复合材料NiO_(x)-ZSM-5的制备及微生物电解池催化析氢性能

Synthesis of NiO_(x)-ZSM-5 Composite Materials and Its Electrocatalytic Hydrogen Evolution Performance in Microbial Electrolysis Cell

在Na_(2)O-TPABr-Al_(2)O_(3)-SiO_(2)-H_(2)O溶胶体系中加入碳球,采用水热晶化法合成ZSM-5分子筛载体,负载镍盐制备复合材料NiO_(x)-ZSM-5.利用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)、氮气吸附-脱附和电化学测试等手段对样品进行表征,利用微生物电解池(MEC)评价其催化析氢性能.结果表明,在碳球作用下ZSM-5分子筛为纳米粒子聚集的椭球形貌,介孔比表面积和介孔孔容明显增加.浸渍焙烧后的黑色斑点NiO_(x)覆盖在晶隙形成的介孔表面和分子筛的表面.相比于纯NiO,镍盐浸渍量为40%的复合材料中多价态镍氧的吸收峰向高结合能方向移动,多价态镍、铝原子和氧空位活性位数量明显增多,显著提高了复合材料的电催化活性,使其具有较高电流密度(8.45 mA/cm^(2))和较低起始析氢过电位(151 mV),优于NiO电极.在MEC运行周期内,复合材料的平均析氢电流密度为(28.64±7.4)A/m^(2),总产气量为(52.67±1.64)mL,H_(2)纯度为(89.07±0.06)%,略高于商用Pt/C电极[(89.05±0.05)%],产氢效率(0.571 m3∙m−3∙d−1)和库仑效率[(76.7±5.4)%]与Pt/C阴极相近,表明复合材料是一种低成本和高效率的析氢材料.

ZSM-5 molecular sieves were synthesized by adding carbon spheres into Na_(2)O-TPABr-Al_(2)O_(3)-SiO_(2)-H_(2)O sol reaction system with hydrothermal crystallization method,then loaded different nickel-salts to prepare NiO_(x)-ZSM-5 composites.The samples were characterized by means of X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),nitrogen adsorption-desorption isotherms and electrochemical tests.In addition,their catalytic hydrogen evolution performances were evaluated by the microbial electrolytic cell(MEC).The results show that the ZSM-5 molecular sieves composed of stacked ZSM-5 nanoparticles under the action of carbon spheres are ellipsoidal morphology,which mesoporous specific surface area and mesoporous pore volume have significantly increased.After immersion and roasting,the speckled NiO_(x) nanoparticles are covered the mesoporous surface formed by the crystal gap and the surface of the molecular sieve.Compared with pure NiO,the composites with 40%nickel-salts show that the absorption peak of multivalent nickels and oxygen shift to the high energy direction.Eventually the electrocatalytic activities are significantly improved by increasing active sites of multivalent nickel,aluminum atoms and oxygen vacancies,the composites exhibit high current density(8.45 mA/cm^(2))and low overpotential(151 mV).During the MEC operation cycle,the average hydrogen evolution current density of the composite is(28.64±7.4)A/m^(2),the total gas production is(52.67±1.64)mL,and the H_(2) purity is(89.07±0.06)%.The hydrogen evolution efficiency(0.571 m3∙m−3∙d−1)and coulombic efficiency[(76.7±5.4)%]of composite cathode are similar to Pt/C cathode,indicating that the composite is a low cost and high efficiency hydrogen evolution material,which offers a possible alternative to Pt cathode.