为了满足日益增长的能源需求和解决环境污染问题，开发高效的电化学能源转换和存储技术势在必行，其中低成本、高效、稳定的电催化剂的设计与合成至关重要。在众多的非金属基催化剂中，过渡金属基自支撑电催化剂因在成本、活性面积、导电性、稳定性以及使用便捷性等方面具有明显优势，近年来备受研究和应用关注。尽管如此，其活性和稳定性还需进一步提升以达到工业化应用的要求。为此各种改性或复合工艺，如掺杂工程、缺陷工程、界面工程等策略被开发利用。其中，离子掺杂工程是指利用物理或化学手段将特定离子（以阴离子为主）引入催化剂基体中，从而能调控其活性位点的电子结构、产生附加缺陷、改变晶体结构，进而显著提升其催化活性，因而被广泛采用。然而需要指出的是，常规离子（特别是阴离子）掺杂工艺往往涉及高温、高压环境以及繁琐的操作步骤，不仅需要专业设备、冗长的操作时间，还常常会造成催化剂原有结构的破坏；因此急需开发更温和、更快速的离子掺杂新工艺。本学位论文旨在解决离子掺杂中存在的上述难题，开发一种简单、快速、温和的电化学阴离子掺杂新工艺。为此，本论文通过系统考察掺杂前驱体、掺杂电位、掺杂时间等条件的影响，建立了Se^2-和S^2-电化学掺杂新工艺，实现了对不同形貌的阵列电极自支撑电催化剂（以镍铁层状双氢氧化物（NiFe LDHs）纳米片阵列和CoP纳米针阵列为例）的可控掺杂；初步探究了掺杂机理和掺杂催化剂的碱性析氧反应（OER）或析氢反应（HER）活性；开展的研究内容和取得的成果如下：

1. 电化学掺杂Se^2-工艺的建立及其在催化剂掺杂中的应用：采用水热法在泡沫Ni基底上生长出NiFe LDH阵列，然后将其浸入含有SeO₂的酸性水溶液中，利用恒电位阴极极化法将Se掺杂进NiFe LDH基体中；通过改变电掺杂时间（300~1800 s）实现了Se掺杂含量在0.92-8.09%范围内的调控并完好保留了纳米片阵列形貌。发现Se_4.71-NiFe LDH/NF催化剂的碱性OER性能最佳，在10和100 mA cm^-2时的过电位分别为243 mV和296 mV，Tafel斜率为36.3 mV dec^-1，优于其它含量的Se-NiFe LDH/NF并且远超NiFe LDH/NF性能。根据原位Raman检测结果结合XPS分析及浸泡对比实验，推测Se的电化学掺杂机理可能为：在电掺杂时，溶液中的SeO₃^2-会被吸附在NiFe LDH表面并被阴极还原成Se_x^2-或Se^2-，随后通过置换的方式进入基体并与Ni和Fe成键。进一步利用该工艺，我们还实现了CoP/CFP阵列的电化学Se掺杂，其Se掺杂含量在3.15-17.95%范围内的调控，并发现Se_7.97-CoP/CFP催化碱性HER时仅需77 mV过电位时就能达到10 mA cm^-2电流密度，相比于前驱体CoP/CFP（η₁₀=107 mV）性能大幅提升。上述结果证实了电化学掺杂Se^2-工艺的普适性和对催化活性提升的有效性。

2. 电化学掺杂S^2-工艺的建立及其在催化剂掺杂中的应用：仍选择NiFe LDH/NF为研究对象，将其浸入含有Na₂S₂O₃的酸性水溶液中，利用恒电位阴极极化法将S掺杂进NiFe LDH基体中；通过改变电掺杂反应时间实现了S掺杂含量在0.47-9.98%范围内的调控。当将S_x-NiFe LDH/NF（x=0.47，2.61，5.29和9.98）作为催化剂应用于碱性OER时，发现S_5.29-NiFe LDH/NF仅需256 mV过电位达到10 mA cm^-2电流密度，仅需294 mV达到100 mA cm^-2电流密度过电位，催化活性明显优于原始NiFe LDH/NF的性能。XPS结合价带谱研究揭示了阴离子掺杂能改变活性位点中心周围的电子密度，改善d电子结构，优化了催化剂对反应中间产物的吸脱附能力，从而提高其电催化性能。

3. 电化学共掺杂Se^2-和S^2-工艺的建立及其在催化剂复合掺杂中的应用：为了验证电化学掺杂的有效性及可拓展性，对NiFe LDH/NF催化剂实施了连续的电化学Se^2-和S^2-掺杂，成功制备出Se, S共掺杂的NiFe LDH/NF催化剂。通过改变电掺杂反应时间，实现了Se、S掺杂含量的调控，获得Se:S比分别有1:2、1:1、2:1的共掺杂样品，从而证实了Se^2-和S^2-掺杂具有较好的兼容性。当将所获得的催化剂样品Se_x, S_y-NiFe LDH/NF（x=3.03，6.44和7.17；y=6.31, 7.34和3.87）用于碱性OER时，发现Se_6.44, S_7.34-NiFe LDH/NF在10和100 mA cm^-2时的过电位分别仅需要230和260 mV，Tafel斜率仅为25.0 mV dec^-1；均明显优于Se^2-或S^2-单独掺杂的样品。本工作为阴离子掺杂以及调控催化剂催化活性提供了新的手段和思路。

In order to meet the increasing energy demands and solve the environmental pollution problems, it is imperative to develop efficient electrochemical energy conversion and storage technology, in which the design and synthesis of low-cost, efficient and stable electrocatalysts are crucial. Among many non-nobel metal catalysts, transition metal-based self-supported electrocatalysts have attracted much attention in recent years because of their obvious advantages in cost, active area, conductivity, stability and ease of use. However, their activity and stability need to be further improved to meet the requirements for industrial applications. For this reason, various modification or hybrid processes, such as doping engineering, defect engineering, interface engineering and other strategies have been developed and used. Among them, ion doping engineering refers to the utilization of physical or chemical means to introduce specific ions into the matrices of catalyst, so as to regulate the electronic structure of its active site, produce additional defects, change the crystal structures, and then significantly improve their catalytic activities. However, it should be pointed out that conventional ion doping processes often involves high temperature, high pressure environment and tedious operation steps, not only requiring professional equipments and tedious operation, but also often causing the damage to the pristine order structures of the catalysts. Therefore, there is an urgent need to develop mild and fast ion doping new processes. This thesis aims to solve the above problems in ion doping and develop a simple, rapid and mild electrochemical anion doping process. To this end, by systematically investigating the influence of doping precursors, doping potential, doping time and other conditions, this paper has established a new electrochemical doping process of Se^2- and S^2-, and realized the controlled doping of self-supported electrocatalysts with different morphologies (NiFe LDHs nanosheet array and CoP nanowerd array as examples). The doping mechanism and the oxygen evolution reaction (OER) or hydrogen evolution reaction (HER) performance in alkaline media of the doped catalysts were also preliminarily investigated. The main research results are listed as follows:

Electrochemical doping of Se^2- and its application in catalyst doping: To establish an electrochemical doping process of Se^2-, NiFe LDH nanoarrays was grown on the substrate of Ni foams were selected and immersed in acidic aqueous solution containing SeO₂, and Se was doped into NiFe LDH matrices via constant potential cathodic polarization method. By varying the electrochemical doping time (300~1800 s), the Se doping content could be tuned in the range of 0.92-8.09% and meanwhile the morphology of the nanosheet arrays was preserved almost intact. It was found that the alkaline OER performance of Se_4.71-NiFe LDH/NF catalyst was the best among all the Se-doped samples. Its overpotential at 10 mA cm^-2 and 100 mA cm^-2 was 243 mV and 296 mV, respectively, and its Tafel slope was 36.3 mV dec^-1, superior to all the other samples. Based on in-situ Raman detection results combined with XPS analysis and immersion contrast experiment, it is speculated that the electrochemical doping mechanism of Se may be as follows: during the electrodoping process, SeO₃^2- anions in solution were first adsorbed onto the surface of NiFe LDH and then were electrochemically reduced to Se_x^2- or Se^2-, followed by entering their matrices via anion substitution. Furthermore, using this process, electrochemical doping of Se into CoP/CFP nanoarrays were also achieved, with a Se doping content ranging from 3.15% to 17.95%. Notably, the as-formed Se_7.97-CoP/CFP catalyst required an overpotential only 77 mV overpotential to reach 10 mA cm^-2 for alkaline HER, much superior to the prinstine CoP/CFP nanoarrays(η₁₀=107 mV). These results confirm the universality of the electrochemical doping process of Se^2- and its effectiveness in enhancing the catalytic activities of self-supported nanoarrays.

Electrochemical doping of S^2- and its application in catalyst doping: Similar with that of Se doping, NiFe LDH/NF nanoarrays were selected and immersed in acidic aqueous solution containing Na₂S₂O₃, and S was doped into NiFe LDH matrices via constant potential cathodic polarization. The doping content of S could be tuned in the range of 0.47-9.98% by changing the reaction time of electrodoping time. Upon serving as the catalysts for alkaline OER, S_5.29-NiFe LDH/NF was found to only need overpotentials of 256 mV and 294 mV to reach 10 mA cm^-2 and 100 mA cm^-2 current density respectively for alkaline OER, much better than the pristine NiFe LDH/NF. In addition, XPS valence band spectrum study futher revealed that S^2- doping can change the electron density around the active sites, improve the d electron distribution, optimize the adsorption and desorption ability of the doped catalyst to the reaction intermediates, thus improving its electrocatalytic performance.

Electrochemical co-doping of Se^2- and S^2- and its application in catalyst composite doping: To verify the effectiveness and scalability of above-establised doping processes, electrochemical doping of Se^2- and S^2- were performed on NiFe LDH/NF nanoarrays in sequence, successfully preparing Se, S co-doped NiFe LDH/NF catalyst. The samples with Se:S ratio of 1:2, 1:1 and 2:1 were obtained by changing the electrodoping time, confirming the good compatibility of Se^2- and S^2- doping. When used as the catalysts for alkaline OER, Se_6.44, S_7.34-NiFe LDH/NF was found to demonstrate the best catalytic performance: requiring overpotential of 230 and 260 mV to reach 10 and 100 mA cm^-2 current density respectively, much better than the samples doped with Se^2- or S^2- alone. This work provides a new method and idea for anion doping and regulating the catalytic activity of catalysts.