活性颗粒增强二氧化铅节能阳极组元相互作用机制与电化学特性

The high energy consumption during the course of zinc electrowinning is mainly caused by high overpotenial of oxygen evolution for lead-silver alloy with strong ploarization, the preparation of new active energy-saving anode has become a very active research field at home and abroad by means of the synergistic effects of active particles and active oxides. Our research find that the diffusion doping of the active particles such as tungsten carbide and cobaltosic oxide in lead dioxide can obviously improve the electrocatalytic activity and decrease the overpotential of oxygen evolution, its energy-saving effect is very significant. In this project, firstly, the rate-determining step of electrode process, reaction rate constant and reaction diffusion coefficient of composite electrodepositing lead dioxide reinforced by active particles will be researched, and the regulation mechanism of preparation process will be obtained. Secondly,the matching relationships between the deposition limit of active particles and the formation amounts of lead oxides, and the dynamic behavior of anodic reaction in zinc electrowinning will be discussed, the structure-activity relationships of material component interaction mechanism and electrochemical characteristics, and the strengthening mechanism of active particles will be ascertained. Finally, the dispersion state and existing configuration of active particles in lead dioxides, initial deposition and growth behavior, the element diffusion and concentration mutation in the interface region will be observed, the interface bonding state and bonding type will be determined, and the criterion of uniform and stable anodes will be obtained. Through above research, the continuous and stable preparation technology of the new active energy-saving anode can be obtained, and the achievements will provide theoretical basis and technology support for clearing extraction with high-efficiency and low-energy consumption during the course of nonferrous metal electrowinning.

铅银合金因强极化导致析氧过电位高是引起锌电积能耗高的主要问题之一，利用活性颗粒与活性氧化物协同效应制备新型活性节能阳极已成为国内外一个非常活跃的研究领域。申请者研究发现：碳化钨、四氧化三钴在二氧化铅中弥散掺杂能明显提高析氧电催化活性，降低析氧过电位，节能效果显著。本项目将：采用流体动力学伏安法，研究复合电沉积制备活性颗粒增强二氧化铅阳极过程速控步骤，反应速率常数与反应扩散系数等，获得制备过程调控规律；考察活性颗粒沉积限度与二氧化铅生成量匹配关系、阳极反应动力学行为等，揭示材料组元相互作用与电催化活性的构效关系及活性颗粒强化机制；研究活性颗粒在活性氧化物中分散状态与存在组态、初期沉积与生长行为，界面元素扩散与浓度突变等，确定界面结合状态与结合方式，获得均匀稳定性判别依据。最终形成新型活性节能阳极的连续稳定制备技术，为我国有色金属电积过程“高效率-低能耗”的清洁提取提供理论依据和技术支撑。

针对锌电积用铅银合金阳极存在的析氧过电位高、易弯曲变形等瓶颈问题，采用复合电沉积技术，在铅基合金基体上稳定制备了碳化钨、四氧化三钴增强二氧化铅活性节能阳极，充分利用活性颗粒与活性氧化物的协同作用，实现了新型活性节能阳极在锌电积溶液中析氧电催化活性的提高，达到了提高锌电积过程电流效率、降低槽电压和电积能耗等目的。.分析了二氧化铅稳定生成条件和物质析出规律，明确了复合电沉积制备二氧化铅电极过程速控步骤，捕捉到了电化学反应中间产物，确定了反应速率常数与反应扩散系数，揭示了阳极反应动力学行为。明确了活性颗粒在二氧化铅中掺杂后的分散状态与存在组态关系，活性颗粒在活性氧化物中的包裹形式以及界面结合状态与结合方式，获得了材料均匀稳定性判别依据。探明了二氧化铅活性节能阳极的制备技术基础及调控规律、组元相互作用与电催化活性构效关系，构建了颗粒增强二氧化铅活性节能阳极电化学制备的物理形核模型，揭示了阳极复合电沉积机理。明确了二氧化铅活性节能阳极电沉积初期和后期的析氧动力学参数、电极反应可逆性、腐蚀电位与腐蚀电流等电化学参数变化规律，探明了恒电流极化时活性节能阳极的析氧电位与极化时间关系以及槽电压、电流效率、电能消耗随电积时间变化规律，获得了新型活性节能阳极的强化腐蚀寿命和一般工业电流密度下的使用寿命，揭示了腐蚀失效本质原因。相比于Pb-1wt%Ag合金阳极，新型二氧化铅活性节能阳极在锌电积模拟溶液中的槽电压降低350mV，电流效率提高2.1%，直流电耗降低327.28kWh/(t·Zn)。以上研究成果的取得，可以为我国有色金属电积过程“高效率-低能耗”的清洁提取提供理论依据和技术支撑。.在项目执行期内，发表学术论文22篇。其中，SCI检索17篇（中科院JCR1区论文5篇；中科院JCR2区论文5篇）。申请发明专利2件。培养毕业博士研究生1人，毕业硕士研究生5人。举办国际学术会议1次、国内学术会议1次，参加国际学术会议1次。