仿生设计单原子电解水制氢催化剂

Hydrogen production via electrolyzed water is a promising clean energy conversion technology. The development of electrocatalyst with high activity and stability has become a hot topic in current research. Single-atom catalysts (SACs) have highly exposed active sites. The low coordination number and quantum size effect endow the catalysts unique electronic structures as well as energy level structures, thereby achieving a significant increase in catalytic activity and selectivity. However, fabricating stable SACs with uniform atomic distribution are still challenging. In the previous studies, we found that collagen molecules possess rich and well-defined phosphorylation sites, and could self-assemble into a 3D porous scaffold with multi-level hierarchical structures, which is considered to be an ideal carrier for facilitating atomic dispersion of metals. Inspired by our previous work, the purpose of this study is to synthesize a novel SACs via biomimetic design: the mononuclear transition metal precursors are anchored to phosphorylated collagen scaffold to prevent migration and aggregation of single atoms; and the carbonized collagen scaffold after high temperature pyrolysis could further regulate the electronic structure of the catalyst through electron transfer with metal single-atom, thereby improving catalytic activity and stability. This project will conduct a systematic study on the following two key scientific issues: “regulation mechanism of micro-nano structure and atomic structure in biomimetic design SACs”, and “structure-activity relationship between SACs structure and catalytic performance”. This study is expected to provide new design theories and methods for the fabrication of SACs.

电解水制氢是一种清洁的能源转换技术，开发高活性、高稳定性的电解水制氢催化剂已成为当今研究热点。单原子催化剂具有高暴露的活性位点，低配位数和量子尺寸效应赋予其独特的电子结构和能级结构，实现催化活性的大幅提升。然而目前合成结构稳定、分布均匀的单原子催化剂仍具挑战。在前期研究中，申请人发现胶原分子具有丰富且位置明确的磷酸化位点，并可组装形成具有等级结构的多孔支架，便于实现金属在三维空间的原子级分散。受此启发，本研究拟通过仿生设计合成一种新型单原子电催化剂：利用磷酸化胶原支架锚定单核过渡金属前驱体，防止单原子的迁移聚集；高温热解后碳化的胶原支架通过与金属单原子的电子传递进一步调节催化剂的电子结构，提升催化活性和稳定性。本项目将围绕“仿生设计单原子催化剂微纳结构和原子结构的调控机制”及“单原子催化剂结构与催化性能的构效关系”两个关键科学问题进行系统研究，有望为单原子催化剂制备提供新的设计理论与方法。

单原子催化剂凭借优异的催化活性和极高的原子利用效率已成为高效电解水催化剂的理想结构，然而设计合理的载体以稳定原子级分散的金属仍存在极大挑战。本研究通过仿生设计，实现了过渡金属钴在三维自组装生物基载体的原子级分散，最终形成新型单原子电催化剂（Co SAs/cBSS）。通过X射线吸收及X光电子能谱等进一步明确了单原子钴与载体间的局域配位环境；电化学测试证实Co SAs/cBSS的电解水析氧性能优于其他同类型催化剂和商用IrO2催化剂，该单原子催化剂在10 mA cm-2电流密度下的过电位仅为293 mV，且在长周期测试种保持稳定的催化性能。通过第一性原理计算，揭示了Co SAs/cBSS增强OER活性的潜在机制：单原子与碳化生物基载体的强相互作用影响了活性位点Co的电子结构，导致金属d带中心适当下移；保证了对含氧中间体强吸附的同时，降低了氧气解析能垒，最终显著提高了电催化活性。本研究利用仿生设计策略构建单原子催化剂，并通过自组装技术对载体的微纳结构和金属单原子活性位点的负载结构进行调控，采用实验和计算相结合揭示单原子催化剂结构与性能的构效关系，为高性能电解水催化剂的开发提供了有益探索。