氧化镍复合材料的制备及其性能研究

发布时间：2018-01-30 14:53

本文关键词： N-O-g-CN/NiO NiO/Au多孔纳米带等离子体共振异质结 NiO纳米带 Au纳米粒子　出处：《浙江理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着人口的增长和现代化工业进程的不断加快,能源短缺和环境污染问题是21世纪全世界所面临的最大挑战,人类迫切需要开发清洁、环保、更经济的能源。氢气由于其导热性好、零碳排放、燃烧性能好、无污染等特点是公认的清洁能源。现阶段氢气的制备方法很多,其中利用太阳光分解水制氢被认为是最环保、最经济、最有优势的制备方法之一,因为该反应只需要太阳光、水和光催化剂。氧化镍(NiO)是一种非常重要的p型半导体材料,在光激发下,能快速产生光生电子-空穴对,且其导带位置低于H~+/H_2还原电势,可以分解水制氢气。但由于NiO的禁带宽度较大,只能吸收紫外光,且光生电子和空穴的再结合率很高,大大地限制了其实际应用。因此,对NiO进行修饰,使其充分利用太阳能变得尤为重要。本文通过探究NiO自身性能及其与半导体光催化剂(g-C_3N_4)和贵金属(Au)复合,制备了复合光催化剂,从而改善其可见光催化性能。还考察了NiO纳米带对有机染料的吸附性能。全文主要包括以下三方面的研究内容:1.经550°C煅烧处理硫脲与尿素(1:1)的混合物,得到多孔状N和O掺杂的g-C_3N_4(记作:N-O-g-CN)。然后以N-O-g-CN为基底,负载NiO纳米颗粒,两者通过表面密切接触形成N-O-g-CN/NiO有机-无机复合光催化材料。我们制备的多孔状N-O-g-CN/NiO复合催化剂在可见光(λ420 nm)照射下能高效分解水制氢且具有良好的稳定性。其中2 wt%N-O-g-CN/NiO的产氢速率是纯N-O-g-CN的5.7倍,是0.5 wt%N-O-g-CN/Pt的2.7倍。光催化性能的大幅度提高可能由于复合物表面存在多孔结构,为催化制氢提供更多的活性位点,以及N-O-g-CN/NiO异质结构引起的界面电荷的快速分离。2.通过水热法制备α-Ni(OH)_2/Au,再通过500°C煅烧制得NiO/Au多孔纳米带结构。考察了在可见光(λ420 nm)照射下,NiO/Au多孔纳米带结构在Na2S和Na_2SO_3水溶液中的催化制氢性能。当Au与NiO的摩尔比为1%时,光催化制氢性能最好,产氢速率为153μmol/h/g,相比于纯NiO有了从无到有的突破。光催化性能的大幅提高可能是由于多孔纳米带结构提供更多的活性位点,以及Au纳米粒子的等离子体共振效应和NiO/Au之间的异质结引起的界面电荷迁移。3.考察了NiO纳米带对有机染料的选择性吸附性能。通过水热反应及热处理制备了拥有较高比表面积的NiO纳米带(102.4 m~2/g)。作为一种有效的吸附剂,对阴离子染料包括甲基蓝(MB),甲基橙(MO)和刚果红(CR)的饱和吸附量分别达到1996,1291和331mg/g。循环吸附实验表明NiO能够作为一种稳定的吸附剂吸附有机染料。
[Abstract]:With the increase of population and the accelerating of modern industry, the problem of energy shortage and environmental pollution is the biggest challenge in the world in 21th century. Human beings urgently need to develop clean and environmental protection. More economical energy. Hydrogen is recognized as a clean energy because of its good thermal conductivity, zero carbon emission, good combustion performance, no pollution and so on. At present, there are many preparation methods of hydrogen. One of the most environmentally friendly, economical and advantageous methods for hydrogen production is the decomposition of water by solar light, because the reaction requires only solar light. Nio is a very important p-type semiconductor material, which can produce photogenerated electron-hole pairs rapidly under photoexcitation. The position of conduction band is lower than that of H- / H-2 reduction potential, which can decompose water to produce hydrogen. However, because of the wide band gap of NiO, it can only absorb ultraviolet light, and the recombination rate of photogenerated electrons and holes is very high. It greatly limits its practical application. Therefore, the NiO is modified. It is very important to make full use of solar energy. In this paper, the composite photocatalyst was prepared by investigating the properties of NiO and its compounding with semiconductor photocatalyst (C3N4) and noble metal (Au4). The adsorption of organic dyes by NiO nanobelts was also investigated. The main contents of this paper are as follows: 1. Thiourea and urea were calcined at 550 掳C. A mixture of 1: 1. The porous N and O doped g-C _ 3N _ 3N _ s _ 4 (denoted as: N-O-g-CNN) were obtained, and then the NiO nanoparticles were loaded on N-O-g-CN substrate. The N-O-g-CN-NiO organic-inorganic composite photocatalytic materials were formed by close contact between the two catalysts. The porous N-O-g-CN-NiO composite catalysts were prepared in the visible light (. The hydrogen production rate of 2 wt%N-O-g-CN/NiO is 5.7 times higher than that of pure N-O-g-CN. The increase of photocatalytic activity may be due to the existence of porous structure on the surface of the complex, which provides more active sites for the catalytic production of hydrogen. And the fast separation of interface charge caused by N-O-g-CN-Ni / nio heterostructure. 2. 伪 -NiOHO / Au was prepared by hydrothermal method. The structure of NiO/Au porous nanobelts was prepared by calcination at 500 掳C. the structure was investigated under visible light (位 420nm) irradiation. When the molar ratio of au to NiO is 1, the photocatalytic hydrogen production is the best. The hydrogen production rate is 153 渭 mol / h / g, which is a breakthrough compared with pure NiO. The significant improvement of photocatalytic performance may be due to the porous nanobelts providing more active sites. The plasmon resonance effect of au nanoparticles and the interfacial charge transfer induced by heterojunction between NiO/Au and au nanoparticles. The selective adsorption of organic dyes by NiO nanobelts was investigated. NiO nanobelts with high specific surface area were prepared by heat treatment. 102.4 mt2 / g. As an effective adsorbent. The saturated adsorption capacity of anionic dyes, including methyl blue MBO, methyl orange molybdenum (MOO) and Congo red red (CRR), was up to 1996, respectively. Cyclic adsorption experiments show that NiO can be used as a stable adsorbent to adsorb organic dyes.
【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ138.13;O643.36

【相似文献】