【作者】 王鑫；

【导师】 曹殿学；

【作者基本信息】 哈尔滨工程大学 ， 材料科学与工程， 2018， 博士

【摘要】 能源和环境问题是人类进入21世纪后所面临的两个最为严峻的问题,所以开发清洁的新能源成为国际研究的重点。燃料电池是利用电化学反应,将存储在燃料中的高效率和低污染的化学能转化成电能的发电装置。燃料电池技术对解决化石能源短缺、利用效率低、导致环境恶化等问题,实现节能减排、发展环保型低碳经济具有极其重要的作用。直接过氧化氢燃料电池（DPFCs）是一种既以H₂O₂作为燃料又以H₂O₂作为氧化剂的新型液态燃料电池,由于H₂O₂具有绿色无毒、可再生、存储运输方便（液态）、电化学活性高、不依赖于化石燃料的特点,因而直接过氧化氢燃料电池成为燃料电池领域的国际研究热点。本论文针对直接过氧化氢燃料电池的开发,设计制备了一系列具有三维开放结构的贵金属阴极和贱金属阳极,分别研究了其催化H₂O₂在酸中电还原（阴极反应）和碱中电氧化（阳极反应）的活性和稳定性,组装并考察了DPFCs的的性能。主要研究内容如下:首先采用化学气相沉积法在Ti₆Al₄V合金片上成功生长出碳包覆碳化钛（C@TiC）纳米线阵列,然后利用电化学共沉积法将Pd和Ni直接沉积在C@TiC纳米线阵列基体上获得Pd-Ni/C@TiC,再利用化学去合金化法去除Ni元素得到具有多孔结构的NP-Pd/C@TiC纳米线电极。FESEM测试分析表明,钛合金表面完全被阵列结构的C@TiC纳米线（长度为7μm,直径为150 nm）所覆盖,电化学共沉积上Pd-Ni后,纳米线形貌转变为纳米冰花结构,当金属Ni被刻蚀除去后,在纳米线上形成了均匀且多孔的贵金属Pd催化剂。利用线性扫描伏安法和计时电流法分别研究了不同H₂SO₄浓度和H₂O₂浓度下NP-Pd/C@TiC电极的催化性能。研究表明:当过氧化氢浓度为2.0 mol L^-1,硫酸浓度为2.0 mol L^-1时,NP-Pd/C@TiC电极表现出最佳的电化学催化性能(0.2 V vs.Ag/AgCl电位下还原电流密度达到了3.47 A mg^-1)。利用电化学共沉积贵金属（Pd）-贱金属（Ni）法,再化学去合金法刻蚀掉贱金属（Ni）从而得到具有多孔结构的NP-Pd/C@TiC纳米线阵列电极,此电极具有较大的电化学活性比表面积,降低了贵金属的使用量,非常适用于直接过氧化氢燃料电池的阴极催化剂。组装并考察了以多孔Ni/Ni foam作为阳极和NP-Pd/C@TiC纳米线电极作为阴极的DPFCs的电池性能。室温条件下,当流速为10 cm³min^-1,阳极电解液为4.0 mol dm^-3KOH+1.0 mol dm^-3H₂O₂,阴极电解液为2.0 mol dm^-3 H₂SO₄+2.0 mol dm^-3 H₂O₂时,电池的最大输出功率为44.2 mW cm^-2。利用方波电势电沉积法,在TiC纳米线阵列基体上直接沉积Pd和Au获得Pd-Au/TiC NAs催化电极,此过程无需任何导电剂和粘合剂。SEM测试分析表明,获得的Pd-Au/TiC NAs催化电极具有不同的微观结构（菠萝根状、雾凇状和羽毛状）。Pd-Au阴极催化剂的形貌可以通过改变电化学的沉积条件来简单地调节和控制。在H₂O₂+H₂SO₄电解液体系中,利用线性扫描伏安法对Pd-Au的相对含量与催化过氧化氢电还原的电化学性能之间的关系进行了研究,随着Pd含量的增加,催化电极的催化活性明显增大,Pd₅Au₁/TiC NAs电极具有最优的催化过氧化氢电还原活性。然后利用线性扫描伏安法和计时电流法系统的研究了不同H₂SO₄浓度和H₂O₂浓度下Pd₅Au₁/TiC NAs电极的催化性能和稳定性。研究表明:Pd₅Au₁/TiC NAs电极在2.0 mol dm^-3 H₂O₂和2.0 mol dm^-3 H₂SO₄电解液中电极电位为0.2 V下,催化过氧化氢电还原的电流密度达到0.480 A cm^–2(4.11 A mg^-1,除以贵金属催化剂的总负载量)。组装并考察了以多孔Ni/Ni foam作为阳极和Pd₅Au₁/TiC NAs电极作为阴极的DPFCs的电池性能。室温条件下,当流速为10 cm³ min^-1,阳极电解液为4.0 mol dm^-3 KOH+1.0 mol dm^-3 H₂O₂,阴极电解液为2.0 mol dm^-3 H₂SO₄+2.0 mol dm^-3H₂O₂时,电池的最大输出功率为56.5 mW cm^-2。利用电化学沉积法,在TiC纳米线阵列基体上直接沉积过渡金属Ni和Co,制备出具有大比表面积的Ni@TiC NAs和Co@TiC NAs纳米线阵列电极。SEM测试分析表明,单根Ni@TiC NAs纳米线的直径为470 nm,且表现出刺状结构,而Co催化剂表现出超薄纳米片结构,单个Co@TiC NAs的直径为405 nm。用循环扫描伏安法和计时电流法在KOH+H₂O₂电解液中分别研究,刺状的Ni@TiC NAs电极和片状的Co@TiC NAs电极的催化活性和稳定性。研究表明,刺状的Ni@TiC NAs电极催化过氧化氢电氧化比片状的Co@TiC NAs电极具有更好的催化活性和稳定性。组装并考察了以Ni@TiC NAs作为阳极和Au-Pd/CFC作为阴极DPFCs的电池性能。室温条件下,电池的开路电压为0.90 V,当流速为10 cm³min^-1,阳极电解液为4.0 mol dm^-3KOH+1.0 mol dm^-3H₂O₂,阴极电解液为2.0 mol dm^-3 H₂SO₄+2.0 mol dm^-3 H₂O₂时,电池的最大输出功率达到了30.2mW cm^-2,其电池性能明显高于文献报道的以贵金属Au-Pd/CFC阳极的电池性能,表明使用贱金属Ni@TiC NAs阳极不仅降低了燃料电池的成本,而且提高了DPFCs的性能。更多还原

【Abstract】 Energy and environmental issues are two of the most serious problems facing mankind in the 21st century,so the development of safe and clean new energy has become the focus of international research.Fuel cells are electrochemical devices that use electrochemical reactions to convert the high efficiency and low-pollution chemical energy stored in fuel into electrical energy.Fuel cell technology is of great importance to solve the problems such as shortage of fossil energy,low utilization efficiency and environmental degradation,so as to realize energy conservation and emission reduction and development of environmentally friendly low-carbon economy.Direct hydrogen peroxide fuel cell（DPFCs）is a new type of liquid fuel cell that uses both H₂O₂ as a fuel and H₂O₂ as an oxidant.Since H₂O₂ is nontoxic,recyclable,easy to store and transport（liquid）,highly electrochemically active,independent of the characteristics of fossil fuels,direct hydrogen peroxide fuel cell becomes an international research hotspot in the field of fuel cells.n this thesis,a series of noble metal cathodes and base metal anodes with three-dimensional open structure were designed and synthesized for the direct hydrogen peroxide fuel cell.The catalytic activities of H₂O₂ in electro-reduction（cathodic reaction）and electro-oxidation in alkali anode reaction)activity and stability,assembly and examination of the performance of DPFCs.The main research contents are as follows:Firstly,the C@TiC nanowire arrays were successfully grown on Ti₆Al₄V alloy by chemical vapor deposition.Then Pd and Ni were directly deposited on the C@TiC nanowire array substrate by electrochemical coprecipitation to prepare Pd-Ni/C@TiC electrode.Finally,the NP-Pd/C@TiC nanowire electrode with porous structure was obtained by chemical de-alloying to remove Ni element.FESEM test results show that the surface of titanium alloy is completely covered by C@TiC nanowires（length 7μm and diameter 150 nm）of the array structure.After Pd-Ni co-deposition on the surface of nanocrystalline nanostructures,when the metal Ni is removed by etching,a uniform and porous noble metal Pd catalyst is formed on the nanowires.The catalytic performance of NP-Pd/C@TiC electrodes under different concentrations of H₂SO₄ and H₂O₂ was studied by linear sweep voltammetry and chronoamperometry.The results show that NP-Pd/C@TiC electrode exhibits the best electrochemical catalytic performance（0.2 V vs.Ag/AgCl potential）when the concentration of hydrogen peroxide is 2.0 mol L^-1 and the concentration of sulfuric acid is 2.0 mol L^-1 Under the reduction of current density reached 3.47 A mg^-1).The NP-Pd/C@TiC nanowire array electrode with porous structure was obtained by electrochemical deposition of noble metal（Pd）-base metal（Ni）method and then by chemical dealkylation to remove base metal（Ni）With a large electrochemical activity of specific surface area,reducing the amount of precious metals,very suitable for direct hydrogen peroxide fuel cell cathode catalyst.The cell performance of DPFCs with porous Ni/Ni foam as the anode and NP-Pd/C@TiC nanowire electrodes as the cathode was assembled and investigated.At room temperature,when the flow rate was 10 cm³min^-1,the anolyte was 4.0 mol dm^-3KOH+1.0 mol dm^-3H₂O₂ and the catholyte was 2.0 mol dm^-3 H₂SO₄+2.0 mol dm^-3 H₂O₂,The maximum output power of the battery is 44.2 mW cm^-2.Pd-Au/TiC NAs catalytic electrodes were deposited directly on TiC nanowire arrays using square-wave potential electrodeposition without any conductive agent and binder.SEM analysis showed that the obtained Pd-Au/TiC NAs catalytic electrodes had different microstructures（pineapple root,haze and feather）.The morphology of the Pd-Au cathode catalyst can be easily adjusted and controlled by changing the electrochemical deposition conditions.In H₂O₂+H₂SO₄ electrolyte system,the relationship between the relative content of Pd-Au and the electrochemical performance of the catalytic reduction of hydrogen peroxide was studied by linear sweep voltammetry.As the Pd content increased,the catalytic electrode The catalytic activity of Pd₅Au₁/TiC NAs electrode has the best catalytic hydrogen peroxide reduction activity.Then,the catalytic performance and stability of Pd₅Au₁/TiC NAs electrode under different concentrations of H₂SO₄ and H₂O₂ were systematically investigated by linear sweep voltammetry and chronoamperometry.The results showed that the current density of Pd₅Au₁/TiC NAs electrode was 0.480 A cm^-2when the electrode potential was 0.2V in 2.0 mol dm^-3 H₂O₂ and 2.0 mol dm^-3 H₂SO₄ electrolyte.mg^-1,divided by the total loading of noble metal catalyst).The cell performance of DPFCs with porous Ni/Ni foam as anode and Pd₅Au₁/TiC NAs electrode as cathode was assembled and investigated.At room temperature,when the flow rate was 10 cm³ min^-1,the anolyte was 4.0 mol dm^-3 KOH+1.0mol dm^-3 H₂O₂ and the catholyte was 2.0 mol dm^-3 H₂SO₄+2.0 mol dm^-3 H₂O₂,The maximum output power of the battery is 56.5 mW cm^-2.Ni/TiC NAs and Co@TiC NAs nanowire array electrodes with large specific surface area were prepared by depositing transition metal Ni and Co directly on TiC nanowire array substrate by electrochemical deposition.SEM analysis shows that the diameter of a single Ni@TiC NAs nanowire is 470 nm and shows a spine structure,while the Co catalyst exhibits an ultrathin nanosheet structure with a single Co@TiC NAs diameter of 405 nm.Cyclic voltammetry and chronoamperometry were used to study the catalytic activity and stability of the prickly Ni@TiC NAs and Co@TiC NAs electrodes in KOH+H₂O₂ electrolyte solution respectively.Studies have shown that the prickly Ni@TiC NAs electrode catalyzed hydrogen peroxide electrooxidation has better catalytic activity and stability than the sheet-like Co@TiC NAs electrode.The cell performance with Ni@TiC NAs as the anode and Au-Pd/CFC as the cathode DPFCs was assembled and investigated.The open circuit voltage of the battery was 0.90 V at room temperature.When the flow rate was 10 cm³ min^-1,the anolyte was 4.0 mol dm^-3KOH+1.0 mol dm^-3H₂O₂ and the catholyte was 2.0 mol dm^-3H₂SO₄+2.0 mol dm^-3 H₂O₂,the maximum output power of the battery reached 30.2 mW cm^-2,and its battery performance was significantly higher than that of the reported battery performance of the noble metal Au-Pd/CFC anode,indicating that the use of the base metal Ni@TiC NAs The anode not only reduces the cost of the fuel cell but also improves the performance of the DPFCs.更多还原