学　术

　　为搭建我校博士后之间的学术交流平台，促进学术水平提升，学校博士后管理办公室组织开展博士后学术沙龙活动。本次沙龙由我校博士后赵小丽、刘勇、郝理、石晛、王晓艳分享其研究成果，诚挚邀请感兴趣的师生参加。

　　一、时　间：2021年11月9日（周二）14：00

　　二、方　式：腾讯会议　会议ID：100275241

　　（请扫描以下二维码进入在线会议）

　　三、主办单位：电子科技大学博士后管理办公室

　　四、承办单位：基础与前沿研究院

　　五、活动安排：

　　报告一：

　　（1）主题：Designing Indium-Based Catalysts for Efficient Carbon Dioxide Electroreduction to Formate

　　（2）主讲人：赵小丽 基础与前沿研究院博士后 

　　（3）交流内容：

　　Electrocatalytic reduction of CO₂ into value-added chemicals and fuels is of intensive urgence and importance to relieve the growing CO₂ emission and achieve the carbon neutrality. At present, the commercialization of CO₂ electroreduction (CO₂ER) is mainly obstructed by the high cost, low selectivity, high overpotential and poor stability of the catalysts. Among the numerous catalyst materials that were studied, indium was found to be selective towards the production of formate. In this talk, we comprehensively reviewed recent progresses on the indium based CO₂ER catalysts. Specifically, aspects regarding the design of different In-based catalysts and reaction mechanism were overviewed. In addition, the construction of In2O3/InN heterostructure and its application for highly efficient CO₂ reduction to formate was discussed in detail. At last, challenges and future perspectives were proposed.

　　Firstly, various In-based metal oxides/sulfides/nitrides with well-designed nanostructures applied for the electrocatalytic formate production were reviewed. Their activity, selectivity and stability were regulated via the doping, defect and electronic structure construction. In situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy and density functional theory calculations were combined to investigate the reaction path and mechanisms.

　　Then, an In2O3/InN heterojunction was constructed and utilized in electrocatalytic CO₂ reduction reaction to formate with high Faradaic efficiency (95.7% at -1.48 V vs. RHE) and outstanding stability. The in-depth experimental analyses together with theoretical studies reveal that the O-N interaction at the interface between In2O3 and InN could provide a charge transfer channel and lead to electron enrichment on the surface of InN, promoting the activation of CO₂ molecules, lowering the Gibbs free energy for the formation of *HCOO intermediate and strengthening the binding with *HCOO during CO2ER.

　　Finally, some prospective viewpoints for future development on CO₂ electroreduction to formate would put forward. (1) the development of better electrocatalyst materials remains at the heart of CO₂ER research. The goal is to increase their active site density and/or promote their site-specific activity. (2) we would have to further our understanding of possible reaction pathways and mechanisms on electrocatalysts with the assistance of theoretical computations and in situ spectroscopic characterizations. (3) The optimization of CO₂ER performance at the cell or system level is urgent for the commercialization. (4) The effective means for the product separation would be under the consideration.

　　主讲人简介：

　　Xiaoli Zhao received her Ph.D. degree in Materials Science and Engineering from Chongqing University in 2019. Currently, she is a postdoc research fellow in the Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China. Her research interest is focusing on the fabrication of bulk heterojunctions for the photovoltaic and catalytic applications.  

　　报告二：

　　（1）主　题：电催化硝酸根还原性能调控及作用机制

　　（2）主讲人：刘勇　基础与前沿研究院博士后 

　　（3）交流内容：

　　报告主要讨论电催化方法应用于硝酸根还原的研究背景、现状以及硝酸根还原活性和选择性的调控方法及其机制。报告内容包括三部分：（1）电催化硝酸根还原的研究背景及现状；（2）硝酸根还原活性和选择性的调控方法；（3）结合我们的前期研究成果，探讨硝酸根还原选择性的调控机制。

　　电催化硝酸根还原的研究背景及现状介绍。硝酸根对水的污染已经导致全球生态系统的失衡并对人类健康构成威胁。电催化法使用电子作为绿色还原剂，具有环境友好、投资成本低、应用灵活等优点。近30多年，电催化硝酸根还原技术已得到广泛的研究，用于处理核废水、地下水、工业废水中的硝酸根，将其选择性还原成无毒的氮气。此外，由于氨更具有经济价值，电催化硝酸根到氨的转化近年来引起了国内外研究人员的关注。氨可用作工业原料及潜在的能源载体，且容易从溶液中分离出来，使得硝酸根还原合成氨成为另一具有前景的方向。

　　硝酸根还原活性和选择性的调控方法。主要介绍催化剂对硝酸根还原活性和选择性的影响和调控方法。从催化剂种类、晶面、缺陷、电子结构、反应路径等方面探讨硝酸根还原活性和选择性的调控及其机制。通过材料几何及电子结构的表征，结合原位表征手段如原位红外、拉曼、电化学质谱、同步辐射等研究硝酸根还原过程中反应中间体和催化剂活性位点的动态变化，结合密度泛函理论等计算方法，揭示硝酸根还原的反应路径和机理，为催化剂的合理设计提供指导。

　　双金属合金催化剂对硝酸根还原选择性的调控及其作用机制。通过热解金属有机框架制备了一系列氮掺杂碳负载的铜镍合金催化剂。该催化剂对硝酸盐还原成氨具有优良的选择性（94.4%）和法拉第效率（79.6%），大大优于单金属铜的性能（选择性60.8%，法拉第效率60.6%）。令人印象深刻的是，镍的引入明显抑制了亚硝酸盐毒副产物的产生。采用在线微分电化学质谱和原位表面增强红外吸收光谱解析了关键反应中间体和反应途径。密度泛函理论计算表明，铜镍合金催化剂中的镍位可促进NO₂氢化为HNO₂并抑制析氢反应，促进氨的选择性生成。这项工作为双金属催化剂的合成提供了一条新的途径，也为硝酸盐还原合成氨反应的机理研究提供了新的思路。

　　主讲人简介：

　　刘勇2008年本科毕业于天津科技大学，2014年博士毕业于中国科学院大学。2014-2019年在攀钢集团研究院工作，2020年1起进入基础与前沿研究院博士后流动站，合作导师董帆教授。主要研究兴趣为电催化在环境和能源领域的应用及机理研究。

　　报告三：

　　（1）主　题：基于多重单分子技术研究nsp13解旋酶调控新冠病毒转录复制过程的分子机制

　　（2）主讲人：郝理 　基础与前沿研究院博士后 

　　（3）交流内容：

　　导致新冠肺炎疫情在全球范围内大流行的罪魁祸首是一种β冠状病毒SARS-CoV-2，解析该病毒生命周期中转录复制过程的分子机制将极大推动相关药物和疫苗的研发。尽管目前已解析了该过程中由多个非结构蛋白（nsp）亚基nsp7/nsp82/nsp12组成Holo-RdRp（RNA依赖性RNA聚合酶全酶）相关高分辨结构，明确了靶向nsp12的核酸类似物瑞德西韦（RDV）等对SARS-CoV-2转录复制的抑制作用，但是RDV在体内疗效的不确定性或许与nsp13解旋酶促进Holo-RdRp回溯（backtrack）有关，从而让病毒相关蛋白发挥校对功能，切除掺入新生RNA链中的RDV，以防止链增长被终止。单分子生物技术作为近年来发展较快的前沿生物物理技术，可以实时检测多个单分子间的动态互作过程，揭示常规手段难以捕获的反应中间态，具有较高的时空分辨率，为研究转录复制及有关过程中的关键问题提供了强有力的工具。

　　在报告中，本课题组拟采用多重单分子技术，探索nsp13解旋酶调控SARS-CoV-2转录复制的动态作用机制。基于磁镊技术设计单分子移位实验，将生物素标记的Holo-RdRp与链霉素包被的磁珠连接，通过记录磁珠的位置信息，实时追踪nsp13解旋酶与Holo-RdRp互作的动态过程，明确nsp13在RNA链上的移位方向、速率、ATP依赖性、浓度依赖性等；同时引入RDV药物，检测其抑制转录复制过程中的动力学特征以及nsp13是否驱动Holo-RdRp回溯，明确nsp13解旋酶在RDV抗病毒中发挥的作用机制；利用光稳定性强的JF549荧光探针标记Holo-RdRp和nsp13，通过自主开发的单分子串联技术，结合磁镊和单分子荧光两者的优势，根据RNA链的延伸变化和荧光探针标记生物分子的荧光信号强弱变化，明确nsp13是以二聚体或者寡聚体的形式在RNA链上移位以及相应RNA的折叠状态，捕获短时甚至瞬时存在的关键中间态复合物，解析nsp13与Holo-RdRp互作所形成移位复合物的构成组分，可视化关键中间态的组装、移位以及解离动态过程，进而在体外重构出nsp13解旋酶完整的调控反应过程，最终从单分子水平上全面揭示nsp13解旋酶调控SARS-CoV-2转录复制过程的分子机制，为研发靶向Holo-RdRp、nsp13的抗病毒药物提供理论依据。

　　主讲人简介：

　　郝理，2020年7月毕业于中国农业大学园艺学院果树学专业，获农学博士学位。现为电子科技大学基础与前沿研究院博士后，主要研究领域为生物化学与生物物理学，研究方向包括DNA损伤修复、转录调控机制、单分子成像以及应用等，在分子生物学相关方向已发表SCI论文1篇和申请国家发明专利4项，已授权国家发明专利3项。

　　报告四：

　　（1）主　题：Light-induced Halogen Defects as Dynamic Active Sites in Bismuth Oxyhalide for CO₂ Photoreduction

　　（2）主讲人：石晛 　基础与前沿研究院博士后

　　（3）交流内容：

　　Defects, which exist universally in photoactive materials, can modulate the electronic structure of photoactive materials and thus directly influence carrier transport behaviour, surface adsorption/desorption, band structure, and reaction pathway. Therefore, defect engineering has become an important research area for the structural optimisation of photoactive materials. However, recent progress in defect engineering suggests that not all defect structures can improve properties of functional materials. In solar cells, a diminishing defect density plays a decisive role in maximising the photovoltaic performance of perovskites. Thus, passivation techniques are used to suppress the harmful effects of defects. However, in photocatalysis, constructing defects on the photocatalyst surface is regarded as an efficient strategy for enhancing photocatalytic properties. The essential reason for this difference lies in the entirely different functional mechanisms of defects in different reaction systems. Herein, the dynamic defects formed on halide perovskites and bismuth oxyhalides due to light-induced halide ion migration are compared as typical examples. 

　　Under illumination, halogen atoms are oxidised by photogenerated holes on halide perovskites. This reduces their ionic radius and allows them to leave the crystal lattice easily and form defects. Moreover, recent studies revealed that light irradiation can reduce the energy barrier of ion migration and facilitate an ultrafast defect-mediated ion migration, leading to increased formation of defects. This results in more severe carrier trapping, which hinders better photoelectric conversion performance since photogenerated charge carriers are supposed to be transported through the halide perovskite to the electrodes or adjacent transport materials. However, the ineluctable existence of X defects induces extra transition levels in the bandgap, thus influencing the optoelectronic process. Interfacial charge carrier transport is also hindered by the scattering or capture of free charges by X defects. Moreover, excessive carrier trapping can lead to the degradation and collapse of the perovskite lattice. Therefore, dynamic X defects caused by light-induced halide ion migration have a devastating effect on halide perovskites used in solar energy conversion.

　　During photocatalysis, defects can also induce a charge trapping effect. However, unlike in the case of a halide perovskite in a solar cell, this charge trapping effect hinders the recombination of photogenerated electron–hole pairs when a photocatalyst is excited by light. As active sites, defects with abundant localised electrons can facilitate electron transport to adsorbed molecules, thus promoting the activation of adsorbed reactants and photocatalytic reaction. The stability of defects was found to change with the reaction conditions, such as gas pressure, atmosphere, and external field, which can induce the dynamic evolution of defects and structural modification of materials. However, the investigation of the positive effects of dynamic defects as active sites in a catalyst is still in its infancy. The formation mechanism and basic nature of dynamic defects, as well as their effects on the catalytic reaction pathway, have not been revealed. Considering the feasibility of dynamic defect formation via light-induced halide ion migration in halide perovskite solar cells, we carried out a systematic study of dynamic halogen defects on bismuth oxyhalide photocatalysts for their application in CO₂ photoreduction.

　　主讲人简介：

　　X. Shi received the Bachelor degree and Ph.D. degree of Oil-Gas Well Engineering from the Southwest Petroleum University, in 2015 and 2020, respectively. He currently works as a Postdoctoral Fellow in the Institute of Fundamental and Frontier Sciences of UESTC. Dr. Shi is working in the field of new energy and devices. His main research interests include the application of bismuth oxyhalide based photocatalysts in energy conversion and environmental treatment.

　　报告五：

　　（1）主　题：新型碳载过渡金属磷化物催化剂的制备与其析氢电催化行为的研究

　　（2）主讲人：王晓艳 　基础与前沿研究院博士后 

　　（3）交流内容：

　　目前人类社会能源供应严重依赖不可再生化石能源，造成环境和能源危机，因此亟待发展新型可持续再生清洁能源。氢气具有高能量密度和清洁无污染等优点，被认为是未来重要的能源载体之一，近年来已引起了大量的关注与研究。

　　利用太阳能、水力发电和风能等间歇性可再生能源，通过电化学或光电化学分解水制备氢气，是非常重要、极具前景的一种未来能源解决方案。析氢反应（hydrogen evolution reaction，HER）在此过程中扮演了关键角色。铂族金属是目前最有效、使用最广泛的析氢催化剂，但是相当昂贵和稀缺。因此，开发储量丰富、低成本和具有高活性的催化剂对于电化学水分解大规模产氢是非常关键。在所有报道的非铂基析氢催化剂中，过渡金属磷化物（transition metal phosphides，TMPs）如CoP、Ni2P和FeP等极具吸引力，在电解水制氢方面展示出巨大的潜力。但是，其催化活性和稳定性仍需进一步增强。

　　本报告以CoP作为过渡金属磷化物的典型代表，通过负载、自组装和构筑分层次结构的设计等方法与手段制备新型碳载过渡金属磷化物析氢催化剂，并对其合成机制、催化机理及性能等进行了深入的探究，以提高过渡金属磷化物的析氢催化性能。

　　主讲人简介：

　　王晓艳于2020年6月获西南大学博士学位。现为电子科技大学基础与前沿交叉研究院博士后。王博士在电催化领域工作，主要研究方向为电催化析氢和硝酸根还原。