染料敏化太阳能电池对电极材料的催化作用计算研究和理性筛选

Dye-Sensitized solar cell (DSC) is one of the most significant ways in the efficient utilization of solar energy. With respect to the large-scale application of DSC, one of the key problems is to further improve the efficiency of platinum (Pt) counter electrode (i.e. decrease the consumption of Pt element) or to develop some low-cost and highly efficient Pt-free counter electrode materials, which is of intriguing interest in the DSC field currently. However, the catalytic mechanism of triiodide reduction reaction (I3- + 2e- →3I-) occurred on the counter electrode (cathode) surface is not clear, and the rational screening and design of active counter electrode materials have been lack of theoretical guidance, which is still at the try-and-error stage. In this project, we would consider the density functional theory (DFT) calculation as the main tool to investigate the catalytic principles related to the cathode reaction by coupling with the microkinetics, aiming at establishing a theoretical framework for understanding the catalytic activity trend of the counter electrode and further proposing a fast rational screening model. In particular, our investigation would focus on the following points: (i) exploring the effect of different Pt surfaces, atomic packing pattern, coordination configuration, and forming Pt-alloy on the catalytic activity of Pt electrode, aiming at understanding how to utilize the expensive Pt element more efficiently; (ii) pre-screening potentially active materials on the basis of the rational screening model, which can be possibly accomplished through calculating some simple and key thermodynamic parameters of a serial of inorganic semiconductor (MX), and being exposed to quantitative confirmation by virtue of DFT calculation and microkinetic analysis at the second stage; (iii) exploring the effect of non-metal element type (X) and its content on the activity of the metallic active-site metallic ion (M); (iv) testing the non-metal doping strategy in improving the catalytic performance of some specific low-activity but cheap metal oxides. We expect that one or two new low-cost but efficient counter electrode materials can be proposed in this project.

染料敏化太阳能电池（DSC）是高效利用太阳能的重要途径，其中提高铂对电极利用效率（降低铂用量）和开发低成本高效非铂对电极是当前大规模应用DSC的研究热点。但是（阴极）对电极催化碘三离子还原反应（I3- + 2e- →3I-）活性机制和高效对电极材料的筛选与设计目前缺少理论框架和指导。本项目计划以密度泛函理论计算为主要工具，结合微动力学等探究DSC阴极反应催化机制，建立活性描述理论框架和对电极材料理性筛选模型，具体研究i）不同晶面、原子堆积结构和配位、合金化等对铂电极催化活性的调变理论，为高效利用铂元素提供依据；ii）建立理论筛选模型，通过无机金属半导体MX关键热力学参数的高通量计算，筛选具有潜在活性的材料并深入研究；iii）针对MX，探究非金属X种类和含量对金属中心M催化性能的调变规律；iv）非金属掺杂等改善氧化物电极催化性能的可行性。最终希望提出1~2种高效低成本的新型对电极材料。

染料敏化太阳能电池（DSC）是太阳能高效利用的重要途径，其中提高铂对电极利用效率和开发低成本高效非铂对电极是当前大规模应用DSC的关键之一。本项目的主要任务是采用密度泛函理论计算和动力学理论分析相结合方法，探究DSC阴极反应等重要电催化反应机制和材料性能对催化活性的影响规律和原理，发展催化活性描述理论框架、为进一步优化对电极性能提供改进方向。在三年实施过程中，项目在新理论计算方法建立、电催化还原反应活性趋势定量确定、重要催化构效机制认知、以及实现活性调控优化等方面取得了积极成果。重要进展包括：（i）发展了显式溶剂多样本统计平均方法，实现了液固界面反应的准确模拟，揭示了碘三离子还原基元反应的关键BEP关系；（ii）发展了基于可逆度迭代的催化反应动力学求解新方法、以及催化活性基本理论及化学势寻优方法。藉此在半定量和定量两种层面上分别建立了催化性能评估模型，指出I*原子吸附能可作为活性描述符，而最佳催化材料的I*原子吸附能应为0.43 eV；（iii）针对金属化合物MX的活性定向优化调控，探究非金属元素（X）种类及含量等调变活性中心金属离子（M）吸附性能的一般规律；以HER为拓展应用，定向设计了WO2.9高性能非Pt电极材料；（iv）揭示了不同Pt暴露晶面等对活性的影响，探索了Pt-skin/M双金属电极活性变化规律，为Pt元素高效利用提供了理论依据；同时面向非铂高效石墨烯材料的设计，项目揭示了石墨烯催化碘三离子还原反应的本征活性和N、S掺杂调控作用及内在机制等。已发表标注本项目编号的SCI学术论文13篇，包括Nature Commun 1篇、ACS Catal (6篇)等高影响因子论文，以及中文核心期刊《中国科学：化学》1篇等。2014-2016年，项目负责人受邀在重要学术会议作主题报告2次，参与组织国际理论化学方面学术会议两次等。获得了中国催化新秀奖（2014）、中国科协青年人才托举工程（2015）和国家自然科学基金优秀青年基金（2016）等科研支持，并培养了博士生两名。总体较好地完成了项目目标。