NiY分子筛的合成及在微生物电解池阴极的析氢性能研究

Synthesis of NiY zeolite and hydrogen evolution performance in cathode of a microbial electrolysis cell

在Na2O-Al2O3-Si O2-H2O体系中添加硝酸镍,采用导向剂法合成了Ni Y分子筛。利用XRD、SEM、TEM、N2吸附-脱附等手段对合成的Ni Y分子筛进行了表征。结果表明,随着镍添加量的增加,结晶度和zeta电位呈先增大后减小的趋势。当Si/Ni(mol ratio)大于5时,硝酸镍对分子筛的形成具有促进作用,当Si/Ni(mol ratio)小于5时,则具有抑制作用。晶粒粒径为1.5-3μm,形貌为凹槽结构的六方或四方柱型,且具有微孔-介孔多级孔道结构特征。通过循环伏安曲线和极化曲线测试,在Si/Ni(mol ratio)=5时,样品的氧化还原性能最强,过电势最小,电催化活性最高。在12 h内,每4 mg的Si/Ni(mol ratio)=5样品,产气总量为10.1 m L,氢气纯度达81.69%,与Pt电极相比其氢气产量提高了28%。Ni Y分子筛表现出良好的析氢催化活性,有望取代Pt成为MEC新型阴极材料。

Ni Y zeolites were synthesized in the system of Na2O-Al2O3-SiO2-H2O with the addition of nickel nitrate by crystallization directing agent and characterized by XRD,SEM,TEM,N2 adsorption-desorption,etc.The results showthat the crystallinity and zeta potential decrease after an increase at first with the increasing of nickel added. It means that nickel nitrate can promote the formation of molecular sieve when Si/Ni（ mol ratio） is greater than 5,while it has an inhibitory effect when Si/Ni（ mol ratio） is less than 5. The Ni Y zeolites with 1.5-3 μm of size not only possess special morphology,six or four square columns with grooved structure,but also have a multiple porous structure including microporous and mesoporous. The sample test by cyclic voltammetry（ CV） and polarization curve（ LSV） in microbial electrolysis cell（ MEC） indicates that the Ni Y zeolites with Si/Ni（ mol ratio） = 5 present the best electrochemical characteristics with an outstanding redox performance,a minimum overvoltage and the highest electrocatalytic activity. Moreover,the hydrogen production yield reaches10.1 m L/4 mg in 12 h with the hydrogen purity of 81.69%,surpassing that with Pt electrodes by about 28%. It suggests that the Ni Y zeolites have a better hydrogen evolution activity and it is possible to replace Pt as a novel cathode catalyst in microbial electrolysis cell.