallest.Under natural condition and xenon light irradiation,the hydrogen production rate and activation energy of Na BH₄ hydrolysis are 11164.1 m L·min^-1·g^-1_cat.and 14005.7 m L·min^-1·g^-1_cat.,respectively.It is worth noting that the catalytic hydrogen production rate is significantly increased and the apparent activation energy is obviously reduced after the introduction of light,indicating that the catalytic activity of g-C₃N₄/Co-M-B/Ni foam composite catalyst is distinctly improved.3.The g-C₃N₄/Co-Mo-B/Ni foam composite catalyst was prepared by chemical deposition method,and the influence of the mole ratio of Co²⁺:Mo O₄^2-on the catalytic performance for the hydrolysis of Na BH₄ was studied.The results are as follows:When the mole ratio of Co²⁺:Mo O₄^2-is 1:1,g-C₃N₄/Co-Mo-B/Ni foam composite catalyst shows the high catalytic activity toward the hydrolysis of Na BH₄with hydrogen production rates of 8372.7 and 9957.7 m L·min^-1·g^-1_cat.under natural condition and xenon light irradiation,respectively.The corresponding activation energies are 55.8 and 52.6 k J·mol^-1,respectively.Moreover,the formation of Mo₂C in the chemical deposition process attracted the photoelectron transfer on g-C₃N₄ and promoted the photocatalysis,thus improving the catalytic activity of g-C₃N₄/Co-Mo-B/Ni foam composite catalyst for Na BH₄hydrolysis.