低碳有机小分子中氢能高效转化为电能的催化基础研究

The key solution to achieving efficient conversion of hydrogen energy stored in small organic molecules (SOMs) to electricity is based on insightful understanding of relevant catalytic mechanisms for electrooxidation and chemical dehydrogenation of SOMs and ensuing rational design and synthesis of highly active and durable catalysts. In recognition of the mismatch of the mechanisms for bulk metal and practical nanocatalyst surfaces, and the drawback for traditional trial-and-error synthesis of catalysts, we propose to conduct an interactive study of (electro)catalytic mechanisms and materials for SOMs, taking the Pt and Pd-based nanofilms and nanocatalysts as the research platforms. In situ molecular vibrational spectroscopies (IR, Raman) and X-ray absorption spectroscopy (XANES, EXAFS), on-line spectrometric methods will be applied, in conjunction with DFT calculations on reaction pathways and catalytic materials, to identify the key reactive intermediates and poisoning species, to make a meaningful correlation among the surface structure, performance and interfacial chemistry, and eventually to harvest a new perception about the structure-property relationship for practical catalysts. Taking the advantages of mechanistic study and structure-property relationship, the common principles for design and synthesis of catalysts will be extended to realize the delicate tuning of electronic structures and chemical surroundings of newly prepared catalysts. The structure-property relationship can then be updated and improved through the interactive feedback of catalytic performances of the new catalysts. Eventually, precise structural information regarding high-performance catalysts may be obtained, together with their preparation methods. The proposed project is of great significance for safe and efficient utilization of hydrogen energy.

C1、C2有机小分子中氢能高效转化为电能的关键在于对其（电）催化本质的深刻理解并据此理性设计出高效率、高稳定性催化剂。为克服传统电催化机理研究与实际催化体系的脱节以及试错法制备催化剂的低效率问题，本项目将以纳米薄膜型和高分散型铂、钯基纳米催化剂为研究对象，开展相关反应机理和催化材料的互动式研究。运用原位分子振动和X-射线吸收光谱方法、在线谱学检测，结合密度泛函理论对反应历程和催化材料的优化计算，确认关键中间体，关联（电）催化剂表面结构、性能与界面化学动态变化，获得对纳米催化剂构效关系的新见解。在反应机理和构效关系指导下，结合催化剂设计和合成方法学的一般性原则，通过选择组分掺杂、电子结构、形貌、载体作用等手段，实现对新制备催化剂的精细电子结构与化学环境的调控，反馈并完善构效关系，最终获得高性能催化剂的精准结构信息与制备方法。本项目对推动氢能的高效与安全利用具有重要意义。

有机小分子（SOM）是氢能安全存储与利用的中间载体。项目组着眼于“甲酸-二氧化碳”产氢与储氢、直接SOM燃料电池这两个氢能转换体系，从分析催化反应机理、实现催化剂理性合成、验证催化剂构效关系三个层面开展了互动式研究工作。具体上，针对甲酸制氢、甲酸电氧化、甲醇电氧化、C2醇（醛）电氧化、二氧化碳电还原和氧气电还原等反应，发展和应用了多种原位和在线谱学技术，研究了模型催化剂上的反应机理，提炼了有效的催化剂设计原则；以调变元素组成、控制形貌结构、改性载体材料为手段，设计合成了多种实用型催化剂，验证了其构效关系，完善了反应机理和催化剂设计原则。项目组成员分工合作，实现了项目目标。重要创新成果如下： .1、设计宽频和电解液层可控的电化学表面增强红外光谱，能同时或选择性检测电催化过程吸附和液相物种；应用宽频红外光谱首次捕获了吸附态乙醛/乙酰以及吸附态乙酸根的振动谱峰，更新了乙醛（醇）电氧化C2路径；.2、发展了高空间和时间分辨的单分子荧光方法，对单个纳米颗粒上（电）催化过程中的活性位点动态变化以及长时活性变化进行解析。建立局域、动态的结构-活性关系，为阳极MOR高效催化剂的设计提供依据。.3、针对“甲酸-二氧化碳”产氢-储氢体系，提出了甲酸-二氧化碳相互转化的催化剂的设计原则，获得了针对双向循环反应的高活性、高稳定性、高选择性的Pd@Bi/C等催化剂；.4、针对Pt-MOx一类催化剂上的甲醇电氧化反应，提出了源于甲酸根/甲酸反应路径的性能提升机制，而非以往普遍认为的“双功能机理”。